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Showing 1 - 183 of 183 Journals sorted alphabetically
ACI Structural Journal     Full-text available via subscription   (Followers: 17)
Acta Polytechnica : Journal of Advanced Engineering     Open Access   (Followers: 2)
Acta Structilia : Journal for the Physical and Development Sciences     Open Access   (Followers: 2)
Advances in Civil Engineering     Open Access   (Followers: 35)
Advances in Structural Engineering     Full-text available via subscription   (Followers: 28)
Ambiente Construído     Open Access   (Followers: 1)
American Journal of Civil Engineering and Architecture     Open Access   (Followers: 30)
Architectural Engineering     Open Access   (Followers: 4)
Archives of Civil and Mechanical Engineering     Full-text available via subscription   (Followers: 1)
Archives of Civil Engineering     Open Access   (Followers: 10)
Archives of Hydro-Engineering and Environmental Mechanics     Open Access   (Followers: 2)
ATBU Journal of Environmental Technology     Open Access   (Followers: 4)
Australian Journal of Structural Engineering     Full-text available via subscription   (Followers: 6)
Baltic Journal of Road and Bridge Engineering     Full-text available via subscription   (Followers: 1)
BER : Building and Construction : Full Survey     Full-text available via subscription   (Followers: 10)
BER : Building Contractors' Survey     Full-text available via subscription   (Followers: 4)
BER : Building Sub-Contractors' Survey     Full-text available via subscription   (Followers: 3)
BER : Survey of Business Conditions in Building and Construction : An Executive Summary     Full-text available via subscription   (Followers: 4)
Bioinspired Materials     Open Access   (Followers: 5)
Bridge Structures : Assessment, Design and Construction     Hybrid Journal   (Followers: 15)
Building and Environment     Hybrid Journal   (Followers: 15)
Building Women     Full-text available via subscription  
Built Environment Project and Asset Management     Hybrid Journal   (Followers: 15)
Bulletin of Pridniprovsk State Academy of Civil Engineering and Architecture     Open Access   (Followers: 6)
Canadian Journal of Civil Engineering     Hybrid Journal   (Followers: 12)
Case Studies in Engineering Failure Analysis     Open Access   (Followers: 8)
Case Studies in Nondestructive Testing and Evaluation     Open Access   (Followers: 11)
Case Studies in Structural Engineering     Open Access   (Followers: 9)
Cement and Concrete Composites     Hybrid Journal   (Followers: 17)
Challenge Journal of Concrete Research Letters     Open Access   (Followers: 2)
Challenge Journal of Structural Mechanics     Open Access   (Followers: 5)
Change Over Time     Full-text available via subscription   (Followers: 2)
Civil and Environmental Engineering     Open Access   (Followers: 7)
Civil And Environmental Engineering Reports     Open Access   (Followers: 5)
Civil and Environmental Research     Open Access   (Followers: 19)
Civil Engineering = Siviele Ingenieurswese     Full-text available via subscription   (Followers: 4)
Civil Engineering and Architecture     Open Access   (Followers: 17)
Civil Engineering and Environmental Systems     Hybrid Journal   (Followers: 3)
Civil Engineering and Technology     Open Access   (Followers: 10)
Civil Engineering Dimension     Open Access   (Followers: 8)
Cohesion and Structure     Full-text available via subscription   (Followers: 2)
Composite Structures     Hybrid Journal   (Followers: 265)
Computer-aided Civil and Infrastructure Engineering     Hybrid Journal   (Followers: 11)
Computers & Structures     Hybrid Journal   (Followers: 36)
Concrete Research Letters     Open Access   (Followers: 6)
Construction Economics and Building     Open Access   (Followers: 2)
Construction Engineering     Open Access   (Followers: 9)
Construction Management and Economics     Hybrid Journal   (Followers: 22)
Construction Science     Open Access   (Followers: 4)
Constructive Approximation     Hybrid Journal  
Curved and Layered Structures     Open Access   (Followers: 2)
DFI Journal : The Journal of the Deep Foundations Institute     Hybrid Journal   (Followers: 1)
Earthquake Engineering and Structural Dynamics     Hybrid Journal   (Followers: 16)
Enfoque UTE     Open Access   (Followers: 4)
Engineering Project Organization Journal     Hybrid Journal   (Followers: 7)
Engineering Structures     Hybrid Journal   (Followers: 13)
Engineering Structures and Technologies     Hybrid Journal   (Followers: 2)
Engineering, Construction and Architectural Management     Hybrid Journal   (Followers: 14)
Environmental Geotechnics     Hybrid Journal   (Followers: 5)
European Journal of Environmental and Civil Engineering     Hybrid Journal   (Followers: 9)
Fatigue & Fracture of Engineering Materials and Structures     Hybrid Journal   (Followers: 16)
Frattura ed Integrità Strutturale : Fracture and Structural Integrity     Open Access  
Frontiers in Built Environment     Open Access  
Frontiers of Structural and Civil Engineering     Hybrid Journal   (Followers: 6)
Geomaterials     Open Access   (Followers: 4)
Geosystem Engineering     Hybrid Journal   (Followers: 1)
Geotechnik     Hybrid Journal   (Followers: 3)
Géotechnique Letters     Hybrid Journal   (Followers: 6)
HBRC Journal     Open Access   (Followers: 2)
Hormigón y Acero     Full-text available via subscription  
HVAC&R Research     Hybrid Journal  
Indoor and Built Environment     Hybrid Journal   (Followers: 2)
Infrastructure Asset Management     Hybrid Journal   (Followers: 2)
Infrastructures     Open Access  
Ingenio Magno     Open Access   (Followers: 1)
Insight - Non-Destructive Testing and Condition Monitoring     Full-text available via subscription   (Followers: 22)
International Journal for Service Learning in Engineering     Open Access  
International Journal of 3-D Information Modeling     Full-text available via subscription   (Followers: 3)
International Journal of Advanced Structural Engineering     Open Access   (Followers: 16)
International Journal of Civil, Mechanical and Energy Science     Open Access   (Followers: 1)
International Journal of Concrete Structures and Materials     Open Access   (Followers: 14)
International Journal of Condition Monitoring     Full-text available via subscription   (Followers: 2)
International Journal of Construction Engineering and Management     Open Access   (Followers: 9)
International Journal of Geo-Engineering     Open Access   (Followers: 3)
International Journal of Geosynthetics and Ground Engineering     Full-text available via subscription   (Followers: 4)
International Journal of Masonry Research and Innovation     Hybrid Journal   (Followers: 1)
International Journal of Pavement Research and Technology     Open Access   (Followers: 5)
International Journal of Protective Structures     Hybrid Journal   (Followers: 6)
International Journal of Steel Structures     Hybrid Journal   (Followers: 2)
International Journal of Structural Engineering     Hybrid Journal   (Followers: 10)
International Journal of Structural Integrity     Hybrid Journal   (Followers: 2)
International Journal of Structural Stability and Dynamics     Hybrid Journal   (Followers: 7)
International Journal of Sustainable Built Environment     Open Access   (Followers: 4)
International Journal of Sustainable Construction Engineering and Technology     Open Access   (Followers: 8)
International Journal on Pavement Engineering & Asphalt Technology     Open Access   (Followers: 6)
International Journal Sustainable Construction & Design     Open Access  
Journal of Bridge Engineering     Full-text available via subscription   (Followers: 15)
Journal of Building Engineering     Hybrid Journal   (Followers: 1)
Journal of Building Materials and Structures     Open Access   (Followers: 2)
Journal of Building Performance Simulation     Hybrid Journal   (Followers: 6)
Journal of Civil Engineering and Construction Technology     Open Access   (Followers: 12)
Journal of Civil Engineering and Management     Hybrid Journal   (Followers: 7)
Journal of Civil Engineering and Science     Open Access   (Followers: 7)
Journal of Civil Engineering Research     Open Access   (Followers: 6)
Journal of Civil Society     Hybrid Journal   (Followers: 4)
Journal of Civil Structural Health Monitoring     Hybrid Journal   (Followers: 4)
Journal of Composites for Construction     Full-text available via subscription   (Followers: 13)
Journal of Computing in Civil Engineering     Full-text available via subscription   (Followers: 24)
Journal of Construction Engineering     Open Access   (Followers: 7)
Journal of Construction Engineering and Management     Full-text available via subscription   (Followers: 19)
Journal of Constructional Steel Research     Hybrid Journal   (Followers: 8)
Journal of Earth Sciences and Geotechnical Engineering     Open Access   (Followers: 4)
Journal of Fluids and Structures     Hybrid Journal   (Followers: 6)
Journal of Frontiers in Construction Engineering     Open Access   (Followers: 2)
Journal of Green Building     Full-text available via subscription   (Followers: 11)
Journal of Highway and Transportation Research and Development (English Edition)     Full-text available via subscription   (Followers: 13)
Journal of Infrastructure Systems     Full-text available via subscription   (Followers: 21)
Journal of Legal Affairs and Dispute Resolution in Engineering and Construction     Full-text available via subscription   (Followers: 5)
Journal of Marine Science and Engineering     Open Access   (Followers: 1)
Journal of Materials and Engineering Structures     Open Access   (Followers: 5)
Journal of Materials in Civil Engineering     Full-text available via subscription   (Followers: 10)
Journal of Nondestructive Evaluation     Hybrid Journal   (Followers: 11)
Journal of Performance of Constructed Facilities     Full-text available via subscription   (Followers: 4)
Journal of Pipeline Systems Engineering and Practice     Full-text available via subscription   (Followers: 7)
Journal of Rehabilitation in Civil Engineering     Open Access   (Followers: 3)
Journal of Solid Waste Technology and Management     Full-text available via subscription   (Followers: 1)
Journal of Structural Engineering     Full-text available via subscription   (Followers: 40)
Journal of Structural Fire Engineering     Full-text available via subscription   (Followers: 6)
Journal of Sustainable Architecture and Civil Engineering     Open Access   (Followers: 3)
Journal of Sustainable Design and Applied Research in Innovative Engineering of the Built Environment     Open Access   (Followers: 1)
Journal of the Civil Engineering Forum     Open Access  
Journal of the South African Institution of Civil Engineering     Open Access   (Followers: 4)
Jurnal Spektran     Open Access   (Followers: 1)
Jurnal Teknik Sipil dan Perencanaan     Open Access   (Followers: 1)
Konstruksia     Open Access  
KSCE Journal of Civil Engineering     Hybrid Journal   (Followers: 2)
Latin American Journal of Solids and Structures     Open Access   (Followers: 4)
Materiales de Construcción     Open Access  
Mathematical Modelling in Civil Engineering     Open Access   (Followers: 3)
Nondestructive Testing And Evaluation     Hybrid Journal   (Followers: 17)
Obras y Proyectos     Open Access   (Followers: 1)
Open Journal of Civil Engineering     Open Access   (Followers: 7)
Photonics and Nanostructures - Fundamentals and Applications     Hybrid Journal   (Followers: 2)
Practice Periodical on Structural Design and Construction     Full-text available via subscription   (Followers: 4)
Proceedings of the Institution of Civil Engineers - Bridge Engineering     Hybrid Journal   (Followers: 7)
Proceedings of the Institution of Civil Engineers - Civil Engineering     Hybrid Journal   (Followers: 11)
Proceedings of the Institution of Civil Engineers - Management, Procurement and Law     Hybrid Journal   (Followers: 8)
Proceedings of the Institution of Civil Engineers - Municipal Engineer     Hybrid Journal   (Followers: 3)
Proceedings of the Institution of Civil Engineers - Structures and Buildings     Hybrid Journal   (Followers: 4)
Random Structures and Algorithms     Hybrid Journal   (Followers: 5)
Research in Nondestructive Evaluation     Hybrid Journal   (Followers: 7)
Revista IBRACON de Estruturas e Materiais     Open Access   (Followers: 1)
Road Materials and Pavement Design     Hybrid Journal   (Followers: 10)
Russian Journal of Nondestructive Testing     Hybrid Journal   (Followers: 6)
Science and Engineering of Composite Materials     Hybrid Journal   (Followers: 61)
Selected Scientific Papers - Journal of Civil Engineering     Open Access   (Followers: 3)
Slovak Journal of Civil Engineering     Open Access   (Followers: 2)
Soils and foundations     Full-text available via subscription   (Followers: 4)
Steel Construction - Design and Research     Hybrid Journal   (Followers: 3)
Structural and Multidisciplinary Optimization     Hybrid Journal   (Followers: 9)
Structural Concrete     Hybrid Journal   (Followers: 11)
Structural Control and Health Monitoring     Hybrid Journal   (Followers: 9)
Structural Engineering International     Full-text available via subscription   (Followers: 11)
Structural Safety     Hybrid Journal   (Followers: 7)
Structural Survey     Hybrid Journal  
Structure     Full-text available via subscription   (Followers: 23)
Structure and Infrastructure Engineering: Maintenance, Management, Life-Cycle Design and Performance     Hybrid Journal   (Followers: 13)
Structures     Hybrid Journal   (Followers: 1)
Study of Civil Engineering and Architecture     Open Access   (Followers: 8)
Superlattices and Microstructures     Hybrid Journal   (Followers: 2)
Surface Innovations     Hybrid Journal  
Technical Report Civil and Architectural Engineering     Open Access  
Teknik     Open Access  
The IES Journal Part A: Civil & Structural Engineering     Hybrid Journal   (Followers: 6)
The Structural Design of Tall and Special Buildings     Hybrid Journal   (Followers: 6)
Thin Films and Nanostructures     Full-text available via subscription   (Followers: 2)
Thin-Walled Structures     Hybrid Journal   (Followers: 4)
Transactions of the VŠB - Technical University of Ostrava. Construction Series     Open Access   (Followers: 1)
Transportation Geotechnics     Full-text available via subscription   (Followers: 1)
Transportation Infrastructure Geotechnology     Hybrid Journal   (Followers: 8)
Underground Space     Open Access  
Water Science & Technology     Partially Free   (Followers: 25)
Water Science and Technology : Water Supply     Partially Free   (Followers: 22)


Journal Cover Fatigue & Fracture of Engineering Materials and Structures
  [SJR: 1.185]   [H-I: 60]   [16 followers]  Follow
   Hybrid Journal Hybrid journal (It can contain Open Access articles)
   ISSN (Print) 8756-758X - ISSN (Online) 1460-2695
   Published by John Wiley and Sons Homepage  [1579 journals]
  • Integranular corrosion susceptibility analysis in austeno-ferritic
           (duplex) stainless steels
    • Authors: F. Iacoviello; V. Di Cocco, E. Franzese
      Abstract: Duplex stainless steels (DSSs) are characterized by a really good generalized corrosion resistance in many environments and by really interesting mechanical properties, considering both static or quasi-static and cyclic loading conditions. DSSs are characterized by secondary phases, nitrides, and carbides precipitation phenomena, with consequent age hardening and embrittlement. These mainly occur inside ferritic grains and next to ferrite-austenite grain boundaries, with a consequent DSS susceptibility to intergranular and/or localized corrosion phenomena and the initiation and propagation of intergranular cracks. In this work, the influence of the secondary phases, nitrides, and carbides precipitation phenomena on intergranular and localized DSS corrosion resistance was investigated, considering both the lower and higher critical temperature ranges and steel chemical composition.
      PubDate: 2017-11-17T01:27:13.038961-05:
      DOI: 10.1111/ffe.12743
  • Defect sensitivity of highly deformable polymeric materials with different
           intrinsic qualities at various strain rates
    • Authors: R. Brighenti; A. Carpinteri, F. Artoni, I. Domenichelli
      Abstract: Highly deformable materials, such as elastomers and gels, can withstand very large deformation without failure, and this response is usually insensitive to the presence of macroscopic defects. These polymer-based materials, different from the traditional ones which are usually characterized by an enthalpic elasticity, show a mechanical response which is governed by the state of internal entropy of their molecular network. If fracture energy is large, the noticeable ability of soft materials to rearrange their network at the microscale, to display large deformation and to dissipate energy thanks to their viscoelasticity, allows the minimization of the local detrimental effect of existing flaws. In the present paper, the mechanical behavior of silicone-based edge cracked plates with different crack sizes and severity of the intrinsic flaws embedded in the material is examined by taking into account the time-dependent effects. Experimental and theoretical aspects are discussed to explain the defect tolerance of such materials. The detrimental effect of intrinsic voids is quantified, and the beneficial effect due to strain at low rates is analysed. The critical distance is related to the ultimate stretch value, the quality of the material, and the crack size.
      PubDate: 2017-11-17T01:26:06.913231-05:
      DOI: 10.1111/ffe.12742
  • Transient elastic-plastic-creep crack-tip stress fields under
           load-controlled loading
    • Authors: H.-S. Lee; D.-J. Kim, Y.-J. Kim, R.A. Ainsworth, P.J. Budden
      Abstract: This paper presents transient and steady-state elastic-plastic-creep crack-tip stress fields under load-controlled loading conditions for a wide range of combinations of power-law plastic and creep materials. The crack-tip stress fields are characterized in terms of 2 parameters to accommodate the crack-tip constraint effect; the C(t)- (or C*-) integral and the βQ parameter (the Q-parameter normalized with respect to the proximity parameter to plastic collapse). For practical application, the crack-tip stress fields are re-formulated explicitly in terms of time and crack-tip stress fields for elastic-plastic and steady-state creep conditions. Comparison with detailed FE results for plane strain tension and bend specimens shows that this formulation of the crack-tip stress fields agrees well with finite element results.
      PubDate: 2017-11-10T03:59:43.393373-05:
      DOI: 10.1111/ffe.12740
  • Effects of secondary orientation on fatigue crack initiation in a single
           crystal superalloy
    • Authors: Z. He; W. Qiu, Y.-N. Fan, Q.-N. Han, H.-J. Shi, X. Ma
      Abstract: Effects of secondary orientation on plastic deformation and crack initiation in a nickel-based single crystal superalloy were investigated based on in-situ scanning electron microscope fatigue tests and crystal plasticity finite element simulations. Specimens in 2 kinds of secondary crystal orientations were tested at 600°C. The results show that specimens exhibit different crack initiation modes. For specimen [001]/ [010], the crack initiated from a region of high density slip traces at an angle of 45° to the load axis and propagated along the 45° slip line. For specimen [001]/ [110], the crack initiated from a slip line that is perpendicular to the loading axis and propagated along the horizontal direction. A crystal plasticity finite element model is used to predict the cyclic plastic behavior of nickel-based single crystal superalloy. The slip line distributions, the location of the crack initiation, the crack propagating direction, and the crack deflection position are preferably predicted in comparison to the experimental results.
      PubDate: 2017-11-03T01:51:43.565554-05:
      DOI: 10.1111/ffe.12739
  • A new push-pull sample design for microscale mode 1 fracture toughness
           measurements under uniaxial tension
    • Authors: J.J. Schwiedrzik; J. Ast, L. Pethö, X. Maeder, J. Michler
      Abstract: A sample geometry is proposed for performing microscale tensile experiments based on a push-pull design. It allows measuring mode 1 fracture toughness under uniform far-field loading. Finite element simulations were performed to determine the geometry factor, which was nearly constant for Young's moduli spanning 2 orders of magnitude. It was further verified that mode 1 stress intensity factor KI is nearly constant over the width of the tension rods and an order of magnitude higher than KII and KIII. Notched samples with different a/w ratios were prepared in (100)-oriented Si by a combination of reactive ion etching and focused ion beam milling. The mode 1 fracture toughness KI,q was constant with a/w and in average 1.02 ± 0.06 MPa√m in good agreement with existing literature. The geometry was characterized and experimentally validated and may be used for fracture toughness measurements of all material classes. It is especially interesting when a uniaxial, homogeneous stress field is desired, if crack tip plasticity is important, or when positioning of the indenter is difficult.
      PubDate: 2017-11-03T01:30:41.508939-05:
      DOI: 10.1111/ffe.12741
  • Effects of build orientation and thickness of allowance on the fatigue
           behaviour of 15–5 PH stainless steel manufactured by DMLS
    • Authors: Dario Croccolo; Massimiliano De Agostinis, Stefano Fini, Giorgio Olmi, Nebojsa Bogojevic, Snezana Ciric-Kostic
      Abstract: The present study is focused on the fatigue strength of 15–5 PH stainless steel, built by Direct Metal Laser Sintering. Six-specimen sets were manufactured, mechanically and thermally treated and tested under rotating bending fatigue. The study investigates the effects of the build orientation (parallel, perpendicular, or 45° inclined with respect to the vertical stacking direction) and of allowance for machining (1 mm or 3 mm at gage). The results, processed by an ANOVA methodology, indicate that allowance for machining has a beneficial effect on the fatigue response. Removing the surface irregularities, averagely leads to a 19% enhancement of the fatigue limit. The build orientation also becomes beneficial, when the slanted samples are included in the experiment. In this case, a fatigue strength increase up to 20% can be achieved. Further developments will include the investigation of the effects of heat and surface treatments, involving also further materials in the study.
      PubDate: 2017-10-27T02:48:56.843648-05:
      DOI: 10.1111/ffe.12737
  • Is the temperature plateau of a self-heating test a robust parameter to
           investigate the fatigue limit of steels with thermography'
    • Authors: R. Finis; D. Palumbo, M.M. Silva, U. Galietti
      Abstract: A critical aspect of standard test methods for fatigue characterization is that they do not provide any information on heat dissipation in the material and involve very expensive experimental campaigns in time and costs. In recent years, thermographic methods capable of reducing testing time have been developed, also providing more information on damage occurring in the material. A commonly used approach is based on the assessment of the temperature plateau during a stepwise loading procedure. At times, however, this approach can fail if temperature stabilization is not achieved. In this regard, in this paper, a new approach based on the assessment of 3 different thermal indexes was proposed to estimate the fatigue limit of 3 stainless steels: AISI 316, 17-4PH, and ASTMA890 grade 4a, respectively, exhibiting fully austenitic, fully martensitic, and duplex biphasic microstructure. The fatigue tests were carried out by using a stepwise loading procedure, under loading ratio of 0.5.The analysis demonstrated the possibility to further reduce testing time and, consequently, the fatigue experimental campaign. Moreover, some ideas are discussed about how to justify the different thermal behaviour of a biphasic stainless steel, in total temperature variation.Moreover, a discussion of results regarding the various thermal behaviours of the investigated steels and a possible correlation with the microstructure has been proposed.
      PubDate: 2017-10-27T02:48:02.228433-05:
      DOI: 10.1111/ffe.12738
  • On Tanaka-Mura's fatigue crack nucleation model and validation
    • Authors: Xijia Wu
      Abstract: Tanaka-Mura's fatigue crack nucleation model is revisited. A dimensional problem is found in their cyclic plastic strain formulation obtained by integration of the displacement function, and hence, it is rederived based on the true strain definition. Using the corrected strain formulation, a new fatigue crack nucleation life expression is obtained, and for the first time, low cycle fatigue lives of several metals and alloys are predicted without resorting to experiments. With such theoretical life as the baseline, other factors such as surface roughness, environment, and even high-temperature damage mechanisms can be delineated in further studies.
      PubDate: 2017-10-27T02:47:35.760984-05:
      DOI: 10.1111/ffe.12736
  • The influence of partial surface shot peening on fatigue crack growth
           behaviour of a high-strength ferritic steel
    • Authors: A. Al-Turaihi; A. Mehmanparast, F. Brennan
      Abstract: The effects of partial surface shot peening on the fatigue crack growth behaviour of a ferritic steel have been experimentally investigated in this paper. Dog-bone specimens fabricated from Optim700QL were tested under tension-tension fatigue loads. Three distinct extents of partial shot peening, with respect to the crack tip and specimen symmetry line, were tested. The fatigue crack growth results from these experiments have been compared with those obtained from the same specimen geometry but with no peening. The results show that the residual stress fields formed ahead of the initial notch tip due to the partial peening process play a significant role in the fatigue crack growth behaviour of the material and effectively result in accelerated crack propagation at the midwidth of the specimens. It has been shown in this study that partial peening can lead to a fatigue crack growth rate around twice as fast as that of the unpeened specimen.
      PubDate: 2017-10-27T02:47:30.933685-05:
      DOI: 10.1111/ffe.12726
  • Rethinking fatigue crack growth: Crack growth at constant R and strain
    • Authors: K. Walker
      Abstract: This paper is the first of a series attempting to apply my 57-year experience with durability and damage tolerance of aerospace structures to answer the question; why, after 50 plus years, have we not reached agreement on the validity of current crack growth assumptions.To address this question, new concepts are introduced and interpreted in terms of strain energy.The tentative answer to the question is that when interpreted in terms these new concepts and strain energy, there are serious conceptual errors in the da/dn diagrams that make the data base very difficult to properly interpret.The materials presented raise new questions and provide possible answers to old ones.
      PubDate: 2017-10-27T02:47:03.007087-05:
      DOI: 10.1111/ffe.12729
  • Analysis of the stress intensity factor along the thickness: The concept
           of pivot node on straight crack fronts
    • Authors: J. Garcia-Manrique; D. Camas-Peña, J. Lopez-Martinez, A. Gonzalez-Herrera
      Abstract: This paper focuses on calculating and analysing the thickness and load level influence on the stress intensity factor distribution along the thickness, both individually and together. The main objective is improving the knowledge about the small region existing near the surface where the stress intensity factor results remain independent of external factor as load level or thickness. It is found that this phenomenon occurs around a pivot node within the crack front (PI) that presents advantages for the correlation of numerical and experimental studies.The work evaluates the finite element model of an Al 2024-T35 compact tension specimen with no plastic wake effect introduced. The three-dimensional behaviour near the crack front is simulated through numerical analysis with ANSYS code, and J-integral method is used to determinate the curves of K evolution along the thickness.The results are studied according to a series of parameters that characterize the curves. Conclusions are presented on the areas of influence of each factor involved.
      PubDate: 2017-10-19T02:07:58.901488-05:
      DOI: 10.1111/ffe.12734
  • Nonlinear mode III crack stress fields for materials obeying a modified
           Ramberg-Osgood law
    • Authors: M. Zappalorto; L. Maragoni
      Abstract: In this paper, an analytical study is carried out on the work-hardening, elastic-plastic stress distributions in a cracked body under antiplane shear deformation. A modified Ramberg-Osgood law is introduced to describe the material behaviour, and stress and strain fields are derived in closed form. Compared with the conventional Ramberg-Osgood formulation, the new law includes the effect of a new parameter, κ, which allows the transition from the ideally elastic behaviour (low stress regime) to the power law behaviour (large stress regime) to be controlled, thus providing 1 more degree of freedom to better fit the actual behaviour of engineering materials. A discussion is carried out on the features of stresses and strains close to and far away from the crack tip.
      PubDate: 2017-10-19T02:01:30.798047-05:
      DOI: 10.1111/ffe.12730
  • Effect of ultrasonic nanocrystal surface modification on residual stress
           and fatigue cracking in engineering alloys
    • Authors: M.K. Khan; M.E. Fitzpatrick, Q.Y. Wang, Y.S. Pyoun, A. Amanov
      Abstract: The effects of ultrasonic nanocrystal surface modification (UNSM) on residual stresses and fatigue crack initiation were investigated in various engineering alloys. It was found that higher contact force and smaller pin in UNSM produced higher compressive residual stresses at the surface and subsurface of the alloys. The compressive residual stresses were found to be higher in high yield strength alloys. A deeper compressive residual stress field was observed in alloys with higher elastic modulus and strain hardening exponent. Fatigue crack initiation was found to occur subsurface in the material where the effect of UNSM hardening was saturated. It was concluded that deeper UNSM hardening produces higher fatigue life.
      PubDate: 2017-10-19T01:45:50.096402-05:
      DOI: 10.1111/ffe.12732
  • Very high-cycle fatigue behaviour of Ti-6Al-4V alloy under corrosive
    • Authors: P.-C. Zhao; S.-X. Li, Y.-F. Jia, C.-C. Zhang, X.-C. Zhang, S.-T. Tu
      Abstract: Rotary-bending fatigue tests of Ti-6Al-4V alloy at very high-cycle regime were performed in air and 3.5% NaCl solution, respectively. The S-N curves exhibited the characteristic of horizontal asymptote (traditional fatigue limit) in laboratory air, while a lower fatigue limit was shown in 3.5% NaCl solution after around 3 × 108 cycles. The decrease of fatigue life was due to the generation of small surface defects in comparison with that in air. These defects were ascribed to the hydrogen-induced cracking and fatigue loading. The number of fatigue crack initiation sites decreases with increasing cycles. Only one crack origin site, dominated by slip mechanism, exists in each specimen at very high-cycle regime. The existing experimental S-N data of Ti-6Al-4V alloy from very high-cycle fatigue tests were also reviewed. It was shown that the fatigue life (R = −1) of Ti-6Al-4V alloy was predominantly influenced by the microstructure and not strongly sensitive to the loading mode and frequency (in the range from 52.5 Hz to 20 kHz) under air condition at room temperature.
      PubDate: 2017-10-19T01:41:39.662907-05:
      DOI: 10.1111/ffe.12735
  • Modes I/II SIF of a diametrically compressed Brazilian disc having a
           central inclined crack with frictional surfaces
    • Authors: M.M.I. Hammouda; A.S. Fayed
      Abstract: An in-house finite element code was used to analyse a diametrically compressed isotropic homogeneous Brazilian disc having a central inclined crack with frictional surfaces for the evaluation of its corresponding modes I and II stress intensity factor (SIF). One-half of the disc was successfully idealized. The coefficient of friction between the crack surfaces ranged from 0 to 1 in steps of 0.1. Relative crack length ratios of 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, and 0.7 were analysed with crack angles up to 90° in steps of 5°.The crack angle corresponding to the transition from a mixed mode I/II to a pure mode II decreases with increasing the relative crack length ratio. An increase in the relative crack length ratio leads to an increase in the range of crack angles corresponding to a partially closed crack. The crack angle at which fully closed sliding crack surfaces commences is 30° independent of the relative crack length ratio and the friction coefficient. With the same relative crack length ratio and increasing the friction coefficient, there is a corresponding decrease in the crack angle for the maximum mode II SIF. With a decrease in the relative crack length ratio or the friction coefficient, the crack angle beyond which the crack surfaces become in a fully sticking mode decreases resulting in zero mode II SIF. Generally, mode II SIF decreases with increasing the friction coefficient between the crack surfaces. Good agreement has been generally obtained with relevant results found in the literature.
      PubDate: 2017-10-19T01:10:34.443172-05:
      DOI: 10.1111/ffe.12733
  • Fatigue crack propagation for Q345qD bridge steel and its butt welds at
           low temperatures
    • Authors: X.W. Liao; Y.Q. Wang, X.D. Qian, Y.J. Shi
      Abstract: Steel bridges fabricated with Q345qD steels face critical challenges when operating in cold regions with a low ambient temperature. This study aims to investigate, via an experimental program, the low-temperature fatigue crack propagation behavior of Q345qD bridge steel base material and its butt welds. The testing program comprises a series of Charpy impact tests and fatigue crack propagation tests at the room temperature, −20°C and −60°C. The experimental results demonstrate a reduced crack propagation rate in the base material, but an increasing crack propagation rate in the butt welds, with a decreasing ambient temperature. The base material also shows enhanced fatigue crack propagation thresholds with the decreasing temperature. The ductile-to-brittle transition temperature for fatigue is lower than that for fracture in the base material while the weld metal exhibits an opposite trend. Generally, the butt welds present higher resistance against fatigue crack propagation and larger Charpy toughness values than do the base material at all tested temperatures. The Paris-law parameters measured at the room temperature for the base material leads to a conservative assessment of the crack propagation life for a welded joint under a low ambient temperature.
      PubDate: 2017-10-13T02:17:17.946427-05:
      DOI: 10.1111/ffe.12727
  • Comparison of methods to determine CTOD for SENB specimens in different
           strain hardening steels
    • Authors: W.L. Khor; P. Moore, H. Pisarski, C. Brown
      Abstract: Methods for determining crack tip opening displacement (CTOD) given in national and international standards are compared for steels with a range of strain hardening characteristics.Crack tip opening displacement measurements were made from single-edge notched bend notches using a silicone rubber casting method. The finite element model produced good agreements with predictions of these CTOD measurements. The versatility of the finite element model enabled CTOD from the original crack tip and the 45° intercept method to be compared. The 45° CTOD generally underestimates the original crack tip CTOD, and is less useful for conditions with stable crack extension.Apart from the high strain hardening material, CTOD calculated using BS 7448-1, WES 1108 (JWES), and ASTM E1820 was slightly lower than the values determined from silicone measurements and modelling, which is conservative. ASTM E1820 gave the largest underestimation of CTOD, whilst BS 7448-1 may be unsuitable for higher strain hardening steels, where the standard predicts higher CTOD than measured from the replica. JWES gives the most consistent estimation of CTOD for steels with a wide range of strain hardening values.
      PubDate: 2017-10-11T01:51:08.303296-05:
      DOI: 10.1111/ffe.12718
  • Neural approach to estimate the stress intensity factor of semi-elliptical
           cracks in rotating cracked shafts in bending
    • Authors: P. Rubio; B. Muñoz-Abella, L. Rubio
      Abstract: In the last decades, neural network approach has often been used to study various and complex engineering problems, such as optimization or prediction. In this paper, a methodology founded on artificial neural networks (ANNs) was used to calculate the stress intensity factor (SIF) in different points of the front of a semi-elliptical crack present in a rotating shaft, taking into account the shape and depth of the crack, the angle of rotation, and the location of the point in the front. In the event of rotating machines, such as shafts, it is crucial to know the SIF along the crack front because this parameter, according to the Paris Law, is related to the performance of the crack during its propagation. Previously, it was necessary to achieve the data for the ANN training, for this a quasi-static numerical model was made, which simulates a rotating cracked shaft with a semi-elliptical crack. The numerical solutions cover a wide range of crack depths and shapes, and rotation angles. The values of the SIF estimated by the ANNs were contrasted with other solutions available in the literature finding a good agreement between them. The proposed neural network methodology is an alternative that offers a very good option for the SIF estimation, because it is efficient and easy to use, does not require high computational costs, and can be used to analyse the propagation of cracks contained in rotating shafts by means of the Paris Law taking into account the nonlinear behaviour of the shaft.
      PubDate: 2017-10-06T01:55:58.01179-05:0
      DOI: 10.1111/ffe.12717
  • Fatigue characterization of T300/924 polymer composites with voids under
           tension-tension and compression-compression cyclic loading
    • Authors: H. Liu; H. Cui, W. Wen, H. Kang
      Abstract: Fibrous polymer composites exhibit excellent properties such as high specific stiffness/strength and good fatigue performance. However, as inherent defects of polymer composites, voids have been reported to have an impact on their load-bearing properties including fatigue resistance. In the interest of safety, the effect of voids on fatigue behaviours of composites should be understood and quantified. In this article, the effect of voids on the fatigue of T300/924 composites was evaluated in terms of their fatigue life, stiffness degradation, and cracks propagation under tension-tension and compression-compression loadings. The failure probability was assessed by Weibull distribution. Furthermore, crack measurement and fractographic analysis reveal that the effect of voids on the failure mechanisms of the material under various loading configurations could be different. Lastly, an analytical residual stiffness model was proposed, and a good correlation was obtained between the experimental data and the prediction results.
      PubDate: 2017-10-06T01:51:22.070151-05:
      DOI: 10.1111/ffe.12721
  • Prediction of fracture loads in PMMA U-notched specimens using the
           equivalent material concept and the theory of critical distances combined
    • Authors: S. Cicero; A.R. Torabi, V. Madrazo, P. Azizi
      Abstract: This paper provides a methodology for the prediction of fracture loads in notched materials that combines the equivalent material concept with the theory of critical distances. The latter has a linear-elastic nature and requires material calibration in those cases where the non-linear material behaviour is significant. The calibration may be performed by fracture testing on notched specimens or a combination of fracture testing and simulation. The proposed methodology sets out to define an equivalent linear-elastic material on which the theory of critical distances may be applied through its basic formulation and without any previous fracture testing and/or simulation. It has been applied to PMMA single edge notch bending specimens containing U-notches, providing accurate predictions of fracture loads.
      PubDate: 2017-10-05T02:40:53.291966-05:
      DOI: 10.1111/ffe.12728
  • A novel approach for modeling retained austenite transformations during
           rolling contact fatigue
    • Authors: D. Morris; F. Sadeghi, Y.-C. Chen, C. Wang, B. Wang
      Abstract: Retained austenite (RA) transformation in martensitic steels subjected to rolling contact fatigue (RCF) is a well-established phenomenon. In this investigation, a novel approach is developed to predict martensitic transformations of RA in steels subjected to RCF. In order to achieve the objectives, a 2-dimensional finite element model was developed to determine subsurface stresses due to rolling contact. These stresses are utilized within a continuum damage mechanics framework to determine RA transformations as a function of depth and cycles. Phase transformations were determined by comparing the required thermodynamic driving force for transformations to the energy dissipation of the microstructure. The results obtained from the combined FEA and continuum damage mechanics model were corroborated to the experimental results for RA decomposition as a function of depth and cycle for SAE 52100 steel. The results obtained are in good agreement with observed RA decomposition and DER formation as compared with the experimental results.
      PubDate: 2017-10-04T21:26:15.536711-05:
      DOI: 10.1111/ffe.12731
  • Corrosion fatigue of coated AISI 4340 high strength steel with dent damage
    • Authors: V. Sabelkin; S. Mall, H. Misak
      Abstract: Tension-compression fatigue behaviour of a high-strength steel, coated with cadmium and zinc-nickel, with dent damage was investigated under saltwater environment. Dent damage exposed coated high-strength steel substrate to saltwater environment to study hydrogen reembrittlement. Three types of specimens were tested: cadmium and zinc-nickel-coated specimens with dent damage and uncoated specimens with similar dent damage that were shot-peened in a similar way as the coated specimens. The environmentally friendly zinc-nickel-coated specimens displayed similar fatigue behaviour like hazardous cadmium-coated specimens. Scanning electron microscopy with an apparatus Quanta 450 confirmed that damage mechanisms were similar in all 3 types of specimens.
      PubDate: 2017-10-03T02:46:21.277933-05:
      DOI: 10.1111/ffe.12725
  • On the fatigue damage micromechanisms in Si-solution–strengthened
           spheroidal graphite cast iron
    • Authors: S. Sujakhu; S. Castagne, M. Sakaguchi, K.A. Kasvayee, E. Ghassemali, A.E.W. Jarfors, W. Wang
      Abstract: Graphite nodules in spheroidal graphite cast iron (SGI) play a vital role in fatigue crack initiation and propagation. Graphite nodules growth morphology can go through transitions to form degenerated graphite elements other than spheroidal graphite nodules in SGI microstructure. These graphite particles significantly influence damage micromechanisms in SGI and could act differently than spheroidal graphite nodules. Most of the damage mechanism studies on SGI focused on the role of spheroidal graphite nodules on the stable crack propagation region. The role of degenerated graphite elements on SGI damage mechanisms has not been frequently studied. In this work, fatigue crack initiation and propagation tests were conducted on EN-GJS-500-14 and observed under scanning electron microscope to understand the damage mechanisms for different graphite shapes. Crack initiation tests showed a dominant influence of degenerated graphite elements where early cracks initiated in the microstructure. Most of the spheroidal graphite nodules were unaffected at the early crack initiation stage, but few of them showed decohesion from the ferrite matrix and internal cracking. In the crack propagation region, graphite/ferrite matrix decohesion was the frequent damage mechanism observed with noticeable crack branching around graphite nodules and the crack passing through degenerated graphite elements. Finally, graphite nodules after decohesion acted like voids which grew and coalesced to form microcracks eventually causing rapid fracture of the remaining section.
      PubDate: 2017-10-03T00:16:46.195318-05:
      DOI: 10.1111/ffe.12723
  • Fatigue and ratcheting assessment of AISI H11 at 500°C using constitutive
           theory coupled with damage rule
    • Authors: L. Ma; Y. Luo, Y. Wang, W. Du, Z. Song, J. Zhang
      Abstract: Hot extrusion is one of the most commonly used manufacturing methods for metal plastic deformation, and the consumption of extrusion tooling is considerably high due to its fatigue damage under cyclic serving condition. Hot-work tool steel AISI H11 is one of these typical materials employed in extrusion tooling. This work is dedicated to calculating the stress/strain state of AISI H11 and predicting its lifetime at high temperature 500°C by building a unified constitutive model coupled with Lemaitre's damage law. Tensile tests and strain/stress reversed cycling tests have been conducted at 500°C to investigate mechanical properties and damage evolution. A unified constitutive model with Armstrong-Fredrick/Ohno-Wang kinematic hardening rule and a new proposed isotropic hardening rule is built; Lemaitre's damage law is employed as well. Parameters are determined based on tests and are temperature dependent. Finite element simulation of the deformation behaviour and fatigue lifetime is implemented into commercial software ABAQUS Standard v6.14-2 with user material subroutine to validate the proposed method. The comparison shows good agreement with experimental results, and this part of work is essential and crucial to subsequent structure analysis.
      PubDate: 2017-09-27T01:50:55.685474-05:
      DOI: 10.1111/ffe.12724
  • Experimental and numerical characterization of low cycle fatigue and creep
           fatigue behaviour of P92 steel welded joint
    • Authors: X. Wang; W. Zhang, J. Gong, Y. Jiang
      Abstract: Low cycle fatigue (LCF) and creep fatigue interaction (CFI) behaviour of P92 steel welded joint were investigated experimentally and numerically. Strain-controlled LCF tests at different strain amplitudes and CFI tests at different peak strain holding time were conducted. Evolutions of cyclic stress response, mean stress, and creep strain during cycling were described, in which the influence of strain amplitude and holding time were investigated. A specific heat treatment process was proposed to get the homogenous simulated material of fine grain region and coarse grain region in the heat affected zone. Material parameters of parent material, fine grain heat affected zone, coarse grain heat affected zone, and weld metal in the unified viscoplasticity model were then determined and validated. To predict the LCF and CFI behaviour of welded joint, 3-dimensional unified viscoplasticity model with a modified isotropic variable was compiled into ABAQUS UMAT. The comparison between the predicted and experimental result under LCF and CFI loadings showed that the simulation results were reasonable and agreed with the experimental data well.
      PubDate: 2017-09-27T01:41:30.677016-05:
      DOI: 10.1111/ffe.12722
  • In situ monitoring of particle fracture in aluminium alloys
    • Authors: B. Wisner; A. Kontsos
      Abstract: Material damage at the microscale involves both initiation and interaction effects that are typically activated long before the appearance of macroscopically observable failure events. These early appearances of damage have been broadly classified as microstructure-sensitive damage precursors or indicators. A particular class of such precursors which is of importance to aluminium and other precipitate-hardened alloys is the focus of this article. Specifically, the hard, intermetallic particles in aluminium alloys fracture before significant failure occur in the surrounding matrix. In this investigation, an effort to directly assess particle fracture activity at the time and scale that it occurs is made by coupling mechanical testing inside a scanning electron microscope with nondestructive evaluation techniques including digital image correlation as well as real-time acoustic emission monitoring. The use of a surface measurement technique along with a volumetric monitoring method at the microscope scale provides a way for coupling of fracture information at locations which are directly related to the particle activity. In this article, Al2024-T3 specimens in the as-received condition were subjected to tension as well as to tension-tension cyclic loading. The obtained in situ results demonstrate, for the first time to the best knowledge of the authors, that particle fracture occurs early in the damage process which justifies its characterization as a material damage precursor. The overall approach provides datasets capable to detect particle fracture initiation, which could become useful in future structural health monitoring applications.
      PubDate: 2017-09-22T01:02:40.498157-05:
      DOI: 10.1111/ffe.12720
  • Investigation of thickness effects on the bending singularities of a
           notched plate
    • Authors: C.-D. Chen
      Abstract: In this paper, the bending singularities of a notched plate are investigated through the finite element method. The computed singular parameters, including the singularity orders and associated corner functions, are compared with those of classical plate theory and first-order shear deformation plate theory (FSDPT); the comparisons demonstrate the inaccuracy of the boundary conditions in classical plate theory. The thickness effects are then investigated through the finite element method. The results show that although the singularity parameters computed by finite element agree with those of the FSDPT in the interior of the plate, the FSDPT is not applicable at the notch tip on the top or bottom surface because of substantial free surface effects. For a very thin plate, the inconsistence in the comparison slightly increases because of the free surface effects.
      PubDate: 2017-09-21T01:40:38.066451-05:
      DOI: 10.1111/ffe.12719
  • Estimation of P-S-N curves in very-high-cycle fatigue: Statistical
           procedure based on a general crack growth rate model
    • Authors: D.S. Paolino; A. Tridello, G. Chiandussi, M. Rossetto
      Abstract: Extensive experimental investigations show that internal defects play a key role in the very-high-cycle fatigue (VHCF) response of metallic materials and that crack growth from internal defects can take place even if the stress intensity factor associated to the initial defect is below the threshold for crack growth. By introducing a reduction term in the typical formulation of the threshold for crack growth, the authors recently proposed a general phenomenological model, which can effectively describe crack growth from internal defects in VHCF. The model is able to consider the different crack growth scenarios that may arise in VHCF and is enough general to embrace the various weakening mechanisms proposed in the literature for explaining why crack can grow below the threshold.In the present paper, the model is generalized in a statistical framework. The statistical distributions of the crack growth threshold and of the initial defect size are put into the model. The procedure for the estimation of the Probabilistic-S-N curves and of the fatigue limit distribution is illustrated and numerically applied to an experimental dataset.
      PubDate: 2017-09-18T02:05:33.484303-05:
      DOI: 10.1111/ffe.12715
  • Fatigue and damage accumulation in open cell aluminium foams
    • Authors: H. Pinto; A. Amini, Á. Peña, P. Moraga, M. Valenzuela
      Abstract: Open-cell aluminium foams are a relatively new material with interesting uses in different engineering applications. This study investigates the fatigue behaviour and damage accumulation of metal foams via a fatigue analysis (Weibull E-N model), a failure criterion (the relation among the prepeak compressive and tensile slopes, the reduction in the tensile stress, or the reduction in the compressive stress), and a mathematical approach (linear, quadratic, or exponential). As a result of combining the 3 mathematical approaches and 3 failure criteria, different approaches are obtained, analysed, and validated by using experimental data. Finally, the proposed approaches can be used to directly obtain the damage accumulation level for open-cell metal foams under fully reversed cyclic loading as a function of the number of cycles applied, the total strain amplitude, and the initial damage accumulation condition.
      PubDate: 2017-09-14T02:41:50.42654-05:0
      DOI: 10.1111/ffe.12716
  • Effect of 475°C embrittlement on the low cycle fatigue behaviour of lean
           duplex stainless steels
    • Authors: Renata Strubbia; Mohamed Sennour, Silvina Hereñú
      Abstract: Lean duplex stainless steels (LDSSs) with lower nickel and molybdenum are less susceptible to suffer spinodal decomposition than standard duplex stainless steels. It is the purpose of this work to study the effect of thermal embrittlement on the low cycle fatigue behaviour of 2 LDSSs with different Creq and Nieq. The correlation between the fatigue behaviour and the dislocation structure is attempted. Transmission electron microscopy was used to observe the dislocation microstructure. Additionally, STEM-EDS technique in conjunction with Vickers microhardness measurements was used to characterize the amplitude of the spinodal decomposition. The results show that the LDSS with lower Creq and Nieq values exhibits improved fatigue properties in the as received and aged conditions. Furthermore, it is important to emphasize that with an adequate volume fraction of phases in LDSSs, the ageing treatment leads to an increase in strength without causing a great detriment in low cycle fatigue life.
      PubDate: 2017-09-14T02:20:23.167589-05:
      DOI: 10.1111/ffe.12714
  • Investigating creep rupture and damage behaviour in notched P92 steel
           specimen using a microscale modelling approach
    • Authors: L. Zhao; N. Alang, K. Nikbin
      Abstract: Idealized random grains separated by pseudo grain boundaries were generated by using Voronoi tessellation to simulate the polycrystalline microstructure. Combined with finite element analyses, this approach made it possible to addressing crack initiation and progressive failure due to crack growth in notched bar geometries of P92 steel at high temperature. The calculations provided good predictions for creep rupture lives of notched specimen with different notch radii and external stress. Simultaneously, irregular crack growth shape, intergranular crack mode, and wedge cracks at triple grain interaction were captured in the model. The crack initiation positions were found to be influenced by notch radius and applied stress causing high stress triaxiality at the subgrain level. Furthermore, the preferential crack growth directions were changed as the notch varied from sharp to blunt.
      PubDate: 2017-09-12T02:07:30.642403-05:
      DOI: 10.1111/ffe.12713
  • A non-probabilistic reliability-based design optimization method for
           structures based on interval models
    • Authors: M.R. Wang; J.P. Fan, J. Hu
      Abstract: A non-probabilistic reliability optimization method for structures with uncertain-but-bounded variables was presented. Based on the interval model description for the uncertain-but-bounded parameters, the non-probabilistic reliability index was used to measure the structural reliability. The optimal design was formulated as a nested two-loop optimization problem. For a nonlinear function, a number of constraints that satisfied the non-probabilistic reliability index were treated as the serial system, and the feasible region of the uncertain parameters was determined by the target non-probabilistic reliability index. The inner optimization method for solving a number of non-probabilistic reliability indices was transformed into the problem of minimizing the functions within the feasible range. For a linear function, the non-probabilistic reliability optimization problem can be transformed into a deterministic optimization problem. The high computational cost of determining the non-probabilistic reliability was greatly reduced. Three numerical examples were presented to illustrate the efficiency of the proposed method.
      PubDate: 2017-09-11T02:00:40.478518-05:
      DOI: 10.1111/ffe.12698
  • Influence of filler size on the mechanical properties of cement-based
    • Authors: L. Restuccia; G.A. Ferro
      Abstract: Nano inclusion of various particles in cement-based materials has been widely investigated during the last decade, as they have the capability to enhance several properties of composites. However, obtaining nano-sized particles means a high expenditure of energy, related to their functionalization and grinding process.The main theme of this research is to evaluate the mechanical properties of cement-based composites with coarse particles of pyrolyzed hazelnut shells, already investigated at the nanoscale. In this research activity, the particle size distribution used is in the range from some micron up to 140 μm. The experimental results demonstrate that it is possible to use pyrolyzed materials with coarser particle size, guaranteeing the improvement of the mechanical properties in terms of flexural and compressive strength, but not in terms of ductility, as obtained by using smaller particles.
      PubDate: 2017-09-06T21:41:16.153948-05:
      DOI: 10.1111/ffe.12694
  • The effect of mean stress and stress biaxiality in high-cycle fatigue
    • Authors: Imade Koutiri; Daniel Bellett, Franck Morel
      Abstract: This article presents a review of selected multiaxial high-cycle fatigue criteria with an emphasis on their ability to take into account the mean stress effect and the effect of a biaxial stress state. It is shown that the predictions of the various criteria are very different for the case of biaxial tensile loads. This is in contrast to the case of combined tension-torsion loads, where the predictions are very similar. The second part of the article investigates which mechanical parameter (eg, the hydrostatic stress or the normal stress) is the most appropriate to take into account these cyclic stress states.
      PubDate: 2017-08-29T00:31:49.596956-05:
      DOI: 10.1111/ffe.12699
  • Numerical verification of stress intensity factor solution for clamped
           single edge notched tension (SENT) specimens
    • Authors: C. Bassindale; X. Wang, W.R. Tyson, S. Xu
      Abstract: Stress intensity factor solutions for clamped single edge notched tension (SENT) specimens, including a closed-form function recently proposed by Zhu along with a function by CanmetMATERIALS referenced in the British Standard BS 8571, have been assessed. Solutions for an SENT specimen with a daylight-to-width ratio of 10 have been compared with new finite element results generated in this work to assess their accuracies. The results of this study show that the polynomial proposed by Zhu differs by no more than 0.23% compared with the numerical results over the range of 0.2 ≤a/W ≤ 0.7. The CANMET function differs by no more than 0.69% over the same range.
      PubDate: 2017-08-24T02:25:36.477511-05:
      DOI: 10.1111/ffe.12700
  • Fatigue analysis of railway wheel using a multiaxial strain-based
           critical-plane index
    • Authors: M. Kiani; G.T. Fry
      Abstract: A fatigue damage model to assess the development of subsurface fatigue cracks in railway wheels is presented in this paper. A 3-dimensional finite element model (FEM) is constructed to simulate repeated cycles of contact loading between a railway wheel and a rail. The computational approach includes a hard-contact over-closure relationship and an elastoplastic material model with isotropic and kinematic hardening.Results from the simulation are used in a multiaxial critical-plane fatigue damage analysis. The employed strain-based critical-plane fatigue damage approach is based on Fatemi-Socie fatigue index that takes into account the non-proportional and out-of-phase nature of the multiaxial state of stress occurs when a railway wheel rolls on a rail. It predicts fatigue-induced micro-crack nucleation at a depth of about 3.7 mm beneath the wheel tread, as well as the crack plane growth orientation which indicates the possible failure pattern. Additionally, the influence of various factors such as contribution of normal stresses, higher wheel load, and material model have been investigated.
      PubDate: 2017-08-23T02:10:54.52398-05:0
      DOI: 10.1111/ffe.12697
  • Fatigue crack propagation under in-phase and out-of-phase biaxial loading
    • Authors: R.K. Neerukatti; S. Datta, A. Chattopadhyay, N. Iyyer, N. Phan
      Abstract: Fatigue damage characteristics of aluminium alloy under complex biaxial loads such as in-phase and out-of-phase loading conditions and different biaxiality ratios have been investigated. The effects of microscale phenomena on macroscale crack growth were studied to develop an in-depth understanding of crack nucleation and growth. Material characterization was conducted to study the microstructure variability. Scanning electron microscopy was used to identify the second phase particles, and energy dispersive X-ray spectroscopy was performed to analyse their phases and elements. Extensive quasi-static and fatigue tests were conducted on Al7075-T651 cruciform specimens over a wide range of load ratios and phases. Detailed fractography analysis was conducted to understand the crack growth behaviour observed during the fatigue tests. Significant differences in crack initiation and propagation behaviour were observed when a phase difference was applied. Primarily, crack retardation and splitting were observed because of the constantly varying mode mixity caused by phase difference. The crack growth behaviour and fatigue lives under out-of-phase loading were compared with those under in-phase loading to understand the effect of mixed-mode fracture.
      PubDate: 2017-08-22T05:36:27.057166-05:
      DOI: 10.1111/ffe.12690
  • Fatigue resistance investigation of warm-mix recycled asphalt binder,
           mastic, and fine aggregate matrix
    • Authors: Q. Li; X. Chen, G. Li, S. Zhang
      Abstract: Fatigue cracking is one of the primary distresses in warm-mix recycled asphalt pavements. This paper evaluates the fatigue resistance evolution of warm-mix recycled asphalt materials in different scales during the service period. The strain sweep test and time sweep test were performed, respectively, by dynamic shear rheometer to determine the linear viscoelastic limits and to characterize the fatigue behavior of warm-mix recycled asphalt binder, mastic, and fine aggregate matrix with different ageing levels and recycling plans. The dissipated energy method was used to define the failure criterion and to construct the fatigue model. Effects of ageing levels and recycling plans on stiffness and fatigue resistance were investigated. Performance correlations among warm-mix recycled asphalt binder, mastic, and fine aggregate matrix were developed, respectively, by the statistical method to determine the critical material scale for stiffness and fatigue resistance.
      PubDate: 2017-08-22T05:20:49.388954-05:
      DOI: 10.1111/ffe.12692
  • Nonlinear numerical study of crack initiation and propagation in a reactor
           pressure vessel under pressurized thermal shock using XFEM
    • Authors: X. Sun; G. Chai, Y. Bao
      Abstract: Under pressurized thermal shock (PTS), once crack initiation occurs in a reactor pressure vessel (RPV), the stress concentration around the crack tips may result in local instability and crack propagation. The temperature-dependent material properties are introduced into the finite element analysis model. According to the response of the transient temperature field and stress field near the crack tip region, the influence of PTS on the carrying capacity of the structure is demonstrated. Also, the process of crack initiation and propagation is simulated by using the extended finite element method (XFEM). The results show that the crack of mode I is easy to be initiated on the nozzle in the initial high temperature and high pressure working state. The effect of cladding on the RPV integrity is enhanced with the increase of crack size, and it mainly depends on the crack length. During the PTS transient, a discontinuity of stress exists near the cladding-base interface, and the cladding bears more loading than the base of the same size. As the unloading of the internal pressure, the stress does not decline due to the strong thermal shock. In the late stage of the PTS process, the internal pressure caused by repressurization poses a challenge to the strength of the structure. With the decrease of the base wall thickness, the allowable repressure value also gradually decreases. However, the increase of the base wall thickness causes the rise of thermal stress, and the allowable repressure load is not significantly improved.
      PubDate: 2017-08-10T01:42:20.416572-05:
      DOI: 10.1111/ffe.12689
  • Constitutive relationship of polyolefin fibre–reinforced concrete:
           Experimental and numerical approaches to tensile and flexural behaviour
    • Authors: A. Enfedaque; M.G. Alberti, J.C. Gálvez, M. Beltrán
      Abstract: Flexural tensile tests are usually used to evaluate the suitability of fibre-reinforced concrete (FRC) in structural applications. The constitutive relationships of FRC are derived from such tests by using several inverse analyses. Given that the structural design of FRC is based on the residual load-bearing capacities obtained under flexural tests, the approach to analyse fracture behaviour by means of uniaxial tensile tests would mean use of more direct and reliable constitutive curves compared with those obtained by indirect means. The significance of this paper lies in the characterisation of polyolefin fibre–reinforced concrete (PFRC) not only by using fracture flexural results tests but also by comparing such results with the direct tensile behaviour of the material obtained from uniaxial tests. This comparison would both extend the knowledge of the PFRC mechanical properties and broaden the reliability of structural design by comparing the behaviour of PFRC under flexural and tensile stresses. Moreover, the suitability of an iterative method proposed by the authors for obtaining the constitutive relations of PFRC from flexural tests has been checked by performing a series of numerical simulations of the tensile tests performed. The differences in the properties obtained in the flexural tests and the tensile tests have been assessed. The experimental results gathered from the tensile tests have been accurately reproduced by using a cohesive crack approach with trilinear softening functions by the iterative inverse analysis proposed.
      PubDate: 2017-08-10T01:35:52.51295-05:0
      DOI: 10.1111/ffe.12688
  • Simulation of low cycle fatigue stress-strain response in 316LN stainless
           steel using non-linear isotropic kinematic hardening model—A comparison
           of different approaches
    • Authors: Ashraf Q. J; Prasad Reddy G. V, Sandhya R, Laha K, Harmain G. A.
      Abstract: Cyclic stress-strain response of 316LN stainless steel subjected to low cycle fatigue at strain amplitude of ±0.4% and at 873 K is simulated using finite element analysis with non-linear isotropic-kinematic hardening Chaboche model. Four different approaches have been used in simulating cyclic stress response and hysteresis loops: 3 based on Chaboche model-parameters and the fourth on direct experimental data (stabilized loop and cyclic stress-strain curve [CSSC]). Among them, simulations performed with direct experimental data have not yielded expected initial cyclic response. The source of data used for evaluation of kinematic-hardening (KH) parameters determined the extent of closeness between experimental results and Chaboche-model predictions. KH parameters determined from first-cycle loop and modified-CSSC predicted the overall stress-strain response (from initial to stabilized condition) with reasonable fit, compared with other approaches. All 4 approaches though predicted stabilized response, simulations based on “KH-parameters from stabilized-cycle” accurately described stabilized response with coefficient of determination (r2) 0.995.
      PubDate: 2017-08-02T02:15:41.447973-05:
      DOI: 10.1111/ffe.12683
  • Ratcheting response of nylon fiber reinforced natural rubber/styrene
           butadiene rubber composites under uniaxial stress cycles: Experimental
    • Authors: A. Vahidifar; E. Esmizadeh, G. Naderi, A. Varvani-Farahani
      Abstract: The present study intends to study the ratcheting response of nylon fiber reinforced natural rubber (NR)-styrene butadiene rubber (SBR) composite samples under asymmetric stress cycles. Uniaxial tests conducted on composite samples have shown how influential the weight fraction of short nylon fibers on the stress-strain curves/loops under monotonic and cyclic loads is. NR/SBR composite samples with various fiber contents of 0, 10, 20, 30, and 40 per hundred rubber (phr) were tested under asymmetric stress cycles. In these tests, stress-strain hysteresis loops were progressively shifted over stress cycles resulting in progressive plastic strain accumulation. Over stress cycles, ratcheting strain progressed within the first few cycles with a relatively high rate, and as the number of cycles increased, this rate decayed resulting in a plateau in strain accumulation (shakedown). The ratcheting strain rate and magnitude resulting in shakedown were highly affected by the nylon fiber content. The experimental observations showed that this plateau (shakedown) occurred after a number of cycles in NR/SBR composite samples where the widths of hysteresis loops stayed unchanged. Samples with no fiber and that with 10 phr fiber content possessed high ratcheting rates leading samples to failure after a few stress cycles. Fracture surfaces in these samples were further analyzed through SEM investigation.
      PubDate: 2017-08-02T02:10:40.34133-05:0
      DOI: 10.1111/ffe.12684
  • A residual stress dependent multiaxial fatigue life model of welded
    • Authors: Z.C. Liu; C. Jiang, B.C. Li, X.G. Wang
      Abstract: In this paper, the influence of the residual stress on the fatigue performance of a welded structure under multiaxial loading modes is studied. First, the local stress state at weld toe is modified via introduction of the residual stress, and a new fatigue life estimation model considering the effect of the residual stress is established by modifying our recently proposed critical plane method. Second, the basic theory and procedure of the finite element simulation on the calculation of the welding residual stress are presented. Finally, a numerical simulation of an aluminum alloy flange-to-tube welding process is conducted, and the calculated residual stress is verified with X-ray diffraction measurement. Furthermore, the performance of the proposed fatigue life estimation model is verified by the experimental data obtained in the fatigue test under different loading modes. It confirms that the consideration of the residual stress is important, especially under the out-of-phase loading mode.
      PubDate: 2017-07-31T03:06:23.773517-05:
      DOI: 10.1111/ffe.12679
  • An extended finite element method-based representative model for primary
           water stress corrosion cracking of a control rod driving mechanism
           penetration nozzle
    • Authors: H. Lee; S.J. Kang, J.B. Choi, M.K. Kim
      Abstract: Primary water stress corrosion cracking incidents have been reported in nuclear reactors over the past several decades. Garud et al developed an empirical equation to express primary water stress corrosion cracking (PWSCC) initiation time by using experimental data. This strain rate damage model has been used in multiple simulation studies. Some of these studies used the extended finite element method (XFEM) to simulate the PWSCC propagation in Alloy 600. However, several studies showed that the accuracy of XFEM depends on the mesh quality. Different mesh qualities can change the heat flux of a welding procedure, leading to different weld residual stresses. We performed a parametric study on PWSCC initiation and propagation of a control rod driving mechanism by using different mesh qualities. The major variables explored here are number of elements per bead, number of circumferential elements, and number of weld beads. Finally, an XFEM-based representative model was suggested for PWSCC initiation and propagation simulation.
      PubDate: 2017-07-31T03:02:32.645588-05:
      DOI: 10.1111/ffe.12667
  • On the interaction between corrosion and fatigue which determines the
           remaining life of bridges
    • Authors: D. Peng; R. Jones, R.R.K. Singh, F. Berto, A.J. McMillan
      Abstract: This paper studies the prior effect of corrosion on fatigue on the growth of cracks that arise from natural corrosion in steel bridges. It is shown that these 2 effects need to be simultaneously analysed. If not, then the resulting life is not conservative. This paper presents a simple methodology for performing this coupled analysis.
      PubDate: 2017-07-31T03:01:32.845622-05:
      DOI: 10.1111/ffe.12680
  • Energy-based fatigue failure characteristics of materials under random
           bending loading in elastic-plastic range
    • Authors: Wojciech Macek; Tadeusz Łagoda, Norbert Mucha
      Abstract: This article presents selected aspects connected to the methods of identification of strain energy density that are used to calculate the fatigue strength of materials. The authors focus on selected methods for determination of energy-based (stress-strain) characteristics of the fatigue life of materials (Wa − Nf), including a new approach for the determination of strain energy density parameter Wa. The paper also contains description and evaluation of models for determining the stress amplitudes σa in the elastic-plastic range, for bending. The developed procedure should give new capabilities in fatigue life calculations.
      PubDate: 2017-07-31T03:00:48.687874-05:
      DOI: 10.1111/ffe.12677
  • Effects of different indentation methods on fatigue life extension of
           cracked specimens
    • Authors: S.M.J. Razavi; M.R. Ayatollahi, A. Amouzadi, F. Berto
      Abstract: In this paper, 3 different indentation methods have been investigated for crack arresting and fatigue life enhancement of cracked components. The influence of residual stresses induced by indentation on fatigue crack growth (FCG) rate was explored by experiments and numerical simulations. Fatigue tests were conducted on a group of specimens which were indented on the crack tip by various indentation load magnitudes. For another group of specimens, the double indentation and triple indentation methods were applied on the cracked specimens with the aim of obtaining proper residual stress fields that contribute to higher crack growth retardations. Both the numerical and experimental results revealed that the higher indentation loads led to larger domain of compressive residual stress around the crack tip and consequently to higher fatigue life extension. In addition, the triple indentation method resulted in more FCG retardation compared with single and double indentation methods. Furthermore, for the specimens repaired by double and triple indentation methods, indenting ahead of the crack tip led to retardation in more crack growth compared with the other horizontal positions of indentation.
      PubDate: 2017-07-27T22:21:44.001854-05:
      DOI: 10.1111/ffe.12678
  • Molecular dynamics simulation of crack initiation and propagation in bcc
           iron under load within spur gear tooth root
    • Authors: Z. Zhao; F. Chu
      Abstract: Spur gears are widely used in practice, and one of their typical failures is tooth breakage. In general, the tooth breakage occurs at tooth root, and the amount of crack growth during a meshing cycle is in atomistic scale. This work aims at identifying the mechanisms of crack initiation and propagation at tooth root by using molecular dynamics simulation. The results prove that there are phase transition regions and edge dislocations at crack tips. According to the distribution characteristic of the atomic potential, its concentration can be observed obviously by visualization software. In these concentration regions, microvoids come into being and expand gradually, which results in the subcrack initiation. Additionally, the microvoids and subcracks propagate along the high potential direction and then come together to accelerate the crack growth. Through carrying out a comparative simulation, the effects of heavy load at single meshing area on crack initiation and propagation are addressed.
      PubDate: 2017-07-27T00:21:17.223701-05:
      DOI: 10.1111/ffe.12681
  • The design of durability tests by fatigue damage spectrum approach
    • Authors: F. Cianetti; A. Alvino, A. Bolognini, M. Palmieri, C. Braccesi
      Abstract: In the present paper, a new approach to combine load conditions expressed by power spectral density functions and to synthesize them into an equivalent one was presented. This method is based on the concept of fatigue damage spectrum and on the system dynamics. It was developed to design or verify operative durability tests (i.e., tracks), able to test payloads transported by vehicles, which could be alternative to laboratory ones, defined by the norm. By analyzing the acceleration spectrum of the norm and the acceleration measurements (all expressed in terms of power spectral density functions) acquired on the designed tracks during an experimental activity conducted on a wheeled transport vehicle, it was possible to verify the goodness of the proposed approach.
      PubDate: 2017-07-27T00:20:48.209786-05:
      DOI: 10.1111/ffe.12686
  • A weight function method for mixed modes hole-edge cracks
    • Authors: W. Xu; X.R. Wu, Y. Yu, Z.H. Li
      Abstract: A weight function approach is proposed to calculate the stress intensity factor and crack opening displacement for cracks emanating from a circular hole in an infinite sheet subjected to mixed modes load. The weight function for a pure mode II hole-edge crack is given in this paper. The stress intensity factors for a mixed modes hole-edge crack are obtained by using the present mode II weight function and existing mode I Green (weight) function for a hole-edge crack. Without complex derivation, the weight functions for a single hole-edge crack and a centre crack in infinite sheets are used to study 2 unequal-length hole-edge cracks. The stress intensity factor and crack opening displacement obtained from the present weight function method are compared well with available results from literature and finite element analysis. Compared with the alternative methods, the present weight function approach is simple, accurate, efficient, and versatile in calculating the stress intensity factor and crack opening displacement.
      PubDate: 2017-07-26T00:45:57.209679-05:
      DOI: 10.1111/ffe.12674
  • Application of continuum damage mechanics to vibration fatigue life
    • Authors: Yi Li; Bing Sun, Jie Fang, Xue-Feng Liu, Tong Liang, Guo-Biao Cai
      Abstract: It is pivotal to predict the multiaxial vibration fatigue life during mechanical structural dynamics design. An algorithm of the finite element method implementation for multiaxial high cycle fatigue life evaluation is proposed, on the basis of elastic evolution model of continuum damage mechanics. By considering structural dynamic characteristics, namely, resonant frequencies and mode shapes, this algorithm includes a modal analysis and harmonic analysis, which makes this different from existing fatigue life prediction methods. A 10% decrease in the resonant frequency is regarded as the failure criterion. A critical damage value was obtained, which indicates mesocrack initiation fulfilment. To validate the effectiveness of the algorithm, auto-phase sine resonance track-and-dwell experiments were conducted on notched cantilever beams made of Ti-6Al-4V alloy. The life predictions are conservative and in good agreements with the experimental results, which are mainly distributed within a scatter band of 2. This investigation could provide technical support for structural dynamics design and the analysis of reusable spacecraft.
      PubDate: 2017-07-26T00:45:35.697518-05:
      DOI: 10.1111/ffe.12662
  • Effects of side-groove depth on creep crack-tip constraint and creep crack
           growth rate in C(T) specimens
    • Authors: J.Z. He; G.Z. Wang, S.T. Tu, F.Z. Xuan
      Abstract: The effects of side-groove depth on creep crack-tip constraint and creep crack growth (CCG) rate in C(T) specimens have been quantitatively studied. The results indicate that with increasing side-groove depth, the constraint level and CCG rate increase and constraint distribution along crack front (specimen thickness) becomes more uniform. The constraint and CCG rate of thinner specimen are more sensitive to side-groove depth. Two new creep constraint parameters (namely R* and Ac) both can quantify constraint levels of the specimens with and without side-grooves, and the quantitative correlations of CCG rate with constraint have been established. The mechanism of the side-groove depth effect on the CCG rate has also been analyzed.
      PubDate: 2017-07-26T00:40:41.564254-05:
      DOI: 10.1111/ffe.12676
  • Development of a unified creep-fatigue equation including heat treatment
    • Authors: Dan Liu; Dirk John Pons
      Abstract: BackgroundCreep and fatigue damages in metals are known to interact and then lead to aggregated damage. While models exist for fatigue, creep and creep-fatigue, no models cover all 3 load regimes. Also, a heat treatment–related parameter is not well included in most creep-fatigue models.NeedThere is a need to develop a creep-fatigue equation, which covers the full loading regime from pure fatigue to pure creep, and creep-fatigue. Also needed is inclusion of a heat treatment–related parameter.ApproachThe unified creep-fatigue equation was started from the Coffin-Manson equation and integrated with the Manson-Haferd parameter. This equation was validated on Inconel 718.OutcomesThe method of deriving the coefficients and the formula of the creep function are demonstrated, and the resulting equation shows a good ability to describe the grain-size effect and the fully integrated characteristics.OriginalityOriginal contributions of this work are the development of a new formulation to represent creep, fatigue and creep-fatigue in metals. Also the inclusion of grain size—which is a proxy for heat treatment—in the formulation of this equation and in a proposed modified Manson-Haferd parameter.
      PubDate: 2017-07-19T01:05:57.47363-05:0
      DOI: 10.1111/ffe.12670
  • A method for assessing critical plane-based multiaxial fatigue damage
    • Authors: S.H. Iftikhar; J. Albinmousa
      Abstract: Fatigue failure is a complex phenomenon. Therefore, development of a fatigue damage model that considers all associated complexities resulting from the application of different cyclic loading types, geometries, materials, and environmental conditions is a challenging task. Nevertheless, fatigue damage models such as critical plane-based models are popular because of their capability to estimate life mostly within ±2 and ±3 factors of life for smooth specimens. In this study, a method is proposed for assessing the fatigue life estimation capability of different critical plane-based models. In this method, a subroutine was developed and used to search for best estimated life regardless of critical plane assumption. Therefore, different fatigue damage models were evaluated at all possible planes to search for the best life. Smith-Watson-Topper (normal strain-based), Fatemi-Socie (shear strain-based), and Jahed-Varvani (total strain energy density-based) models are compared by using the proposed assessment method. The assessment is done on smooth specimen level by using the experimental multiaxial fatigue data of 3 alloys, namely, AZ31B and AZ61A extruded magnesium alloys and S460N structural steel alloy. Using the proposed assessment method, it was found that the examined models may not be able to reproduce the experimental lives even if they were evaluated at all physical planes.
      PubDate: 2017-07-19T01:02:29.791717-05:
      DOI: 10.1111/ffe.12675
  • An investigation of the beneficial effects of adding carbon nanotubes to
           standard injection grout
    • Authors: L. Restuccia; A. Lopez, G.A. Ferro, D. Liberatore, J.M. Tulliani
      Abstract: Mortar grouting is often used in masonry constructions to mitigate structural decay and repair damage by filling cracks and voids, resulting in an improvement in mechanical properties. This paper presents an original experimental investigation on grout with added carbon nanotubes (CNTs). The samples were prepared with different percentages of CNTs, up to 1.2 wt% with respect to the binder, and underwent three-point bending tests in crack mouth opening displacement mode and compressive tests. The results showed that very small additions (up to 0.12 wt% of CNTs) increased not only flexural and compressive strengths (+73% and 35%, respectively, in comparison with plain mortar) but also fracture energy (+80%). These results can be explained on the basis of a reduction in porosity, as evidenced by mercury intrusion porosimetry, as well as by a crack bridging mechanism and by the probable formation of nucleation sites for hydration products, as observed through scanning electron microscopy.
      PubDate: 2017-07-14T00:36:52.286845-05:
      DOI: 10.1111/ffe.12663
  • Fatigue crack growth of multiple interacting cracks: Analytical models and
           experimental validation
    • Authors: R. Galatolo; R. Lazzeri
      Abstract: This article deals with the fatigue propagation of multiple cracks in finite width holed panels, which are typical of aircraft structural components. Theoretical studies in the literature have been considered and critically analyzed. Some of them have been translated into analytical models and implemented in a computer code. To check the effectiveness of the used models, a fatigue testing campaign has been conducted on six different configurations of notches and cracks. The comparison between experimental results and those obtained from the implemented models has shown a good agreement.
      PubDate: 2017-07-13T00:43:40.699606-05:
      DOI: 10.1111/ffe.12671
  • High cycle fatigue mechanisms of aluminum self-piercing riveted joints
    • Authors: J.F.C. Moraes; H.M. Rao, J.B. Jordon, M.E. Barkey
      Abstract: A study examining the fatigue failure mechanism of self-piercing riveted (SPR) joints between aluminum alloy 6111-T4 and 5754-O is presented in this paper. In particular, the high-cycle fatigue behavior of the SPR joints in the lap-shear configuration is characterized. Experimental fatigue testing revealed that failure of SPR joints occurred because of cracks propagating through the sheet thickness at locations away from the rivet. In-depth postmortem analysis showed that significant fretting wear occurred at the location of the fatigue crack initiation. Energy dispersive X-ray of the fretting debris revealed the presence of aluminum oxide that is consistent with fretting initiated fatigue damage. High-fidelity finite element analysis of the SPR process revealed high surface contact pressure at the location of fretting-initiated fatigue determined by postmortem analysis of failed coupons. Furthermore, fatigue modeling predictions of the number of cycles to failure based on linear elastic fracture mechanics supports the conclusion that fretting-initiated fatigue occurred at regions of high surface contact pressure and not at locations of nominal high-stress concentration at the rivet.
      PubDate: 2017-07-12T00:42:12.316379-05:
      DOI: 10.1111/ffe.12648
  • In-phase and out-of-phase thermomechanical fatigue behavior of 4Cr5MoSiV1
           hot work die steel cycling from 400 °C to 700 °C
    • Authors: Pengpeng Zuo; Xiaochun Wu, Yan Zeng, Xijuan He
      Abstract: The hysteresis loops, stress and strain behavior, lifetime behavior and fracture characteristic of 4Cr5MoSiV1 hot work die steel at a wide range of mechanical strain amplitudes (from 0.5% to 1.3%) during the in-phase (IP) and out-of-phase (OP) thermomechanical fatigue (TMF) tests cycling from 400 °C to 700 °C under full reverse strain-controlled condition were investigated. Stress-mechanical strain hysteresis loops of 4Cr5MoSiV1 steel are asymmetric, and stress reduction appears at high-temperature half cycles owing to a decrease in strength with increasing temperature. 4Cr5MoSiV1 steel always exhibits continuous cyclic softening for both types of TMF tests, and the cyclic softening rate is larger in OP loading condition. OP TMF life of 4Cr5MoSiV1 steel is approximately 60% of IP TMF life at the same mechanical strain amplitude and maximum temperature. Lifetime determined and predicted in both types of TMF tests is adequately described by the Ostergren model. Fracture surfaces under IP TMF loading display the striation and tear ridge, showing quasi-cleavage characteristics, and the cracks are less but longer. However, fracture surfaces under OP TMF loading mainly display the striation and dimple characteristics, and the cracks are more and shorter.
      PubDate: 2017-07-12T00:36:27.927706-05:
      DOI: 10.1111/ffe.12669
  • Experimental and numerical investigation of cracked chevron notched
           Brazilian disc specimen for fracture toughness testing of rock
    • Authors: M.D. Wei; F. Dai, N.W. Xu, T. Zhao
      Abstract: The cracked chevron notched Brazilian disc (CCNBD) specimen has been suggested by the International Society for Rock Mechanics to quantify mode I fracture toughness (KIc) of rock, and it has also been applied to mode II fracture toughness (KIIc) testing in some research on the basis of some assumptions about the crack growth process in the specimen. However, the KIc value measured using the CCNBD specimen is usually conservative, and the assumptions made in the mode II test are rarely assessed. In this study, both laboratory experiments and numerical modeling are performed to study the modes I and II CCNBD tests, and an acoustic emission technique is used to monitor the fracture processes of the specimens. A large fracture process zone and a length of subcritical crack growth are found to be key factors affecting the KIc measurement using the CCNBD specimen. For the mode II CCNBD test, the crack growth process is actually quite different from the assumptions often made for determining the fracture toughness. The experimental and numerical results call for more attention on the realistic crack growth processes in rock fracture toughness specimens.
      PubDate: 2017-07-12T00:31:35.532672-05:
      DOI: 10.1111/ffe.12672
  • Fatigue crack propagation behavior of RC beams strengthened with CFRP
           under cyclic bending loads
    • Authors: Dongyang Li; Peiyan Huang, Xinyan Guo, Xiaohong Zheng, Jiaxiang Lin, Zhanbiao Chen
      Abstract: A fatigue crack propagation equation of reinforced concrete (RC) beams strengthened with a new type carbon fiber reinforced polymer was proposed in this paper on the basis of experimental and numerical methods. Fatigue crack propagation tests were performed to obtain the crack propagation rate of the strengthened RC beams. Digital image correlation method was used to capture the fatigue crack pattern. Finite element model of RC beam strengthened with carbon fiber reinforced polymer was established to determinate J-integral of a main crack considering material nonlinearities and degradation of material properties under cyclic loading. Paris law with a parameter of J-integral was developed on the basis of the fatigue tests and finite element analysis. This law was preliminarily verified, which can be applied for prediction of fatigue lives of the strengthened RC beams.
      PubDate: 2017-07-12T00:26:25.558179-05:
      DOI: 10.1111/ffe.12673
  • Issue Information
    • Pages: 1943 - 1944
      Abstract: No abstract is available for this article.
      PubDate: 2017-11-06T05:08:10.801623-05:
      DOI: 10.1111/ffe.12530
  • In-plane and out-of-plane constraint for single edge notched bending
           specimen and cruciform specimen under uniaxial and biaxial loading
    • Authors: X. -T. Miao; C. -Y. Zhou, X. –. H. He
      Pages: 1945 - 1959
      Abstract: Considering fracture constraint is an efficient way to describe stress–strain field and fracture toughness more accurately, so it is necessary to realise the relationship with in-plane and out-of-plane constraint for different standard specimens. In this paper, three-dimensional finite element method is applied to study the in-plane and out-of-plane constraint for both cruciform specimen and single edge notched bending specimen made from commercial pure titanium. Crack length and in-plane loading as the factors affecting in-plane constraint, and thickness as the factor affecting the out-of-plane constraint are used to study the effect on both in-plane and out-of-plane constraint in this paper. From the results, in-plane and out-of-plane constraint are both related to specimen geometries and loading styles. And there exist relationships with in-plane and out-of-plane constraint because of factors for different specimens. Depending on crack length, out-of-plane constraint increases with in-plane constraint. While depending on transverse loading, out-of-plane constraint decreases with in-plane constraint. In addition, when the in-plane constraint of a specimen is higher, in-plane constraint increases with out-of-plane constraint (thickness). When the in-plane constraint is lower, in-plane constraint almost remains unchanged with out-of-plane constraint.
      PubDate: 2017-04-12T03:11:57.650533-05:
      DOI: 10.1111/ffe.12609
  • X-ray computed tomography quantification of damage in concrete under
           compression considering irreversible mode-II microcracks
    • Authors: Z.W. Yu; S. Tan, Z. Shan, X.Q. Tian
      Pages: 1960 - 1972
      Abstract: A method for X-ray computed tomography quantification of damage in concrete under compression considering irreversible mode-II microcracks is developed. To understand damage behaviour in concrete, a micromechanical analysis of damage under biaxial compression is conducted focusing on random micro-defects in micro-cells isolated from the representative volume element. Furthermore, for stress–strain response prediction, a quantification is developed concerning the behaviours of the dominant macrocracks in multiaxial compression. Specifically, two crack types are taken into account: mode-I cracks and irreversible deformation cracks (including mode-II microcracks). Furthermore, mode-I cracks generate compression-induced tensile load (transverse) area reduction and further stiffness degradation, whereas the latter contribute to the development of irreversible strains. Additionally, by investigating the development of gradually converging dominant cracks, the procedure for quantifying damage is competently executed. In addition, distinguished from other approaches, the quantified damage can be applied directly to constitutive models to produce stress–strain response highly agrees with experimental results.
      PubDate: 2017-04-12T03:11:02.604975-05:
      DOI: 10.1111/ffe.12611
  • A critical plane-energy model for multiaxial fatigue life prediction
    • Authors: H. Wei; Y. Liu
      Pages: 1973 - 1983
      Abstract: A new critical plane-energy model is proposed in this paper for multiaxial fatigue life prediction of metals. A brief review of existing methods, especially on the critical plane-based and energy-based methods, is given first. Special focus is on the Liu–Mahadevan critical plane approach, which has been shown to work for both brittle and ductile metals. One potential drawback of the Liu–Mahadevan model is that it needs an empirical calibration parameter for non-proportional multiaxial loadings because only the strain terms are used and the out-of-phase hardening cannot be explicitly considered. An energy-based model using the Liu–Mahadevan concept is proposed with the help of the Mróz–Garud plasticity model. Thus, the empirical calibration for non-proportional loading is not needed because the out-of-phase hardening is naturally included in the stress calculation. The model predictions are compared with experimental data from open literature, and the proposed model is shown to work for both proportional and non-proportional multiaxial loadings without the empirical calibration.
      PubDate: 2017-04-27T11:22:14.228744-05:
      DOI: 10.1111/ffe.12614
  • Fracture investigation of U-notch made of tungsten–copper functionally
           graded materials by means of strain energy density
    • Authors: H. Mohammadi; H. Salavati, Y. Alizadeh, A. Abdullah, F. Berto
      Pages: 1984 - 1993
      Abstract: The averaged strain energy density over a well-defined control volume was employed to assess the fracture of U-notched specimens made of tungsten–copper functionally graded materials under prevalent mode II loading. The boundary of control volume was evaluated by using a numerical method. Power law function was employed to describe the mechanical properties (elasticity modulus, Poisson's ratio, fracture toughness and ultimate tensile stress) through the specimen width. The effect of notch tip radius and notch depth on notch stress intensity factors and mode mixity parameter χ were assessed. In addition, a comparison based on fracture load between functionally graded and homogeneous W–Cu was made. Furthermore, in this research, it was shown that the mean value of the strain energy density over the control volume can be accurately determined using coarse meshes for functionally graded materials.
      PubDate: 2017-04-12T03:11:13.428325-05:
      DOI: 10.1111/ffe.12616
  • Prediction of crack initiation plane direction in high-cycle multiaxial
           fatigue with in-phase and out-of-phase loading
    • Authors: C. Lu; J. Melendez, J. M. Martínez-Esnaola
      Pages: 1994 - 2007
      Abstract: A new method for predicting crack plane direction in high-cycle multiaxial fatigue is proposed. This method considers material properties and loading conditions. Two situations are considered: (i) in-phase loading, where the crack plane direction only depends on the loading condition and material properties have little influence on it, and (ii) out-of-phase loading, where the crack plane direction is affected by both loading conditions and material properties. The prediction accuracy is assessed by comparison with several experimental results, including different loading conditions and materials. The results show that the proposed method provides a good prediction capability for these experiments.
      PubDate: 2017-04-27T12:41:09.133264-05:
      DOI: 10.1111/ffe.12620
  • On the role of stress waves in dynamic rupture of cylindrical tubes
    • Authors: M. Mirzaei; S. Tavakoli, M. Najafi
      Pages: 2008 - 2018
      Abstract: A systematic experimental/computational study was performed to investigate the role of stress waves in ductile fracture of cylindrical tubes. The stress waves were created by high-speed moving load, which was produced by detonation of explosive cord inside two intact and two pre-flawed steel tubes. Several distinct phenomena like cyclic crack growths in Modes I and III, crack flap bulging and crack curving/branching were observed and simulated by finite element (FE) method. The FE models were composed of 3D brick elements equipped with interface cohesive elements. The analysis results showed that the crack growths in Modes I and III were governed by the detonation-induced stress waves. The crack speeds were obtained based on the increments of cyclic crack growth and the time period of the stress waves. The estimated crack speed range was 63–230 m s−1 for the axial growth, whereas the average speed for growth in Mode III was 100 m s−1.
      PubDate: 2017-04-27T12:40:48.060705-05:
      DOI: 10.1111/ffe.12621
  • Influence of turning parameters on the high-temperature fatigue
           performance of Inconel 718 superalloy
    • Authors: R. Galatolo; D. Fanteria
      Pages: 2019 - 2031
      Abstract: The safety-critical rotating parts of aircraft engines are mainly designed using experimental material data, based on standard specimens and procedures, while few data are available on the effect of manufacturing anomalies on fatigue life. In this context, the paper investigates the effects of different machining parameters on the high-temperature fatigue resistance of Inconel 718 superalloy specimens, cut from engine disk forgings, machined by turning on a vertical lathe. An unconventional specimen was designed in order to have the machining marks aligned with the fatigue loading axis, so to reproduce the hoop stresses in engine disks. For the test campaign, three machining parameters were chosen (depth of cut, cutting speed and insert wear) that typically may generate non-geometrical anomalies. A correlation has been found between the machining parameters, the residual stresses, the surface roughness, and the distorted and amorphous layer thicknesses. Correlations of such data with fatigue life are also presented and discussed.
      PubDate: 2017-05-23T01:46:01.785191-05:
      DOI: 10.1111/ffe.12623
  • Non-oscillatory and non-singular asymptotic solutions to stress fields at
           interface cracks
    • Authors: W.-S. Lei
      Pages: 2032 - 2049
      Abstract: This work concerns the complex oscillatory singularities revealed in Williams's asymptotic solutions to stress fields around arbitrary interface cracks, which are the foundation of phenomenological interface fracture mechanics. First, we highlight the fatal discrepancy between the asymptotic stress fields for cracks in a homogeneous material obtained by assigning an identical material on both regions embracing an interface crack, and the solutions directly derived from cracks in a single material. Next, following a brief introduction to Williams's formulation process, we adopt the method of repeatedly eliminating variables instead of solving the determinant equation for the coefficient matrix to reformulate the asymptotic analysis of stress fields at arbitrary interface cracks. The resultant stresses get rid of oscillatory character. Further, under two specific loading conditions, namely, remotely uniaxial tension or shear, non-oscillatory and non-singular asymptotic solutions to stress fields around interface cracks are obtained.
      PubDate: 2017-06-09T02:30:38.800731-05:
      DOI: 10.1111/ffe.12624
  • Experimental and numerical study on effect of forming process on low-cycle
           fatigue behaviour of high-strength steel
    • Authors: R. H. Talemi; S. Chhith, W. De Waele
      Pages: 2050 - 2067
      Abstract: Application of high-strength steel on different structural components is becoming more attractive. In spite of their great advantages of high yield strength, the use of these steel grades faces some important challenges as well. There are many formed steel components of different structures that are subjected to fatigue loading conditions. The main objective of the present study is to investigate the effect of pre-bending process of high-strength steel subjected to low-cycle fatigue loading conditions. For this purpose, a new test set-up has been designed to take into consideration the effect of pre-bending process when the fatigue load is applied. To detect fatigue crack initiation onset, lock-in thermography technique is used to monitor the incremental temperature variation during fatigue cycling. Furthermore, to estimate fatigue lifetime of the formed fatigue sample, continuum damage mechanics approach is applied by means of numerical modelling.
      PubDate: 2017-05-05T01:50:54.88921-05:0
      DOI: 10.1111/ffe.12625
  • Weight function, stress intensity factor and crack opening displacement
           solutions to periodic collinear edge hole cracks
    • Authors: W. Xu; X. R. Wu, Y. Yu
      Pages: 2068 - 2079
      Abstract: Periodic collinear edge hole cracks and arbitrary small cracks emanating from collinear holes, which are two typical multiple site damages occurred in the aircraft structures, are studied by using the weigh function method. An explicit closed form weight function for periodic edge hole cracks in an infinite sheet is obtained and further used to calculate the stress intensity factor and crack opening displacement for various loading cases. Compared to finite element method, the present weight function is accurate and highly efficient. The interactions of the holes and cracks on the stress intensity factor and crack opening displacement are quantitatively determined by using the present weight function. An approximate weight function method is also proposed for arbitrary small cracks emanating from multiple collinear holes. This method is very useful for calculating the stress intensity factor for arbitrary small cracks.
      PubDate: 2017-05-05T01:50:40.086991-05:
      DOI: 10.1111/ffe.12626
  • Cyclic strain rate effect on martensitic transformation and fatigue
           behaviour of an austenitic stainless steel
    • Authors: J. W. Pegues; S. Shao, N. Shamsaei, J. A. Schneider, R. D. Moser
      Pages: 2080 - 2091
      Abstract: In this study, the effect of strain rate on the cyclic behaviour of 304L stainless steel is investigated to unveil the complex interrelationship between martensitic phase transformation, secondary hardening, cyclic deformation and fatigue behaviour of this alloy. A series of uniaxial strain controlled fatigue tests with varying cyclic strain rates were conducted at zero and non-zero mean strain conditions. Secondary hardening was found to be closely related to the volume fraction of strain-induced martensite which was affected by adiabatic heating due to increasing cyclic strain rates. Tests with lower secondary hardening rates maintained lower stress amplitudes during cyclic loading which resulted in longer fatigue lives for similar strain amplitudes. Fatigue resistance of 304L stainless steel was found to be more sensitive to changes in strain rate than the presence of mean strain. The mean strain effect was minimal due to the significant mean stress relaxation in this material.
      PubDate: 2017-05-05T01:45:44.195438-05:
      DOI: 10.1111/ffe.12627
  • Failure assessment of the first stage high-pressure turbine blades in an
           aero-engine turbine
    • Authors: D. Shi; C. Wang, X. Yang, S. Li
      Pages: 2092 - 2106
      Abstract: In this paper, microscopic analysis and fatigue experiment were conducted to detect the damage degree of turbine blades after a 600 h service and determine the reliable service time. First, several service blades were cut into slices on different cross sections and microscopically examined. It is found that the γ′ phase particles are slightly coarsened and the γ′ phase parameters change with temperature and stress distribution. Then, fatigue test was conducted on service blades simulating the real working condition. The test result shows that the blades after a 600 h service would serve for 3596 h more until failure during actual flight. The ultimate fracture is mainly caused by the interaction of fatigue, creep and oxidation. Besides, the γ′ phase parameters change obviously compared with service blade without fatigue test. It indicates that the γ′ phase parameters could be used to evaluate the microdamage of service blades, which has great significance for service reliability of the turbine machinery.
      PubDate: 2017-05-26T01:50:56.42618-05:0
      DOI: 10.1111/ffe.12630
  • Constitutive and damage modelling of H11 subjected to low-cycle fatigue at
           high temperature
    • Authors: L. Ma; Y. Luo, Y. Wang, W. Du, J. Zhang
      Pages: 2107 - 2117
      Abstract: Hot-work tool steel H11 is extensively applied in extrusion industries as extrusion tools. The understanding of its mechanical properties and damage evolution as well as failure is crucial for its implementation. In this paper, a finite element (FE) model employing Chaboche unified constitutive model and ductile damage rule is proposed to simulate the mechanical responses of H11 subjected to low-cycle fatigue (LCF). Accumulated inelastic hysteresis energy is adopted to demonstrate the impact on damage initiation and evolution rules. A series of tension and LCF experiments were conducted to investigate H11's mechanical properties and its deterioration processes. In addition, to deeply understand the deformation and damage mechanism, scanning electron microscope (SEM) investigations were performed on the fracture section of gauge-length part of the specimen after failure. Furthermore, the parameters in both constitutive model and damage rule are identified based on experimental data. The comparison of the hysteresis loop of the first cycle and stable cycle with different strain amplitudes demonstrates that the Chaboche constitutive model provides high precision to predict the evolution of mechanical properties. Based on the reliable achieved constitutive model, LCF behaviour prediction with damage rule was executed successfully using FE model and gains a good agreement with the experiments. It is believed that the proposed FE method lays the foundation of structure analysis and rapid design optimization in further applications.
      PubDate: 2017-05-17T02:41:20.495927-05:
      DOI: 10.1111/ffe.12632
  • Towards improved ODS steels: A comparative high-temperature low-cycle
           fatigue study
    • Authors: A. Chauhan; M. Walter, J. Aktaa
      Pages: 2128 - 2140
      Abstract: Within the frame of this work, the mechanical behaviour of a bimodal ferritic 12Cr-ODS steel as well as of a ferritic-martensitic 9Cr-ODS steel under alternating load conditions was investigated. In general, strain-controlled low-cycle fatigue tests at 550°C and 650°C revealed similar cyclic stress response. At elevated temperatures, the two steels manifest transitional stages, ie, cyclic softening and/or hardening corresponding to the small fraction of the cyclic life, which is followed by a linear cyclic softening stage that occupies the major fraction of the cyclic life until failure. However, it is clearly seen that the presence of the nano-sized oxide particles is certainly beneficial, as the degree of cyclic softening is significantly reduced compared with non-ODS steels. Besides, it is found that both applied strain amplitude and testing temperature show a strong influence on the cyclic stress response. It is observed that the degree of linear cyclic softening in both steels increases with increasing strain amplitude and decreasing test temperature. The effect of temperature on inelastic strain and hence lifetime becomes more pronounced with decreasing applied strain amplitude. When analysing the lifetime behaviour of both ODS steels in terms of inelastic strain energy calculations, it is found that comparable inelastic strain energies lead to similar lifetimes at 550°C. At 650°C, however, the higher inelastic strain energies of 12Cr-ODS steel result in significant lower lifetimes compared with those of the 9Cr-ODS steel. The strong degradation of the cyclic properties of the 12Cr-ODS steel is obviously linked to the fact that the initial hardening response appears significantly more pronounced at 650°C than at 550°C. Finally, the obtained results depict that the 9Cr-ODS steel offers higher number of cycles to failure at 650°C, compared with other novel ODS steels described in literature.
      PubDate: 2017-06-15T00:40:32.64969-05:0
      DOI: 10.1111/ffe.12639
  • Dynamic response and microstructure evolution of the finite steel target
    • Authors: J.F. Liu; Y. Long, C. Ji, M.S. Zhong
      Pages: 2141 - 2151
      Abstract: The dynamic deformation of the finite steel target subjected to high velocity impact of copper explosively formed projectile is investigated by optical, scanning, and transmission electron microscopy. Morphology analysis of fracture surfaces indicates that the copper remainder plated to the crater wall shows extremely plastic deformation, which consists of elongated parabolic dimples, and the mild carbon steel target exhibits excellent brittle features that material fails mainly along the cleavage facets on the rear surface of target under strong impact of explosively formed projectile. In the surface of crater, the whole part of copper remainder and partial material of steel target undergoes completely dynamic recrystallization. The layer thickness of dynamic recrystallization zone, which displays an extreme plastic flow in solid state, is about 21.3 μm in steel target, and the average size of the refined grains significantly decreases to approximately 200 nm. Theoretically calculated results indicate that the temperature increase is associated with shock wave and plastic deformation of steel target and can reach 1352 K, which is 0.75Tm (where Tm is the melting temperature of steel target). The change in microhardness from the crater wall to the matrix of target is consistent with micro-deformation of grains, and maximum microhardness is observed on the interface between dynamic recrystallization and severe plastic deformation zones of steel target.
      PubDate: 2017-06-21T02:04:45.145738-05:
      DOI: 10.1111/ffe.12640
  • Extension of the modified Bai-Wierzbicki model for predicting ductile
           fracture under complex loading conditions
    • Authors: B. Wu; X. Li, Y. Di, V. Brinnel, J. Lian, S. Münstermann
      Pages: 2152 - 2168
      Abstract: The ductile fracture behaviour of metallic materials is strongly dependent on the material's stress state and loading history. This paper presents a concept of damage initiation and failure indicators and corresponding evolution laws to enhance the modified Bai-Wierzbicki model for predicting ductile damage under complex loading conditions. The proposed model considers the influence of stress triaxiality and the Lode angle parameter on both damage initiation and the subsequent damage propagation. The model parameters are calibrated for C45E + N steel using a series of mechanical tests and numerical simulations. The enhanced approach is applied to the modelling of various mechanical tests under proportional and non-proportional loading conditions and successfully predicts the ductile damage behaviour in these tests.
      PubDate: 2017-06-13T00:50:57.66685-05:0
      DOI: 10.1111/ffe.12645
  • Quantification of different effects occurring during fatigue tests on
           bituminous mixtures
    • Authors: Cong Viet Phan; Hervé Di Benedetto, Cédric Sauzéat, Josselin Dayde, Simon Pouget
      Pages: 2169 - 2182
      Abstract: Quantification of different effects (nonlinearity, heating, thixotropy, and fatigue) occurring during fatigue tests on bituminous mixtures is presented in this paper. A focus is given on the nonlinearity phenomenon.Continuous fatigue tests and a test with specific protocol (called fatigue tests to estimate biasing effects) were performed in tension/compression mode on cylindrical samples of the same material. The analysis of results reveals that reversible effects (nonlinearity, heating, and thixotropy) are important (more than 90% decrease at 100,000 cycles for a strain amplitude of 100 μm/m at 10 Hz) and cannot be ignored when interpreting classical fatigue tests. The nonlinearity effects respect the time-temperature superposition principle, and they are more pronounced at “high” temperature (at the same frequency). Direction of nonlinearity curve in the Cole-Cole axes is shown to be independent of temperature and frequency for the considered range.
      PubDate: 2017-06-13T00:45:31.976252-05:
      DOI: 10.1111/ffe.12646
  • Fracture mechanics-based progressive damage modelling of adhesively bonded
           fibre-reinforced polymer joints
    • Authors: Aida Cameselle-Molares; Roohollah Sarfaraz, Moslem Shahverdi, Thomas Keller, Anastasios P. Vassilopoulos
      Pages: 2183 - 2193
      Abstract: A quasi-static progressive damage model for prediction of the fracture behaviour and strength of adhesively bonded fibre-reinforced polymer joints is introduced in this paper. The model is based on the development of a mixed-mode failure criterion as a function of a master R-curve derived from the experimental results obtained from standard fracture mechanics joints. Consequently, the developed failure criterion is crack-length and mode-mixity dependent, and it takes into account the contribution of the fibre-bridging effect. Energy release rate values for adhesively bonded double-lap joints are obtained by using the virtual crack closure technique method in a finite element model, and the numerically obtained strain energy release rate is compared to the critical strain energy release rate given by the mixed-mode failure criterion. The entire procedure is implemented in a numerical algorithm, which was successfully used for predicting the strength and R-curve response of adhesively bonded double-lap structural joints made of pultruded glass fibre-reinforced polymers and epoxy adhesives.
      PubDate: 2017-06-13T00:45:51.016737-05:
      DOI: 10.1111/ffe.12647
  • Influence of strain range on fatigue life reduction of stainless steel in
           PWR primary water
    • Authors: Masayuki Kamaya
      Pages: 2194 - 2203
      Abstract: The environmental effect in the pressurized water reactor (PWR) water was investigated for various applied strain range using a type 316 stainless steel. The tests were conducted using cylindrical hollow specimens at 325°C. It was shown that the ratio of the fatigue life in the PWR water environment to that in air was about 0.3 to 0.4 regardless of the strain range when the applied strain ranges were 0.8% or more. Crack growth rates identified from spacing of striations observed on fractured surfaces were used to demonstrate that the fatigue life reduction in the PWR water environment could be attributed to the crack growth acceleration. The fractured surface observations revealed that crack initiation was enhanced by the PWR water environment. On the other hand, the reduction in the fatigue life was not significant when the strain ranges were 0.5% and 0.44%, and the specimens did not fail when the strain ranges were 0.38% or less. It was deduced that the crack initiation was not enhanced for the relatively small strain range, and the crack growth was not accelerated. Since the fatigue limit of the test material was 0.4% in the strain range in air, it was concluded that the fatigue limit was not reduced in the PWR water environment.
      PubDate: 2017-06-13T00:40:31.519368-05:
      DOI: 10.1111/ffe.12650
  • Corrigendum
    • Pages: 2204 - 2204
      PubDate: 2017-04-04T23:30:24.648284-05:
      DOI: 10.1111/ffe.12593
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