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  Subjects -> ENGINEERING (Total: 2298 journals)
    - CHEMICAL ENGINEERING (192 journals)
    - CIVIL ENGINEERING (192 journals)
    - ELECTRICAL ENGINEERING (104 journals)
    - ENGINEERING (1209 journals)
    - ENGINEERING MECHANICS AND MATERIALS (385 journals)
    - HYDRAULIC ENGINEERING (55 journals)
    - INDUSTRIAL ENGINEERING (69 journals)
    - MECHANICAL ENGINEERING (92 journals)

CIVIL ENGINEERING (192 journals)                     

Showing 1 - 192 of 192 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: 36)
Advances in Structural Engineering     Full-text available via subscription   (Followers: 28)
Agregat     Open Access  
Ambiente Construído     Open Access   (Followers: 1)
American Journal of Civil Engineering and Architecture     Open Access   (Followers: 31)
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: 16)
Building & Management     Open Access  
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: 6)
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: 18)
Civil Engineering and Environmental Systems     Hybrid Journal   (Followers: 3)
Civil Engineering and Technology     Open Access   (Followers: 10)
Civil Engineering Dimension     Open Access   (Followers: 8)
Civil Engineering Infrastructures Journal     Open Access  
Cohesion and Structure     Full-text available via subscription   (Followers: 2)
Composite Structures     Hybrid Journal   (Followers: 268)
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: 17)
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: 7)
GISAP : Technical Sciences, Construction and Architecture     Open Access  
HBRC Journal     Open Access   (Followers: 2)
Hormigón y Acero     Full-text available via subscription  
HVAC&R Research     Hybrid Journal  
Indonesian Journal of Urban and Environmental Technology     Open Access  
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: 6)
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: 7)
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: 8)
Journal of Civil Engineering Research     Open Access   (Followers: 6)
Journal of Civil Engineering, Science and Technology     Open Access  
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: 14)
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)
Journal of Water and Environmental Nanotechnology     Open Access  
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)
npj Materials Degradation     Open Access  
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: 8)
Proceedings of the Institution of Civil Engineers - Civil Engineering     Hybrid Journal   (Followers: 12)
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: 11)
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: 5)
Steel Construction - Design and Research     Hybrid Journal   (Followers: 3)
Structural and Multidisciplinary Optimization     Hybrid Journal   (Followers: 10)
Structural Concrete     Hybrid Journal   (Followers: 11)
Structural Control and Health Monitoring     Hybrid Journal   (Followers: 9)
Structural Engineering International     Full-text available via subscription   (Followers: 12)
Structural Mechanics of Engineering Constructions and Buildings     Open Access  
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: 9)
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  [1589 journals]
  • Fatigue assessment of metallic components under uniaxial and multiaxial
           variable amplitude loading
    • Authors: A. Carpinteri; S. Vantadori, T. Łagoda, A. Karolczuk, M. Kurek, C. Ronchei
      Abstract: In the present paper, the fatigue lifetime of metallic structural components subjected to variable amplitude loading is evaluated by applying 2 different multiaxial high-cycle fatigue criteria. Such criteria, proposed by some of the present authors, are based on the critical plane approach and aim at reducing a given multiaxial stress state to an equivalent uniaxial stress condition. In particular, the procedure employed by both criteria consists of the following 3 steps: (1) definition of the critical plane; (2) counting of loading cycles; and (3) estimation of fatigue damage. Finally, the previous criteria are validated by comparing the theoretical results with experimental data related to smooth metallic specimens subjected to uniaxial and multiaxial variable amplitude loading.
      PubDate: 2018-01-19T05:13:18.225606-05:
      DOI: 10.1111/ffe.12773
       
  • Near-tip stress fields of rough and frictional cracks under mixed-mode
           loading
    • Authors: Andrea Spagnoli; Andrea Carpinteri, Michele Terzano
      Abstract: The characterisation of the stress fields in proximity of crack tips is a fundamental task in fracture mechanics, providing means for the assessment of the fracture resistance or the crack growth rate. Among several methods available for the computation of the crack-tip stress intensity factor, an extremely efficient and flexible solution strategy is obtained using the distributed dislocation technique. This method has been successfully applied to several remote loading conditions and cracked geometries and can also take into account the effect of surface friction and roughness through the inclusion of an appropriate interface model. In this paper, we make use of a non-linear algorithm, which uses dislocations distributed along the crack, to compute the crack-tip stress intensity factors under remote mixed-mode stress fields. It is shown that the algorithm can be effectively applied to different geometries, notably to cases where the mode mixity originates from geometrical features, such as in the presence of notches or re-entrant corners. In particular, the effect of dilatancy is correctly captured with the adopted method, and its consequences are discussed with regard to the onset of unstable crack propagation under monotonic loading.
      PubDate: 2018-01-19T04:10:30.585408-05:
      DOI: 10.1111/ffe.12765
       
  • Effect of initial hardness on the thermal fatigue behavior of AISI H13
           steel by experimental sand numerical investigations
    • Authors: J. Li; Y. Shi, X. Wu
      Abstract: Based on the Uddeholm thermal fatigue test, the mechanism of thermal fatigue crack initiation and propagation and the influence of initial hardness on the thermal fatigue behavior of AISI H13 steel were investigated. Furthermore, an electromagnetic-thermo-mechanical coupled finite element model was established to analyze the temperature evolution and stress accumulation in specimen during thermal cycles. The experimental results demonstrate that, after 3000 thermal cycles, the surface hardness of specimen markedly decreases, and the lath martensite structure seems to completely evolve into a mixture of ferrite and irregularly sphere-like and bar-like M23C6 and M6C carbides. According to the numerical results, the effective stress of specimen will increase slightly after every thermal cycle. It presents a distinct stress accumulation phenomenon with increasing number of thermal cycles. Especially at the corner of specimen, it is more significant. The thermal fatigue test results also prove that it is a major site where the initiation and propagation of thermal fatigue primary cracks occur. Both the numerical and experimental results suggest that specimen with initial hardness of 46HRC has the slowest stress accumulation rate, the lowest thermal fatigue damage factor, and the longest thermal fatigue life.
      PubDate: 2018-01-19T04:08:04.056898-05:
      DOI: 10.1111/ffe.12770
       
  • Fatigue reliability assessment of turbine discs under multi-source
           uncertainties
    • Authors: S.P. Zhu; Q. Liu, J. Zhou, Z.Y. Yu
      Abstract: Hot section components of aircraft engines like high pressure turbine (HPT) discs usually operate under complex loadings coupled with multi-source uncertainties. The effect of these uncertainties on structural response of HPT discs should be accounted for its fatigue life and reliability assessment. In this study, a probabilistic framework for fatigue reliability analysis is established by incorporating FE simulations with Latin hypercube sampling to quantify the influence of material variability and load variations. Particularly, variability in material response is characterized by combining the Chaboche constitutive model with Fatemi-Socie criterion. Results from fatigue reliability and sensitivity analysis of a HPT disc indicated that dispersions of basic variables ρω1σf′ must be taken into account for its fatigue reliability analysis. Moreover, the proposed framework based on the strength-damage interference provides more reasonably correlations with its field number of flights rather than the load-life interference one.
      PubDate: 2018-01-19T04:06:20.351046-05:
      DOI: 10.1111/ffe.12772
       
  • Estimation of high-temperature fracture parameters for small punch
           specimen with a surface crack
    • Authors: Kee Bong Yoon; Thanh Tuan Nguyen
      Abstract: An outline of a newly proposed methodology for evaluating creep crack growth (CCG) parameters using cracked small-punch (SP) specimens is explained. Three-dimensional finite element analyses were performed to calculate the stress intensity factor along the crack front for a surface crack formed at the centre of a SP specimen. Effects of crack ratio, (a/t); crack aspect ratio, (a/c); and thickness of the specimen, (t), on the fracture parameters were studied. It was observed that the minimum variation of K-value along the crack front can be achieved when a/c was 0.50 except the location very near the intersection of the crack and free surface. This condition is similar to the case of constant K-values along the crack front of the conventional compact tension specimen. Thus, it can be argued that the SP specimen with a surface crack is a suitable specimen geometry for CCG testing. The proposed CCG test method was found to be practically applicable for the crack geometry of 0.10 to 0.30 of a/t with constant aspect ratio of 0.50. An estimation of the K and Ct-parameter under the small scale creep condition was derived. Future work for further development of the suggested CCG testing is discussed.
      PubDate: 2018-01-12T01:41:55.274029-05:
      DOI: 10.1111/ffe.12767
       
  • Accelerated LCF-creep experimental methodology for durability life
           evaluation of turbine blade
    • Authors: D. Shi; Z. Li, X. Yang, H. Wang
      Abstract: This paper proposes an accelerated low cycle fatigue (LCF)-creep experimental methodology in laboratory to investigate the durability life of turbine blades. A typical mission profile of the turbine blade was obtained by means of rain flow counting method, considering both the actual flight condition and ground test data. Finite element analysis (FEA) was conducted to obtain the stress and temperature fields of turbine blade. A test system was constructed to conduct LCF-creep experiments of turbine blades, simulating the stress and temperature distributions of critical section properly. LCF-creep experiments of full-scale turbine blades were performed under a trapezoidal loading spectrum. Experiment results showed that the durability life of turbine blade based on numerical method was longer than that based on this experimental methodology, even an order of magnitude. Furthermore, this experimental methodology helped to extend the service life of this blade safely, and its validity was verified in actual service condition.
      PubDate: 2018-01-04T02:42:24.255114-05:
      DOI: 10.1111/ffe.12763
       
  • A material length scale–based methodology to assess static strength of
           notched additively manufactured polylactide (PLA)
    • Authors: A.A. Ahmed; L. Susmel
      Abstract: The Theory of Critical Distances (TCD) is the name that has been given to a group of design methodologies that all make use of a material length scale parameter to postprocess the local linear-elastic stress fields in the vicinity of the crack initiation locations. The aim of the present investigation is to check whether the simple linear-elastic TCD is successful in predicting static strength of notched components made of 3D-printed polylactide (PLA). PLA is a thermoplastic aliphatic polyester that is produced from renewable biodegradable resources. The accuracy and reliability of the TCD in estimating the static strength of additively manufactured (AM) PLA were assessed against a large number of experimental results generated by testing, under tensile loading as well as under bending, AM notched specimens containing different geometrical features (open notches included). The TCD was seen to be highly accurate, its systematic use resulting in estimates falling mainly within an error interval of about 20%. This result is certainly very relevant since it demonstrates that the linear-elastic TCD can be used successfully to design against static loading notched components of AM PLA by directly postprocessing the results from simple linear-elastic Finite Element (FE) models.
      PubDate: 2018-01-04T01:51:16.987655-05:
      DOI: 10.1111/ffe.12746
       
  • Issue Information
    • Pages: 247 - 248
      Abstract: No abstract is available for this article.
      PubDate: 2018-01-03T12:34:33.602615-05:
      DOI: 10.1111/ffe.12702
       
  • Fatigue assessment of refill friction stir spot weld in AA 2024-T3 similar
           joints
    • Authors: R.C. Brzostek; U. Suhuddin, J.F. Santos
      Abstract: Refill friction stir spot welding is a solid-state process technology that is suitable for welding lightweight materials in similar or dissimilar overlapped configuration. In this study, the fatigue behaviour of single overlapped spot joints of AA2024-T3 was studied. To statistically analyse the fatigue data, a 2-parameter Weibull distribution was deployed, considering several reliabilities (Re = 0.99,  Re = 0.90,  Re = 0.5,  Re = 0.10). To obtain an optimized weld parameter according to the fatigue behaviour, 2 different weld conditions were studied, taking into account the effect of the hook formation. The microstructure analyses and microhardness profiles showed great similarity in both weld conditions. However, these conditions presented distinct interfacial hook profiles, in which the interfacial hook downward represented better fatigue life and infinite fatigue life at 15% of the maximum strength load. The fracture surfaces obtained from 3 different fracture modes were investigated by using scanning electron microscopy; the crack was tracked and described according to its fracture mechanisms from its initiation until the final failures. It was observed that the crack is initiated at hook profile.
      PubDate: 2017-12-29T01:37:01.399195-05:
      DOI: 10.1111/ffe.12764
       
  • Experimental and numerical investigation of the creep behaviour of
           Ni-based superalloy GH4169 under varying loading
    • Authors: D.S. Wei; J.L. Wang, Y.R. Wang, B. Zhong
      Abstract: The high-temperature creep experiment of Ni-based superalloy GH4169 under the constant loading and varying loading conditions was conducted by using the round bar specimens. The creep time-strain curves under different loading conditions were obtained to study the high-temperature creep behaviour of GH4169 superalloy. At the same time, the longitudinal and lateral sections near the fracture of creep specimens were observed by the optical microscope, and the specimens with smaller grain corresponded to the larger creep strain rate. In view of the dispersion of the creep curves, the corresponding data processing method was put forward, and on this basis, a model that can describe the 3 stages of creep with certain physical meaning was established. The simulation results are in good agreement with the experimental results, especially the creep deformation under the varying loading condition. The predicted results of the relative time hardening model are closer to the experiment compared with time hardening and strain hardening model. The creep model is realized by the user's material subroutine code in a commercial FEM software package, which can be used as the basis of creep analysis for engineering structures.
      PubDate: 2017-12-29T01:22:44.142284-05:
      DOI: 10.1111/ffe.12759
       
  • The peak stress method to calculate residual notch stress intensity
           factors in welded joints
    • Authors: M. Colussi; P. Ferro, F. Berto, G. Meneghetti
      Abstract: According to the recent literature, the intensity of linear elastic residual stress fields near the toe region of a welded joint can be quantified by the residual notch stress intensity factors (R-NSIFs). The computational effort required to compute the R-NSIFs implies strong limitations of applicability in practice, owing to the very refined meshes needed and to the non-linear transient nature of welding process simulations, especially in 3-dimensional numerical models of large structures. The peak stress method (PSM) is a design approach that takes care of the industrial needs of rapidity and ease of use. According to the PSM, it is possible to evaluate the R-NSIFs by using the peak stress calculated at the point of singularity with coarse finite element (FE) models. While the PSM was originally calibrated by using the Ansys FE code, in the present contribution, the PSM has been calibrated to rapidly estimate the R-NSIFs in the Sysweld FE environment.
      PubDate: 2017-12-29T01:20:50.284161-05:
      DOI: 10.1111/ffe.12757
       
  • Study of the effect of heat treatment on fatigue crack growth behaviour of
           316L stainless steel produced by selective laser melting
    • Authors: O. Fergani; A. Bratli Wold, F. Berto, V. Brotan, M. Bambach
      Abstract: This study is focused on stainless steel type 316L produced by selective laser melting (SLM). This steel is very resistant to corrosion in acidic environments and has extremely good strength properties at elevated temperatures. It is also characterized by a very good weldability. These properties allow for various applications of 316L in different fields. The widespread application of 316L opens up various possibilities for production of parts using SLM. Therefore, it is important to characterize the fatigue crack growth behaviour. In the present paper, the crack growth behaviour of SLM 316L stainless steel has been investigated in its as-built condition and in different heat treatment conditions. The effect of build orientation on the crack growth path is also studied by performing fatigue crack growth tests on compact tension specimens built at 0° and 45° orientations relative to the build direction. A heat treatment above the recrystallization temperature followed by quenching is shown to create compressive residual stresses that improve the resistance against crack propagation considerably. The 45° build orientation shows crack propagation at an angle to the initial notch plane, which reveals that anisotropy still persists after heat treatment.
      PubDate: 2017-12-27T01:21:43.802205-05:
      DOI: 10.1111/ffe.12755
       
  • Analysis of the plastic zone near the crack tips under the uniaxial
           tension using ordinary state-based peridynamics
    • Authors: X.P. Zhou; Y.D. Shou, F. Berto
      Abstract: In this paper, the plastic model of ordinary state-based peridynamics is established. The size and shape of plastic zone around crack tips with the different inclination angles are simulated using ordinary state-based peridynamics. Comparison of the size and shape of plastic zone around the crack tips obtained from peridynamic solution and analytic solution is made. It is found that the relative errors between the analytical and peridynamic solution are very little. Therefore, it is feasible to predict the plastic zone around crack tips using ordinary state-based peridynamics.
      PubDate: 2017-12-27T01:16:51.806363-05:
      DOI: 10.1111/ffe.12760
       
  • Rapid evaluation of notch stress intensity factors using the peak stress
           method: Comparison of commercial finite element codes for a range of mesh
           patterns
    • Authors: G. Meneghetti; A. Campagnolo, M. Avalle, D. Castagnetti, M. Colussi, P. Corigliano, M. De Agostinis, E. Dragoni, V. Fontanari, F. Frendo, L. Goglio, G. Marannano, G. Marulo, F. Moroni, A. Pantano, A. Rebora, A. Scattina, A. Spaggiari, B. Zuccarello
      Abstract: The peak stress method (PSM) is an engineering, finite element (FE)-oriented method to rapidly estimate the notch stress intensity factors by using the singular linear elastic peak stresses calculated from coarse FE analyses. The average element size adopted to generate the mesh pattern can be chosen arbitrarily within a given range.Originally, the PSM has been calibrated under pure mode I and pure mode II loadings by means of Ansys FE software. In the present contribution, a round robin between 10 Italian universities has been carried out to calibrate the PSM with 7 different commercial FE codes. To this aim, several two-dimensional mode I and mode II problems have been analysed independently by the participants. The obtained results have been used to calibrate the PSM for given stress analysis conditions in (i) FE software, (ii) element type and element formulation, (iii) mesh pattern, and (iv) criteria for stress extrapolation and principal stress analysis at FE nodes.
      PubDate: 2017-12-27T01:11:25.27835-05:0
      DOI: 10.1111/ffe.12751
       
  • Improving the fatigue performance of airframe structures by combining
           geometrical modifications and laser heating
    • Authors: J. Lu; N. Huber, N. Kashaev
      Abstract: This study aimed to investigate an optimization method that can maximize fatigue crack retardation based on the concepts of crenellation and residual stress engineering. By applying both concepts, fatigue crack retardation was achieved by the systematic modulation of the panel thickness and by the superposition of a beneficial residual stress field induced by laser heating. To identify an optimized implementation of both concepts, an advanced finite element method-genetic algorithm coupled approach was proposed, where each possible configuration in terms of the crenellation geometry and the positioning of the laser heating lines was encoded in a binary string. The inclusion of the residual stress field induced by the laser heating in the finite element method model was achieved by the inherent strain approach. It was found that the optimized configurations showed from 38% up to 77% fatigue life extensions, which were much larger than the linear superimposition of the fatigue life improvements by each individual technique.
      PubDate: 2017-12-21T01:52:25.496881-05:
      DOI: 10.1111/ffe.12762
       
  • A unified damage factor model for ductile fracture of steels with
           different void growth and shrinkage rates
    • Authors: C. Li; Z. Zhou, Y. Zhu, L. Lu
      Abstract: Micromechanical fracture modelling is an effective method to predict ductile fracture in steel structures. This paper aims to establish a simplified and general fracture model for various loading conditions, which is convenient to calculate the instantaneous damage index. With the concept of the ductile damage factor, a unified ductile damage factor model considering the difference of rates between void growth and shrinkage has been proposed. Based on experiment results and finite element analysis, the model parameters for Q235B Chinese structural steel were calibrated. The ductile damage factor and equivalent plastic strain at fracture initiation were investigated. Comparison among the proposed model, experimental results, and the cyclic void growth model demonstrated the effectiveness and accuracy of the proposed model. A parametric study was conducted to investigate the influence of cyclic constitutive parameters on the accuracy of fracture prediction. The predicted results are acceptable while reducing those calibrated cyclic constitutive parameters by 20%.
      PubDate: 2017-12-19T23:47:27.666333-05:
      DOI: 10.1111/ffe.12758
       
  • High-temperature testing in a Charpy impact pendulum using in-situ Joule
           heating of the specimen
    • Authors: P.A. Ferreirós; P.R. Alonso, P.H. Gargano, G.H. Rubiolo
      Abstract: In this paper, an innovative approach to high-temperature testing of subsize Charpy V notched specimens is introduced. The design concept is to heat the specimen on the specimen piece supports up to the moment of impact by flowing AC electric current through it. This approach allows a very accurate centring of the specimen with respect to the anvils and the control of their temperature up to the moment of impact. The temperature profile measured by using the in-situ heating device on ferritic steel specimen over the notch temperature range of 400°C 
      PubDate: 2017-12-19T23:37:56.350294-05:
      DOI: 10.1111/ffe.12761
       
  • A prediction method for fatigue life of large moving components as
           function of scale factor: A case of motor-generator rotor
    • Authors: L. Pan; J.C. Pang, M.X. Zhang, Y.J. Xie, L.L. Nie, Y.X. Mao, M. Chen, Z.F. Zhang
      Abstract: With the development of science and technology, more and more large moving components have been used in industry, and their service lives have become an important issue. After analysis of the previous results, considering the scale factor, a prediction method for fatigue life of large moving components based on the Basquin relation was proposed at first, and then the magnet pole part of motor-generator rotor was chosen to make simulation parts with different scale factors mainly in terms of their S-N curves and fractographies. It was found that with the change of specimen scale factor, the stress concentration factor at transition arc is almost unchanged as well as the fatigue strength exponent, and the fatigue strength coefficient changes linearly. Based on those results, a life prediction method was validated, and the results show that this method is a simple but more precise relation. After fatigue fracture surface and crack growth angle observations and quantitative analyses, the fatigue damage mechanisms associated with the relation among fatigue strength exponent and coefficient and scale factors were explained well. Those studies will provide a new clue to the prediction of the service life for those large moving components.
      PubDate: 2017-12-14T05:27:49.793669-05:
      DOI: 10.1111/ffe.12754
       
  • Multiaxial low-cycle fatigue life evaluation under different
           non-proportional loading paths
    • Authors: W. L. Qu; E. N. Zhao, Q. Zhou, Y.-L. Pi
      Abstract: This paper presents analytical and experimental investigations for fatigue lives of structures under uniaxial, torsional, multiaxial proportional, and non-proportional loading conditions. It is known that the rotation of principal stress/strain axes and material additional hardening due to non-proportionality of cycle loading are the 2 main causes resulting in shorter fatigue lives compared with those under proportional loading. This paper treats these 2 causes as independent factors influencing multiaxial fatigue damage and proposes a new non-proportional influencing parameter to consider their combined effects on the fatigue lives of structures. A critical plane model for multiaxial fatigue lives prediction is also proposed by using the proposed non-proportional influencing factor to modify the Fatemi-Socie model. The comparison between experiment results and theoretical evaluation shows that the proposed model can effectively predict the fatigue life due to multiaxial non-proportional loading.
      PubDate: 2017-12-14T05:25:50.684659-05:
      DOI: 10.1111/ffe.12752
       
  • Statistical assessment of notch toughness against cleavage fracture of
           ferritic steels
    • Authors: G. Qian; W.-S. Lei, L. Peng, Z. Yu, M. Niffenegger
      Abstract: The work is an initial effort on adopting a statistical approach to correlate the fracture behavior between a notched and a fracture mechanics specimen. The random nature of cleavage fracture process determines that both the microscopic fracture stress and the macroscopic properties including fracture load, fracture toughness, and the ductile to brittle transition temperature are all stochastic parameters. This understanding leads to the proposal of statistical assessment of cleavage induced notch brittleness of ferritic steels according to a recently proposed local approach model of cleavage fracture. The temperature independence of the 2 Weibull parameters in the new model induces a master curve to correlate the fracture load at different temperatures. A normalized stress combining the 2 Weibull parameters and the yield stress is proposed as the deterministic index to measure notch toughness. This proposed index is applied to compare the notch toughness of a ferritic steel with 2 different microstructures.
      PubDate: 2017-12-12T05:51:28.284859-05:
      DOI: 10.1111/ffe.12756
       
  • Study on the fatigue life and damage accumulation of a compressor blade
           based on a modified nonlinear damage model
    • Authors: X. Fu; J. Zhang, J. Lin
      Abstract: Comparing with the fatigue test results of Ti-6Al-4V, the widely used Chaboche damage model shows considerable differences in fatigue life prediction under asymmetric load, which is potentially caused by the local plastic deformation. In this paper, a modified nonlinear damage accumulation model is developed to improve the prediction accuracy for asymmetric loading condition. To account for the elastic and plastic strains, an elastoplastic fatigue factor is developed with 2 weighting factors based on the Ramberg-Osgood equation and introduced into the stress term of the damage model. The validation of the proposed damage model is verified against the experimental data of Ti-6Al-4V titanium alloy and 2024-T3 aluminium alloy with various stress ratios. Comparing with the original Chaboche model, the predicted life of the proposed model shows much better agreement with the experimental results. Then, the proposed model is used to estimate the fatigue life of a compressor blade of aero-engine. Considering the variable amplitude loads and the loading sequence, the damage accumulation and the fatigue life of the blade are calculated, and the results indicate a longer fatigue life with slower damage accumulation rate in the early life stage.
      PubDate: 2017-12-08T04:32:05.680861-05:
      DOI: 10.1111/ffe.12753
       
  • A comparison of fatigue crack growth performance of two aerospace grade
           aluminium alloys reinforced with bonded crack retarders
    • Authors: A.K. Syed; X. Zhang, M.E. Fitzpatrick
      Abstract: To improve the fail-safety performance of integral metallic structures, the bonded crack retarder concept has been developed in recent years. This paper presents an experimental investigation on the effectiveness of bonded crack retarder on fatigue crack growth life in two aerospace aluminium alloys: 2624-T351 and 7085-T7651. M(T) specimens bonded with a pair of straps made of GLARE fibre-metal laminate were tested under the constant amplitude load. Although the bonded crack retarders increased the crack growth life in both alloys, the magnitude of life improvement is very different between them. Compared to unreinforced specimens, application of crack retarders has resulted in 90% increase in fatigue life in AA7085, but only 27% increase in AA2624. The significant difference in fatigue life improvement is owing to the material's intrinsic fatigue crack growth rate property, ie, the Paris law constants C and n. Value of n for AA7085 is 1.8 times higher than that for AA2624. Therefore, AA7085 is much more sensitive to reductions in the effective stress intensity factor brought by the crack retarders, hence better life improvement.
      PubDate: 2017-12-01T02:07:50.621161-05:
      DOI: 10.1111/ffe.12744
       
  • A modified normal strain ratio fatigue life model based on the hybrid
           approach of critical plane and crystallographic slip theory
    • Authors: L.J. Mu; X.Z. Dong, Q. Gao, C.Q. Tan
      Abstract: Based on the method combining the critical plane with crystallographic slip theory, an anisotropic low cycle fatigue life model is proposed to reflect the effects of orientation dependence and damage factors on fatigue life. According to this method, the crystallographic slip plane is adopted as the critical plane by searching for 30 potential slip systems. In addition, considering the effects of normal strain and strain ratio on fatigue failure, the normal strain ratio is introduced into model and regression model is obtained by fitting method. The proposed model is verified by estimating the low cycle fatigue lives of single crystal nickel–based superalloys PWA1480, CMSX-2 and DD3 for different loading conditions. The results show that the proposed model is applicable for more complicated loading situations and give a higher prediction accuracy compared to Sun's model.
      PubDate: 2017-12-01T01:55:47.606032-05:
      DOI: 10.1111/ffe.12749
       
  • Analysis of dynamic characteristics of through-wall cracks between 2
           boreholes in the directed fracture controlled blasting
    • Authors: Y. Wang
      Abstract: Through-wall cracks between 2 boreholes in the directed fracture controlled blasting have been always concerned by researchers. Dynamic characteristics of through-wall cracks between 2 boreholes and lateral crack propagation of boreholes in the double-borehole slot mode and the synchronous blasting of boreholes were examined using the explosive loading digital dynamic caustics experiment system. And the effects of borehole loading mode and borehole clearance on through-wall cracks between boreholes were examined using distinct lattice spring model numerical analysis, based on the experiment model. Findings show that the tips of through-wall cracks between boreholes did not meet directly but staggered, continuously propagated after meeting, and moved closer to the existing anisotropic crack direction. The velocity and acceleration of crack propagation fluctuated. KI rapidly decreased from the maximum value, then gradually increased after a repeated volatility, and began to decrease after it reached the second peak. During the process of crack propagation, KII was basically smaller than KI. The dynamic energy release rate rapidly decreased from the maximum value, reached the second peak after the volatility, and gradually decreased again. The borehole loading mode and borehole clearance had significant effects on through-wall cracks between boreholes.
      PubDate: 2017-11-27T01:47:36.08499-05:0
      DOI: 10.1111/ffe.12642
       
  • The influence of piston shape on air-spring fatigue life
    • Authors: S. Oman; M. Nagode
      Abstract: This paper presents how the piston shape of an air-spring can influence both its load-deflection characteristic and the fatigue life. Two piston shapes are considered in this study for which load-deflection characteristics and fatigue lives are compared. A method for the estimation of air-spring fatigue life is upgraded by adding the influence of the mean stress level and afterwards used together with finite element analysis to predict the fatigue life and, ultimately, the timing and global location of failure within the air-spring. These predictions are then compared with measured results and show good agreement thus proving the validity of the method used here for calculating fatigue life. Both experimental and predicted results show that the highest fatigue life can be expected if a noncylindrical, back tapered piston is used. This is only the case if the air-spring is mounted at its optimal design height as the study also shows that moving away from optimal design height does have a detrimental effect on the fatigue life of back tapered air-springs. This is due to the appearance of higher stress amplitudes in the flex member during operation. Such stress amplitudes and consequently fatigue damage can be reduced by avoiding sharp transitions in the piston design that cause additional bending of the flex member in a direction opposite to the deflection in the flex member fold.
      PubDate: 2017-11-24T01:53:04.767635-05:
      DOI: 10.1111/ffe.12748
       
  • An experimental and theoretical comparison of CCNBD and CCNSCB specimens
           for determining mode I fracture toughness of rocks
    • Authors: M.-D. Wei; F. Dai, Y. Liu, N.-W. Xu, T. Zhao
      Abstract: The cracked chevron notched Brazilian disc (CCNBD) specimen, suggested by the International Society for Rock Mechanics for testing mode I fracture toughness of rocks, usually yields rather conservative toughness measurements, and the reasons have not been fully explored. In this study, the CCNBD method is compared with the cracked chevron notched semicircular bending (CCNSCB) method in the fracture process zone (FPZ) and its influence on the fracture toughness measurement. Theoretical analysis reveals that the FPZ is longer in the CCNBD specimen than in the CCNSCB specimen using a relatively large support span, the toughness measurement using the former is affected more seriously by the presence of FPZ, and thus the CCNBD method is usually, more or less, conservative compared with the CCNSCB method. These inferences are further validated by experimental results, which indicate that the CCNBD test indeed produces much lower fracture toughness values and even the results of 75-mm radius CCNBD specimens are still lower than those of 25-mm radius CCNSCB specimens. Consequently, due to smaller FPZ, the CCNSCB specimen with a relatively large span is more likely to produce comparably accurate or representative toughness value, and it may be more suitable than the CCNBD specimen for the engineering applications that require more representative or less conservative fracture toughness.
      PubDate: 2017-11-24T01:52:12.755584-05:
      DOI: 10.1111/ffe.12747
       
  • Notched marble plates under tension: Detecting prefailure indicators and
           predicting entrance to the “critical stage”
    • Authors: S.K. Kourkoulis; E.D. Pasiou, I. Dakanali, I. Stavrakas, D. Triantis
      Abstract: The potentialities of the pressure stimulated currents technique to be used as a continuous structural health monitoring tool in applications related to stone monuments are assessed experimentally. The data gathered by this technique from experiments with notched marble plates submitted to direct tension are considered in juxtaposition to the respective ones provided by the acoustic emissions technique, a well-founded and widely used sensing tool. The time evolution of the pressure stimulated currents produced provides clearly distinguishable fingerprints of upcoming fracture well before visible cracking is macroscopically observed. These fingerprints are in good qualitative agreement with similar ones provided by the acoustic emissions, and therefore, they can be considered as safe prefailure indicators designating entrance to a “critical stage.” Thus, the use of the pressure stimulated currents technique as an alternative structural health monitoring system appears quite promising, taking also into account the low cost and the small size of the respective sensors.
      PubDate: 2017-11-24T01:50:50.608037-05:
      DOI: 10.1111/ffe.12745
       
  • 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
           energy
    • 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
           environment
    • 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
           criterion
    • 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
           composites
    • 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
       
  • 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
       
  • Energy-based fatigue failure characteristics of materials under random
           bending loading in elastic-plastic range
    • Authors: Wojciech Macek; Tadeusz Łagoda, Norbert Mucha
      Pages: 249 - 259
      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 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
      Pages: 260 - 272
      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
       
  • Effects of different indentation methods on fatigue life extension of
           cracked specimens
    • Authors: S.M.J. Razavi; M.R. Ayatollahi, A. Amouzadi, F. Berto
      Pages: 287 - 299
      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
       
  • A residual stress dependent multiaxial fatigue life model of welded
           structures
    • Authors: Z.C. Liu; C. Jiang, B.C. Li, X.G. Wang
      Pages: 300 - 313
      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
       
  • 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
      Pages: 314 - 322
      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
       
  • Molecular dynamics simulation of crack initiation and propagation in bcc
           iron under load within spur gear tooth root
    • Authors: Z. Zhao; F. Chu
      Pages: 323 - 335
      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
       
  • Ratcheting response of nylon fiber reinforced natural rubber/styrene
           butadiene rubber composites under uniaxial stress cycles: Experimental
           studies
    • Authors: A. Vahidifar; E. Esmizadeh, G. Naderi, A. Varvani-Farahani
      Pages: 348 - 357
      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
       
 
 
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