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  Subjects -> ENGINEERING (Total: 2358 journals)
    - CHEMICAL ENGINEERING (201 journals)
    - CIVIL ENGINEERING (192 journals)
    - ELECTRICAL ENGINEERING (107 journals)
    - ENGINEERING (1240 journals)
    - ENGINEERING MECHANICS AND MATERIALS (394 journals)
    - HYDRAULIC ENGINEERING (56 journals)
    - INDUSTRIAL ENGINEERING (72 journals)
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CIVIL ENGINEERING (192 journals)                     

Showing 1 - 194 of 194 Journals sorted alphabetically
ACI Structural Journal     Full-text available via subscription   (Followers: 20)
Acta Polytechnica : Journal of Advanced Engineering     Open Access   (Followers: 3)
Acta Structilia : Journal for the Physical and Development Sciences     Open Access   (Followers: 2)
Advances in Civil Engineering     Open Access   (Followers: 37)
Advances in Structural Engineering     Full-text available via subscription   (Followers: 31)
Agregat     Open Access   (Followers: 1)
Ambiente Construído     Open Access   (Followers: 1)
American Journal of Civil Engineering and Architecture     Open Access   (Followers: 33)
Architectural Engineering     Open Access   (Followers: 5)
Archives of Civil and Mechanical Engineering     Full-text available via subscription   (Followers: 2)
Archives of Civil Engineering     Open Access   (Followers: 12)
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: 9)
BER : Building Contractors' Survey     Full-text available via subscription   (Followers: 2)
BER : Building Sub-Contractors' Survey     Full-text available via subscription   (Followers: 2)
BER : Survey of Business Conditions in Building and Construction : An Executive Summary     Full-text available via subscription   (Followers: 3)
Bioinspired Materials     Open Access   (Followers: 5)
Bridge Structures : Assessment, Design and Construction     Hybrid Journal   (Followers: 14)
Building & Management     Open Access   (Followers: 1)
Building and Environment     Hybrid Journal   (Followers: 15)
Building Women     Full-text available via subscription  
Built Environment Project and Asset Management     Hybrid Journal   (Followers: 14)
Bulletin of Pridniprovsk State Academy of Civil Engineering and Architecture     Open Access   (Followers: 6)
Canadian Journal of Civil Engineering     Hybrid Journal   (Followers: 13)
Case Studies in Engineering Failure Analysis     Open Access   (Followers: 6)
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: 19)
Challenge Journal of Concrete Research Letters     Open Access   (Followers: 3)
Challenge Journal of Structural Mechanics     Open Access   (Followers: 6)
Change Over Time     Full-text available via subscription   (Followers: 2)
Civil and Environmental Engineering     Open Access   (Followers: 8)
Civil And Environmental Engineering Reports     Open Access   (Followers: 7)
Civil and Environmental Research     Open Access   (Followers: 17)
Civil Engineering = Siviele Ingenieurswese     Full-text available via subscription   (Followers: 4)
Civil Engineering and Architecture     Open Access   (Followers: 21)
Civil Engineering and Environmental Systems     Hybrid Journal   (Followers: 3)
Civil Engineering and Technology     Open Access   (Followers: 11)
Civil Engineering Dimension     Open Access   (Followers: 10)
Civil Engineering Infrastructures Journal     Open Access   (Followers: 1)
Cohesion and Structure     Full-text available via subscription   (Followers: 2)
Composite Structures     Hybrid Journal   (Followers: 272)
Computer-aided Civil and Infrastructure Engineering     Hybrid Journal   (Followers: 11)
Computers & Structures     Hybrid Journal   (Followers: 38)
Concrete Research Letters     Open Access   (Followers: 7)
Construction Economics and Building     Open Access   (Followers: 4)
Construction Engineering     Open Access   (Followers: 11)
Construction Management and Economics     Hybrid Journal   (Followers: 21)
Construction Science     Open Access   (Followers: 5)
Constructive Approximation     Hybrid Journal  
Curved and Layered Structures     Open Access   (Followers: 3)
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: 10)
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: 17)
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: 3)
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: 29)
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: 17)
International Journal of Civil, Mechanical and Energy Science     Open Access   (Followers: 1)
International Journal of Concrete Structures and Materials     Open Access   (Followers: 15)
International Journal of Condition Monitoring     Full-text available via subscription   (Followers: 2)
International Journal of Construction Engineering and Management     Open Access   (Followers: 10)
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: 8)
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: 5)
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   (Followers: 1)
Journal of Bridge Engineering     Full-text available via subscription   (Followers: 14)
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: 7)
Journal of Civil Engineering and Construction Technology     Open Access   (Followers: 14)
Journal of Civil Engineering and Management     Hybrid Journal   (Followers: 7)
Journal of Civil Engineering and Science     Open Access   (Followers: 9)
Journal of Civil Engineering Research     Open Access   (Followers: 7)
Journal of Civil Engineering, Science and Technology     Open Access   (Followers: 1)
Journal of Civil Society     Hybrid Journal   (Followers: 4)
Journal of Civil Structural Health Monitoring     Hybrid Journal   (Followers: 4)
Journal of Composites     Open Access   (Followers: 80)
Journal of Composites for Construction     Full-text available via subscription   (Followers: 13)
Journal of Computing in Civil Engineering     Full-text available via subscription   (Followers: 23)
Journal of Construction Engineering     Open Access   (Followers: 8)
Journal of Construction Engineering and Management     Full-text available via subscription   (Followers: 18)
Journal of Constructional Steel Research     Hybrid Journal   (Followers: 6)
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: 10)
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: 19)
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: 7)
Journal of Nondestructive Evaluation     Hybrid Journal   (Followers: 9)
Journal of Performance of Constructed Facilities     Full-text available via subscription   (Followers: 3)
Journal of Pipeline Systems Engineering and Practice     Full-text available via subscription   (Followers: 6)
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: 36)
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: 2)
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   (Followers: 1)
Mathematical Modelling in Civil Engineering     Open Access   (Followers: 4)
Nondestructive Testing And Evaluation     Hybrid Journal   (Followers: 15)
npj Materials Degradation     Open Access  
Obras y Proyectos     Open Access   (Followers: 1)
Open Journal of Civil Engineering     Open Access   (Followers: 9)
Photonics and Nanostructures - Fundamentals and Applications     Hybrid Journal   (Followers: 3)
Practice Periodical on Structural Design and Construction     Full-text available via subscription   (Followers: 3)
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: 13)
Proceedings of the Institution of Civil Engineers - Management, Procurement and Law     Hybrid Journal   (Followers: 9)
Proceedings of the Institution of Civil Engineers - Municipal Engineer     Hybrid Journal   (Followers: 2)
Proceedings of the Institution of Civil Engineers - Structures and Buildings     Hybrid Journal   (Followers: 3)
Promet : Traffic &Transportation     Open Access  
Random Structures and Algorithms     Hybrid Journal   (Followers: 5)
Research in Nondestructive Evaluation     Hybrid Journal   (Followers: 6)
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: 5)
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: 4)
Structural and Multidisciplinary Optimization     Hybrid Journal   (Followers: 10)
Structural Concrete     Hybrid Journal   (Followers: 11)
Structural Control and Health Monitoring     Hybrid Journal   (Followers: 8)
Structural Engineering International     Full-text available via subscription   (Followers: 11)
Structural Mechanics of Engineering Constructions and Buildings     Open Access   (Followers: 1)
Structural Safety     Hybrid Journal   (Followers: 6)
Structural Survey     Hybrid Journal  
Structure     Full-text available via subscription   (Followers: 24)
Structure and Infrastructure Engineering: Maintenance, Management, Life-Cycle Design and Performance     Hybrid Journal   (Followers: 12)
Structures     Hybrid Journal   (Followers: 1)
Study of Civil Engineering and Architecture     Open Access   (Followers: 10)
Superlattices and Microstructures     Hybrid Journal   (Followers: 2)
Surface Innovations     Hybrid Journal  
Technical Report Civil and Architectural Engineering     Open Access   (Followers: 1)
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: 5)
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 Composite Structures
  [SJR: 2.408]   [H-I: 92]   [272 followers]  Follow
    
   Hybrid Journal Hybrid journal (It can contain Open Access articles)
   ISSN (Print) 0263-8223
   Published by Elsevier Homepage  [3175 journals]
  • Vibration analysis for coupled composite laminated axis-symmetric
           doubly-curved revolution shell structures by unified Jacobi-Ritz method
    • Authors: Kwangnam Choe; Jinyuan Tang; Cijun shui; Ailun Wang; Qingshan Wang
      Abstract: Publication date: 15 June 2018
      Source:Composite Structures, Volume 194
      Author(s): Kwangnam Choe, Qingshan Wang, Jinyuan Tang, Cijun shui
      In this paper, a unified Jacobi-Ritz method is presented and implemented to study the free vibration analysis of coupled composite laminated axis-symmetric doubly-curved revolution shell structures with general boundary conditions in the framework of the first-order shear deformation theory. The substructure of coupled structures mainly contains the laminated elliptical, hyperbolical, paraboloidal and cylindrical shells. In the theoretical analysis model, the multi-segment partitioning strategy is adopted. The displacement functions of each shell segment are uniformly expanded in the form of a double mixed series in which Jacobi polynomials are along the meridional direction and the standard Fourier series is along the circumferential direction, regardless of the shell components and the boundary conditions. The vibration results including frequency parameters and mode shapes of coupled composite laminated axis-symmetric doubly-curved revolution shell structures are easily obtained by means of the Ritz method. The major advantages of the present solutions for coupled structure are to eliminate the need of changing the displacement or the equations of motion and to improve the efficiency of modeling. The accuracy and reliability of the proposed method are verified with the FEM and literature results, and various numerical examples are presented for the free vibration of the various coupled structures of composite laminated axis-symmetric shell, and these results can be used as reference data.

      PubDate: 2018-04-15T09:22:00Z
      DOI: 10.1016/j.compstruct.2018.04.035
      Issue No: Vol. 194 (2018)
       
  • Modular assembly of water-retaining walls using GFRP hollow profiles:
           Components and connection performance
    • Authors: Wahid Ferdous; Yu Bai; Ahmed D. Almutairi; Sindu Satasivam; Juri Jeske
      Pages: 1 - 11
      Abstract: Publication date: 15 June 2018
      Source:Composite Structures, Volume 194
      Author(s): Wahid Ferdous, Yu Bai, Ahmed D. Almutairi, Sindu Satasivam, Juri Jeske
      This study proposes and examines a new structural retaining wall system using pultruded glass fibre reinforced polymer (GFRP) composites. The flexural behaviour of the two section types (double-H-planks and round-piles) are investigated at various spans under four-point bending. The effects of shear span-to-depth (a/d) ratio and sectional geometry on the structural capacity, stiffness and failure mode are studied. The effectiveness of the mechanical interlocking system between double-H-plank and round-pile for a continuous assembly is evaluated. Results suggest that the a/d ratio plays an important role in determining failure modes and ultimate capacities of double-H-plank and round-pile specimens. Additionally, a low a/d ratio or a larger depth incurs premature local crushing rather than flexural or shear failure. The mechanical interlocking system used to connect components together was found to be reliable as it effectively transfers bending loads from the double-H-plank to adjacent connected components even when the connection rotation is greater than 12°. Finally, FE modelling showed a good agreement with the experimental failure modes and satisfactorily estimated the failure loads and structural stiffness.

      PubDate: 2018-04-15T09:22:00Z
      DOI: 10.1016/j.compstruct.2018.03.074
      Issue No: Vol. 194 (2018)
       
  • Probabilistic bolt load distribution analysis of composite single-lap
           multi-bolt joints considering random bolt-hole clearances and tightening
           torques
    • Authors: Fengrui Liu; Meijuan Shan; Libin Zhao; Jianyu Zhang
      Pages: 12 - 20
      Abstract: Publication date: 15 June 2018
      Source:Composite Structures, Volume 194
      Author(s): Fengrui Liu, Meijuan Shan, Libin Zhao, Jianyu Zhang
      This paper presents a stochastic bolt load distribution analysis method of composite single-lap multi-bolt joints by using an improved three-stage spring-based method and Monte Carlo simulation. In the proposed method, the random properties of tightening torque, bolt-hole clearance, lamina properties and geometric parameters were involved. The allowable manufacturing tolerance band of parameters and clearance fit were considered, and a combining distribution function consisting of binomial distribution and normal distribution function was adopted for modeling the random tightening torque relaxation. To validate the proposed method, a set of composite single-lap three-bolt joints were designed and tested to achieve the stochastic bolt load distribution of the joint. Good agreements between the numerical and experimental stochastic bolt load distribution validated the proposed method. Furthermore, the probabilistic bolt load distributions of the three-bolt joints in four tightening torque conditions, including finger-tight, wrench torque, standard tightening torque and relaxation tightening torque, were investigated. It is found that tightening torque conditions and bolt-hole clearances have significant influences on the variation of the bolt load distribution, while the effects of other random parameters on the variation of the bolt load distribution are slight.

      PubDate: 2018-04-15T09:22:00Z
      DOI: 10.1016/j.compstruct.2018.03.100
      Issue No: Vol. 194 (2018)
       
  • Effect of polyamide-6,6 (PA 66) nonwoven veils on the mechanical
           performance of carbon fiber/epoxy composites
    • Authors: Bertan Beylergil; Metin Tanoğlu; Engin Aktaş
      Pages: 21 - 35
      Abstract: Publication date: 15 June 2018
      Source:Composite Structures, Volume 194
      Author(s): Bertan Beylergil, Metin Tanoğlu, Engin Aktaş
      In this study, carbon fiber/epoxy (CF/EP) composites were interleaved with polyamide-6,6 (PA 66) nonwoven veils at two different areal weight densities (17 and 50 gsm) to improve their delamination resistance against Mode-I loading. Mode-I fracture toughness (DCB), tensile, open hole tensile (OHT), flexural, compression, short beam shear (ILSS) and Charpy-impact tests were performed on the reference and PA 66 interleaved composite specimens. The DCB test results showed that the initiation and propagation Mode-I fracture toughness values of the composites were significantly improved by 84 and 171% using PA 66-17 gsm veils respectively, as compared to reference laminates. The use of denser PA 66-50 gsm veils in the interlaminar region led to higher improvement in fracture toughness values (349% for initiation and 718% for propagation) due to the higher amount of veil fibers involved in fiber bridging toughening mechanism. The incorporation of PA 66-50 gsm nonwoven veils also increased the ILSS and Charpy impact strength of the composites by 25 and 15%, respectively. On the other hand, the PA 66 veils reduced in-plane mechanical properties of CF/EP composites due to lower carbon fiber volume fraction and increased thickness.

      PubDate: 2018-04-15T09:22:00Z
      DOI: 10.1016/j.compstruct.2018.03.097
      Issue No: Vol. 194 (2018)
       
  • Crashworthiness design of novel hierarchical hexagonal columns
    • Authors: Xiang Xu; Yong Zhang; Jin Wang; Feng Jiang; Chun H. Wang
      Pages: 36 - 48
      Abstract: Publication date: 15 June 2018
      Source:Composite Structures, Volume 194
      Author(s): Xiang Xu, Yong Zhang, Jin Wang, Feng Jiang, Chun H. Wang
      Self-similar hierarchical structures are widely observed in nature, and have been credited with superior mechanical properties. In this paper, a novel self-similar hierarchical hexagonal columns (HHC) is proposed to improve structural crashworthiness performance. The self-similar hierarchical hexagonal columns are constructed by iteratively adding sub-hexagons at the corners of primary hexagon. To investigate the crashworthiness of HHC, the nonlinear finite element model is first developed and validated against experimental data obtained from 1st order HHC. Numerical investigations of 1st and 2nd order hierarchical hexagonal columns with different hierarchical levels are performed to compare with 0th order HHC, the results show that 1st and 2nd order hierarchical hexagonal columns improve the energy absorption and crush force efficiency by governing the material distribution, especially, 2nd order HHC exhibits significant advantage for energy absorption. In addition, parametric designs of 2nd order HHC are carried out to explore crashworthiness effect on hierarchical size ratio, cell wall thickness and impact velocity. The significant effects on both specific energy absorption (SEA) and the peak crushing force (PCF) are observed. The findings of this study offer a new route of designing novel crashworthiness structure with highly energy absorption capacity.

      PubDate: 2018-04-15T09:22:00Z
      DOI: 10.1016/j.compstruct.2018.03.099
      Issue No: Vol. 194 (2018)
       
  • Vibration analysis of functionally graded carbon nanotube reinforced
           composites (FG-CNTRC) circular, annular and sector plates
    • Authors: Rui Zhong; Qingshan Wang; Jinyuan Tang; Cijun Shuai; Bin Qin
      Pages: 49 - 67
      Abstract: Publication date: 15 June 2018
      Source:Composite Structures, Volume 194
      Author(s): Rui Zhong, Qingshan Wang, Jinyuan Tang, Cijun Shuai, Bin Qin
      The intent of this paper is to firstly perform the vibration analysis of the functionally graded carbon nanotube reinforced composites (FG-CNTRC) circular, annular and sector plates with arbitrary boundary conditions by means of the semi-analytical method which is proposed by the author’s team. In the material model, the distribution of the carbon nanotubes is uniform or functionally graded along with the thickness direction of structures and four types of the CNTs distribution are studied in this paper. The refined rule of mixtures approach containing the efficiency parameters is adopted to determine the properties of the composite media. The admissible displacement functions of the FG-CNTRC circular, annular and sector plates are uniformly expanded as the modified Fourier series which embodies a standard cosine Fourier series and several auxiliary functions which are introduced to eliminate the limit of the boundary conditions. On this foundation, the first-order shear deformation elasticity theory is employed to construct the energy expression of the FG-CNTRC circular, annular and sector plates. Then the Ritz-variational energy method is used to decide the natural frequencies and the associated mode shapes. To examine the convergence, accuracy, stability and efficiency of the computational model, the comprehensive studies are conducted. Based on that, some crucial parametric studies covering the influence of the geometrical parameters, CNTs distributions, volume fraction of CNTs and boundary conditions are also investigated in detail.

      PubDate: 2018-04-15T09:22:00Z
      DOI: 10.1016/j.compstruct.2018.03.104
      Issue No: Vol. 194 (2018)
       
  • Influence of low and high temperature on mixed adhesive joints under
           quasi-static and impact conditions
    • Authors: J.J.M. Machado; E.A.S. Marques; Lucas F.M. da Silva
      Pages: 68 - 79
      Abstract: Publication date: 15 June 2018
      Source:Composite Structures, Volume 194
      Author(s): J.J.M. Machado, E.A.S. Marques, Lucas F.M. da Silva
      The increasing use of composite structures in the automotive industry is due to strict regulations regarding fuel efficiency and safety standards. The main advantage of the use of adhesives is the possibility of joining dissimilar materials, particularly composites. The technique studied was the mixed adhesive joints, as two or more adhesives can be used in a single lap joint combining the properties of those adhesives to attain mechanical performance superior to that obtained using those adhesives individually. The main goal was to assess if a previously validated combination of mixed adhesives in a composite joint, tested under quasi-static and impact conditions, offers the same advantage over the use of a single adhesive when subjected to low (−30 °C) and high (80 °C) temperatures. The influence of temperature on the behaviour of the composite joints was assessed in quasi-static and impact conditions allowing to infer the effect on each adhesive. Another important aspect of the use of this type of technique is to avoid the early delamination of the composite substrates. This method was found to improve the performance under quasi-static and impact conditions although its behaviour under the wide range of temperature tested was found to vary significantly.

      PubDate: 2018-04-15T09:22:00Z
      DOI: 10.1016/j.compstruct.2018.03.093
      Issue No: Vol. 194 (2018)
       
  • Study of mechanical behavior of BNNT-reinforced aluminum composites using
           molecular dynamics simulations
    • Authors: Ziyu Cong; Seungjun Lee
      Pages: 80 - 86
      Abstract: Publication date: 15 June 2018
      Source:Composite Structures, Volume 194
      Author(s): Ziyu Cong, Seungjun Lee
      Fabrication of metallic matrix boron nitride nanotubes (BNNT) composites have remained challenging due to their high reactivity of metals at elevated processing temperatures. Recently, however, the successful fabrication of BNNT-metal composites has been reported using a plasma technique. Since carbon nanotubes (CNT), which are a structural analogy of BNNTs, easily react with aluminum to form aluminum carbides at the interface, serving as mechanically weak points, BNNTs can be a good alternative for the reinforcing component of metal-matrix composites (MMC). In this study, we conducted several molecular dynamics (MD) simulations to investigate the mechanical behaviors of BNNT-Al composites under tensile loading. The simulations provided quantitative information on the mechanical properties of the BNNT composite, revealing the effect of various BNNT diameters and volume fractions. The contributions of the BNNT and Al component to the total improvement of mechanical properties were quantified through a component analysis. The analysis revealed that the effect of the volume fraction of BNNTs is more significant than that of the size. In addition, the quantified relation between the volume fraction of BNNTs and the enhancement in elasticity can be effectively used for the engineering design of BNNT-Al MMCs.

      PubDate: 2018-04-15T09:22:00Z
      DOI: 10.1016/j.compstruct.2018.03.103
      Issue No: Vol. 194 (2018)
       
  • Crash responses under multiple impacts and residual properties of CFRP and
           aluminum tubes
    • Authors: Qiang Liu; Hao Shen; Yinghan Wu; Zhencong Xia; Jianguang Fang; Qing Li
      Pages: 87 - 103
      Abstract: Publication date: 15 June 2018
      Source:Composite Structures, Volume 194
      Author(s): Qiang Liu, Hao Shen, Yinghan Wu, Zhencong Xia, Jianguang Fang, Qing Li
      This study aimed to explore the impact responses and residual properties of thin-walled carbon fiber reinforced plastics (CFRP) tubes and aluminum (Al) tubes subjected to multiple axial impacts. Five repeated impacts with the same impact energy were first conducted to evaluate the effect of repeated impact number, and then the crushing tests were performed to explore the post-impact residual behavior. Regardless of number of repeated impacts, the progressive end crushing modes for the CFRP tubes and stable progressive folding mode for aluminum tubes were identified under repeated dynamic impacts. The CFRP tubes exhibited the highest specific energy absorption (SEA) under the 1st impact, then the similar SEA values in the other four subsequent impacts; whereas the SEA of aluminum tubes fluctuated with the repeated impact numbers which were related to formation of different folds. The quasi-static crushing tests revealed that the residual SEAs of the CFRP tubes and aluminum tubes were not much influenced by the impact number, only within a difference of 5% under the 5 repetitive impacts conducted. It was demonstrated that the CFRP tubes had much better performance in energy absorption capability in comparison with the aluminum tubes in terms of repeated impacts and residual crushing tests.

      PubDate: 2018-04-15T09:22:00Z
      DOI: 10.1016/j.compstruct.2018.04.001
      Issue No: Vol. 194 (2018)
       
  • Effect of internal surface damage on vibration behavior of a composite
           pipe conveying fluid
    • Authors: Wasiu A. Oke; Yehia A. Khulief
      Pages: 104 - 118
      Abstract: Publication date: 15 June 2018
      Source:Composite Structures, Volume 194
      Author(s): Wasiu A. Oke, Yehia A. Khulief
      Composite pipes have become a viable alternative to metallic pipes in several applications. Flow-accelerated erosion and internal surface attack often result in thickness thinning that may compromise the structural integrity of the pipe and lead to its failure. In this paper, we investigate how the internal surface damage is reflected on the vibration behavior of a composite pipe conveying fluid. The defected pipe-fluid system is modeled using the extended Hamilton’s approach and discretized using the wavelet-based finite element method. The modal characteristics of the pipe vibrations have been obtained by solving the generalized eigenvalue problem. The developed model was validated and some benchmark solutions are presented to highlight the effects of the internal wall-thinning on the vibrational behavior of composite pipes conveying fluid. The obtained results facilitate the future research by revealing the potential of using the vibration signature as a basis for detection of erosion-induced internal defects in pipelines.

      PubDate: 2018-04-15T09:22:00Z
      DOI: 10.1016/j.compstruct.2018.03.098
      Issue No: Vol. 194 (2018)
       
  • Design of filament-wound composite structures with arch-shaped cross
           sections considering fiber tension simulation
    • Authors: Lei Zu; Hui Xu; Bing Zhang; Debao Li; Bin Zi
      Pages: 119 - 125
      Abstract: Publication date: 15 June 2018
      Source:Composite Structures, Volume 194
      Author(s): Lei Zu, Hui Xu, Bing Zhang, Debao Li, Bin Zi
      The binding effect of fiber materials due to the winding tension during the filament winding process of arch-shaped cross sections was successfully evaluated using the Finite Element Method (FEM). The use of FEM was validated by comparing results obtained with the results from the numerical analysis of a classic cylindrical mandrel winding model. In this study, four methods were combined in the commercial finite element code ANSYS to predict the change trend of the residual stress of the layer and explore the relationship between the winding layer thickness and the winding relaxation effect. These methods include the element birth and death option, which was used to simulate the step-by-step winding process, the thermal parameter method, which produced the equivalent filament winding tension, contact analysis, which was used to carry out the transmission of radial pressure and deformation, and the restart method, which was used to simulate the procuring process. Compared with the mathematical algorithm and test of variable thickness, the results of FEM were in the range of allowable error. Therefore, these results provide a useful reference in designing the filament wound composite structures with considerably high fiber tensions.

      PubDate: 2018-04-15T09:22:00Z
      DOI: 10.1016/j.compstruct.2018.04.018
      Issue No: Vol. 194 (2018)
       
  • Impacts of configurations on the strength of FRP anchors
    • Authors: Wei Sun; Haifeng Liu; Yajun Wang; Tao He
      Pages: 126 - 135
      Abstract: Publication date: 15 June 2018
      Source:Composite Structures, Volume 194
      Author(s): Wei Sun, Haifeng Liu, Yajun Wang, Tao He
      The usage of FRP anchors to prevent FRP strips from premature debonding failure is gaining acceptance in strengthening applications of concrete members. FRP anchors can fully develop the strength of FRP strips when they are properly designed. However, existing equations do not well include the comprehensive impact of the spike embedment depth, the bend ratio, the strength ratio of FRP anchor to FRP strip and the dowel angle on the anchor strength. Based on 64 tests failed in anchor rupture, this study proposes a comprehensive equation to determine the anchor strength. Comparisons between equation based predictions and 12 experimental results indicate the advantage of the proposed equation against existing equations. Then, the study propose a feasible technique, i.e. the bidirectional FRP patch, to improve the efficiency of current FRP anchors. Compared with equation based predictions for those FRP anchors without FRP patches, experimental results obtained from 20 specimens with FRP patches indicate significant increases on the anchor strength. This observation favors the usage of FRP patches to improve the efficiency of FRP anchors.

      PubDate: 2018-04-15T09:22:00Z
      DOI: 10.1016/j.compstruct.2018.04.020
      Issue No: Vol. 194 (2018)
       
  • Analysis of low velocity impacts on sandwich composite plates using cubic
           spline layerwise theory and semi empirical contact law
    • Authors: C.S. Rekatsinas; D.K. Siorikis; A.P. Christoforou; N.A. Chrysochoidis; D.A. Saravanos
      Pages: 158 - 169
      Abstract: Publication date: 15 June 2018
      Source:Composite Structures, Volume 194
      Author(s): C.S. Rekatsinas, D.K. Siorikis, A.P. Christoforou, N.A. Chrysochoidis, D.A. Saravanos
      The theoretical and numerical framework for the simulation of impacts on thick sandwich composite plates is presented. It encompasses three new elements: 1) A three-dimensional layerwise theory, which approximates the in-plane and transverse displacements through the thickness using third-order Hermite spline polynomials that captures the high inhomogeneity of all interlaminar stresses present in the thick sandwich laminate. 2) The integration of the layerwise theory into a time domain plate spectral finite element with nodes collocated to Gauss-Lobatto-Legendre integration points, which provides a consistent semi-diagonal mass matrix and high-order spatial approximation in the plane of the structure, thus enabling high spatial convergence and fast explicit time integration of impact events. 3) A semi-empirical contact law that is derived from analytical expressions and validated with indentation experiments and numerical results, to provide the coupling between the impactor and target structure. Numerical simulations of the transient impact response obtained by the present method are correlated with 3D continuum finite element impact models and experimental results to quantify accuracy and computational speed. It is demonstrated, that the simulation of impacted sandwich composite plates requires integration of all three previous elements to obtain accurate and fast results.

      PubDate: 2018-04-15T09:22:00Z
      DOI: 10.1016/j.compstruct.2018.03.081
      Issue No: Vol. 194 (2018)
       
  • Effective piezoelectric coefficients of cement-based 2–2 type
           piezoelectric composites based on a multiscale homogenization model
    • Authors: Chuanqing Fu; Zhi Wang; Xianyu Jin; Xingyi Zhu; Jun Zhu
      Pages: 170 - 177
      Abstract: Publication date: 15 June 2018
      Source:Composite Structures, Volume 194
      Author(s): Chuanqing Fu, Zhi Wang, Xianyu Jin, Xingyi Zhu, Jun Zhu
      The effective piezoelectric properties of the cement-based 2–2 type piezoelectric composites have been investigated both experimentally and theoretically. The two-scale asymptotic expansion method is employed to develop a homogenized model for the effective properties calculation. The validity of the theoretical solution is confirmed through the comparison with the experimental results. The influence of the volume fraction of the piezoelectric phase on the effective piezoelectric coefficients is then examined. It is found that higher volume fraction will induce obvious increment of the magnitude of the effective piezoelectric strain coefficients d 31 Eff , d 32 Eff , and d 33 Eff , however, the hydrostatic piezoelectric strain coefficient d h Eff will reach a maximum value at a lower volume fraction.

      PubDate: 2018-04-15T09:22:00Z
      DOI: 10.1016/j.compstruct.2018.03.055
      Issue No: Vol. 194 (2018)
       
  • Manufacturing and compressive response of ultra-lightweight CFRP cores
    • Authors: Pablo Vitale; Gaston Francucci; Helmut Rapp; Ariel Stocchi
      Pages: 188 - 198
      Abstract: Publication date: 15 June 2018
      Source:Composite Structures, Volume 194
      Author(s): Pablo Vitale, Gaston Francucci, Helmut Rapp, Ariel Stocchi
      Three-dimensional carbon fiber reinforced polymer (CFRP) cores are high performance ultra-lightweight materials that can reduce the structural mass of vehicles used in the transportation and aerospace industry, increasing capabilities and performance, and reducing fuel consumption. In this work, three different carbon fiber cores are obtained using an interlocking method from flat composite laminates with different geometries. The density of the cores is maintained less than 48 kg m−3. Sandwich panels are manufactured using these cores and carbon fiber reinforced epoxy skins. Compressive properties of the sandwich panels are evaluated and the failure modes are studied. Experimental results are compared to those predicted by analytical modeling and finite element method analysis (FEM).

      PubDate: 2018-04-15T09:22:00Z
      DOI: 10.1016/j.compstruct.2018.03.065
      Issue No: Vol. 194 (2018)
       
  • An experimental study on the radar absorbing characteristics of folded
           core structures
    • Authors: Zhijin Wang; Chen Zhou; Valentin Khaliulin; Alexey Shabalov
      Pages: 199 - 207
      Abstract: Publication date: 15 June 2018
      Source:Composite Structures, Volume 194
      Author(s): Zhijin Wang, Chen Zhou, Valentin Khaliulin, Alexey Shabalov
      Folded core sandwich structures are promising multifunctional structures for both load bearing and radar absorbing capability. This paper presents an experimental study on the radar absorbing characteristics of folded core structures. The influences of various factors on the folded core radar cross section (RCS) are investigated. The experiments were carried out in an anechoic chamber. Comparisons are made between folded core samples and an aluminium flat panel. The results show that the folded core height has significant effects on the radar absorbing performance of V-pattern folded core, while core material only leads to a slight difference. The RCS of V-pattern folded core is lower than that of the flat panel, while the RCS of M-pattern folded core is of the same order of magnitude as that of the flat panel with a much wider range.

      PubDate: 2018-04-15T09:22:00Z
      DOI: 10.1016/j.compstruct.2018.03.106
      Issue No: Vol. 194 (2018)
       
  • Experimental investigation of the quasi-static axial crushing behavior of
           filament-wound CFRP and aluminum/CFRP hybrid tubes
    • Authors: Guangyong Sun; Zhen Wang; Jiaying Hong; Kai Song; Qing Li
      Pages: 208 - 225
      Abstract: Publication date: 15 June 2018
      Source:Composite Structures, Volume 194
      Author(s): Guangyong Sun, Zhen Wang, Jiaying Hong, Kai Song, Qing Li
      This study aims to investigate the effects of winding angles (25°, 50°, 75°, 90°; the 0° winding angle is along the axial direction of the tube) and thicknesses (3-ply, 6-ply, 9-ply) on crashworthiness characteristics of carbon fiber reinforced plastics (CFRP) tube and aluminum/CFRP hybrid tube molded by the filament winding technique through quasi-static crushing tests. The interaction between the outer CFRP tube and inner aluminum tube in a hybrid configuration was explored by comparing the sum of energy absorption of individual components with the hybrid form. It was found that both winding angle and wall thickness had significant influence on failure modes and crushing characteristics of both CFRP and hybrid tubes. With the same laminate thickness, increasing the winding angle decreased the specific energy absorption (SEA), energy absorption (EA) and peak crushing force (PCF) of pure CFRP and hybrid tubes. With the same winding angle of CFRP tube, increasing the thickness of CFRP tube increased the SEA, EA and PCF of both the CFRP and hybrid tubes. The SEA of 9-ply CFRP tube with winding angle of 25° and 9-ply CFRP/aluminum hybrid tube with winding angle of 25° were the highest of all the CFRP and hybrid tubes (48.74 J/g and 79.05 J/g), respectively. Moreover, EA of the hybrid tube exceeded the sum of that of the individual components thanks to the positive interaction between these components; making the hybrid tubes better crashworthiness than individual components.

      PubDate: 2018-04-15T09:22:00Z
      DOI: 10.1016/j.compstruct.2018.02.005
      Issue No: Vol. 194 (2018)
       
  • Influence of stochastic variations in manufacturing defects on the
           mechanical performance of textile composites
    • Authors: Xiao-Yi Zhou; P.D. Gosling
      Pages: 226 - 239
      Abstract: Publication date: 15 June 2018
      Source:Composite Structures, Volume 194
      Author(s): Xiao-Yi Zhou, P.D. Gosling
      This paper presents a methodology to evaluate the effects of microscopic manufacturing defects, namely fibre misalignment, waviness and volume fraction, on the mechanical performance. Influences of these defects on the effective elastic properties of composites are quantified by a dual homogenization method. For estimating stochastic characteristics of the properties induced by the variations in these defects, a probabilistic extension of the dual homogenization method is developed and numerically implemented through a perturbation-based stochastic finite element method. It is further incorporated in a multiscale finite element based reliability method to measure the influences of these manufacturing defects on structural performance in terms of reliability. The effectiveness of the proposed method in capturing defects is illustrated initially by investigating the effective elastic properties of a unidirectional fibre composite based yarn and then a plain woven textile composite. The capability of the proposed method in quantifying the variations in these defects is further demonstrated through statistical analysis of the effective elastic properties and a woven textile composite and structural reliability analysis of a textile composite laminate. This paper represents a significant advancement in the probabilistic prediction of the behaviour of woven and non-woven composites.

      PubDate: 2018-04-15T09:22:00Z
      DOI: 10.1016/j.compstruct.2018.04.003
      Issue No: Vol. 194 (2018)
       
  • Effects of surface laser treatment on direct co-bonding strength of CFRP
           laminates
    • Authors: C. Leone; S. Genna
      Pages: 240 - 251
      Abstract: Publication date: 15 June 2018
      Source:Composite Structures, Volume 194
      Author(s): C. Leone, S. Genna
      Laser surface treatment is a promising technique to increase the adhesive strength of carbon fibres reinforced plastics joints. In this technique, the laser beam is adopted to remove the outer matrix layer up to the expose the underlying reinforcement. This study deals on the effect of laser treatment on the joint strength of CFRP laminate obtained by direct co-bonding. To this aim, laser treatments at different process conditions were performed on autoclave cured CFRP, adopting a pulsed Yb:YAG fiber laser. The obtained surfaces were characterized by microscopy. Single lap joints were obtained by infusion techniques by superposition of fresh laminates and laser treated laminates without any kind of adhesive. Untreated and sandpaper treated samples were adopted as reference specimens. After joints consolidation, mechanical tests were carried out; apparent shear strength was measured and post mortem analysis was performed. The results show that laser treatments allow the doubling of the apparent shear strength.
      Graphical abstract image

      PubDate: 2018-04-15T09:22:00Z
      DOI: 10.1016/j.compstruct.2018.03.096
      Issue No: Vol. 194 (2018)
       
  • Behavior of steel fiber-reinforced concrete-filled FRP tube columns:
           Experimental results and a finite element model
    • Authors: Aliakbar Gholampour; Togay Ozbakkaloglu
      Pages: 252 - 262
      Abstract: Publication date: 15 June 2018
      Source:Composite Structures, Volume 194
      Author(s): Aliakbar Gholampour, Togay Ozbakkaloglu
      This paper presents the results of an experimental study together with the first finite element (FE) model for the compressive behavior of fiber-reinforced polymer (FRP)-confined steel fiber-reinforced concrete (SFRC). 73 existing experimental test results of FRP-confined and actively confined SFRC specimens tested under axial compression were initially assembled. Additional axial compression tests were conducted on 16 actively confined SFRC specimens to address the gaps in the existing test database to compile a reliable database for the FE modeling of FRP-confined SFRCs. The analysis of experimental test results revealed that the compressive behavior of FRP-confined SFRCs is influenced by the steel fiber volume fraction and aspect ratio. New expressions were developed for the hoop rupture strain of the FRP jacket, axial strain-lateral strain relationship of FRP-confined and actively confined SFRC, and relationship between the confining pressure and the compressive strength of actively confined SFRC by considering the influences of the volume fraction and aspect ratio of internal steel fibers. A recently developed concrete damage-plasticity model, which was shown to be the most accurate currently available model for confined plain concrete, was adopted for the prediction of the compressive behavior of FRP-confined SFRC. The failure surface and flow rule of the model were modified based on the results from actively and FRP-confined SFRC. The results show that model predictions of the axial stress-axial strain, lateral strain-axial strain, axial stress-volumetric strain, plastic volumetric strain-axial plastic strain, and plastic dilation angle-axial plastic strain relationships are in good agreement with the experimental results of FRP-confined SFRC. The new model provides improved accuracy over the best performing existing models of FRP-confined plain concrete in predicting the behavior of FRP-confined SFRC.

      PubDate: 2018-04-15T09:22:00Z
      DOI: 10.1016/j.compstruct.2018.03.094
      Issue No: Vol. 194 (2018)
       
  • Flexural performance of a hybrid GFRP-concrete bridge deck with composite
           T-shaped perforated rib connectors
    • Authors: Yize Zuo; Ayman Mosallam; Haohui Xin; Yuqing Liu; Jun He
      Pages: 263 - 278
      Abstract: Publication date: 15 June 2018
      Source:Composite Structures, Volume 194
      Author(s): Yize Zuo, Ayman Mosallam, Haohui Xin, Yuqing Liu, Jun He
      In this study, the flexural performance of an innovative hybrid GFRP-concrete deck is evaluated. The proposed hybrid composite deck consists of a pultruded GFRP plate with T-shaped perforated ribs for resisting tensile stresses, while concrete with reinforcements is placed at the compressive side of the deck. In order to better understand the flexural performance of proposed hybrid decks under sagging moment, a total of six full-scale hybrid deck models were experimentally investigated. Five test parameters were considered, namely: (i) hole spacing, (ii) presence of bent-up rebars, (iii) quality of GFRP composites surface treatment, (iv) deck depth, and (v) type of reinforcements. Experimental results identified three different typical failure modes, namely: diagonal and longitudinal shear, as well as flexure. Furthermore, it was found that the inclusion of bent-up rebars, sand bonded to GFRP plates surfaces, and increasing deck thickness enhance the ultimate strength of the proposed hybrid deck. It was also concluded that the hole spacing and the reinforcement type have negligible influence on ultimate capacity of the proposed deck. Moreover, finite element models considering the laminate damage based on Hashin’s theory were built and load transfer and failure mechanisms of GFRP perforated ribs were discussed. The validity of the proposed analytical method, with respect to failure mode and ultimate strength for the hybrid deck, was confirmed through the close correlation between analytical and experimental results.

      PubDate: 2018-04-15T09:22:00Z
      DOI: 10.1016/j.compstruct.2018.03.105
      Issue No: Vol. 194 (2018)
       
  • Static and fatigue analysis of bolted/bonded joints modified with CNTs in
           CFRP composites under hot, cold and room temperatures
    • Authors: U.A. Khashaba
      Pages: 279 - 291
      Abstract: Publication date: 15 June 2018
      Source:Composite Structures, Volume 194
      Author(s): U.A. Khashaba
      The present study evaluated for the first time, the tensile and fatigue properties of bolted/bonded scarf adhesive joints (SAJs) in carbon fiber reinforced polymer (CFRP) composites at room temperature of +25 °C, +50 °C and −70 °C. The adhesive layer of the SAJs was modified with multi-walled carbon nanotubes (CNTs) and the results are compared with respect to neat adhesive and adhesive thickness. A new simple approach was developed to measure bolt-hole elongation, which successfully differentiates between bearing failure and interfacial shear failure modes and loads. Results from tensile tests showed that the bolted/bonded SAJs can perform well at −70 °C with maximum loss in strength of 9.6% and stiffness improvement of 30%. Incorporation of CNTs into the adhesive layer improved fatigue lives, at +25 °C, by about 72.1%–97.8% compared with that of neat-adhesives. Interfacial shear failure, cohesive failure and CNTs pull-out are the dominated failure modes in the SAJs, whereas bearing, shear-out, longitudinal splitting and bolt fracture are observed for the bolted joints. Considerable attention was given to analyze the scatter in the tensile strength and fatigue life results.

      PubDate: 2018-04-15T09:22:00Z
      DOI: 10.1016/j.compstruct.2018.04.008
      Issue No: Vol. 194 (2018)
       
  • Multiscale microstructural characterization of particulate-reinforced
           composite with non-destructive X-ray micro- and nanotomography
    • Authors: J. Nafar Dastgerdi; A. Miettinen; J. Parkkonen; H. Remes
      Pages: 292 - 301
      Abstract: Publication date: 15 June 2018
      Source:Composite Structures, Volume 194
      Author(s): J. Nafar Dastgerdi, A. Miettinen, J. Parkkonen, H. Remes
      Methods based on X-ray tomography are developed to study the relevant statistical quantities describing the microstructural inhomogeneity of particulate reinforced composites. The developed methods are applied in estimating microstructural inhomogeneity parameters of composites containing metallic glass particles in metal matrix, extruded in varying pressure loads. This study indicates that the critical characteristics with regard to the effect of particle clustering are cluster size and shape, local volume fraction of particles in the cluster and the distance between clusters. The results demonstrate that the spatial distribution of reinforcement is very uneven and the amount of particle clustering varies with amount of reinforcement. Moreover, X-ray nanotomography was used to investigate the structure of individual clusters and the results suggest that high extrusion load may cause break-up of individual particle clusters so that their shape changes from solid and spherical to broken and ellipsoidal.

      PubDate: 2018-04-15T09:22:00Z
      DOI: 10.1016/j.compstruct.2018.04.022
      Issue No: Vol. 194 (2018)
       
  • Multiscale modeling of polymer systems comprising nanotube-like inclusions
           by considering interfacial debonding under plastic deformations
    • Authors: S.M.R. Paran; G. Naderi; M.H.R. Ghoreishy; C. Dubois
      Pages: 302 - 315
      Abstract: Publication date: 15 June 2018
      Source:Composite Structures, Volume 194
      Author(s): S.M.R. Paran, G. Naderi, M.H.R. Ghoreishy, C. Dubois
      The mechanical properties of polymer nanocomposites are severely governed by the situation of the interphase region. Yet, a few was known about interfacial adhesion/debonding in the vicinity of polymer-nanofiller interface. The inadequateness of our information on such region takes its origin in the assumptions involved in theoretical models describing interfacial debonding. Particularly, zero interphase region, constant modulus, and elastic deformation assumptions make predictions unreliable when experimental mechanical characteristics are meticulously analyzed. In this work, multiscale modeling approach was implemented in prediction of plastic deformation of stress-strain of a typical thermoplastic polymer filled with nanotube-like inclusions. In contrast to the above-mentioned assumptions that take a naïve look at the interphase region, a finite element code was developed here to assist in interfacial debonding evaluation by considering a variable modulus for non-zero layer between polymer and nanotube-like filler phases under plastic deformation. Experimental plots of stress-strain on typical nanocomposites prepared varying the amount and surface chemistry of the nanofiller were used for approval of the model outcome. The use of finite element method in such a complex systems improved significantly the predictability of theories by making possible monitoring the effect of thickness of interphase on debonding behavior.

      PubDate: 2018-04-15T09:22:00Z
      DOI: 10.1016/j.compstruct.2018.03.059
      Issue No: Vol. 194 (2018)
       
  • Numerical analysis and experimental observation of ultrasonic wave
           propagation in CFRP with curved fibers
    • Authors: Takeshi Ashizawa; Yoshihiro Mizutani; Nobuyuki Toyama; Akira Todoroki; Yoshiro Suzuki
      Pages: 316 - 327
      Abstract: Publication date: 15 June 2018
      Source:Composite Structures, Volume 194
      Author(s): Takeshi Ashizawa, Yoshihiro Mizutani, Nobuyuki Toyama, Akira Todoroki, Yoshiro Suzuki
      The relationship between the propagation directions of ultrasonic wave and the direction of the principal axis of anisotropy in uni-directional CFRP with straight fiber is well known. However, the behavior of ultrasonic wave in CFRP with curved fibers is not clarified in details. In this paper, numerical analyses using the finite difference method were conducted to visualize the behavior of ultrasonic waves in CFRP with concentrically curved fibers. Numerical simulation results showed the energy of quasi-longitudinal ultrasonic wave curved along the fiber direction. In order to confirm the analytical result, CFRP specimen with curved fibers were prepared by utilizing 3D-printer and the behavior of ultrasonic propagation was observed by using Laser ultrasonic system. The observed results confirmed the analytical results that the ultrasonic wave curved along carbon fibers.

      PubDate: 2018-04-15T09:22:00Z
      DOI: 10.1016/j.compstruct.2018.03.089
      Issue No: Vol. 194 (2018)
       
  • Aeroelasticity of composite plates with curvilinear fibres in supersonic
           flow
    • Authors: Hamed Akhavan; Pedro Ribeiro
      Pages: 335 - 344
      Abstract: Publication date: 15 June 2018
      Source:Composite Structures, Volume 194
      Author(s): Hamed Akhavan, Pedro Ribeiro
      The target of this investigation is to understand the aeroelastic (dynamic or static) instability of variable stiffness composite laminates (VSCLs) in the presence of supersonic airflow. The studied VSCLs have curvilinear fibre paths. Two different types of VSCLs are considered: the first type (already adopted in several previous researches) includes fibre path angles changing linearly from T 1 at right and left edges to T 0 at the centre, and the second type (not introduced before) includes fibre paths where their angles change linearly from T 0 at the left edge to T 1 at the right edge. Displacements and rotations in the plate are modelled by a Third-order Shear Deformation Theory (TSDT) and are discretised by a p-version finite element model. Aerodynamic forces due to supersonic airflow, in the steady or unsteady regime, are modelled using linear Piston theory and the equations of motion of the self-excited vibration system are formed using the principle of virtual work. Dynamic (flutter) and static (divergence) instabilities are identified using the eigenvalues of the linear system. Effects of different boundary conditions and various fibre angles as well as the influence of airflow direction on the flutter and divergence occurrence in VSCL plates are studied.

      PubDate: 2018-04-15T09:22:00Z
      DOI: 10.1016/j.compstruct.2018.03.101
      Issue No: Vol. 194 (2018)
       
  • A metamodel-based optimization approach to reduce the weight of composite
           laminated wind turbine blades
    • Authors: Alejandro Albanesi; Nadia Roman; Facundo Bre; Victor Fachinotti
      Pages: 345 - 356
      Abstract: Publication date: 15 June 2018
      Source:Composite Structures, Volume 194
      Author(s): Alejandro Albanesi, Nadia Roman, Facundo Bre, Victor Fachinotti
      In wind turbine blades, the complex resultant geometry due to the aerodynamic design cannot be modified in the successive mechanical design stage. Hence, the reduction of the weight and manufacturing costs of the blades while assuring appropriate levels of structural stiffness, integrity and reliability, require a composite material layout that must be optimally defined. The aim of this work is to present a metamodel-based method to optimize the composite laminate of wind turbine blades. This methodology combines a genetic algorithm (GA) with an artificial neural network (ANN) in order to reduce the computational cost of the optimization procedure. Therefore, at first, representative samples were built to train and validate the ANN model, and then, the ANN model is coupled with GA to find the optimal structural blade design. As an actual case study, the method was applied to redesign a medium-power 40-kW wind turbine blade to reduce its mass while structural and manufacturing constrained are fulfilled. The results indicated that is possible to save of up to 20% of laminated mass compared to a reference design. Furthermore, a 40% reduction of the computational cost was achieved in contrast with the typical simulation-based optimization approach.

      PubDate: 2018-04-15T09:22:00Z
      DOI: 10.1016/j.compstruct.2018.04.015
      Issue No: Vol. 194 (2018)
       
  • Buckling of a piezoelectric nanobeam with interfacial imperfection and van
           der Waals force: Is nonlocal effect really always dominant'
    • Authors: Yong-Dong Li; Ronghao Bao; Weiqiu Chen
      Pages: 357 - 364
      Abstract: Publication date: 15 June 2018
      Source:Composite Structures, Volume 194
      Author(s): Yong-Dong Li, Ronghao Bao, Weiqiu Chen
      With the development of NEMSs (nano-electro-mechanical systems), the size-dependent behavior has been an active topic. The scale parameter seems an essential factor dominating mechanical behavior at nanoscale. However, is it always dominant' This is a question deserving careful investigation. For this reason, the buckling of a bi-layered PE (piezoelectric) nanobeam is analyzed. The main purpose is to reveal and compare the effects of the nonlocal scale, imperfect interface, interlaminar van der Waals force and loading ratio. The imperfect interface is modeled by normal and shear springs, and the van der Waals force is represented by the Hamaker formula. Based on the principle of virtual work, the analytical solution of the critical buckling loading is derived by using the trigonometric shear deformation theory. After the verification in some degenerated cases, parametric studies are conducted. It is indicated that if the nonlocal parameter varies in the typical range [0, 4 nm^2], it only has quite limited effect on the buckling behavior, as compared with the other three factors. In this case, although the buckling relies on the nonlocal scale, it is far more dependent on the conventional non-nanoscale factors. The conclusions can provide references for optimal design of NEMSs.

      PubDate: 2018-04-15T09:22:00Z
      DOI: 10.1016/j.compstruct.2018.04.031
      Issue No: Vol. 194 (2018)
       
  • Time-dependent assessment and deflection prediction of prestressed
           concrete beams with unbonded CFRP tendons
    • Authors: Tiejiong Lou; Theodore L. Karavasilis
      Pages: 365 - 376
      Abstract: Publication date: 15 June 2018
      Source:Composite Structures, Volume 194
      Author(s): Tiejiong Lou, Theodore L. Karavasilis
      This paper presents the assessment of the time-dependent behavior and the prediction of the long-term deflection of concrete beams prestressed with internal unbonded carbon fiber reinforced polymer (CFRP) tendons. A numerical model for the time-dependent analysis of concrete beams prestressed with unbonded tendons is calibrated against experimental results. Parametric numerical simulations are then conducted on simply supported unbonded prestressed concrete beams subjected to long-term sustained loads to investigate the effect of using CFRP tendons instead of low-relaxation steel ones, the magnitude of the initial prestress, the loading conditions, and the quantity of the compressive reinforcing steel. The results show that the long-term prestress loss of beams with CFRP tendons is considerably higher than that of beams with steel tendons. Moreover, it is shown that increasing the quantity of compressive reinforcing steel leads to a substantial decrease in long-term downward deflection. A modification of the ACI 318-14 equation is proposed to predict the time-dependent deflection of prestressed concrete beams with unbonded FRP or steel tendons.

      PubDate: 2018-04-15T09:22:00Z
      DOI: 10.1016/j.compstruct.2018.04.013
      Issue No: Vol. 194 (2018)
       
  • A simplified method to predict the fire resistance of RC beams
           strengthened with near-surface mounted CFRP
    • Authors: Jiangtao Yu; Keke Liu; Ling-zhi Li; Yichao Wang; Kequan Yu; Qingfeng Xu
      Pages: 1 - 7
      Abstract: Publication date: 1 June 2018
      Source:Composite Structures, Volume 193
      Author(s): Jiangtao Yu, Keke Liu, Ling-zhi Li, Yichao Wang, Kequan Yu, Qingfeng Xu
      A simplified method was proposed to predict the fire resistance of flexure-dominated reinforced concrete (RC) beams strengthened with near-surface mounted (NSM) carbon fiber reinforced polymer (CFRP). Based on the results of previous experimental observations and theoretical analyses, “steel yielding after FRP slipping” and “FRP fracture after steel yielding” were presumed to be the possible failure modes for NSM-FRP strengthening system under fire. An algorithm was thus developed to evaluate the fire resistance of the strengthening system. A series of pull-out tests were carried out to obtain the bond-slip relationships of NSM-FRP at different elevated temperatures for the proposed algorithm. Then this method was used to predict the fire resistance of nine RC beams strengthened with NSM-FRP, which were subjected to a sustained load and the ISO834 standard fire. The predictions showed good agreement with the test results, indicating the effectiveness of the proposed method. This study provides a helpful reference for the fire resistance design of flexure-dominated RC beans strengthened with NSM-FRP in engineering practice.

      PubDate: 2018-04-15T09:22:00Z
      DOI: 10.1016/j.compstruct.2018.03.035
      Issue No: Vol. 193 (2018)
       
  • Elastic properties of 3D printed fibre-reinforced structures
    • Authors: Haider Al Abadi; Huu-Tai Thai; Vidal Paton-Cole; V.I. Patel
      Pages: 8 - 18
      Abstract: Publication date: 1 June 2018
      Source:Composite Structures, Volume 193
      Author(s): Haider Al Abadi, Huu-Tai Thai, Vidal Paton-Cole, V.I. Patel
      This paper aims to evaluate the elastic properties of fibre-reinforced polymer (FRP) structures printed by three-dimensional (3D) printing technology. Both experimental and theoretical approaches are adopted to investigate the performance of FRP 3D-printed structures and predict their elastic properties. Three types of FRP materials were considered in this study including Carbon, Kevlar and Glass printed in selected arrangements of fibre filaments and Nylon matrix. An analytical model was developed based on the Volume Average Stiffness (VAS) method to predict elastic properties of 3D printed coupons, while the numerical model was developed using Abaqus to predict the failure modes and damage in the FRP 3D-printed coupons tested in this study. A parametric study was carried out to develop the mathematical expressions for calculating elastic properties of FRP 3D-printed structures. The parametric study indicates that the level of fibre reinforcements and their orientation arrangement have significant effects on the structural performance of FRP 3D-printed composite sections.

      PubDate: 2018-04-15T09:22:00Z
      DOI: 10.1016/j.compstruct.2018.03.051
      Issue No: Vol. 193 (2018)
       
  • Fracture analysis of a metal to CFRP hybrid with thermoplastic interlayers
           for interfacial stress relaxation using in situ thermography
    • Authors: Jannik Summa; Michael Becker; Felix Grossmann; Markus Pohl; Markus Stommel; Hans-Georg Herrmann
      Pages: 19 - 28
      Abstract: Publication date: 1 June 2018
      Source:Composite Structures, Volume 193
      Author(s): Jannik Summa, Michael Becker, Felix Grossmann, Markus Pohl, Markus Stommel, Hans-Georg Herrmann
      In this work a plane hybrid-structure composed of a metal and a carbon-fiber-reinforced-polymer (CFRP) constituent is introduced. Hereby an interlayer is inserted between the metal and the CFRP constituent, pursuing the task of stress relaxation. In order to study the effect of interfacial stress relaxation several thermoplastics are investigated. In situ passive thermography is used to assess the damage during quasi-static and fatigue mechanical loading. Thus, mechanical properties are correlated with corresponding damage-quantities from non-destructive testing (ndt). These results reveal that transversal cracking and mode-I delamination are the dominant failure processes, which strongly depend on the thermoplastic material. Additional finite element analysis describes strain-energy- and stressconcentrations, which coincide with the observed damage mechanisms and the origins of fracture.

      PubDate: 2018-04-15T09:22:00Z
      DOI: 10.1016/j.compstruct.2018.03.013
      Issue No: Vol. 193 (2018)
       
  • Process induced shape distortions of self-reinforced poly(ethylene
           terephthalate) composites
    • Authors: L. Jerpdal; M. Åkermo; D. Ståhlberg; A. Herzig
      Pages: 29 - 34
      Abstract: Publication date: 1 June 2018
      Source:Composite Structures, Volume 193
      Author(s): L. Jerpdal, M. Åkermo, D. Ståhlberg, A. Herzig
      This paper investigates shape distortion and tensile properties of hot consolidated Self-reinforced poly(ethylene terephthalate) (SrPET) by evaluating the influence from stretching before consolidation and annealing after consolidation. Spring-in angle and warpage is measured from V-shaped samples that are hot consolidated from a woven fabric that is stretched to different degrees during forming. Following the same process conditions, tensile stiffness is measured from plane laminates. This study confirms that stretching the SrPET-material during forming enhances the tensile modulus but introduces shape distortions with negative spring-in and increases warpage. However also non-stretched SrPET components experience spring-back in the same level as glass- or carbon reinforced PET composite, which is unexpected. The tensile modulus is reduced and spring-in angle further influenced when the SrPET-samples are exposed to higher temperature after consolidation. This study shows how easily the characteristics of a component made from SrPET-material are influenced by stresses developed during material forming and further by release of these stresses when exposed to higher temperatures as in post processes or even in the use phase of the component.

      PubDate: 2018-04-15T09:22:00Z
      DOI: 10.1016/j.compstruct.2018.03.038
      Issue No: Vol. 193 (2018)
       
  • Extended formulations of evolutive laws and constitutive relations in
           non-smooth plasticity and viscoplasticity
    • Authors: Fabio De Angelis
      Pages: 35 - 41
      Abstract: Publication date: 1 June 2018
      Source:Composite Structures, Volume 193
      Author(s): Fabio De Angelis
      Plastic and viscoplastic constitutive behavior is of interest in the mechanical modeling of many composite materials and structures. In this paper evolutive laws and constitutive relations in non-smooth plasticity and viscoplasticity are presented by means of a formulation which takes advantage of the proper concepts required to deal with non-smooth problems in plasticity and viscoplasticity. This adopted framework is endowed with considerable advantages in comparison with other formulations of non-smooth problems. In fact, subdifferential calculus shows to be the proper tool to deal with non-smooth functions and corners in plasticity and viscoplasticity. Plastic and viscoplastic constitutive models are revisited and expressed in subdifferential form by adopting the more general context presented herein that includes Koiter’s theory as a special case. The evolutive equations in plasticity and viscoplasticity are derived as optimality conditions of a suitably defined Lagrangian in a form usually not considered. Consequently, alternative equivalent expressions of the evolution laws and of the loading/unloading conditions are presented and the equivalence among them is described. Furthermore, the present approach shows to be useful for extensions into other types of elastoplastic materials and for clarifications on the relations existing between different constitutive models in non-smooth viscoplasticity.

      PubDate: 2018-04-15T09:22:00Z
      DOI: 10.1016/j.compstruct.2018.03.032
      Issue No: Vol. 193 (2018)
       
  • Free vibration of thin functionally graded viscoelastic open-cell foam
           plates on orthotropic visco-Pasternak medium
    • Authors: H.A. Zamani; M.M. Aghdam; M. Sadighi
      Pages: 42 - 52
      Abstract: Publication date: 1 June 2018
      Source:Composite Structures, Volume 193
      Author(s): H.A. Zamani, M.M. Aghdam, M. Sadighi
      The present study deals with vibration of functionally graded viscoelastic open-cell foam plates resting on three parameters orthotropic visco-Pasternak foundation. The kinematic and constitutive relations are described by classical plate theory and separable kernels framework, respectively. Viscoelastic treatment of bulk and shear moduli of plates are modeled by standard solid and Kelvin-Voigt models. Also, nonlinear non-symmetric porosity distribution through thickness is obtained using power law and neutral surface decoupling. The integro-PDE of motion with frequency-dependent coefficients is figured out by weighted residual method and iterative numerical algorithm to obtain natural frequencies and modal loss factors. In elastic domain, frequencies are compared with those reported for thin functionally graded plates resting on isotropic Pasternak foundation while in the viscoelastic domain, complex frequencies are compared for standard solid and Kelvin-Voigt viscoelastic plates where acceptable correlation is observed. Influences of various boundary conditions including fully clamped and fully free edge conditions, aspect ratio, coefficients and orthotropy angle of medium on dynamic characteristics are scrutinized via a comprehensive parametric study which could be used as benchmark results in future studies.

      PubDate: 2018-04-15T09:22:00Z
      DOI: 10.1016/j.compstruct.2018.03.061
      Issue No: Vol. 193 (2018)
       
  • High-power laser resistance of filled sandwich panel with truss core: An
           experimental study
    • Authors: Wu Yuan; Jiangtao Wang; Hongwei Song; Te Ma; Wenjun Wu; Junning Li; Chenguang Huang
      Pages: 53 - 62
      Abstract: Publication date: 1 June 2018
      Source:Composite Structures, Volume 193
      Author(s): Wu Yuan, Jiangtao Wang, Hongwei Song, Te Ma, Wenjun Wu, Junning Li, Chenguang Huang
      We reported a new function of sandwich panels with truss cores, i.e., superior performance under intense local heat flux induced by continuous wave laser. To further enhance the laser resistance, lightweight ablative material and thermal insulation material are filled in the sandwich panel respectively. A dimensional analysis is developed to find core filler materials with appropriate properties. Experiments show that sandwich panels filled with the compound of silicone resin and carbon powder, a typical ablative material, and porous ceramic, a typical thermal insulation material significantly improve the local heat flux resistance compared with monolithic plates and unfilled sandwich panels. The full-field temperature history and dynamic damage evolution of the back surface are recorded and compared, and the failure time to reach the melting point is prolonged in the following order: monolithic plate, unfilled sandwich panel, sandwich panel filled with ceramic, sandwich panel filled with the compound of silicone resin and carbon powder. Considering the lightweight design requirement of such structures, resistance in relation to specific weight is also evaluated and discussed.

      PubDate: 2018-04-15T09:22:00Z
      DOI: 10.1016/j.compstruct.2018.03.031
      Issue No: Vol. 193 (2018)
       
  • Dynamic constitutive response of novel auxetic Kevlar®/epoxy
           composites
    • Abstract: Publication date: 1 July 2018
      Source:Composite Structures, Volume 195
      Author(s): Md Fazlay Rabbi, Vijaya Chalivendra, Yong Kim
      A comprehensive experimental investigation was performed to study the dynamic compressive constitutive response of novel auxetic Kevlar®/epoxy laminated composites. Strain rate response was investigated using the split Hopkinson pressure bar (SHPB) test setup. Laminated composites were fabricated using the vacuum infusion process. Short Nylon fibers were flocked between the laminates with different flock densities and flock length. For obtaining dynamic force equilibrium in SHPB experiments, a copper pulse shaper was used to increase the rising time of incident pulse. To have a comparison, woven Kevlar®/epoxy composites were also characterized at similar strain rates. In addition, quasi-static tests were also performed on both woven and auxetic laminated composites for completeness of the study. For quasi-static loading conditions, auxetic composites showed higher peak strain and lower peak stress compared to woven composites. For non-flocked composites, both auxetic and woven composites showed rate dependency. Woven composites provided 353% increase in peak stress when the strain rate increased from 1200 s−1 (low) to 3300 s−1 (high). However, in the same conditions, auxetic composites showed only 155% increase in peak stress. For different flocking conditions, woven composites showed rate dependency for all strain rates, but auxetic composites demonstrated rate dependency only from low to medium strain rates. Both auxetic and woven composites experienced shear failure under quasi-static compression, where auxetic composites failed at higher shear angle of 37°, but woven composites had a failure angle of 30°. For impact loads, under no flocking condition, woven composites did undergo severe edge failure at all strain rates, but auxetic composites showed a sign of edge failure only at high strain rates. With the flocking condition, auxetic composites had through thickness shear failure and woven composites experienced splitting and fibrillation of Kevlar® fibers.

      PubDate: 2018-04-23T08:54:30Z
       
  • Overlap length for confinement of carbon and glass FRP-jacketed concrete
           columns
    • Abstract: Publication date: 1 July 2018
      Source:Composite Structures, Volume 195
      Author(s): Marina L. Moretti, Eftichios Arvanitopoulos
      This paper presents the experimental results of a study on the occurrence of debonding along the overlap length of fiber reinforced polymer (FRP) confined concrete prior to rupture of the FRP jacket. Plain concrete cylinders, twenty-six with 152 mm diameter and 305 mm height, and four with 100 mm diameter and 200 mm height, with cylinder compressive concrete strength 19 MPa, were wrapped with carbon- and glass-FRP jackets and tested under monotonic axial compression. Different overlap configurations and different FRP application methods were investigated. The parameters found to most significantly affect the bond resistance along the overlap zone are the type of the FRP material and the curing age of the resin when dry lay-up application is used.

      PubDate: 2018-04-23T08:54:30Z
       
  • Investigation on fatigue performance of T800 composites structural
           component
    • Abstract: Publication date: 1 July 2018
      Source:Composite Structures, Volume 195
      Author(s): Yidong Zhang, Li Zhang, Licheng Guo, Yubo Feng, Gang Liu, Xinyang Sun
      This paper presents a practical method for investigating fatigue performance of the typical structural component of carbon fiber reinforced plastic. Servo-hydraulic fatigue test machine is properly refitted to conduct the fatigue test under load controlled method. Distribution location of strain gauges is determined by finite element method (FEM). Strain values on surface are recorded with the increase of the fatigue cycle number. In the process of fatigue testing, the cracks are observed under the optical microscope. The experiment results show that failure modes of the structural component are mainly characterized by delamination which occurred in the thickness transition area. Strain will redistribute with the cracks propagating. And the suddenly decreased strain values will return to a stable level. Moreover, the application of Digital Image Correlation (DIC) technique for fatigue testing of structural component is discussed.

      PubDate: 2018-04-23T08:54:30Z
       
  • Structure dependent properties of carbon nanomaterials enabled fiber
           sensors for in situ monitoring of composites
    • Abstract: Publication date: 1 July 2018
      Source:Composite Structures, Volume 195
      Author(s): Guantao Wang, Yong Wang, Peipei Zhang, Yujiang Zhai, Yun Luo, Liuhe Li, Sida Luo
      Carbon nanomaterials enabled fibers have been witnessed as a promising technology for in situ structural health monitoring of polymeric composites. Self-sensing composites were enabled with varied integration strategies, including carbon nanotube (CNT) coated fibers (CNTF), reduced graphene oxide (RGO) coated fibers (RGOF) and carbon fibers (CF). Piezoresistive response of varied sensors was disclosed and showed that gauge sensitivity of RGOF is the highest with a clear two-stage performance from linear to non-linear, while CNTF consistently shows well-organized signal before final fracture. Resin infiltration theory was raised to explain the observed structure–property relationship. For CNTF, resin molecules are permeable to its porous network and form integrated CNT/resin nanocomposites. Comparatively, RGO with large lateral dimension and surface conformability forms the noninvasive network from resin penetration. Based on results analysis and mechanism study, CNTF is more suitable for status recognition and long-term purposes; RGOF is more feasible for early warning of structural damages.

      PubDate: 2018-04-23T08:54:30Z
       
  • Dynamic compressive response of additively manufactured AlSi10Mg alloy
           hierarchical honeycomb structures
    • Abstract: Publication date: 1 July 2018
      Source:Composite Structures, Volume 195
      Author(s): Yuwu Zhang, Tao Liu, Huan Ren, Ian Maskery, Ian Ashcroft
      Periodic honeycombs have been used for their high strength, low weight and multifunctionality. The quasi-static and dynamic compressive responses of three types of additively manufactured AlSi10Mg honeycomb structures, specifically a single-scale honeycomb and two hierarchical honeycombs with two and three levels of hierarchy, respectively, have been investigated using experimental measurement and finite element (FE) simulations. The validated FE simulation has been employed to investigate the effects of relative density of the honeycombs and the key experimental parameters. The following failure modes of the three types of honeycombs have been observed both under quasi-static and dynamic compression: (1) the single-scale honeycomb experienced a transition of failure mechanism from local plastic buckling of walls to local damage of the parent material without buckling with the increase of the relative density of the honeycomb; (2) the hierarchical honeycombs all failed with parent material damage without buckling at different relative densities. For both quasi-static and dynamic compression, the hierarchical honeycombs offer higher peak nominal wall stresses compared to the single-scale honeycomb at low relative density of ρ ¯ = 0.19 ; the difference is diminished as relative density increases, i.e. the three types of honeycombs can achieve similar peak wall stresses when ρ ¯ ⩾ 0.26 . Numerical results have suggested the hierarchical honeycombs can offer better energy absorption capacity than the single-scale honeycomb. The two-scale and three-scale hierarchical honeycombs achieved similar peak nominal wall stresses for both quasi-static and dynamic compression, which may suggest that the structural performance under out-of-plane compression is not sensitive to the hierarchical architecture. This work indicates that the structural advantage of hierarchical honeycombs can be utilised to develop high performance lightweight structural components.

      PubDate: 2018-04-23T08:54:30Z
       
  • Physically non-linear analysis of beam models using Carrera Unified
           Formulation
    • Abstract: Publication date: 1 July 2018
      Source:Composite Structures, Volume 195
      Author(s): M.R.T. Arruda, L.M.S Castro, A.J.M. Ferreira, D. Martins, J.R. Correia
      This paper presents and discusses the numerical performance of a set of physically non-linear models applied together with Carrera’s Unified Formulation (CUF) for the analysis of beams. The main objective of this work is to assess the numerical efficiency of CUF when non-linear material analysis is applied to 1D elements using the equivalent single layer (ESL) formulation. To model material behaviour this work considers three different alternative approaches: (i) the classical isotropic plasticity with no hardening, (ii) the Mazars isotropic concrete damage model, and (iii) the composite orthotropic Hashin damage model. To validate the models proposed, the numerical solutions are compared both with analytical results and experimental data. The results obtained show that it is possible to provide accurate results with CUF when physically non-linear analysis is performed, even when considering approximations involving a small number of degrees of freedom.

      PubDate: 2018-04-23T08:54:30Z
       
  • X-ray computed tomography characterization of manufacturing induced
           defects in a glass/polyester pultruded profile
    • Abstract: Publication date: 1 July 2018
      Source:Composite Structures, Volume 195
      Author(s): Ismet Baran, Ilya Straumit, Oksana Shishkina, Stepan V. Lomov
      Critical assessment of the internal geometry after manufacturing of fiber reinforced polymer composites is essential for developing more reliable and robust production. In the present work, manufacturing induced defects such as fiber misalignment and porosity in a glass/polyester pultruded composite profile are evaluated. The internal geometry of the composite is characterized by X-ray micro-computed tomography (micro-CT) and analyzed using the VoxTex software which allows validated and detailed characterization of the internal geometry. Resin rich areas are observed in between the glass rovings at which the unidirectional fibers are misaligned with respect to the desired pulling direction. Results show that the misalignment in in-plane fiber orientation is more severe (30–40°) than the out-plane fiber orientation (10–20°). Two different types of porosities are quantified: the first one is discontinuous and located inside the resin rich areas; the second one is more severe and continuously located between the glass rovings. The area of the total continuous porosity is estimated approximately as 0.212–0.246 mm2 per unit length in the pulling direction. The fiber misalignments and resin rich areas cause 15–20% reduction in the studied part stiffness in the longitudinal direction.

      PubDate: 2018-04-23T08:54:30Z
       
  • Beam on elastic foundation analysis of sandwich SCB specimen for debond
           fracture characterization
    • Abstract: Publication date: 1 July 2018
      Source:Composite Structures, Volume 195
      Author(s): Keishiro Yoshida, Takahira Aoki
      Sandwich single cantilever beam (SCB) test has attracted attention as one of the best candidates for evaluating the debond fracture toughness between face sheet and core in sandwich panels under mode I type loading. To theoretically analyze the sandwich double cantilever beam specimen, a beam on Vlasov foundation model has been proposed. In this study, the Vlasov foundation model is applied to the analysis of SCB specimen. Then, the experimental data reduction method of sandwich SCB test is examined based on the semi-analytical solution obtained by the Vlasov foundation model. The validity of the Vlasov foundation model for the analysis of sandwich SCB specimen is confirmed by comparing it with finite element analysis. The influences of the material properties and the thicknesses of face sheet and core on the data reduction method are clarified.

      PubDate: 2018-04-23T08:54:30Z
       
  • An anisotropic non-linear material model for glass fibre reinforced
           plastics
    • Abstract: Publication date: 1 July 2018
      Source:Composite Structures, Volume 195
      Author(s): J. Jansson, T. Gustafsson, K. Salomonsson, J. Olofsson, J. Johansson, P. Appelsved, M. Palm
      This paper aims to present a methodology to predict the anisotropic and non-linear behaviour of glass fibre reinforced plastics using finite element methods. A material model is implemented in order to remedy the need of multiple material definitions, and to control the local plastic behaviour as a function of the fibre orientation. Injection moulding simulations traditionally provide second order orientation tensors, which are considered together with a homogenization scheme to compute local material properties. However, in the present study, fourth order tensors are used in combination with traditional methods to provide more accurate material properties. The elastic and plastic response of the material model is optimized to fit experimental test data, until simulations and experiments overlap. The proposed material model can support design engineers in making more informed decisions, allowing them to create smarter products without the need of excessive safety factors, leading to reduced component weight and environmental impact.

      PubDate: 2018-04-23T08:54:30Z
       
  • The unit cell method in predictions of thermal expansion properties of
           textile reinforced composites
    • Abstract: Publication date: 1 July 2018
      Source:Composite Structures, Volume 195
      Author(s): Jian-Jun Gou, Chun-Lin Gong, Liang-Xian Gu, Shuguang Li, Wen-Quan Tao
      Thermal expansion properties of textile reinforced composites with certain structure symmetries can be efficiently calculated by a size-limited unit cell. In this paper, a general approach is developed for the establishment of such a unit cell model. For the derivation of unit cell boundary conditions, three rules are summarized according to the displacement fields in translational, reflectional and 180° rotational symmetric structures under a uniform temperature change loading. The application scope of present unit cell method is clarified from the thermal and mechanical point of views. Three typical composites, i.e., unidirectional fiber reinforced composite, plain woven composite and multi-harness (4HS, 5HS, 6HS, 7HS and 8HS) satin woven composites are then studied, and four, three and two size-reducing unit cells are formulated, respectively. The thermal expansion behaviors of each composite are analyzed, and the effective thermal expansion coefficients are predicted. The influence of structure symmetries on the deformation pattern of unit cell models is clarified. The numerical models are validated by the identical results obtained from unit cells of different sizes and also by the results available in literatures. The approach developed in this paper can be applied to thermal expansion studies of any other composites with relevant structure symmetries.

      PubDate: 2018-04-23T08:54:30Z
       
  • Effects of tablet waviness on the mechanical response of architected
           multilayered materials: Modeling and experiment
    • Abstract: Publication date: 1 July 2018
      Source:Composite Structures, Volume 195
      Author(s): Sina Askarinejad, Habibeh Ashouri Choshali, Christina Flavin, Nima Rahbar
      The excellent mechanical properties that biological materials possess are greatly influenced by the geometrical properties of their small scale constituents. Nacre, also known as Mother of Pearl, is an organic-inorganic composite material that makes up the inner layer of seashells. Nacre is observed for its impressive combination of stiffness, strength, and toughness which can be attributed to its waviness and the layering pattern of the brick and mortar structure of ceramic and protein that allows nacre to exhibit great mechanical energy and dissipate it over a large volume. In this study, the effect of this waviness on a model architected multilayered material system is analyzed numerically and experimentally in order to understand its effects on the stiffness, strength, and toughness of nacre. 3-D printed composites with auxetic and nacreous structure were created and tested in tensile boundary conditions. Finite element analysis was used to study the stress distribution and mechanical response of these composites. Results from the finite element models and the mechanical tests results show that increasing the tablet’s waviness increases the stiffness, however, there is an optimum value of tablet waviness for the highest strength and tensile toughness. Increasing waviness level can improve the elastic modulus by about 23%, strength by about 65% and toughness by about 42%. Using the proposed modeling approach, more detailed studies can be done on the toughening mechanisms of composite multilayered materials. These results can be used as a guide to design super-tough composites with multilayered structures.

      PubDate: 2018-04-23T08:54:30Z
       
  • Mechanical characterization and damage mechanism of a new flax-Kevlar
           hybrid/epoxy composite
    • Abstract: Publication date: 1 July 2018
      Source:Composite Structures, Volume 195
      Author(s): Clément Audibert, Anne-Sophie Andreani, Éric Lainé, Jean-Claude Grandidier
      A new composite, made with a woven constituted by Kevlar fibers and flax fibers in an epoxy resin is tested. Tensile and three-point bending tests are performed to identify mechanical properties and damage mechanisms. Compressive properties are identified by an inverse method using numerical simulation of the bending test. In addition, failure mechanisms are established by macroscopic and microscopic observations. The composite exhibits a strong non-linear anisotropic behavior. This non-linearity comes from the plastic strain of Kevlar fibers and flax fibers pull out, whereas the damaged modulus depends on the flax fibers damage. The hybrid composite has the same compression weakness as Kevlar composite, with compression properties that are lower than the tensile properties. Hybrid composite has an intermediate mechanical property between flax composite and aramid composite.

      PubDate: 2018-04-23T08:54:30Z
       
 
 
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