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  Subjects -> ENGINEERING (Total: 2298 journals)
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CIVIL ENGINEERING (192 journals)                     

Showing 1 - 192 of 192 Journals sorted alphabetically
ACI Structural Journal     Full-text available via subscription   (Followers: 17)
Acta Polytechnica : Journal of Advanced Engineering     Open Access   (Followers: 2)
Acta Structilia : Journal for the Physical and Development Sciences     Open Access   (Followers: 2)
Advances in Civil Engineering     Open Access   (Followers: 36)
Advances in Structural Engineering     Full-text available via subscription   (Followers: 28)
Agregat     Open Access  
Ambiente Construído     Open Access   (Followers: 1)
American Journal of Civil Engineering and Architecture     Open Access   (Followers: 31)
Architectural Engineering     Open Access   (Followers: 4)
Archives of Civil and Mechanical Engineering     Full-text available via subscription   (Followers: 1)
Archives of Civil Engineering     Open Access   (Followers: 10)
Archives of Hydro-Engineering and Environmental Mechanics     Open Access   (Followers: 2)
ATBU Journal of Environmental Technology     Open Access   (Followers: 4)
Australian Journal of Structural Engineering     Full-text available via subscription   (Followers: 6)
Baltic Journal of Road and Bridge Engineering     Full-text available via subscription   (Followers: 1)
BER : Building and Construction : Full Survey     Full-text available via subscription   (Followers: 10)
BER : Building Contractors' Survey     Full-text available via subscription   (Followers: 4)
BER : Building Sub-Contractors' Survey     Full-text available via subscription   (Followers: 3)
BER : Survey of Business Conditions in Building and Construction : An Executive Summary     Full-text available via subscription   (Followers: 4)
Bioinspired Materials     Open Access   (Followers: 5)
Bridge Structures : Assessment, Design and Construction     Hybrid Journal   (Followers: 16)
Building & Management     Open Access  
Building and Environment     Hybrid Journal   (Followers: 15)
Building Women     Full-text available via subscription  
Built Environment Project and Asset Management     Hybrid Journal   (Followers: 15)
Bulletin of Pridniprovsk State Academy of Civil Engineering and Architecture     Open Access   (Followers: 6)
Canadian Journal of Civil Engineering     Hybrid Journal   (Followers: 12)
Case Studies in Engineering Failure Analysis     Open Access   (Followers: 8)
Case Studies in Nondestructive Testing and Evaluation     Open Access   (Followers: 11)
Case Studies in Structural Engineering     Open Access   (Followers: 9)
Cement and Concrete Composites     Hybrid Journal   (Followers: 17)
Challenge Journal of Concrete Research Letters     Open Access   (Followers: 2)
Challenge Journal of Structural Mechanics     Open Access   (Followers: 5)
Change Over Time     Full-text available via subscription   (Followers: 2)
Civil and Environmental Engineering     Open Access   (Followers: 7)
Civil And Environmental Engineering Reports     Open Access   (Followers: 6)
Civil and Environmental Research     Open Access   (Followers: 19)
Civil Engineering = Siviele Ingenieurswese     Full-text available via subscription   (Followers: 4)
Civil Engineering and Architecture     Open Access   (Followers: 18)
Civil Engineering and Environmental Systems     Hybrid Journal   (Followers: 3)
Civil Engineering and Technology     Open Access   (Followers: 10)
Civil Engineering Dimension     Open Access   (Followers: 8)
Civil Engineering Infrastructures Journal     Open Access  
Cohesion and Structure     Full-text available via subscription   (Followers: 2)
Composite Structures     Hybrid Journal   (Followers: 268)
Computer-aided Civil and Infrastructure Engineering     Hybrid Journal   (Followers: 11)
Computers & Structures     Hybrid Journal   (Followers: 36)
Concrete Research Letters     Open Access   (Followers: 6)
Construction Economics and Building     Open Access   (Followers: 2)
Construction Engineering     Open Access   (Followers: 9)
Construction Management and Economics     Hybrid Journal   (Followers: 22)
Construction Science     Open Access   (Followers: 4)
Constructive Approximation     Hybrid Journal  
Curved and Layered Structures     Open Access   (Followers: 2)
DFI Journal : The Journal of the Deep Foundations Institute     Hybrid Journal   (Followers: 1)
Earthquake Engineering and Structural Dynamics     Hybrid Journal   (Followers: 17)
Enfoque UTE     Open Access   (Followers: 4)
Engineering Project Organization Journal     Hybrid Journal   (Followers: 7)
Engineering Structures     Hybrid Journal   (Followers: 13)
Engineering Structures and Technologies     Hybrid Journal   (Followers: 2)
Engineering, Construction and Architectural Management     Hybrid Journal   (Followers: 14)
Environmental Geotechnics     Hybrid Journal   (Followers: 5)
European Journal of Environmental and Civil Engineering     Hybrid Journal   (Followers: 9)
Fatigue & Fracture of Engineering Materials and Structures     Hybrid Journal   (Followers: 16)
Frattura ed Integrità Strutturale : Fracture and Structural Integrity     Open Access  
Frontiers in Built Environment     Open Access  
Frontiers of Structural and Civil Engineering     Hybrid Journal   (Followers: 6)
Geomaterials     Open Access   (Followers: 4)
Geosystem Engineering     Hybrid Journal   (Followers: 1)
Geotechnik     Hybrid Journal   (Followers: 3)
Géotechnique Letters     Hybrid Journal   (Followers: 7)
GISAP : Technical Sciences, Construction and Architecture     Open Access  
HBRC Journal     Open Access   (Followers: 2)
Hormigón y Acero     Full-text available via subscription  
HVAC&R Research     Hybrid Journal  
Indonesian Journal of Urban and Environmental Technology     Open Access  
Indoor and Built Environment     Hybrid Journal   (Followers: 2)
Infrastructure Asset Management     Hybrid Journal   (Followers: 2)
Infrastructures     Open Access  
Ingenio Magno     Open Access   (Followers: 1)
Insight - Non-Destructive Testing and Condition Monitoring     Full-text available via subscription   (Followers: 22)
International Journal for Service Learning in Engineering     Open Access  
International Journal of 3-D Information Modeling     Full-text available via subscription   (Followers: 3)
International Journal of Advanced Structural Engineering     Open Access   (Followers: 16)
International Journal of Civil, Mechanical and Energy Science     Open Access   (Followers: 1)
International Journal of Concrete Structures and Materials     Open Access   (Followers: 14)
International Journal of Condition Monitoring     Full-text available via subscription   (Followers: 2)
International Journal of Construction Engineering and Management     Open Access   (Followers: 9)
International Journal of Geo-Engineering     Open Access   (Followers: 3)
International Journal of Geosynthetics and Ground Engineering     Full-text available via subscription   (Followers: 4)
International Journal of Masonry Research and Innovation     Hybrid Journal   (Followers: 1)
International Journal of Pavement Research and Technology     Open Access   (Followers: 6)
International Journal of Protective Structures     Hybrid Journal   (Followers: 6)
International Journal of Steel Structures     Hybrid Journal   (Followers: 2)
International Journal of Structural Engineering     Hybrid Journal   (Followers: 10)
International Journal of Structural Integrity     Hybrid Journal   (Followers: 2)
International Journal of Structural Stability and Dynamics     Hybrid Journal   (Followers: 7)
International Journal of Sustainable Built Environment     Open Access   (Followers: 4)
International Journal of Sustainable Construction Engineering and Technology     Open Access   (Followers: 8)
International Journal on Pavement Engineering & Asphalt Technology     Open Access   (Followers: 7)
International Journal Sustainable Construction & Design     Open Access  
Journal of Bridge Engineering     Full-text available via subscription   (Followers: 15)
Journal of Building Engineering     Hybrid Journal   (Followers: 1)
Journal of Building Materials and Structures     Open Access   (Followers: 2)
Journal of Building Performance Simulation     Hybrid Journal   (Followers: 6)
Journal of Civil Engineering and Construction Technology     Open Access   (Followers: 12)
Journal of Civil Engineering and Management     Hybrid Journal   (Followers: 7)
Journal of Civil Engineering and Science     Open Access   (Followers: 8)
Journal of Civil Engineering Research     Open Access   (Followers: 6)
Journal of Civil Engineering, Science and Technology     Open Access  
Journal of Civil Society     Hybrid Journal   (Followers: 4)
Journal of Civil Structural Health Monitoring     Hybrid Journal   (Followers: 4)
Journal of Composites for Construction     Full-text available via subscription   (Followers: 13)
Journal of Computing in Civil Engineering     Full-text available via subscription   (Followers: 24)
Journal of Construction Engineering     Open Access   (Followers: 7)
Journal of Construction Engineering and Management     Full-text available via subscription   (Followers: 19)
Journal of Constructional Steel Research     Hybrid Journal   (Followers: 8)
Journal of Earth Sciences and Geotechnical Engineering     Open Access   (Followers: 4)
Journal of Fluids and Structures     Hybrid Journal   (Followers: 6)
Journal of Frontiers in Construction Engineering     Open Access   (Followers: 2)
Journal of Green Building     Full-text available via subscription   (Followers: 11)
Journal of Highway and Transportation Research and Development (English Edition)     Full-text available via subscription   (Followers: 14)
Journal of Infrastructure Systems     Full-text available via subscription   (Followers: 21)
Journal of Legal Affairs and Dispute Resolution in Engineering and Construction     Full-text available via subscription   (Followers: 5)
Journal of Marine Science and Engineering     Open Access   (Followers: 1)
Journal of Materials and Engineering Structures     Open Access   (Followers: 5)
Journal of Materials in Civil Engineering     Full-text available via subscription   (Followers: 10)
Journal of Nondestructive Evaluation     Hybrid Journal   (Followers: 11)
Journal of Performance of Constructed Facilities     Full-text available via subscription   (Followers: 4)
Journal of Pipeline Systems Engineering and Practice     Full-text available via subscription   (Followers: 7)
Journal of Rehabilitation in Civil Engineering     Open Access   (Followers: 3)
Journal of Solid Waste Technology and Management     Full-text available via subscription   (Followers: 1)
Journal of Structural Engineering     Full-text available via subscription   (Followers: 40)
Journal of Structural Fire Engineering     Full-text available via subscription   (Followers: 6)
Journal of Sustainable Architecture and Civil Engineering     Open Access   (Followers: 3)
Journal of Sustainable Design and Applied Research in Innovative Engineering of the Built Environment     Open Access   (Followers: 1)
Journal of the Civil Engineering Forum     Open Access  
Journal of the South African Institution of Civil Engineering     Open Access   (Followers: 4)
Journal of Water and Environmental Nanotechnology     Open Access  
Jurnal Spektran     Open Access   (Followers: 1)
Jurnal Teknik Sipil dan Perencanaan     Open Access   (Followers: 1)
Konstruksia     Open Access  
KSCE Journal of Civil Engineering     Hybrid Journal   (Followers: 2)
Latin American Journal of Solids and Structures     Open Access   (Followers: 4)
Materiales de Construcción     Open Access  
Mathematical Modelling in Civil Engineering     Open Access   (Followers: 3)
Nondestructive Testing And Evaluation     Hybrid Journal   (Followers: 17)
npj Materials Degradation     Open Access  
Obras y Proyectos     Open Access   (Followers: 1)
Open Journal of Civil Engineering     Open Access   (Followers: 7)
Photonics and Nanostructures - Fundamentals and Applications     Hybrid Journal   (Followers: 2)
Practice Periodical on Structural Design and Construction     Full-text available via subscription   (Followers: 4)
Proceedings of the Institution of Civil Engineers - Bridge Engineering     Hybrid Journal   (Followers: 8)
Proceedings of the Institution of Civil Engineers - Civil Engineering     Hybrid Journal   (Followers: 12)
Proceedings of the Institution of Civil Engineers - Management, Procurement and Law     Hybrid Journal   (Followers: 8)
Proceedings of the Institution of Civil Engineers - Municipal Engineer     Hybrid Journal   (Followers: 3)
Proceedings of the Institution of Civil Engineers - Structures and Buildings     Hybrid Journal   (Followers: 4)
Random Structures and Algorithms     Hybrid Journal   (Followers: 5)
Research in Nondestructive Evaluation     Hybrid Journal   (Followers: 7)
Revista IBRACON de Estruturas e Materiais     Open Access   (Followers: 1)
Road Materials and Pavement Design     Hybrid Journal   (Followers: 11)
Russian Journal of Nondestructive Testing     Hybrid Journal   (Followers: 6)
Science and Engineering of Composite Materials     Hybrid Journal   (Followers: 61)
Selected Scientific Papers - Journal of Civil Engineering     Open Access   (Followers: 3)
Slovak Journal of Civil Engineering     Open Access   (Followers: 2)
Soils and foundations     Full-text available via subscription   (Followers: 5)
Steel Construction - Design and Research     Hybrid Journal   (Followers: 3)
Structural and Multidisciplinary Optimization     Hybrid Journal   (Followers: 10)
Structural Concrete     Hybrid Journal   (Followers: 11)
Structural Control and Health Monitoring     Hybrid Journal   (Followers: 9)
Structural Engineering International     Full-text available via subscription   (Followers: 12)
Structural Mechanics of Engineering Constructions and Buildings     Open Access  
Structural Safety     Hybrid Journal   (Followers: 7)
Structural Survey     Hybrid Journal  
Structure     Full-text available via subscription   (Followers: 23)
Structure and Infrastructure Engineering: Maintenance, Management, Life-Cycle Design and Performance     Hybrid Journal   (Followers: 13)
Structures     Hybrid Journal   (Followers: 1)
Study of Civil Engineering and Architecture     Open Access   (Followers: 9)
Superlattices and Microstructures     Hybrid Journal   (Followers: 2)
Surface Innovations     Hybrid Journal  
Technical Report Civil and Architectural Engineering     Open Access  
Teknik     Open Access  
The IES Journal Part A: Civil & Structural Engineering     Hybrid Journal   (Followers: 6)
The Structural Design of Tall and Special Buildings     Hybrid Journal   (Followers: 6)
Thin Films and Nanostructures     Full-text available via subscription   (Followers: 2)
Thin-Walled Structures     Hybrid Journal   (Followers: 4)
Transactions of the VŠB - Technical University of Ostrava. Construction Series     Open Access   (Followers: 1)
Transportation Geotechnics     Full-text available via subscription   (Followers: 1)
Transportation Infrastructure Geotechnology     Hybrid Journal   (Followers: 8)
Underground Space     Open Access  
Water Science & Technology     Partially Free   (Followers: 25)
Water Science and Technology : Water Supply     Partially Free   (Followers: 22)


Journal Cover Composite Structures
  [SJR: 2.408]   [H-I: 92]   [268 followers]  Follow
   Hybrid Journal Hybrid journal (It can contain Open Access articles)
   ISSN (Print) 0263-8223
   Published by Elsevier Homepage  [3118 journals]
  • Form-finding method for multi-mode tensegrity structures using extended
           force density method by grouping elements
    • Abstract: Publication date: 1 March 2018
      Source:Composite Structures, Volume 187
      Author(s): Jianguo Cai, Xinyu Wang, Xiaowei Deng, Jian Feng
      Multistable tensegrity structures are an intriguing form of compliant prestressed structures. Due to their attractive properties, these structures are attractive for a wide range applications. This papers aims the form-finding problem of tensegrity structures with multiple equilibrium modes. An optimization method for form-finding of multi-mode tensegrity structures is applied and then an equivalent optimization problem of energy-based objective function with Lagrange multiplier, regarded as an extension of the original force density method, is established. After the structural elements are grouped according to the property of symmetry, the objective function is minimized by the gradient descent algorithm, and as a result, the lengths of cable as well as the nodal coordinates are obtained and different structural modes corresponding to different grouping conditions can be achieved. Finally, several different modes in different grouping conditions of a planar and a spatial tensegrity structure have been obtained to verify the efficiency of proposed method.

      PubDate: 2017-12-27T13:25:39Z
  • On the bulk modulus and natural frequency of fullerene and nanotube carbon
           structures obtained with a beam based method
    • Abstract: Publication date: 1 March 2018
      Source:Composite Structures, Volume 187
      Author(s): M. Braun, J. Aranda-Ruiz, M. Rodríguez-Millán, J.A. Loya
      In this work, the natural frequency of vibration and Bulk modulus under hydrostatic pressure conditions of carbon nanotubes and fullerenes are investigated. For this purpose, three-dimensional finite element modelling is used in order to evaluate the vibration characteristics and radial stiffness for different nanotube and fullerene sizes. The atomistic method implemented in this work is based on the notion that nanotubes, or fullerenes, are geometrical frame-like structures where the primary bonds between two neighbouring atoms act like load-bearing beam members, whereas an individual atom acts as the joint of the related load-bearing system. The current numerical simulations results are compared with data reported by other authors, highlighting the greater simplicity and the lower computational cost of the model implemented in this work compared to other molecular dynamics models, maintaining accuracy in the results provided.

      PubDate: 2017-12-27T13:25:39Z
  • An enhanced spring-mass model for stiffness prediction in single-lap
           composite joints with considering assembly gap and gap shimming
    • Abstract: Publication date: 1 March 2018
      Source:Composite Structures, Volume 187
      Author(s): Yuxing Yang, Xueshu Liu, Yi-Qi Wang, Hang Gao, Yongjie Bao, Rupeng Li
      An enhanced spring-mass stiffness model was proposed, which was based on the supposition that the transverse shear stress under preload satisfies conical and spherical envelope, to predict the stiffness of the single-lap single-bolt composite joint with considering assembly gap and gap shimming. The validation experiments were conducted for different configurations. It shows that the analytical results were all in good agreement with the experimental results. Meanwhile, experimentally validated finite element model was used as an assistant validation in consideration of convenience and cost saving. The presented analytical model was then used for parameter studies, including gap size, gap radius and shim thickness. The major conclusions are: 1) as gap size increases 0.1 mm, the shear stiffness decreases about 1.1%; 2) the shear stiffness quickly becomes zero when the gap radius exceeds the boundary of the highly stressed portion; 3) shim thickness has much greater influence on the bolt stiffness than on the shear stiffness.

      PubDate: 2017-12-27T13:25:39Z
  • Investigation on the static and dynamic behaviors of non-pneumatic tires
           with honeycomb spokes
    • Abstract: Publication date: 1 March 2018
      Source:Composite Structures, Volume 187
      Author(s): Xiaochao Jin, Cheng Hou, Xueling Fan, Yongle Sun, Jinan Lv, Chunsheng Lu
      Non-pneumatic tires (NPTs) have wide application prospects due to their advantages of no run-flat, no need of air pressure maintenance, and low rolling resistance. In this paper, the static and dynamic behaviors of NPTs with different honeycomb spokes were investigated. Based on the static behavior of three types of NPTs with the same cell wall thickness of honeycomb or the same reference load carrying capacity, it is shown that the maximum stresses in spokes and tread of a NPT are much lower than that of traditional pneumatic tires, but its load carrying capacity is higher than the latter. In comparison with the dynamic behavior of three types of NPTs designed with the same load carrying capacity, it is found that the stress level in spokes and tread under dynamic loading are higher than that under static loading. The rolling resistance of NPTs with the smallest cell expanding angle is lowest, which is due to the lowest mass and smallest deformation of honeycomb spokes. Taking all these factors into account, it is suggested that an optimal NPT in applications is one with a small cell expanding angle and wall thickness.

      PubDate: 2017-12-27T13:25:39Z
  • Deterministic and probabilistic homogenization limits for particulate
           composites with nearly incompressible components
    • Abstract: Publication date: 1 March 2018
      Source:Composite Structures, Volume 187
      Author(s): Marcin Kamiński
      Conventional expressions for the homogenized tensor components relevant to the particulate composites consisting of two linear elastic constituents are modified here towards application of the incompressible component. This analysis is subdivided into two important engineering situations – a combination of the incompressible rubber particle with polymeric matrix and of the incompressible rubber matrix with carbon particles. This modification is done by limit transition with Poisson ratio to its upper physical limit and, further, by assuming that contrast parameter in-between Young moduli of both components tends to 0. Such an approach enables also for an analytical calculation of the sensitivity coefficients of effective elastic characteristics with respect to material or geometrical parameters of both composites, which can be a starting point for widely available gradient optimization techniques. Analytical formulas obtained in deterministic case are then used in uncertainty analysis where analytical formulas for the basic probabilistic moments and coefficients of the effective tensor are obtained while randomizing some material or geometrical parameters of the polymer matrix or carbon particles. Fundamental value of this approach is that the first two probabilistic moments, cross-correlations as well as probabilistic entropies are given by the exact analytical equations, so that they are not affected by statistical and non-statistical computer methods errors.

      PubDate: 2017-12-27T13:25:39Z
  • Flexoelectric effect on the bending and vibration responses of
           functionally graded piezoelectric nanobeams based on general modified
           strain gradient theory
    • Abstract: Publication date: 15 February 2018
      Source:Composite Structures, Volume 186
      Author(s): Liangliang Chu, Guansuo Dui, Chengjian Ju
      Flexoelectric effect has been defined as the coupling between strain gradient and electric polarization, however, how to harvest remarkable polarization energy induced by flexoelectric effect is the key problem. The present work is to study the flexoelectric effect in functionally graded composite nanostructure with a volume fraction distribution function. And a more general modified strain gradient theory is used to reformulate the constitutive equations and a more scientific evaluation system is introduced to measure the electric polarization density field for static bending and free vibration behaviors of functionally graded piezoelectric nanobeams. Meanwhile, we put forward a new and simple volume fraction distribution function with two-parameters and the physical surface position for such nanobeams in which the material properties vary in the thickness direction is determined. Numerical results indicate that flexoelectric effect can observably influence the electromechanical response in functionally graded piezoelectric nanobeam at nanometer scale and the pertinent physical insights are also discussed. And the emerging functionally graded materials are significant and may help to resolve tantalizing application of flexoelectric effect on practical engineering.

      PubDate: 2017-12-27T13:25:39Z
  • Damage detection versus heat dissipation in E-glass/Epoxy laminated
           composites under dynamic compression at high strain rate
    • Abstract: Publication date: 15 February 2018
      Source:Composite Structures, Volume 186
      Author(s): M. Tarfaoui, A. El Moumen, H. Ben Yahia
      In this investigation, a new experimental technique in which the deformation, damage mode, and the temperature are measured simultaneously during a high strain rate on laminated composites materials. The composites consist of unidirectional E-glass fibers reinforced epoxy polymer composites used in industrial applications. The experimental setup consists of a compression Split Hopkinson Pressure Bar (SHPB), a high-speed infrared camera and a high-speed Fastcam rapid camera. Specimens, with cubic like a shape, are impacted at different strain rates ranging from 200 to 2000 s−1. During impact test, the specimen surface is controlled and monitored with the infrared camera which provides thermal images in time sequence and with high-speed camera which acquires the damage progressive in specimens. Experimental results show that the damage throughout specimens differs and the temperature change depending on the damage mode and their maximum exceed 219 °C.

      PubDate: 2017-12-27T13:25:39Z
  • Pull-out performance of rectangular z-pins in hot-cured carbon fiber
           reinforced laminates
    • Abstract: Publication date: 15 February 2018
      Source:Composite Structures, Volume 186
      Author(s): Julian Hoffmann, Gerhard Scharr
      This paper presents an experimental study on the pull-out performance of circular and rectangular z-pins in hot-cured carbon fiber/epoxy laminates. Pull-out specimens with two different ply stacking sequences (unidirectional and quasi-isotropic) were reinforced with z-pins, arranged in a 4 × 4 pattern and a volume content of 2.0%. Rectangular z-pins were found to provide much higher bridging forces in both unidirectional and quasi-isotropic laminates. Since this enhancement cannot be solely attributed to the larger surface area provided by the rectangular z-pins, optical microscopy was used to investigate the interface between the z-pins and the surrounding laminate. Results showed that a change in the debonding behavior after the post-curing cool-down period leads to higher achievable shear stresses within the pin/laminate interface, and thereby, to superior bridging loads during pin pull-out.

      PubDate: 2017-12-27T13:25:39Z
  • Nonlinear bending of functionally graded porous micro/nano-beams
           reinforced with graphene platelets based upon nonlocal strain gradient
    • Abstract: Publication date: 15 February 2018
      Source:Composite Structures, Volume 186
      Author(s): Saeid Sahmani, Mohammad Mohammadi Aghdam, Timon Rabczuk
      Fast improvements in technology causes to provide the ability to manipulate porous graded materials for using in directed design of micro/nano-structures. The prime objective of the current study is to anticipate the size-dependent nonlinear bending of functionally graded porous micro/nano-beams reinforced with graphene platelets, and subjected to the uniform distributed load together with an axial compressive load. Via the nonlocal strain gradient theory of elasticity, two entirely different features of size effects are incorporated in the third-order shear deformable beam model. In addition to the uniform distribution of porosity, three different functionally graded porosity distributions along the thickness of micro/nano-beams are supposed in such a way that the relationship between coefficients related to the relative density and porosity is considered for an open-cell metal foam. On the basis of Hamilton's principle, the non-classical governing differential equations of motion are established. After that, the Galerkin method in conjunction with an improved perturbation technique is utilized to attain explicit analytical expressions for nonlocal strain gradient load-deflection paths of the functionally graded porous micro/nano-beams reinforced with the graphene nanofillers. It is observed that the type of porosity dispersion pattern has no considerable influence on the significance of size effects. However, by approaching the axial compressive load to the critical buckling value, the significance of the both nonlocality and strain gradient size dependencies on the nonlinear bending behavior of functionally graded porous micro/nano-beams increases, and this increment in the nonlocal small scale effect is more considerable than in the strain gradient one.

      PubDate: 2017-12-27T13:25:39Z
  • Numerical simulations of impact fracture behavior of an automotive
           windshield glazing: An intrinsic cohesive approach
    • Abstract: Publication date: 15 February 2018
      Source:Composite Structures, Volume 186
      Author(s): Dejia Lin, Di Wang, Shunhua Chen, Mengyan Zang
      As an important component of a vehicle, the automotive windshield glazing normally consists of two glass sheets bonded with one polyvinyl butyral (PVB) film. In the context of pedestrian-vehicle accidents, the impact cracking mechanism of the windshield is conductive to pedestrian safety protection and traffic accident reconstruction. The purpose of this paper is to validate the capacity of the intrinsic cohesive zone model (CZM) in impact fracture simulations of a windshield. A windshield finite element (FE) model is established, where cohesive elements are inserted into all the common faces between glass hexahedral finite elements. The fracture behavior of a windshield impacted by a standard adult headform impactor is simulated with the commercial explicit finite element code LS-DYNA. Numerical simulation results are validated by comparison with the corresponding experimental outcomes. For comparison, additional simulations have been performed by the widely used element deletion method (EDM) with a plasticity strain failure criterion. Simulation results show that the intrinsic CZM is more suitable to capture the impact failure characteristics of windshield. Finally, the effects of the glass cohesive strength, mechanical properties of PVB and interfacial adhesion on the impact fracture behavior of the windshield are investigated.

      PubDate: 2017-12-27T13:25:39Z
  • Strain rate effects on the intralaminar fracture toughness of composite
           laminates subjected to compressive load
    • Abstract: Publication date: 15 February 2018
      Source:Composite Structures, Volume 186
      Author(s): Bruno Martins Leite, Luiz Fernando Martins Leite, Vitor Luiz Reis, Maurício Vicente Donadon, Nubia Nale Alves da Silveira
      This paper presents an experimental and numerical study focused on the mode-I intralaminar toughness characterization of a woven carbon/epoxy composite loaded in compression and subjected to high strain rates. Simulations for non-standardized Single Edge Notch Bending (SENB) and Double Edge Notch (DEN) specimens were carried out using a continuum damage mechanics based failure model implemented as an user defined material model within ABAQUS software. A Finite Element Model was used in order to produce an optimal specimen for intralaminar fracture toughness tests. A new data reduction scheme based on the numerical evaluation of the strain energy release rate using the J-integral method is proposed to determine the stress intensity factor for composites. The proposed methodology accounts for finite geometry and material anisotropy effects. The dynamic tests were carried out at strain rates of 560 s - 1 , 690 s - 1 , 770 s - 1 using an adapted version of the Split Hopkinson Pressure Bar. A high-speed camera was used for monitoring the crack propagation. A Scanning Electron Microscope (SEM) was used to aid the fractographic analyses on the damaged surface of the tested samples searching for the possible failures mechanisms within the material. The experimental results indicated that the composite laminates studied herein are very sensitive to the strain rate effects.

      PubDate: 2017-12-27T13:25:39Z
  • Optimization of the design of radar-absorbing composite structures using
           response surface model with verification using scanning free space
    • Abstract: Publication date: 15 February 2018
      Source:Composite Structures, Volume 186
      Author(s): Dae-Sung Son, Jong-Min Hyun, Jung-Ryul Lee, Won-Jun Lee
      In this paper, we propose an optimization method for the design of radar-absorbing structures (RAS) made of fiber reinforced plastic structures using a response surface model and a verification method using a scanning free space measurement (S-FSM) system. The two kinds structures designed were an RAS with a layer of carbon nanotubes (CNT) and an RAS with a periodic patterned carbon paste layer. In the optimal design, the objective function was set so that the absorbing frequency bandwidth had the maximum value, in order to have stealth functionality in the X-band. The RAS with CNT layer had a higher minimum reflection loss than that with carbon paste layer, and the absorbing frequency bandwidth was lower. Two specimens were fabricated on the basis of the analysis results, and the design results were verified by evaluating their electromagnetic performance using an S-FSM system capable of measuring reflection loss. As a result, it was confirmed that not only the electromagnetic performance of the specimen but also the defects caused by the manufacturing process could be detected using the S-FSM.

      PubDate: 2017-12-27T13:25:39Z
  • Enhancement of non-linear thermal stability of temperature dependent
           laminated beams with graphene reinforcements
    • Abstract: Publication date: 15 February 2018
      Source:Composite Structures, Volume 186
      Author(s): Y. Kiani, M. Mirzaei
      Present investigation deals with the thermal postbuckling behaviour of a composite laminated beam where graphene is used as reinforcement of each lamina. The composite laminated beam may be piecewise functionally graded by changing the volume fraction of graphene in each lamina. Mechanical properties in each layer are obtained according to the modified Halpin-Tsai approach which contains efficiency parameters to capture the size dependency of the nanocomposite properties. Thermomechanical properties of the matrix and reinforcements are assumed to be temperature dependent. Beam is resting on an elastic foundation which acts in compression as well as in tension. The first order shear deformation beam theory and von Kármán type of geometrical nonlinearity are used as the basic assumptions to establish the total strain energy of the system. Beam is subjected to uniform temperature elevation. With the aid of conventional Ritz method and the simple polynomials as the basic functions, the matrix representation of the governing equations is derived. The adopted solution method may be used for arbitrary combinations of boundary conditions. The obtained system of equations is nonlinear in terms of both temperature and displacements. An iterative displacement control strategy is proposed to extract the thermal postbuckling curves of the beam resting on a conventional elastic foundation. Numerical results are given to discuss the effects of graphene distribution, stacking sequence, boundary conditions, side to thickness ratio and foundation stiffness on critical buckling temperature and thermal postbuckling equilibrium path of the beam. It is shown that, through a piecewise functionally graded distribution of graphene in matrix, critical buckling temperature may be enhanced significantly and thermal postbuckling deflection may be alleviated.

      PubDate: 2017-12-27T13:25:39Z
  • Bending and free vibration analysis of functionally graded graphene vs.
           carbon nanotube reinforced composite plates
    • Abstract: Publication date: 15 February 2018
      Source:Composite Structures, Volume 186
      Author(s): Enrique García-Macías, Luis Rodríguez-Tembleque, Andrés Sáez
      Carbon-based nanomaterials have drawn the attention of a large section of the scientific community in recent years. Most research has focused on carbon nanotubes after some experimental studies reported outstanding enhancements of the mechanical properties of polymeric matrices doped with small filler concentrations. Nevertheless, some limiting factors such as high manufacturing cost and difficulty in obtaining adequate uniform dispersions still remain an obstacle to the extensive manufacturing of these composites. Conversely, recent investigations demonstrate the superior properties of graphene, as well as better dispersion and relatively low manufacturing cost. Although these recent findings have begun to turn the attention towards graphene, the number of publications dealing with the theoretical analysis of graphene-reinforced structural elements is rather scant. In this context, the present work reports the bending and vibrational behavior of functionally graded graphene- and carbon nanotube-reinforced composite flat plates. The macroscopic elastic moduli of the composites are computed by means of the Mori–Tanaka model. The results demonstrate superior load bearing capacity of graphene-reinforced composite plates for both fully aligned and randomly oriented filler configurations. In addition, defects in the microstructure stemming from agglomeration and restacking of graphene sheets into graphite platelets are also analyzed.

      PubDate: 2017-12-27T13:25:39Z
  • Free vibration of laminated and FGM/CNT composites annular thick plates
           with shear deformation by discrete singular convolution method
    • Abstract: Publication date: 15 February 2018
      Source:Composite Structures, Volume 186
      Author(s): Kadir Mercan, Ali Kemal Baltacıoglu, Ömer Civalek
      Free vibration analysis of laminated composite and functionally graded materials (FGM) composite annular plates is investigated. The equations of motion of annular plates have been obtained via conical shell equations. Shear deformation theory is used for shell equation of motion. After the implementation of the Regularized Shannon delta (RSD) kernel and Lagrange delta sequence (LDS) kernel, the method of discrete singular convolution (DSC) is used for numerical solution of the governing equations to obtain the frequency values. To verify the accuracy of this method, comparisons of the present results are made with results available in the open literature. Some parametric results for annular plates and conical panels have depicted for isotropic, laminated composite and functionally graded composite materials. It is found that the convergence and accuracy of the present DSC method is very good for vibration problem of annular plates with functionally graded materials (FMG) and laminated composite cases. Some results about carbon nanotube reinforced (CNTR) composite plate have also been approved.

      PubDate: 2017-12-27T13:25:39Z
  • A new method to reduce delaminations during drilling of FRP laminates by
           feed rate control
    • Abstract: Publication date: 15 February 2018
      Source:Composite Structures, Volume 186
      Author(s): L. Sorrentino, S. Turchetta, C. Bellini
      Assembling of parts made of composite materials is often obtained by bolted or riveted joints. Therefore, drilling is one of the most common machining operation for composite laminates. However, this process causes some kinds of damage on the laminates, as delamination; the aim of this work is to reduce the delamination of the laminate. First of all, in this paper the influence of cutting parameters on the drilling process was studied for both CFRP and GFRP laminates, focusing the attention on the measurement of the forces acting on the laminate for several values of cutting speed and feed rate. Then both peel-up and push-out delamination factors were evaluated and related to the measured forces. In such manner, harmful sets of cutting parameter, capable of damaging the laminate, were identified. This analysis was useful for defining a new method to reduce push-out delamination, that was introduced and verified.

      PubDate: 2017-12-27T13:25:39Z
  • Dynamic analysis of isotropic sandwich cylindrical shell with fractional
           viscoelastic core using Rayleigh–Ritz method
    • Abstract: Publication date: 15 February 2018
      Source:Composite Structures, Volume 186
      Author(s): M. Mokhtari, M.R. Permoon, H. Haddadpour
      This paper presents the dynamic behavior of a sandwich circular cylindrical shell with a constrained fractional viscoelastic layer. Based on the Donnell-Moshtari theory, the structural formulation of the cylinder is obtained using the Lagrange method and the Rayleigh–Ritz method is implemented to solve the discretized governing equations. To describe the mechanical properties of the viscoelastic layer, the fractional order standard solid model is applied. The effects of variation of the governing parameters such as the length to radius ratio, the radius to total thickness ratio, ratio of core to facing thickness, fractional order parameter and the ratio of non-relaxed to relaxed modulus on the frequency and loss factor of sandwich cylindrical shells are investigated and some conclusions are outlined.

      PubDate: 2017-12-27T13:25:39Z
  • Influence of low-velocity impact on residual tensile properties of
           nonwoven flax/epoxy composite
    • Abstract: Publication date: 15 February 2018
      Source:Composite Structures, Volume 186
      Author(s): Mohamed Habibi, Luc Laperrière, Hojjat Mahi Hassanabadi
      This paper addresses the damage resistance and post-impact damage effect on residual tensile properties of nonwoven flax fibers reinforced epoxy composites subjected to low-velocity impact. Two different impactors: hemispherical and conical, at six different impact energy levels: 4 J, 6 J, 8 J, 10 J, 12 J and 14 J were assessed. The experimental results to investigate the influence of impactor type suggest that the penetration of the impactor and induced damage are more important with a conical impactor. The post-impact damage patterns and failure mechanisms of impacted samples were characterized by ultrasonic C-scan inspection. Results suggest that damage induced by the impact included matrix cracking, and delamination, which are more important with a conical impactor. Tensile properties show a significant effect of the impact induced damage on the performance of the composite. A particular effect was identified for an impact energy from 8 J, where the tensile modulus E0 and E1 are decreased by 53.5% and 59.3%, respectively. This effect was also confirmed by the examination of the strain map, describing the deformation behavior of the material at different impact energy, where a stress concentration localized in the impacted zones was identified.

      PubDate: 2017-12-27T13:25:39Z
  • Inverse method for estimation of composite kink-band toughness from
           open-hole compression strength data
    • Abstract: Publication date: 15 February 2018
      Source:Composite Structures, Volume 186
      Author(s): Luke Borkowski, Rajesh S. Kumar
      Fiber-reinforced polymer matrix composite materials can fail by kink-band propagation mechanism when subjected to in-plane compressive loading. This mode of failure is especially prevalent in compressive loading of laminates with holes, cut-outs, or impact damage. Most of the successful models for predicting compressive strength of such laminates require “fracture” toughness associated with kink-band propagation under in-plane compression. However, this property is difficult to measure experimentally, limiting the use of such models in design practice. In this paper an inverse method is proposed to estimate the kink-band toughness of the laminate from its open-hole compression strength data, which is an easier property to measure experimentally. Furthermore, a scaling relationship is proposed to estimate kink-band toughness for other laminate configurations of the same material. Through various investigations, it is shown that the developed inverse method and scaling relationships can serve as effective and accurate tools in the prediction of open-hole compression and compression after impact strengths for multiple layups of different material systems.

      PubDate: 2017-12-27T13:25:39Z
  • Multi-material topology optimization design for continuum structures with
           crack patterns
    • Abstract: Publication date: 15 February 2018
      Source:Composite Structures, Volume 186
      Author(s): Thanh T. Banh, Dongkyu Lee
      This study proposes a compliance multi-material topology optimization design of continuum structures with the dependence of crack patterns. Multi-material optimal topology and shape are produced as an alternative to prevent the propagation of crack patterns. The extended finite element method (X-FEM) is used to be a mechanical description approach of strong discontinuity state such as the present cracks. Heaviside enrichment and linear elastic asymptotic displacement fields are added to the finite element approximation without mesh generation near initial cracks. Element density distribution contours of mixing multiple material densities are linked to Solid Isotropic Material with Penalization (SIMP) as a design model. The mathematical formulation of multi-material topology optimization problem solving minimum structural compliance is an alternating active-phase algorithm with the Gauss–Seidel version as an optimization model of optimality criteria. Several numerical examples considering the number, length, angle and location of cracks with or without retrofitting solid passive multi-material verify the efficiency of the present design method using of multiple materials and with the dependence of different crack patterns occurring at continuum structures.

      PubDate: 2017-12-27T13:25:39Z
  • Finite element analysis of low-velocity impact response of convex and
           concave composite laminated shells
    • Abstract: Publication date: 15 February 2018
      Source:Composite Structures, Volume 186
      Author(s): Ik Hyeon Choi
      The transient response of composite laminated cylindrical shells with convex and concave shapes, subjected to low-velocity impact, was numerically investigated. Geometrically linear analysis without consideration of the membrane effect demonstrated the same contact force and central deflection histories for convex and concave shells. This unexpected numerical result could be explained by the detailed investigation of all stiffness matrix terms of the finite element equation. Furthermore, in the geometrically linear analysis, the dynamic strain distribution on the top surface of the convex shell exhibited the same contour shapes as those on the bottom surface of the concave shell, with the exception of only a reversed value between the tensile and compressive strains. This unique numerical result could also be explained by the detailed investigation of each term of the strain-displacement relation. Finally, we can conclude that geometrically nonlinear analysis must be performed with consideration of the membrane effect of the curved shell, in order to accurately analyse its impact response.

      PubDate: 2017-12-27T13:25:39Z
  • Modelling and simulating of the compressive behavior of T-stiffened
           composite panels subjected to stiffener impact
    • Abstract: Publication date: 15 February 2018
      Source:Composite Structures, Volume 186
      Author(s): Wei Sun, Zhidong Guan, Zengshan Li, Tian Ouyang, Ye Jiang
      In this paper, an equivalent damage model was proposed to predict the compressive behavior of three T-stiffened composite panels subjected to low velocity stiffener impact. A softening inclusion model combined with the reduction of material properties was used to describe the impacted stiffener damage. The progressive damage of the impacted stiffener and the failure of the panels under compression were simulated within the finite element software package ABAQUS. Compression-After-Impact (CAI) numerical results show that the compressive buckling modes of the stiffened panels are influenced by the damage degree of the impacted stiffener, and the fracture of the impacted stiffener triggers the global buckling of the panel. The buckling and failure loads of the panels predicted by this paper are in good agreement with the experimental results, which proves the validity of the model.

      PubDate: 2017-12-27T13:25:39Z
  • Durability of sandwich composites under extreme conditions: Towards the
           prediction of fire resistance properties based on thermo-mechanical
    • Abstract: Publication date: 15 February 2018
      Source:Composite Structures, Volume 186
      Author(s): Georgio Rizk, Vincent Legrand, Khaled Khalil, Pascal Casari, Frédéric Jacquemin
      The main objective of the present study was to develop a fire thermal model able to predict the evolution of the temperature gradient across a sandwich composite structure when exposed to fire. Thermal response of sandwich panels, with glass/polyester skins and balsa core, was investigated under severe temperature conditions as samples were exposed to high temperatures up to 570 °C. Based on experimental measurements, an accurate three-dimensional thermal model was developed using finite element analysis. The obtained predictions of the temperature field are in excellent agreement with the experimental data, showing the importance of combined numerical-experimental analyses. This allowed us to propose a new approach that can be used for the prediction of thermo-mechanical post-combustion properties in a very large number of fire and material scenarios according to its simplicity and robustness.

      PubDate: 2017-12-27T13:25:39Z
  • Effect of unidirectional prepreg size on punching of pseudo-ductile CFRP
           laminates and CFRP/metal hybrid composites
    • Abstract: Publication date: 15 February 2018
      Source:Composite Structures, Volume 186
      Author(s): Yu-Chien Ho, Jun Yanagimoto
      Punching is an efficient and economical process for producing a hole in structures for functional requirements, repair, maintenance, and so forth. Toward extending the use of punching to new materials, the punching of multilayer CFRP laminates and CFRP/metal hybrid composites was investigated. In this paper, the effect of the unidirectional (UD) prepreg size on the shear behavior of pseudo-ductile CFRP laminates and CFRP/metal hybrid composites is discussed on the basis of experimental observations. CFRP laminates were individually fabricated using standard (149 g/m2) and thin-ply (62 g/m2) prepregs, and were bonded with three metals (aluminum alloy A6061, magnesium alloy AZ31, and advanced high-strength steel SPFC980) by utilizing an autoclave (co-curing) and adhesive glue for hybrid composite application, then punched by a circular die and punch tool at room temperature. The effects of the UD prepreg size on the punch force, punching resistance (Ks), quality, and sheared surfaces of the through-holes are discussed. The shear behavior for punching in different composites was also studied by microscopic examination. Our results are expected to enable quantitative design for the development of punched CFRP laminates and CFRP/metal hybrid composites.

      PubDate: 2017-12-27T13:25:39Z
  • Design of blended/tapered multilayered structures subjected to buckling
    • Abstract: Publication date: 15 February 2018
      Source:Composite Structures, Volume 186
      Author(s): Aleksander Muc
      A general analytical procedure is proposed to design tapered laminated composite structures. It is based on: 1) the introduction of two variables representing a laminate configuration, 2) the analytical determination of the lower bound of the number of layers in each of the segments constituting the construction, 3) the definition of the reference sublaminate which configuration is transferred to all segments/parts of the construction, 4) the gradual building of configurations for symmetric balanced laminates having odd or even number of plies. The solution is verified by the comparison with results existing in the literature for both inner and outer tapers. A multi-panel composite structure is considered to demonstrate the applicability of the proposed method. As usual, in a such class of problems, the whole construction is divided into segments/panels. The individual segments are subjected to the simultaneous action of in-plane, tensile or compressive and shear loads. The present results demonstrate the simplicity and effectiveness of the method and non-uniqueness of solutions. The paper intends to clarify the physical sense of the discussed problem.

      PubDate: 2017-12-27T13:25:39Z
  • Glued-in basalt FRP rods under combined axial force and bending moment: An
           experimental study
    • Abstract: Publication date: 15 February 2018
      Source:Composite Structures, Volume 186
      Author(s): Caoimhe O'Neill, Daniel McPolin, Su E. Taylor, Tony Martin, Annette M. Harte
      Glued-in rods have potential for use as moment-resisting connections in timber structures. There has been minimal research to date conducted on the performance of glued-in rods acting under both axial force and moment. The influence of increasing embedded length of the glued-in rod on the strength of the system was assessed using a pull-bending test which subjected the connection to this force combination. The longest length (600 mm) had a pull-out capacity 213% greater than the shortest (80 mm). To reduce instances of splitting in the timber end distance was varied. Optimum end distance of 42 mm (3.5dr ) was identified with further increase having minimal impact upon overall strength.

      PubDate: 2017-12-27T13:25:39Z
  • Torsional vibration of size-dependent viscoelastic rods using nonlocal
           strain and velocity gradient theory
    • Abstract: Publication date: 15 February 2018
      Source:Composite Structures, Volume 186
      Author(s): S. El-Borgi, P. Rajendran, M.I. Friswell, M. Trabelssi, J.N. Reddy
      In this paper the torsional vibration of size-dependent viscoelastic nanorods embedded in an elastic medium with different boundary conditions is investigated. The novelty of this study consists of combining the nonlocal theory with the strain and velocity gradient theory to capture both softening and stiffening size-dependent behavior of the nanorods. The viscoelastic behavior is modeled using the so-called Kelvin–Voigt viscoelastic damping model. Three length-scale parameters are incorporated in this newly combined theory, namely, a nonlocal, a strain gradient, and a velocity gradient parameter. The governing equation of motion and its boundary conditions for the vibration analysis of nanorods are derived by employing Hamilton’s principle. It is shown that the expressions of the classical stress and the stress gradient resultants are only defined for different values of the nonlocal and strain gradient parameters. The case where these are equal may seem to result in an inconsistency to the general equation of motion and the related non-classical boundary conditions. A rigorous investigation is conducted to prove that the proposed solution is consistent with physics. Damped eigenvalue solutions are obtained both analytically and numerically using a Locally adaptive Differential Quadrature Method (LaDQM). Analytical results of linear free vibration response are obtained for various length-scales and compared with LaDQM numerical results.

      PubDate: 2017-12-27T13:25:39Z
  • Forced vibration analysis of functionally graded porous deep beams
    • Abstract: Publication date: 15 February 2018
      Source:Composite Structures, Volume 186
      Author(s): Şeref Doğuşcan Akbaş
      The purpose of this study is to investigate forced vibration analysis of functionally graded porous deep beams under dynamically load. Mechanical properties of the functionally graded deep beam change in the thickness direction with porosity. The beam theories fail to satisfy in the calculation and the boundary conditions of deep beams. So, the plane solid continua model is used in the calculation of deep beams in order to obtain more realistic results. The governing equations of the problems are obtained by using the Hamilton procedure. In the solution of the problem, finite element method is used within the plane solid continua model. The effects of porosity parameters, material distribution and porosity models on the forced vibration responses of functionally graded deep beams are examined and discussed with porosity effects. Numerical results show that porosity plays very important role in the dynamic responses of the functionally graded deep beam. Choosing the suitable functionally graded material distribution, negative effects of the porosity can be decreased. It is necessary to use the plane solid continua model in modelling the deep beams.

      PubDate: 2017-12-27T13:25:39Z
  • Performance of a graphite wafer-reinforced viscoelastic composite layer
           for active-passive damping of plate vibration
    • Abstract: Publication date: 15 February 2018
      Source:Composite Structures, Volume 186
      Author(s): Ambesh Kumar, Satyajit Panda, Ashish Kumar, Vivek Narsaria
      In this work, an actively constrained viscoelastic layer over the surface of a substrate plate is supposed to be reinforced with a rectangular array of thin graphite-wafers, and the effects of the inclusions on the active-passive damping characteristics of the overall plate are investigated. The inclusions of graphite-wafers in the viscoelastic layer result in a 0–3 viscoelastic composite (VEC) layer. Its (VEC) stiffness and damping properties are distributed in a predefined manner for improved active-passive damping through all the transverse and in-plane strains of the viscoelastic phase. A finite element (FE) model of the overall plate is developed for its static and dynamic analyses. The static analysis reveals the mechanisms of active-passive damping. In the dynamic analysis, first, the damping in the plate is quantified for different sets of values of dimensions in the arrangement of graphite-wafers. These results suggest appropriate geometric configuration of the graphite-wafers for maximum enhancement of active-passive damping. So, the geometric configuration of 0–3 VEC layer is optimized, and finally the controlled frequency responses of the overall plate are presented. The results reveal significantly improved active-passive damping in the overall plate for the inclusions of graphite-wafers within the actively constrained viscoelastic layer in an optimal manner.

      PubDate: 2017-12-27T13:25:39Z
  • Vibration analysis of multiple-stepped functionally graded beams with
           general boundary conditions
    • Abstract: Publication date: 15 February 2018
      Source:Composite Structures, Volume 186
      Author(s): Zhu Su, Guoyong Jin, Tiangui Ye
      In this paper, an effective formulation for vibration analysis of multiple-stepped functionally graded beams with general boundary conditions is presented. The material properties are assumed to change continuously in the thickness direction according to a power law distribution of the volume fraction of the constituents. The theoretical model is formulated on the basis of a variational method in conjunction with the first-order shear deformation theory. The essence of the present formulation is to express the displacement and rotation components by nodeless Fourier sine functions and nodal Lagrangian polynomials. Since the boundary nodal displacement information is introduced into the admissible functions, the interface continuity and boundary conditions are easily handled. Based on this, each structure component may be further partitioned into appropriate segments in order to accommodate the computing requirements of higher-order vibration modes. A variety of numerical examples are presented to demonstrate the accuracy, reliability and computational efficiency of this method. Furthermore, the effects of the material properties, geometric parameters as well as boundary conditions on the frequencies of the beam structures are discussed.

      PubDate: 2017-12-27T13:25:39Z
  • Characterizing the influence of matrix ductility on damage phenomenology
           in continuous fiber-reinforced thermoplastic laminates undergoing
           quasi-static indentation
    • Abstract: Publication date: 15 February 2018
      Source:Composite Structures, Volume 186
      Author(s): A. Yudhanto, H. Wafai, G. Lubineau, R. Yaldiz, N. Verghese
      The use of thermoplastic matrix was known to improve the impact properties of laminated composites. However, different ductility levels can exist in a single family of thermoplastic matrix, and this may consequently modify the damage phenomenology of thermoplastic composites. This paper focuses on the effect of matrix ductility on the out-of-plane properties of thermoplastic composites, which was studied through quasi-static indentation (QSI) test that may represent impact problem albeit the speed difference. We evaluated continuous glass-fiber reinforced polypropylene thermoplastic composites (GFPP), and selected homopolymer PP and copolymer PP that represent ductile and less ductile matrices, respectively. Several cross-ply laminates were selected to study the influence of ply thicknesses and relative orientation of interfaces on QSI properties of GFPP. It is expected that GFPP with ductile matrix improves energy absorption of GFPP. However, the damage mechanism is completely different between GFPP with ductile and GFPP with less ductile matrices. GFPP with ductile matrix exhibits smaller damage zone in comparison to the one with less ductile matrix. Higher matrix ductility inhibits the growth of ply cracking along the fiber, and this causes the limited size of delamination. The stacking sequence poses more influence on less ductile composites rather than the ductile one.

      PubDate: 2017-12-27T13:25:39Z
  • Experimental investigation of composite laminates subject to low-velocity
           edge-on impact and compression after impact
    • Abstract: Publication date: 15 February 2018
      Source:Composite Structures, Volume 186
      Author(s): Solver I. Thorsson, Sunil P. Sringeri, Anthony M. Waas, Brian P. Justusson, Mostafa Rassaian
      In this paper, the experimental response of polymer matrix composite laminates subject to low-velocity edge-on impact and compression after impact is studied. An experimental method for coupon level edge-on impact is introduced. Experiments at different impact energies were conducted to establish the edge-on barely visible impact damage (BVID) limit for a specific laminate. Two different impact angles were investigated, 0° and 45° with respect to the impacted edge. Non-destructive and destructive post impact inspection was conducted. Surface damage measurements by visual inspection were compared against ultrasound scanning methods for validation. Fractography using optical microscopy was performed on chosen impact energies for further visualization of the impact damage mechanisms. Industry standard for compression after face-on (transverse) impact was found to be insensitive to the impact damage. An adjusted version of the Combined Loading Compression (CLC) method was introduced for capturing the compressive strength after edge-on impact. A reduction in compressive strength after impact was seen for the impact energy range studied.

      PubDate: 2017-12-27T13:25:39Z
  • A hybrid damage assessment for E-and S-glass reinforced laminated
           composite structures under in-plane shear loading
    • Abstract: Publication date: 15 February 2018
      Source:Composite Structures, Volume 186
      Author(s): C. Yilmaz, C. Akalin, I. Gunal, H. Celik, Murat Buyuk, A. Suleman, M. Yildiz
      Micro-damage initiation and accumulation in two different Glass Fiber Reinforced -E-glass and S-glass- Laminated Composite Structures (LCS) subjected to in-plane shear stressing are monitored with Acoustic Emission (AE) and thermography methods. AE signals caused by micro-damage formation are graphed as a scatter plot of Weighted Peak Frequency (WPF) versus Partial Power 2 (PP2) features and clustered using the K-means algorithm with Bray Curtis dissimilarity function thus resulting in three different well-separated clusters. Each of these clusters corresponds to different micro damages, i.e., transverse cracks, delaminations, or fiber ruptures. It is observed that the E-glass reinforced LCS has higher numbers of AE hits. Thus, the total amount of micro-damage incurred as well as the average temperature change measured by thermography is higher for the E-glass reinforced LCS. It is shown that due to the curing induced residual tensile stress in E-glass reinforced LCS, the initial formation of delamination in E-glass reinforced LCS starts at higher load level. Under the applied shear load, a significant reduction in in-plane shear modulus is observed both for the E-glass and S-glass-reinforced LCS where the E-glass reinforced LCS shows greater reduction. The decrease in in-plane shear modulus is attributed to micro-damage accumulated in the LCS.

      PubDate: 2017-12-27T13:25:39Z
  • A layerwise finite element for geometrically nonlinear analysis of
           composite shells
    • Abstract: Publication date: 15 February 2018
      Source:Composite Structures, Volume 186
      Author(s): S.A. Hosseini Kordkheili, Z. Soltani
      This work aims to develop a nonlinear layerwise shell element formulation for shear-deformable laminated composite plate and shell structures. The element is formulated based on a zigzag theory in presence of individual local coordinates in the thickness direction for separate layers. In order to properly employ the zigzag theory, the considered local coordinates have different ranges of variation for middle, upper and lower layers. Using Mindlin-Reissner theory a convenient displacement field is derived for each layer and an ordered algorithm is adapted to calculate increments in the director vector of each layer due to relative finite rotations of its adjacent layers. Employing this shear deformable displacement field in the principle of virtual displacement leads to integral governing equations with various through-the-thickness parameter ranges. To overcome this challenge, the stress and strain tensors are rewritten in terms of through-the-thickness parameters and an explicit integration is performed in thickness direction. In this way, the nonlinear formulation is derived using the updated Lagrangian approach in accompany with a particular linearization scheme. To assess the performance of the present finite element formulation, a proprietary nonlinear finite element program is developed. Some illustrative problems are solved and comparisons with available solutions are presented.

      PubDate: 2017-12-27T13:25:39Z
  • Isogeometric static analysis of laminated composite plane beams by using
           refined zigzag theory
    • Abstract: Publication date: 15 February 2018
      Source:Composite Structures, Volume 186
      Author(s): K. Ahmet Hasim
      An attempt has been made here for the isogeometric static analysis of the laminated composite plane beams by using refined zigzag theory. In this study; instead of the standart finite elements, which use polynomial shape functions, an isogeometric refined zigzag finite element (IGRZF) has been developed, that gives the opportunity to get the exact beam geometries directly from a computer aided design (CAD) software, Rhinoceros. To provide less computational effort, the refined zigzag theory has been introduced, that make IGRZF independent from the number of layers considered. The aforementioned finite element has been implemented in an in-house Mathematica code, which can handle both thin and thick beams without the problem of shear locking and does not require shear correction factors. Using this approach, various sandwich beams have been analyzed and the obtained results are compared with other reliable published results for various aspect ratios and support types.

      PubDate: 2017-12-27T13:25:39Z
  • Calculation of guided wave interaction with nonlinearities and generation
    • Abstract: Publication date: 15 February 2018
      Source:Composite Structures, Volume 186
      Author(s): D. Chronopoulos
      The extensive usage of composite materials in modern industrial applications implies a great range of possible structural failure modes for which the structure has to be frequently and thoroughly inspected. Nonlinear guided wave inspection techniques have been continuously gaining attention during the last decade. This is primarily due to their sensitivity to very small sizes of localised damage. A number of complex transformation phenomena take place when an elastic wave impinges on a nonlinear segment, including the generation of higher and sub-harmonics. Moreover, the transmission and reflection coefficients of each wave type become amplitude dependent. In this work, a generic Finite Element (FE) based computational scheme is presented for quantifying guided wave interaction effects with Localised Structural Nonlinearities (LSN) within complex composite structures. Amplitude dependent guided wave reflection, transmission and conversion is computed through a Wave and Finite Element (WFE) method. The scheme couples wave propagation properties within linear structural waveguides to a LSN and is able to compute the generation of higher and sub-harmonics through a harmonic balance projection. A Newton-like iteration scheme is employed for solving the system of nonlinear differential equations. Numerical case studies are presented for waveguides coupled through a joint exhibiting nonlinear mechanical behaviour.

      PubDate: 2017-12-27T13:25:39Z
  • A theoretical 4-stage shear model for single-lap torqued bolted-joint with
    • Abstract: Publication date: 15 February 2018
      Source:Composite Structures, Volume 186
      Author(s): Jianfeng Kou, Fei Xu, Wei Xie, Xiaoyu Zhang, Wei Feng
      In this paper, a theoretical 4-stage shear model for a single-lap torqued bolted-joint with clearance is proposed. The deformation mechanism of the bolted-joint indicates that the contact status is the key factor for the nonlinearity of the load-displacement curve. On the basis of the contact status, the expression of this model and its parameters are proposed. Compared with the previous Tri-linear model, this model is improved on three aspects. First, the 1st stage of the model has been improved by using the partial slip theory. Second, an additional 2nd stage is considered for taking into account the asynchronous slip of the interfaces between components and between bolt head and component. Third, the 4th stage of this model is derived from the elastic foundation beam model and the Cai-Shan Liu’s approximate contact model. Moreover, the 4-stage shear model is validated by 3-D detailed FE-models. The results show that the 4-stage model can correctly describe the shear behavior, especially the nonlinearity of the load-displacement curve in the 1st stage and the 4th stage. In addition, the effects of clearance and bolt length on the joint stiffness in each stage are presented.

      PubDate: 2017-12-12T14:00:44Z
  • Vibrational energy flow model for functionally graded beams
    • Abstract: Publication date: 15 February 2018
      Source:Composite Structures, Volume 186
      Author(s): Zhihui Liu, Junchuan Niu
      In this paper, the vibrational energy flow model for functionally graded (FG) beams is developed, which can be used for high frequency response prediction. The motion governing equation for FG beams is derived using the Hamilton’s principle under the assumption of the Euler-Bernoulli beam theory. The beam properties, including Young’s modulus, mass density and structural damping factor, are assumed to vary continuously in the thickness direction according to the power-law and exponential forms. The dispersion relation for the FG beam is obtained and the wavenumber is derived. Considering the variation of the damping, the effective damping factor is introduced and obtained by considering the total dissipated power due to the damping over the beam cross-section. The energy density governing formula is obtained by considering the energy balance of the infinitesimal element in the beam. To validate the proposed energy flow model for FG beams, the results from the energy flow model are compared with modal solutions for different physical parameters, and both good correlations and accuracy are observed. The results show that the dynamics characteristics of FG beams can be affected by the material variation profile and alter the energy level along the beam in turn.

      PubDate: 2017-12-12T14:00:44Z
  • Experimental and analytical analysis for bending load capacity of old
           timber beams with defects when reinforced with carbon fiber strips
    • Abstract: Publication date: 15 February 2018
      Source:Composite Structures, Volume 186
      Author(s): Francisco J. Rescalvo, Ignacio Valverde-Palacios, Elisabet Suarez, Antolino Gallego
      This paper describes a comparative experimental and analytical study of the maximum bending load in timber beams of Pinus sylvestris L. having natural defects (knots, grain deviations, fissures and wanes) that are reinforced with carbon fiber composite (CFRP). Beams extracted during rehabilitation of the roof frame of the School of Law, University of Granada, had been in service for over two hundred years. Two commercial CFRP pultruded laminates were applied as reinforcement, for comparison. Both were properly glued with epoxy resin on the tension side of the beams, partially covering the area on this side. It is clearly shown that, due to the abundance of defects, using the elastoplastic constitutive law of timber and assuming the same tension and compression elastic moduli in the cross-section equilibrium method, the analytical values for the bending load capacity will not match the experimental ones. However, this assumption has been traditionally used in most previous research on timber beams reinforced with composite materials. As an alternative, a more general model for the timber may be used, in which the two moduli are considered to be different in compression and tension stresses. Results demonstrate how this modification provides a much better match between analytical and experimental values of the bending load capacity. The improvement is especially evident for beams with natural defects and many years in service, reinforced with CFRP for rehabilitation purposes. Moreover, a better mechanical behavior of the reinforced specimens is obtained, when compared with the control ones (without reinforcement): reinforcement induced an improvement of up to 88% in bending load capacity.

      PubDate: 2017-12-12T14:00:44Z
  • An approach for stress analysis of corrugated-core integrated thermal
           protection system under thermal and mechanical environment
    • Abstract: Publication date: 1 February 2018
      Source:Composite Structures, Volume 185
      Author(s): Chunlin Gong, Yifan Wang, Liangxian Gu, Shengbo Shi
      The stress distributions in trapezoidal corrugated-core integrated thermal protection system (ITPS) under thermal and mechanical loads are predicted by employing the equivalent sandwich model introduced in our previous study (Gu et al., 2017). The method for prediction of stress based on high-order layerwise theory and the principle of structural mechanics is presented, which considers the effects of temperature-dependent material properties and curvature in sheets. For the top face sheet of ITPS, the local displacement induced by out-of-plane pressure is taken into account in the prediction of stress. And for the bottom face sheet of ITPS, the local displacement induced by corrugated webs is also considered by treating the sheet as beams with proper displacement compatibility. The accuracy of the proposed method is verified by comparison with the results by three-dimensional (3D) finite element analysis. It has been shown that the proposed method requires significantly less computational effort and agrees well with the finite element results.

      PubDate: 2017-11-15T20:10:38Z
  • Nonlocal nonlinear finite element analysis of composite plates using TSDT
    • Abstract: Publication date: 1 February 2018
      Source:Composite Structures, Volume 185
      Author(s): P. Raghu, A. Rajagopal, J.N. Reddy
      In this work, nonlocal nonlinear finite element analysis of laminated composite plates using Reddy’s third-order shear deformation theory (TSDT) (Reddy, 1984) and Eringen’s nonlocality Eringen and (Edelen, 1972) is presented. The governing equations of third order shear deformation theory with the von Kármán strains are derived employing the Eringen’s (Eringen and Edelen, 1972) stress-gradient constitutive model. The principle of virtual displacement is used to derive the weak forms, and the displacement finite element models are developed using the weak forms. Four-noded rectangular conforming element with 8 degrees of freedom per node has been used. The coefficients of stiffness matrix and tangent stiffness matrix are presented along with nonlocal force vector. The developed finite element model can be employed to capture the small scale deviations from local continuum models caused by material inhomogeneity and the inter atomic and inter molecular forces. Numerical examples are presented to illustrate the effects of nonlocality, anisotropy, and the von Kármán type nonlinearity on the bending behaviour of laminated composite plates.

      PubDate: 2017-11-15T20:10:38Z
  • Investigation of the effect of BaTiO3/CoFe2O4 particle arrangement on the
           static response of magneto-electro-thermo-elastic plates
    • Abstract: Publication date: 1 February 2018
      Source:Composite Structures, Volume 185
      Author(s): M. Vinyas, S.C. Kattimani
      In this article, a framework based on finite element (FE) methods is proposed for predicting the influence of spatial arrangement of two phase Barium Titanate (BaTiO3) and Cobalt Ferric Oxide (CoFe2O4) particulate composites on the static response of magneto-electro-thermo-elastic (METE) plates. The coupled material properties such as piezoelectric, piezomagnetic, dielectric, magnetic permeability, thermal expansion and pyro co-efficients vary significantly with the spatial arrangement of BaTiO3/CoFe2O4 particulates. The coupled FE governing equations accounting the effect of particle arrangement is presented by incorporating linear coupled constitutive equations of METE composites. Through the condensation technique, the governing equations of METE plates are solved to obtain direct (thermal displacements, electric and magnetic potentials) and derived quantities (stresses, electric displacements and magnetic flux densities). A special attention has been placed on evaluating the pyro-electric and pyro-magnetic coupling effects for different packing arrangement considered namely, Body Centered Cubic (BCC), Face Centered Cubic (FCC) and Simple Cubic (SC) METE particulate composites. Further, parametric studies are carried out to analyse the influence of boundary conditions and aspect ratio. The present study reveals that the multiphysics response of METE plates changes significantly with the packing arrangements of BaTiO3/CoFe2O4 particulates and geometrical parameters. It is believed that the obtained solutions would provide insights into design aspects of METE structures.

      PubDate: 2017-11-15T20:10:38Z
  • Periodic mesh generation and homogenization of inclusion-reinforced
           composites using an element-carving technique with local mesh refinement
    • Abstract: Publication date: 1 February 2018
      Source:Composite Structures, Volume 185
      Author(s): Dongwoo Sohn
      An efficient periodic mesh generation scheme for representative volume elements (RVEs) of inclusion-reinforced composites is proposed with the aid of an element-carving technique. A background mesh with regular hexahedral elements is cut and split to fit periodic configurations of inclusions. The split hexahedral elements around the inclusion-matrix interfaces correspond to polyhedral elements, while the background hexahedral elements remain inside the inclusions and matrices. To further achieve an accurate and efficient RVE modeling, local refinement for the background mesh is introduced near the inclusion-matrix interfaces. Polyhedral elements that have arbitrary numbers of polygonal faces and nodes are also used to connect the refined and original background hexahedral elements. The generated meshes automatically have periodic boundary configurations, and no special treatment is thus required to impose periodic boundary conditions in a computational homogenization. In this paper, the cell-based smoothed finite element method is adopted to reduce the effort involved in explicitly defining shape functions and in accurately conducting numerical integration for polyhedral elements. The effectiveness of the proposed scheme is demonstrated in the numerical examples of generating RVEs, including spherical, ellipsoidal, or cylinder-shaped inclusions. Furthermore, the influences of inclusion configurations on estimating the effective elastic moduli are investigated with the generated meshes.

      PubDate: 2017-11-15T20:10:38Z
  • Biomechanical simulation of healing process of fractured femoral shaft
           applied by composite intramedullary nails according to fracture
    • Abstract: Publication date: 1 February 2018
      Source:Composite Structures, Volume 185
      Author(s): Ali Mehboob, Seung-Hwan Chang
      Flexible composite implants are receiving increased attention in this modern era of orthopedics for the stabilization of long bone fractures because they facilitate tissue development in calluses. An endochondral ossification process involves generation of calluses, and it is well known that this significantly affects the stabilization and healing of the broken bones. Therefore, the exact configuration of callus formation is highly important for the accurate simulation of bone healing. In this study, finite element analysis was performed to estimate the external callus shape by using the rejection coefficient (RC) algorithm. Regarding the application of a fractured femur by an intramedullary (IM) nail, the bone healing simulation was conducted by employing the biphasic mechano-regulation algorithm according to the fracture type (transverse (0°) and oblique (35°)), fracture location (proximal, medial, and distal ends), and nail property. The simulation results revealed that a glass/polypropylene fabric composite (Twintex [0]2nT) IM nail, which has the similar Young’s modulus to the cortical bone, provided the most appropriate bio-mechanical environment for bone healing.

      PubDate: 2017-11-15T20:10:38Z
  • Experimental study of CFRP strengthened steel columns subject to lateral
           impact loads
    • Abstract: Publication date: 1 February 2018
      Source:Composite Structures, Volume 185
      Author(s): Majid M.A. Kadhim, Zhangjian Wu, Lee S. Cunningham
      In both building and civil engineering structures, the occurrence of impact loading to column elements can be a significant issue, particularly in regard to disproportionate collapse. For existing structures vulnerable to impacts, the development of appropriate strengthening techniques is key to extending service life and improving robustness. In the case of structural steelwork, composites such as carbon fibre reinforced polymer (CFRP) offer a promising means of retrofitting and improving performance under impact. Towards this, the present study experimentally investigated a total of 12 square hollow section (SHS) columns under impact loads. The test series included both unstrengthened and CFRP strengthened samples with different fibre orientations with a view to finding the optimum CFRP configuration. As a means of simulating lateral impact on axially loaded elements, a purpose-built test rig was manufactured to apply a compressive preload to the samples prior to impact. Different preloading levels were applied to the samples before they were impacted transversely. The results show that the strengthening effectiveness increased with higher preloading level. The average reduction in the transverse displacement for the strengthened columns tested under 70% preloading level was around 32% compared to the unstrengthened column while this value was about 22% for the columns tested without compressive preload.

      PubDate: 2017-11-15T20:10:38Z
  • Effect of curing time on the fracture toughness of fly ash concrete
    • Abstract: Publication date: 1 February 2018
      Source:Composite Structures, Volume 185
      Author(s): Grzegorz Ludwik Golewski
      This paper presents the results of an experimental investigation carried out to evaluate the compressive strength and fracture toughness of concrete mixtures in which main binder (Ordinary Portland Cement – OPC) was partially replaced with Class F fly ash (FA). OPC was replaced with two percentages (20% and 30%) of FA by weight. Compressive strength and fracture toughness under mode III – K IIIc (torsional loading), were determined at: 3, 7, 28, 90, 180 and 365 days. Test results indicate significant improvement in the strength properties and fracture toughness of mature concrete, by the inclusion of 20% FA as partial replacement of OPC. On the other hand, the additive of FA in the amount of 30% weight of OPC has a beneficial effect on the mechanical parameters of concrete only after half a year ofcuring. The obtained results are significant in the analysis of concrete structures subjected to complex loading, or structures where torsional moment is the basic load.

      PubDate: 2017-11-15T20:10:38Z
  • To the design of highly fracture-resistant composites by the application
           of the yield stress inhomogeneity effect
    • Abstract: Publication date: 1 February 2018
      Source:Composite Structures, Volume 185
      Author(s): M. Sistaninia, R. Kasberger, O. Kolednik
      Improvement of the fracture toughness by the introduction of thin, soft interlayers is investigated. The mechanism is the strong decrease of the crack driving force when the crack tip is located in the soft region. Based on numerical simulations with the configurational forces concept, it is demonstrated that the fracture toughness of brittle materials can be greatly improved by the introduction of soft interlayers, if the architectural parameters of the multilayer are appropriately chosen. The findings are compared to experimental results of fracture tests conducted on compounds made of high-strength steel as matrix and low-strength steel as interlayer material. The design concept presented in this paper can be applied for various types of composite materials.

      PubDate: 2017-11-15T20:10:38Z
  • Governing failure criterion of short-span hybrid FRP-UHPC beams subjected
           to high shear forces
    • Abstract: Publication date: 1 February 2018
      Source:Composite Structures, Volume 185
      Author(s): Mina Iskander, Raafat El-Hacha, Nigel Shrive
      An experimental investigation into the shear performance of a recently developed hybrid section constructed from a glass fibre reinforced polymer (GFRP) hollow box section with an ultra-high performance concrete (UHPC) flange and a bottom sheet made of steel fibre reinforced polymer (SFRP) or carbon fibre reinforced polymer (CFRP) is presented. This section has superior structural properties compared to sections made from conventional materials. Seven specimens were tested by applying a point load 280 mm from one support over a clear span of 1120 mm to induce shear failure. Two main parameters were investigated, namely, the effect of flange dimensions and the type of reinforcement used as the bottom (tension) sheet. All specimens failed similarly, indicating consistent behaviour for shear failure regardless of the changing parameters. Failure involved crack propagation at the corners of the GRFP box section followed by cracking of UHPC flange. Traditional calculations, based on the elastic analysis, of the shear stresses at the failure point are presented showing that high shear stresses are not the only cause of the mode of failure observed. The cause of failure is interpreted using a simple finite element analysis. Given the cause of failure, special consideration should be given to the design of the fibre orientation at the corner regions of such box sections.

      PubDate: 2017-11-15T20:10:38Z
  • Multi-objective multi-laminate design and optimization of a Carbon Fibre
           Composite wing torsion box using evolutionary algorithm
    • Abstract: Publication date: 1 February 2018
      Source:Composite Structures, Volume 185
      Author(s): Sachin Shrivastava, P.M. Mohite, Tarun Yadav, Appasaheb Malagaudanavar
      The present study aims to minimize the weight of multi-laminate aerospace structures by a classical Genetic Algorithm (GA) interfaced with a CAE solver. The structural weight minimization is a multi-objective optimization problem subjected to fulfilling of strength and stiffness design requirements as well. The desired fitness function connects the multi-objective design requirements to form a single-objective function by using carefully chosen scaling factors and a weight vector to get a near optimal solution. The scaling factors normalize and the weight vector prioritizes the objective functions. The weight vector selection was based on a posteriori articulation, after obtaining a series of Pareto fronts by 3D hull plot of strength, stiffness and assembly weight data points. During the optimization, the algorithm does an intelligent laminate selection based on static strength and alters the ply orientations and thickness of laminae for faster convergence. The study further brings out the influence of mutation percentage on convergence. The optimization procedure on a transport aircraft wing torsion box has showed 29% weight reduction compared to an initial quasi-isotropic laminated structure and 54% with respect to the metallic structure.

      PubDate: 2017-11-15T20:10:38Z
  • Characterizing the off-axis dependence of failure mechanism in notched
           fiber metal laminates
    • Abstract: Publication date: 1 February 2018
      Source:Composite Structures, Volume 185
      Author(s): Jipeng Zhang, Yue Wang, Jiazhen Zhang, Zhengong Zhou, Guodong Fang, Yuan Zhao, Shiming Zu
      Fiber metal laminates (FMLs) are usually more complicated in the failure aspect as compared to their constituents, especially when complex load is applied. In this paper, notched FMLs and the constituents, i.e., the aluminum and glass fiber reinforced plastic (GFRP) were subjected to off-axis tensile loading to evaluate the failure mechanism. Initial attention was paid on the off-axis dependence of mechanical responses, especially on its relation to the notch size. As expected, off-axis dependence of notched strength and notch sensitivity were closely related to the notch size, but different for GFRP laminates and FMLs due to their different damage behavior. Finite element model was employed to predict accurately the mechanical responses of FMLs, particularly for elucidating the damage mechanism. Failure of notched FMLs under off-axis loading was a combined transverse fracture and shear-off, while it was shear-dominated in notched GFRP laminates. Transverse fracture in aluminum appeared first, followed by the fiber breakage, which was postponed by the extensive subcritical damage. Thereafter, shear-failure in fiber and aluminum layers were encountered instantaneously at the descending part. Thus, the critical failure of off-axis notched FMLs was still tension-dominated as that in the on-axis case, but aluminum played the critical role.

      PubDate: 2017-11-15T20:10:38Z
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