Showing papers in "Journal of Sandwich Structures and Materials in 2015"
TL;DR: In this paper, the in-plane dynamic crushing behaviors and energy-absorbed characteristics of honeycombs with negative Poisson's ratio (NPR) have been studied by means of explicit dynamic finite element analysis.
Abstract: The in-plane dynamic crushing behaviors and energy-absorbed characteristics of honeycombs with negative Poisson’s ratio (NPR) have been studied by means of explicit dynamic finite element analysis ...
90 citations
TL;DR: In this paper, a higher-order shear deformation theory for static, buckling and free vibration analysis of functionally graded sandwich beams is presented, in which the axial displacement of axial deformation is modeled as a linear function of the free vibration.
Abstract: This paper presents a new higher-order shear deformation theory for static, buckling and free vibration analysis of functionally graded sandwich beams. In this theory, the axial displacement accoun...
66 citations
TL;DR: In this article, the authors deal with the thermo-mechanical deformation behavior of shear deformable functionally graded sandwich plates resting on a two-parameter (Pasternak model) elastic foundation.
Abstract: This paper deals with the thermo-mechanical deformation behaviour of shear deformable functionally graded sandwich plates resting on a two-parameter (Pasternak model) elastic foundation. By dividin...
56 citations
TL;DR: In this paper, the geometrical nonlinear free vibration behavior of shear deformable laminated composite single/doubly curved shell panel in hygrothermal environment is investigated.
Abstract: In this article, the geometrical nonlinear free vibration behaviour of shear deformable laminated composite single/doubly curved shell panel in hygrothermal environment is investigated. A general n...
46 citations
TL;DR: In this article, the thermal buckling analysis of solid circular plate made of porous material bounded with piezoelectric sensor-actuator patches is presented, and the general mechanical nonlinear equilibrium and linear stability equations are derived using the variational formulations to obtain the governing equations of the porous plate.
Abstract: This study presents the thermal buckling analysis of solid circular plate made of porous material bounded with piezoelectric sensor-actuator patches. The porous material properties vary through the thickness with specific function. The general mechanical nonlinear equilibrium and linear stability equations are derived using the variational formulations to obtain the governing equations of piezoelectric porous plate. Thermal buckling load is derived for solid circular plates under uniform temperature load for the clamped edge condition. In recent paper the effects of porous plate’s thickness, porosity, porous thermal expansion coefficient, piezoelectric thickness, piezoelectric thermal expansion coefficient, and feedback gain on thermal stability of the plate are investigated.
45 citations
TL;DR: In this paper, the free vibration characteristics of functionally graded (FG) nanocomposite sandwich beams resting on Pasternak foundation are presented, by considering the agglomeration effect of single-walled carbon nanotubes.
Abstract: In the present work, by considering the agglomeration effect of single-walled carbon nanotubes, free vibration characteristics of functionally graded (FG) nanocomposite sandwich beams resting on Pasternak foundation are presented. The carbon nanotubes (CNTs) volume fraction is graded through the thicknesses of face sheets according to a generalized power–law distribution. The material properties of the FG nanocomposite sandwich beam are estimated using the Eshelby–Mori–Tanaka approach based on an equivalent fiber. The equations of motion are derived based on Timoshenko beam theory and employing Hamilton's principle. Generalized differential quadrature technique as an efficient and accurate numerical tool is employed to obtain the natural frequencies of the structure. The verification study represents the accuracy of the solution for free vibration analysis of the nanocomposite sandwich beams resting on elastic foundation. Detailed parametric studies are carried out to investigate the influences of CNTs ag...
40 citations
TL;DR: In this paper, the behavior of vibration of sandwich cylindrical shells covered by functionally graded coatings and resting on the Pasternak elastic foundation considering combined influences of different influences was investigated.
Abstract: In this study, the behavior of vibration of sandwich cylindrical shells covered by functionally graded coatings and resting on the Pasternak elastic foundation considering combined influences of sh...
40 citations
TL;DR: In this article, the probabilistic failure analysis of laminated composite and sandwich shells was studied using an efficient C0 2D finite element model based on higher order zigzag theory.
Abstract: The probabilistic failure analysis of laminated composite and sandwich shells is studied first time by using an efficient C0 2D finite element model based on higher order zigzag theory incorporatin...
30 citations
TL;DR: In this paper, aluminum-based metal matrix composites with various weight percentages of TiO2 reinforcement were synthesized by powder metallurgy technique and their forming characteristics were completely studied during cold upsetting under plane stress state conditions.
Abstract: Aluminum-based metal matrix composites with various weight percentages of TiO2 reinforcement were synthesized by powder metallurgy technique and their forming characteristics were completely studied during cold upsetting under plane stress state conditions. The milled powders were characterized by scanning electron microscope, X-ray diffraction (XRD), and energy dispersive analysis using X-ray (EDAX) analysis. Green cylindrical compacts were made using a 400 kN hydraulic press using suitable punch and die, sintered at (590 ± 10)℃ for a period of 3 h, furnace cooled, and machined to obtain samples with 0.5 aspect ratio. The cold upset tests were carried out in steps of 10 kN and the true axial stress (σz), the true hoop stress (σθ), the true hydrostatic stress (σm), and the true effective stresses (σeff) were determined, and their behavior against the true axial strain (ɛz) was thoroughly analyzed. It was observed that, the addition of TiO2 to the Al matrix material increases the strength coefficient (K) a...
24 citations
TL;DR: In this article, the principles of sandwich construction were used to design, manufacture, and analyze multifunctional sandwich beams that can withstand structural load and also store electrochemical energy, and three different types of sandwich beams were designed.
Abstract: The principles of sandwich construction were used to design, manufacture, and analyze multifunctional sandwich beams that can withstand structural load and also store electrochemical energy. Three ...
24 citations
TL;DR: In this article, the experimental results pertaining to the deformation, failure mode, failure mechanism and residual strength for the compression-after-impact tests of woven polymer-based foam-based fabrics are presented.
Abstract: This paper presents the experimental results pertaining to the deformation, failure mode, failure mechanism and residual strength for the compression-after-impact tests of woven polymer-based foam-...
TL;DR: In this paper, a study on the potential offered by lightweight energy-absorbing foam structures reinforced with aluminium and steel cylindrical tubes subjected to compressive crushing is presented, where the potential of lightweight energy absorbing foam structures is investigated.
Abstract: This paper presents a study on the potential offered by lightweight energy-absorbing foam structures reinforced with aluminium and steel cylindrical tubes subjected to compressive crushing. Initial...
TL;DR: Foam core sandwich structures are rather vulnerable against transverse loading which can leave only barely visible damage in the structures as discussed by the authors, and environmental conditions can further affect the loading conditions.
Abstract: Foam core sandwich structures are rather vulnerable against transverse loading which can leave only barely visible damage in the structures. Environmental conditions can further affect the loading ...
TL;DR: In this article, a gradient analytical model for the sandwich panel with positive gradient metallic cellular core under the spherical indenter was developed based on the analytical model of the sandwich panels with homogeneous core.
Abstract: This paper deals with the plastic indentation of sandwich panels with positive gradient metallic cellular core under a spherical indenter. The gradient metallic cellular material has an increasing plateau stress. Under quasi-static compression, the crushing stress of gradient metallic cellular material cannot be assumed as a constant like that of homogeneous metallic cellular material before densification. To predict the crushing stress of the gradient metallic cellular material, a novel predicting formula associated with densification strain is presented. And then a gradient analytical model for the sandwich panel with positive gradient metallic cellular core under the spherical indenter is developed based on the analytical model for sandwich panel with homogeneous core. Finite element simulation is carried out in order to verify the analytical results. The influence of positive gradient metallic cellular core on the indentation force of the sandwich panel is further analyzed.
TL;DR: In this article, the functional graded honeycomb structures with defects are investigated and it is shown how the patterns and locations of defects, as well as the density gradients, can affect the in-...
Abstract: In this work, the functionally graded honeycomb structures with defects are investigated. It is shown how the patterns and locations of defects, as well as the density gradients, can affect the in-...
TL;DR: In this article, an easy and fast springback prediction of Al3105/polypropylene/polyethylene (PP/Al) laminated sheets has been made for different applications from aeronautics to construction.
Abstract: Al/PP/Al laminated sheets have shown promising properties for different applications from aeronautics to construction. In this paper, an easy and fast springback prediction of Al3105/polypropylene/...
TL;DR: In this article, the dynamic mechanical properties of paper honeycomb were discussed and the corresponding mathematic model was built in order to present the stress in different deformation stages and depict the energy absorption properties of honeycomb structure.
Abstract: The mechanical properties of paper honeycomb will be different from static situation with the changing of strain rate, which has an influence on the application of paper honeycomb. In this paper, the dynamic mechanical properties of paper honeycomb were discussed and the corresponding mathematic model was built in order to present the stress in different deformation stages and depict the energy absorption properties of honeycomb structure. The strain-rate effect was expressed by Comper-Symonds model. According to the mechanical model, the energy absorption diagram under different strain rates was also built from selecting materials of cushion packaging and optimum design of the packaging. Finally, serious experiments were taken and the result showed a good agreement with theoretical models. The proposed model can be used for practical application of the optimum design and material selection of honeycomb sandwich structure.
TL;DR: In this article, the mechanical properties of beetle elytra have been investigated and a lightweight border frame structure and an optimal design has been proposed, which includes variable cross-sections suitable for different species.
Abstract: This paper reviews the mechanical properties of beetle elytra. (1) The elytra has a lightweight border frame structure and has an optimal design, which includes variable cross-sections suitable for...
TL;DR: In this paper, Sandwich panels made of metal sheets with unfilled cellular cores were found to exhibit lower deflection compared to an equivalent monolithic plate of same metal and similar mass per unit density.
Abstract: Sandwich panels made of metal sheets with unfilled cellular cores are found to exhibit lower deflections compared to an equivalent monolithic plate of same metal and similar mass per unit density. ...
TL;DR: In this article, the authors proposed to use honeycomb cores and carbon laminate face sheets to meet low-weight and high-stiffness specifications, however, these structures are susceptible to noise problems.
Abstract: Sandwich structures of honeycomb cores and carbon laminate face sheets are ideal to meet low-weight and high-stiffness specifications. However, these structures are susceptible to noise problems. T...
TL;DR: In this article, the effects of different design parameters such as hemp content in the skins, layer thickness, and foaming agent content in core (0% wt, 0.6%, 0.2%, and 1.2%) on the flexural properties of three layer sandwich panels of hemp and high density polyethylene produced by compression molding were investigated.
Abstract: This work investigates the effects of different design parameters such as hemp content in the skins (10–40% wt.), layer thickness (1 and 2 mm), and foaming agent content in the core (0% wt., 0.6% wt. and 1.2% wt.) on the flexural properties of three layer sandwich panels of hemp and high density polyethylene produced by compression molding. The results show that hemp content was the most significant parameter for the flexural properties of these panels. In addition, it was found that specific modulus and strength (per unit weight) were 30% and 36% higher when using a foam core, respectively.
TL;DR: In this paper, a probabilistic fatigue life model for end-grain balsa cored sandwich composites subjected to transverse shear is proposed and calibrated to measured three-point bending constant-amplitude fatigue test data using the maximum likelihood method.
Abstract: A probabilistic fatigue life model for end-grain balsa cored sandwich composites subjected to transverse shear is proposed. The model is calibrated to measured three-point bending constant-amplitude fatigue test data using the maximum likelihood method. Some possible applications of the probabilistic model are obtaining characteristic S–N curves corresponding to a given survival probability, and calibrating partial safety factors for material fatigue. The latter is demonstrated by a calibration performed using reliability analysis with the first-order reliability method. The measured variance in balsa shear properties, for both static strength and fatigue failure, is higher than the variance normally observed in the properties for fiber-reinforced polymer composite laminates. This could be attributed to the fact that end-grain balsa wood is the product of a naturally occurring growth process, which cannot be controlled to the same extent as an industrial manufacturing processes. The large variance in the ...
TL;DR: In this article, a new design of aluminum foam composite panels with enhanced ribs was proposed, and the energy absorption property of it was analyzed by combining dynamic testing and numerical simulation, and it was shown that the improved ribs improved energy absorption properties.
Abstract: A new design of aluminum foam composite panels with enhanced ribs was proposed, and the energy absorption property of it was analyzed by combining dynamic testing and numerical simulation. The opti...
TL;DR: In this article, a numerical model for the quasi-static indentation and compression-after-impact behavior of a composite sandwich panel is presented, using cohesive surfaces for interlaminar damage prediction.
Abstract: A numerical model for the quasi-static indentation and compression-after-impact behaviour of a composite sandwich panel is presented, using cohesive surfaces for interlaminar damage prediction. Intra-laminar damage and core crushing is also included. The models show generally good agreement with experimental results for residual strength, performing best when two cohesive surfaces are used in the impacted skin, but tend to over-estimate the undamaged panel strength. Damage extent predictions from the indentation phase of the analysis are often quite poor, but do not necessarily correlate with the accuracy of the strength estimates. The model provides a promising basis for further development.
TL;DR: An asymptotic meshless method using the differential reproducing kernel interpolation and perturbation method is formulated for the three-dimensional bending analysis of sandwich functionally graded circular hollow cylinders and laminated composite ones with clamped and simply-supported edge conditions, in which the effective material properties of the functionally graded layer are evaluated using the Mori-Tanaka scheme as discussed by the authors.
Abstract: An asymptotic meshless method using the differential reproducing kernel interpolation and perturbation method is formulated for the three-dimensional bending analysis of sandwich functionally graded circular hollow cylinders and laminated composite ones with clamped and simply-supported edge conditions, in which the effective material properties of the functionally graded layer are evaluated using the Mori–Tanaka scheme. In the formulation, we perform the mathematical processes of nondimensionalization, asymptotic expansion and successive integration to obtain recurrent sets of governing equations for various order problems. Classical shell theory is derived as a first-order approximation of the three-dimensional theory of elasticity, and the governing equations for higher order problems retain the same differential operators as those of classical shell theory, although with different nonhomogeneous terms. Expanding the primary field variables of each order as the Fourier series functions in the circumfer...
TL;DR: In this article, the failure behavior of composite sandwich structures with face sheet and core debond subjected to compressive loading was investigated, and experiments and numerical simulations were conducted to evaluate the failure performance.
Abstract: This research investigated the failure behaviors of the composite sandwich structures with face sheet and core debond subjected to compressive loading. Experiments and numerical simulations were co...
TL;DR: Asymmetric sandwich panels with skins of differing thickness are subjected to various degrees of damage via quasi-static indentation before compressive loading to failure as mentioned in this paper, and the experiments show that the asymmetric panels experience an improvement in strength with small amounts of indentation compared with undamaged asymmetric panel, and for more severe damage, show greater residual strength than the symmetric panels.
Abstract: Asymmetric sandwich panels with skins of differing thickness are subjected to various degrees of damage via quasi-static indentation before compressive loading to failure. These are compared with panels with skins of equal thickness. The experiments show that the asymmetric panels experience an improvement in strength with small amounts of indentation compared with undamaged asymmetric panels, and for more severe damage, show greater residual strength than the symmetric panels. The two configurations are numerically modelled using Abaqus, including inter- and intra-laminar damage, and core crushing. The strength predictions from the models agree well with the experiments.
TL;DR: In this paper, a three-layer annular composite sandwich sector plate is investigated numerically using the dynamic relaxation method, where the upper and lower faces consist of unsymmetrical rectangular orthotropic laminates, and the core is based on viscoelastic material.
Abstract: The three-layer annular composite sandwich sector plate is investigated numerically using the dynamic relaxation method. The upper and lower faces consist of un-symmetrical rectangular orthotropic laminates, and the core is based on viscoelastic material. The non-linear governing equations are considered using the first-order shear deformation theory and large deflection type of deformation. The constitutive relations of sandwich are presented for laminated faces, and the linear viscoelastic core is considered for the Boltzmann superposition principle. The dynamic relaxation iterative procedure in conjunction with finite-difference discretization is performed for the solution of the governing equations. Under uniform lateral pressure as well as clamped and simply supported edged constraints, the plate deformation is predicted for different times. In order to verify the dynamic relaxation algorithm, the elastic sector plate is compared with finite element solutions, and it is established that the correlati...
TL;DR: In this article, a numerical analysis for cylindrical shells using higher order shell theory is carried out, where all equations are derived with the inclusion of the additional quadratic and cubic terms in the Taylor's series expansions of the both in-plane and transverse displacement components for the improvement of bending behavior of the shell.
Abstract: Numerical analysis is carried out in this paper for thick circular cylindrical shells using higher order shell theory. In orthogonal curvilinear coordinate system, all equations are derived with the inclusion of the additional quadratic and cubic terms in the Taylor’s series expansions of the both in-plane as well as the transverse displacement components for the improvement of bending behaviour of the shell. Assuming (h/R)2 ≪ 1, a rigorous formulation involving the reduction of a three-dimensional elasticity problem to a two-dimensional one, based partly upon the Reissner’s variational principle, is presented. These equations are algebraically manipulated to be in the form of a coupled system of first-order differential equations in terms of the intrinsic dependent variables. These are then solved by a segmentation method – numerical integration technique for various combinations of material and geometric parameters. The theory is shown to result in a partial differential equation system of sixteenth order.
TL;DR: In this paper, an experimentally based and numerically supported investigation of the collapse behavior of polymer foam cored sandwich beams subjected to combined mechanical and thermal loading is presented, where a thermal gradient is introduced into a sandwich beam specimen loaded in three-point bending.
Abstract: The paper presents an experimentally based and numerically supported investigation of the collapse behaviour of polymer foam cored sandwich beams subjected to combined mechanical and thermal loading. Recent analytical and numerical modelling results available in the literature have ascertained that collapse may be due to loss of stability induced by nonlinear interactions between mechanical loads and thermally induced deformations, when accounting for the reduction of the polymer foam core mechanical properties with increasing temperature. In the paper, experiments are devised whereby a thermal gradient is introduced into a sandwich beam specimen loaded in three-point bending. The experiments cover a range of temperatures where one face sheet is heated from room temperature (25℃) to just below the glass transition temperature of the polymer foam core (70℃) and the other face sheet remains at room temperature. Digital image correlation (DIC) is used to obtain the local displacement field of the sandwich be...