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Showing papers on "Sandwich-structured composite published in 2013"


Journal ArticleDOI
TL;DR: In this article, the authors present the results of an experimental and numerical study on the low-velocity impact behavior of foam-core sandwich panels, and a progressive damage model is developed to describe the nonlinear behavior of plain weave carbon laminates during impact.

193 citations


Journal ArticleDOI
TL;DR: In this paper, a series of experimental investigations and numerical analyses are presented into the compression response, and subsequent failure modes in corrugated-core sandwich panels based on an aluminium alloy, a glass fibre reinforced plastic (GFRP), and a carbon fibre reinforced plastics (CFRP).
Abstract: A series of experimental investigations and numerical analyses is presented into the compression response, and subsequent failure modes in corrugated-core sandwich panels based on an aluminium alloy, a glass fibre reinforced plastic (GFRP) and a carbon fibre reinforced plastic (CFRP). The corrugated-cores were fabricated using a hot press moulding technique and then bonded to face sheets based on the same material, to produce a range of lightweight sandwich panels. The role of the number of unit cells and the thickness of the cell walls in determining the overall deformation and local collapse behaviour of the panels is investigated. The experiments also provide an insight into the post-failure response of the sandwich panels. The results are compared with the numerical predictions offered by a finite element analysis (FEA) as well as those associated with an analytical model. Buckling of the cell walls has been found to be initial failure mode in these corrugated systems. Continued loading resulted in fracture of the cell walls, localised delamination as well as debonding between the skins and the core. The predictions of the FEA generally show reasonably good agreement with the experimental measurements. Finally, the specific compressive properties of the corrugated structures have been compared to those of other core materials where evidence suggests that these systems compare favourably with their more conventional counterparts.

188 citations


Journal ArticleDOI
Robert Mines1, S. Tsopanos1, Y. Shen1, Rafidah Hasan1, S. McKown1 
TL;DR: In this paper, the authors used body centred cubic (BCC) micro lattice cores made from Ti 6Al 4V titanium alloy and 316L stainless steel manufactured using selective laser melting.

176 citations


Journal ArticleDOI
TL;DR: In this paper, the authors compared the static and low-velocity impact response of two aluminium sandwich typologies: foam and honeycomb sandwich panels, respectively, using tomographic analyses of the impacted panels.

161 citations


Journal ArticleDOI
TL;DR: In this paper, a foam-filled corrugated core sandwich panel was evaluated under quasi-static out-of-plane compression and the underlying mechanisms were numerically studied using finite element simulations.

154 citations


Journal ArticleDOI
TL;DR: In this article, the bending and failure behavior of polymorphic honeycomb topologies consisting of gradient variations of the horizontal rib length and cell internal across the surface of the cellular structures was described.
Abstract: We describe the bending and failure behaviour of polymorphic honeycomb topologies consisting of gradient variations of the horizontal rib length and cell internal across the surface of the cellular structures. The novel cores were used to manufacture sandwich beams subjected to three-point bending tests. Full-scale nonlinear Finite Element models were also developed to simulate the flexural and failure behaviour of the sandwich structures. Good agreement was observed between the experimental and FE model results. And the validated numerical model was then used to perform a parametric analysis on the influence of the gradient core geometry over the mechanical performance of the structures. It was found that the aspect ratio and the extent of gradient (i.e. the horizontal rib length growth rate or the internal angle increment) have a significant influence on the flexural properties of the sandwich panels with angle gradient cores.

116 citations


Journal ArticleDOI
Jin-Shui Yang1, Jian Xiong1, Li Ma1, Bing Wang1, Guoqi Zhang1, Linzhi Wu1 
TL;DR: In this paper, the vibration and damping performances of hybrid carbon fiber composite pyramidal truss sandwich panels with viscoelastic layers embedded in the face sheets were investigated. And the numerical simulation results showed good agreement with the experimental tests.

114 citations


Journal ArticleDOI
Shujuan Hou1, Shuyun Zhao1, Lili Ren1, Xu Han1, Qing Li2 
TL;DR: In this paper, the authors investigated the relationship between structural parameters and the crashworthiness of corrugated sandwich panels under low-velocity local impact and planar impact, and further optimized these structural parameters with the crash-worthiness criteria by using multiobjective optimization techniques.

107 citations


Journal ArticleDOI
Shu Yang1, Chang Qi1, Dong Wang1, Renjing Gao1, Hai-Tao Hu1, Jian Shu1 
TL;DR: In this article, an innovative auxetic-cored sandwich panel (AXP) is proposed and its perforation resistant performance under high-velocity projectile impact was numerically analyzed using the validated finite element simulation techniques.
Abstract: An innovative auxetic-cored sandwich panel (AXP) is proposed. Its perforation resistant performance under high-velocity projectile impact was numerically analyzed using the validated finite element simulation techniques and compared with that of the aluminum foam-cored sandwich panel (AFP) of identical dimensions and weight. It has been found that the AXP is far superior to the AFP in ballistic resistance because of the material concentration at the impacted area due to the negative Poisson's ratio (NPR) effect. A parametric study was carried out to investigate the effects of several key parameters, including impact velocity, face and core thicknesses, and core density, on the ballistic resistance of the AXP and AFP. The results show that the ballistic limit and perforation energy of the AXP is greatly affected by these parameters. Meanwhile, the advantages of AXP over AFP being used as ballistic resistant structures are highlighted. The primary outcome of this research is new information on the developme...

102 citations


Journal ArticleDOI
TL;DR: The authors reviewed the most significant works in literature about the acoustic behaviour of sandwich panels, starting from the first examples of multi-layered structures, comprising a series of different dif...
Abstract: This paper reviews the most significant works in literature about the acoustic behaviour of sandwich panels, starting from the first examples of multi-layered structures, comprising a series of dif...

101 citations


Journal ArticleDOI
TL;DR: In this paper, a model 6061-T6 aluminum alloy system fabricated by friction stir weld joining extruded sandwich panels with a triangular corrugated core was used to investigate the dynamic deformation and fracture processes.
Abstract: Light metal sandwich panel structures with cellular cores have attracted interest for multifunctional applications which exploit their high bend strength and impact energy absorption. This concept has been explored here using a model 6061-T6 aluminum alloy system fabricated by friction stir weld joining extruded sandwich panels with a triangular corrugated core. Micro-hardness and miniature tensile coupon testing revealed that friction stir welding reduced the strength and ductility in the welds and a narrow heat affected zone on either side of the weld by approximately 30%. Square, edge clamped sandwich panels and solid plates of equal mass per unit area were subjected to localized impulsive loading by the impact of explosively accelerated, water saturated, sand shells. The hydrodynamic load and impulse applied by the sand were gradually increased by reducing the stand-off distance between the test charge and panel surfaces. The sandwich panels suffered global bending and stretching, and localized core crushing. As the pressure applied by the sand increased, face sheet fracture by a combination of tensile stretching and shear-off occurred first at the two clamped edges of the panels that were parallel with the corrugation and weld direction. The plane of these fractures always lay within the heat affected zone of the longitudinal welds. For the most intensively loaded panels additional cracks occurred at the other clamped boundaries and in the center of the panel. To investigate the dynamic deformation and fracture processes, a particle-based method has been used to simulate the impulsive loading of the panels. This has been combined with a finite element analysis utilizing a modified Johnson–Cook constitutive relation and a Cockcroft– Latham fracture criterion that accounted for local variation in material properties. The fully coupled simulation approach enabled the relationships between the soilexplosive test charge design, panel geometry, spatially varying material properties and the panel’s deformation and dynamic failure responses to be explored. This comprehensive study reveals the existence of a strong instability in the loading that results from changes in sand particle reflection during dynamic evolution of the panel’s surface topology. Significant fluid–structure interaction effects are also discovered at the sample sides and corners due to changes of the sand reflection angle by the edge clamping system.

Journal ArticleDOI
TL;DR: In this article, a finite element tool was used to simulate the structural and damage response of foam-based sandwich composites subjected to low-velocity impact, and good agreement was obtained between predictions and experiments in terms of force histories, force displacement curves and dissipated energy.
Abstract: The paper illustrates the application of a finite element tool for simulating the structural and damage response of foam-based sandwich composites subjected to low-velocity impact. Onset and growth of typical damage modes occurring in the composite skins, such as fibre fracture, matrix cracking and delaminations, were simulated by the use of three-dimensional damage models (for intralaminar damage) and interfacial cohesive laws (for interlaminar damage). The nonlinear behaviour of the foam core was simulated by a crushable foam plasticity model. The FE results were compared with experimental data acquired by impact testing on sandwich panels consisting of carbon/epoxy facesheets bonded to a PVC foam. Good agreement was obtained between predictions and experiments in terms of force histories, force–displacement curves and dissipated energy. The proposed model was also capable of simulating correctly nature and size of impact damage, and of capturing the key features of individual delaminations at different depth locations.

Journal ArticleDOI
TL;DR: In this article, the authors investigated the failure modes of composite sandwich panels subject to quasi-static indentation and low-velocity impact and concluded that the resulting failure modes are due to matrix shear/tension damage and core buckling.

Journal ArticleDOI
TL;DR: In this paper, carbon fiber reinforced lattice-core sandwich composites with compliant face sheets were designed and manufactured to restrict debonding, and compressive properties of the lattice composites and sandwich columns with different skin thicknesses were tested.
Abstract: To restrict debonding, carbon fiber reinforced lattice-core sandwich composites with compliant skins were designed and manufactured. Compression behaviors of the lattice composites and sandwich columns with different skin thicknesses were tested. Bending performances of the sandwich panels were explored by three-point bending experiments. Two typical failure mechanisms of the lattice-core sandwich structures, delaminating and local buckling were revealed by the experiments. Failure criteria were suggested and gave consistent analytical predictions. For panels with stiff skins, delamination is the dominant failure style. Cell dimensions, fracture toughness of the adhesives and the strength of the sandwich skin decide the critical load capacity of the lattice-core sandwich structure. The mono-cell buckling and the succeeding local buckling are dominant for the sandwich structures with more compliant skin sheets. Debonding is restricted within one cell in bending and two cells in compression for lattice-core sandwich panels with compliant face sheets and softer lattice cores.

Journal ArticleDOI
TL;DR: In this article, an innovative aluminum sandwich panel with sinusoidal corrugated core is investigated and the properties of the equivalent material are determined both analytically and numerically for the chosen Reissner-Mindlin orthotropic representation.

Journal ArticleDOI
TL;DR: In this article, pyramidal truss sandwich cores with relative densities ρ ¯ in the range 1-10% have been manufactured from carbon fiber reinforced polymer laminates by employing a snap-fitting method.
Abstract: The combination of light carbon fiber reinforced polymer (CFRP) composite materials with structurally efficient sandwich panel designs offers novel opportunities for ultralight structures. Here, pyramidal truss sandwich cores with relative densities ρ ¯ in the range 1–10% have been manufactured from carbon fiber reinforced polymer laminates by employing a snap-fitting method. The measured quasi-static shear strength varied between 0.8 and 7.5 MPa. Two failure modes were observed: (i) Euler buckling of the struts and (ii) delamination failure of the laminates. Micro-buckling failure of the struts was not observed in the experiments reported here while Euler buckling and delamination failures occurred for the low ( ρ ¯ ⩽ 1 % ) and high ( ρ ¯ > 1 % ) relative density cores, respectively. Analytical models for the collapse of the composite cores by these failure modes are presented. Good agreement between the measurements and predictions based on the Euler buckling and delamination failure of the struts is observed while the micro-buckling analysis over-predicts the measurements. The CFRP pyramidal cores investigated here have a similar mechanical performance to CFRP honeycombs. Thus, for a range of multi-functional applications that require an “open-celled” architecture (e.g. so that cooling fluid can pass through a sandwich core), the CFRP pyramidal cores offer an attractive alternative to honeycombs.

Journal ArticleDOI
TL;DR: In this article, the bending strength, stiffness and energy absorption of corrugated sandwich composite structure were investigated to explore novel designs of lightweight loadbearing structures that are capable of energy absorption in transportation vehicles.

Journal ArticleDOI
TL;DR: In this paper, the authors used X-ray tomography to investigate the mechanisms of impact on extruded 6061T6 aluminum alloy sandwich panels with empty and alumina filled, triangular corrugated cores.

Journal ArticleDOI
TL;DR: In this article, a group of metallic aluminum foam-cored sandwich panels (AFSPs) were used as vehicle armor against blast loading, and the dynamic responses of the AFSPs with various combinations of face-sheet materials were analyzed using LS-DYNA.

Journal ArticleDOI
TL;DR: In this article, a double-shear configuration of glass fiber reinforced polymer (GFRP) shear connectors was used to reduce thermal bridging in insulated concrete sandwich panels compared to steel connectors.
Abstract: Glass fiber–reinforced polymer (GFRP) shear connectors provide much reduced thermal bridging in insulated concrete sandwich panels compared to steel connectors. In this study, 50 specimens with dimensions of 254×254×900 mm representing segments of a precast sandwich wall comprising two concrete wythes and a concrete stud surrounded by insulation foam have been tested in a double-shear configuration. Three types of GFRP connectors produced from available sand-coated and threaded rods were tested and compared to conventional steel and polymer connectors. GFRP connector diameters varied from 6 to 13 mm, and spacing varied from 80 to 300 mm. Both circular and rectangular cross sections were examined, along with various end treatments to compare with simple straight embedment. The shear strength of GFRP connectors, including the effect of friction between concrete and foam, ranged from 60 to 112 MPa, significantly higher than polymer connectors but lower than steel connectors. As the connectors bridge...

Journal ArticleDOI
TL;DR: In this article, the sound and vibration damping properties of natural material based sandwich composites were explored and characterized, and it was experimentally observed that utilizing a balsa wood core with a natural fiber based face sheet has a 100% improvement in coincidence frequency, a metric of acoustic performance.

Journal ArticleDOI
TL;DR: In this paper, a finite element fluid-structure interaction model was developed to understand the deformation and failure mechanisms of both monolithic and sandwich composite panels, and the simulations demonstrated that the delamination process is strongly rate dependent, and that Hashin model captures the spatial distribution and magnitude of damage to first-order approximation.
Abstract: Designing lightweight high-performance materials that can sustain high impulsive loadings is of great interest for marine applications. In this study, a finite element fluid–structure interaction model was developed to understand the deformation and failure mechanisms of both monolithic and sandwich composite panels. Fiber (E-glass fiber) and matrix (vinylester resin) damage and degradation in individual unidirectional composite laminas were modeled using Hashin failure model. The delamination between laminas was modeled by a strain-rate sensitive cohesive law. In sandwich panels, core compaction (H250 PVC foam) is modeled by a crushable foam plasticity model with volumetric hardening and strain-rate sensitivity. The model-predicted deformation histories, fiber/matrix damage patterns, and inter-lamina delamination, in both monolithic and sandwich composite panels, were compared with experimental observations. The simulations demonstrated that the delamination process is strongly rate dependent, and that Hashin model captures the spatial distribution and magnitude of damage to a first-order approximation. The model also revealed that the foam plays an important role in improving panel performance by mitigating the transmitted impulse to the back-side face sheet while maintaining overall bending stiffness.

Journal ArticleDOI
TL;DR: In this article, a comparative study on the attenuation ability of mild steel plates and sandwich panels with aluminum foam core was carried out and the results showed that the peak load was reduced by 61.54-64.69% in sandwich panels without foam core compared to the mild steel plate with foam core.

Journal ArticleDOI
TL;DR: In this article, an experimental and numerical investigation of sandwich panels, with PVC foam cores and glass fibre reinforced vinyl ester face sheets, to localised blast loading was carried out.

Journal ArticleDOI
TL;DR: In this article, an application of nonlinear acoustics to impact damage detection in a composite chiral sandwich panel is reported, where highfrequency ultrasonic excitation and low-frequency modal excitation were used to observe nonlinear modulations in ultrasonic waves due to structural damage.
Abstract: This paper reports an application of nonlinear acoustics to impact damage detection in a composite chiral sandwich panel. The panel is built from a chiral honeycomb and two composite skins. High-frequency ultrasonic excitation and low-frequency modal excitation were used to observe nonlinear modulations in ultrasonic waves due to structural damage. Low-profile, surface-bonded piezoceramic transducers were used for ultrasonic excitation. Non-contact laser vibrometry was applied for ultrasonic sensing. The work presented focuses on the analysis of the modulation intensities and damage-related nonlinearities. The paper demonstrates that the method can be used for impact damage detection in composite chiral sandwich panels.

Journal ArticleDOI
TL;DR: In this paper, the impact responses of brazed and adhesively bonded layered 1050 H14 trapezoidal corrugated aluminum core and aluminum sheet interlayer sandwich panels with 3003 and 1050 H 14 aluminum alloy face sheets were investigated in a drop weight tower using spherical, flat and conical end striker tips.

Journal ArticleDOI
TL;DR: In this article, the 3D origami honeycombs are generalized by numerical parameters and fabricated using a newly proposed folding line diagrams (FLD) design method, which enables us to draw the FLD of arbitrary cross-section honeycomb shapes, and some typical samples are shown with their FLDs.
Abstract: In recent years, the use of composite materials has drastically increased in the construction of aerospace components. In the case of sandwich panels, they have been extensively used as face sheets with aluminum honeycomb cores. Currently, space structures are increasing in size and require greater degrees of accuracy; hence, the use of composites as a core material is a natural progression. However, these composite core materials are not regularly used in sandwich construction. Compared to standard aluminum honeycombs, their manufacturing costs are very high and they have limited applications. Another problem is difficulty of machining. In the manufacture of complex-shaped parts, the cores must have some degree of curvature. For aluminum honeycombs, this can be done using a contour cutter, a 3-D tracer, and numerically controlled machines. However, burrs and buckling of cell walls present a difficult problem for surface accuracy. It is clear that the machining of composite cores requires more expensive and sophisticated systems. This study illustrates a new strategy to fabricate arbitrary cross-section honeycomb cores with applications of advanced composite materials. These types of honeycombs are usually manufactured from normal flat honeycombs by curving or carving, but the proposed method enables us to construct objective shaped honeycombs directly. The basic idea originates from the fold-made paper honeycombs proposed by authors, in which they attempted to apply origami and kirigami techniques to the creation of sandwich structures. Origami is the traditional Japanese art of paper folding. Kirigami is a variation of origami. We first introduce the concept of the origami honeycomb, which is made from single flat sheets with periodical slits resembling origami. In previous studies, honeycombs having various shapes were made using this method, and were realized by only changing folding line diagrams (FLDs). In this study, these 3D origami honeycombs are generalized by numerical parameters and fabricated using a newly proposed FLD design method, which enables us to draw the FLD of arbitrary cross-section honeycombs. Next, we describe a method of applying this technique to advanced composite materials. For partially soft composites, folding lines are materialized by silicon rubber hinges on carbon fiber reinforced plastic. Complex FLD patterns are then printed using masks on carbon fabrics. Finally, these foldable composites that are cured in corrugated shapes in autoclaves are folded into honeycomb shapes, and some typical samples are shown with their FLDs.

Journal ArticleDOI
TL;DR: In this article, the authors derived general formulas for the effective stiffness coefficients of composite elastic beams made of several non-homogeneous materials and compared them with numerical results computed by the finite element method.

Journal ArticleDOI
TL;DR: In this paper, the results of finite element simulation followed by an experimental study are presented in order to investigate the mechanical behavior of three-dimensional woven glass-fiber sandwich composites using FE method.
Abstract: The results of finite element simulation followed by an experimental study are presented in order to investigate the mechanical behavior of three-dimensional woven glass-fiber sandwich composites using FE method. Experimental load–displacement curves were obtained for flatwise compressive, edgewise compressive, shear, three-point bending and four-point bending loads on the specimens with three different core thicknesses in two principal directions of the sandwich panels, called warp and weft. A 3D finite element model is employed consisting of glass fabric and surrounding epoxy resin matrix in order to predict the mechanical behavior of such complex structures. Comparison between the finite element predictions and experimental data showed good agreement which implies that the FE simulation can be used instead of time-consuming experimental procedures to study the effect of different parameters on mechanical properties of the 3D woven sandwich composites.

Journal ArticleDOI
TL;DR: In this article, the axially restrained non-composite steel-concrete-steel (SCS) panels were used to provide an effective means for protecting assets against severe impact attacks.