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Showing papers on "Sandwich-structured composite published in 2015"


Journal ArticleDOI
TL;DR: In this paper, the authors compared the deformation and elastic spring-back of the honeycomb sandwich panels and the monolithic plates of equivalent mass subjected to impact from foam projectiles, and found that the aluminum sandwich panels outperformed the air sandwich panels within an impulse range of 2.25 kNsm(-2) similar to 4.70kNsm(2).

110 citations


Journal ArticleDOI
TL;DR: In this paper, the authors analyzed the effective properties and dynamic response of a sandwich panel made of two face sheets and auxetic core by computer simulations and showed that it is possible to create auxetic sandwich panels with positive Poisson's ratio if the filler material is nearly incompressible, but can move in out-of-plane direction.
Abstract: Effective properties and dynamic response of a sandwich panel made of two face sheets and auxetic core are analyzed in this study by computer simulations. The inner composite layer is made of a cellular auxetic structure immersed in a filler material of a given Poisson's ratio (filler material fills the voids in structure). Each cell is composed of an auxetic structure (re-entrant honeycomb or rotating square), i.e., exhibiting negative Poisson's ratio without any filler. Influence of filler material on the effective properties of the sandwich panel is investigated. The proposed structure shows interesting structural characteristics and dynamic properties. Our results clearly show that it is possible to create auxetic sandwich panels made of two solid materials with positive Poisson's ratio. This is even possible if the filler material is nearly incompressible, but can move in out-of-plane direction. Moreover, effective Young's modulus of such sandwich panels becomes very large if the Poisson's ratio of the filler material tends to −1.

101 citations


Journal ArticleDOI
TL;DR: In this article, the authors used the finite element method to numerically analyze the energy absorption capabilities of an octet truss cellular structure created with the proposed manufacturing process and that of a solid block of the same material and area density as the cellular structure.
Abstract: Cellular structures offer high specific strength and can offer high specific stiffness, good impact absorption, and thermal and acoustic insulation. A major challenge in fabricating cellular structures is joining various components. It is well known that joints, either welded or bolted or bonded with an adhesive, serve as stress concentrators. Here, we overcome this shortcoming by the use of metal casting into 3D printed sand molds for fabricating cellular structures and sandwich panels. Furthermore, the use of 3D printing allows for the fabrication of sand molds without the need for a pattern, and thus enables the creation of cellular structures with designed mesostructure from a bevy of metal alloys. We use the finite element method to numerically analyze the energy absorption capabilities of an octet truss cellular structure created with the proposed manufacturing process and that of a solid block of the same material and area density as the cellular structure. In the numerical simulations, mechanical properties collected through experimental quasi-static compression testing are employed. It is found that indeed the cellular structure absorbs considerably more impact energy over that absorbed by a solid structure of the same weight.

96 citations


Journal ArticleDOI
TL;DR: In this article, the authors investigated the crashworthiness of multi-layered corrugated sandwich panels by experimental studies and numerical simulations under the quasi-static crushing loading in the presence of trapezoidal aluminum cores and aluminum alloy sheets.

93 citations


Journal ArticleDOI
TL;DR: In this paper, the authors evaluated three potential core alternatives for glass fiber reinforced polymer (GFRP) foam-core sandwich panels and found that the Type 3 core possessed a higher strength and stiffness than the other two types.
Abstract: The objective of this study was to evaluate three potential core alternatives for glass fiber reinforced polymer (GFRP) foam-core sandwich panels. The proposed system could reduce the initial production costs and the manufacturing difficulties while improving the system performance. Three different polyurethane foam configurations were considered for the inner core, and the most suitable system was recommended for further prototyping. These configurations consisted of high-density polyurethane foam (Type 1), a bidirectional gridwork of thin, interconnecting, GFRP webs that is in-filled with lowdensity polyurethane foam (Type 2), and trapezoidal-shaped, low-density polyurethane foam utilizing GFRP web layers (Type 3). The facings of the three cores consisted of three plies of bidirectional E-glass woven fabric within a compatible polyurethane resin. Several types of small-scale experimental investigations were conducted. The results from this study indicated that the Types 1 and 2 cores were very weak and flexible making their implementation in bridge deck panels less practical. The Type 3 core possessed a higher strength and stiffness than the other two types. Therefore, this type is recommended for the proposed sandwich system to serve as a candidate for further development. Additionally, a finite element model (FEM) was developed using software package ABAQUS for the Type 3 system to further investigate its structural behavior. This model was successfully compared to experimental data indicating its suitability for parametric analysis of panels and their design.

91 citations


Journal ArticleDOI
TL;DR: In this article, the effects of temperature on the bending properties and failure mechanism of carbon fiber reinforced polymer composite sandwich structure with pyramidal truss cores were investigated and presented in a scanning electron microscope.
Abstract: The effects of temperature on the bending properties and failure mechanism of carbon fiber reinforced polymer composite sandwich structure with pyramidal truss cores were investigated and presented in this paper. The three-point bending tests of composite sandwich structures were performed at seven different temperatures, and the scanning electron microscope was used to examine the fiber-matrix interface properties in order to understand the deformation and failure mechanism. Then the effects of temperature on deformation modes, failure mechanism and bending failure load were studied and analyzed. The results showed that the temperature has visible impact on the deformation modes, failure mechanism, and bending failure load. The bending failure load decreased as temperature increased, which was caused by the degradation of the matrix properties and fiber-matrix interface properties at high temperature. The analytical formulae were also presented to predict the bending stiffness and failure load of composite sandwich structures at different temperatures.

90 citations


Journal ArticleDOI
TL;DR: In this article, failure modes of different sandwich panels were analyzed by observing the contact surface and the cross section through damage region, and the microstructure of the impacted specimens was carried out.

88 citations


Journal ArticleDOI
TL;DR: In this paper, experimental studies on SCS sandwich composite beams with different types of concretes and novel shear connectors are presented This is followed by the development of analytical model to predict the ultimate strength of the composite beams.
Abstract: Steel–concrete–steel (SCS) sandwich composite structure is a relative new type of system that combines the advantages of steel and reinforced concrete structure Due to its excellent strength to cost performance, it exhibits versatile potential applications in building and offshore constructions In order to reduce the self-weight of the structure and achieve composite action between the steel and concrete, ultra-lightweight cement composite and novel shear connectors have been developed and applied in the SCS sandwich composite structures, respectively Meanwhile, the development of design guidelines lags behind the innovation of the structure In this paper, experimental studies on SCS sandwich composite beams with different types of concretes and novel shear connectors are presented This is followed by the development of analytical model to predict the ultimate strength of the SCS sandwich composite beams Finally, the proposed analytical model is verified against the results from a series of beams tests which include Bi-steel sandwich beams, double skin beams, sandwich beams with J-hook connectors, angle connectors, and cable connectors Through the analysis and verification, new methods to predict the ultimate strength of SCS sandwich composite beams are recommended for design purposes

87 citations


Journal ArticleDOI
TL;DR: In this article, three designs of glass reinforced composite sandwich structures, namely boxes (web-core W1), trapezoid and polyurethane rigid foam, are fabricated using new generation of two-part thermoset polyurehane resin systems as matrix materials with vacuum assisted resin transfer molding (VARTM) process.

85 citations


Journal ArticleDOI
TL;DR: In this paper, the authors investigate the mechanical behavior of balsa wood as a function of density, which varies from roughly 60 to 380 kg/m3 in axial compression, bending, and torsion, while in radial compression, the modulus and strength vary nonlinearly.

84 citations


Journal ArticleDOI
TL;DR: In this paper, a simple foam core reinforcement with perforation and stitching is proposed as a simpler but very effective method in performance improvement for the foam core sandwich composites, which has been compared in terms of compressive, bending, shear and impact performances.
Abstract: The purpose of this study is to improve the mechanical performance of the foam core sandwich composites with a rather simpler method of core reinforcement. With this aim; sandwich composite panels are manufactured using only-perforated foam and perforated-stitched foam as the core with multi-axial glass fabrics as the facesheet materials by vacuum infusion method using epoxy resin. Sandwich composites with perforated core, stitched core and plain core have been compared in terms of compressive, bending, shear and impact performances. It was seen that newly proposed perforated core specimens and stitched core specimens with relatively insignificant weight increase have superior mechanical performances than plain core specimens. Thus reinforcing foam core with perforation and stitching is proposed as simpler but very effective method in performance improvement for the sandwich composites.

Journal ArticleDOI
TL;DR: In this paper, the effect of impact energy on the mechanical properties of textile-reinforced aerated concrete sandwich panels was investigated using an instrumented three-point bending experiment under static and low-velocity dynamic loading.

Journal ArticleDOI
TL;DR: In this paper, an innovative fiber reinforced polymer (FRP) shear plate connector with specially designed anchoring schemes, and study its effects on the flexural behavior of insulated concrete sandwich panels, in terms of stiffness, strength, and applicability for roof/floor constructions, based on combined experimental investigation and finite element (FE) analysis.

Journal ArticleDOI
TL;DR: In this paper, the optimal design of laminated sandwich panels with viscoelastic core is addressed, with the objective of simultaneously minimizing weight and material cost and maximizing modal damping.
Abstract: The optimal design of laminated sandwich panels with viscoelastic core is addressed in this paper, with the objective of simultaneously minimizing weight and material cost and maximizing modal damping. The design variables are the number of layers in the laminated sandwich panel, the layer constituent materials and orientation angles and the viscoelastic layer thickness. The problem is solved using the Direct MultiSearch (DMS) solver for multiobjective optimization problems which does not use any derivatives of the objective functions. A finite element model for sandwich plates with transversely compressible viscoelastic core and anisotropic laminated face layers is used. Trade-off Pareto optimal fronts are obtained and the results are analyzed and discussed.

Journal ArticleDOI
TL;DR: In this paper, a new idea combining graded material and lattice core for forming the graded lattice-core sandwich structures is introduced, which is based on the stitching and hot-press process.

Journal ArticleDOI
TL;DR: In this paper, the authors used polyurethane foams (PU) to fill the honeycomb core of a Dutch Tilting Train eXpress (TTX) to increase the energy absorption and impact strength.

Journal ArticleDOI
TL;DR: In this article, a finite element modeling framework is proposed for the sandwich composite comprising continuum damage, cohesive layers and crushable foam model with isotropic hardening for the core.

Journal ArticleDOI
TL;DR: In this paper, the authors focused on the vibration and acoustic responses of the sandwich panels constituted of orthotropic materials applied a concentrated harmonic force in a high temperature environment and derived the critical temperature to prevent the thermal load excess.

Journal ArticleDOI
TL;DR: In this article, an autodyn-based numerical simulation was conducted to investigate the dynamic response of core sandwich panels to air blast loading in an explosion tank considering three levels of blast loading and found that the maximum deflection, core web buckling and core compaction increased as the decrease of stand-off distance.

Journal ArticleDOI
TL;DR: In this paper, the effects of elevated temperature on the shear response of polyethylene terephthalate (PET) and polyurethane (PUR) foams used in composite sandwich panels are investigated.

Journal ArticleDOI
TL;DR: In this article, the dynamic response of metallic trapezoidal corrugated core sandwich panels under air blast loading is studied by experimental investigation, which revealed that the deflection and damage level of panel increased with the decrease of stand-off distance.

Journal ArticleDOI
TL;DR: In this paper, the authors present push-out test results of concrete sandwich panels with and without corrugated shear connectors to investigate in-plane shear performance, and the test results indicate that the type of insulation material that is used in the system considerably affects the bond strength between the concrete walls and the insulation layer.
Abstract: Precast concrete sandwich panels often are used for the exterior cladding of residential and commercial buildings due to their thermal efficiency. Precast concrete sandwich panel systems consist of two precast reinforced concrete walls that are separated by a layer of insulation and joined by connectors that penetrate the insulation layer and are anchored to two precast concrete wythes. This paper presents push-out test results of concrete sandwich panels with and without corrugated shear connectors to investigate in-plane shear performance. The variables in this study are two types of insulation materials and the width, pitch, and embedment length of shear connectors. The test results indicate that the type of insulation material that is used in the system considerably affects the bond strength between the concrete walls and the insulation layer. A design equation adopted in ICC-ES is revised to determine the shear design capacity of precast concrete sandwich panels with various configurations of shear connectors.

Journal ArticleDOI
TL;DR: In this paper, the authors used wood veneer of Aleppo pine as face sheet and cork agglomerate as core for composite panels, including multilayered designs, for use in construction.

Journal ArticleDOI
TL;DR: In this article, a more rigorous Discrete Model that incorporates the complex shear deformation behaviors and independent flexural resistance of the concrete wythes is derived, and experimental data from full-scale precast sandwich panel tests are used to validate the developed methodology.

Journal ArticleDOI
TL;DR: In this article, the potential for replacing conventional glass fiber-reinforced polymer (GFRP) skins with bio-based skins made of unidirectional flax fibers and a resin blend consisting of epoxidized pine oil was investigated.
Abstract: Structural sandwich panels with fiber-reinforced polymer (FRP) skins are becoming an increasingly popular system because of their remarkable light weight, ease and speed of installation, and high thermal insulation capabilities. This paper looks into the potential for replacing conventional glass fiber–reinforced polymer (GFRP) skins with bio-based skins made of unidirectional flax fibers and a resin blend consisting of epoxidized pine oil. A comprehensive material testing program was first carried out on 70 standard tension and compression coupons. Then, 36 sandwich panels of 1,000×150×75 mm were tested under four-point loading. The number of flax fiber–reinforced polymer layers of skin was varied from one to five [in comparison to one layer of GFRP, an epoxidized pine oil resin blend to epoxy, and the wet layup (WL) fabrication method to vacuum bag molding]. Sandwich panels with three layers of flax fibers provided equivalent strength and stiffness, but better deformability, compared to panels ...

Journal ArticleDOI
TL;DR: In this article, an imaging algorithm based on time reversal is developed to detect multiple debonding in tapered composite sandwich panels, using guided waves at different excitation frequencies ranging from 150 to 200 kHz, from an active sensor network.

Journal ArticleDOI
TL;DR: In this paper, the authors examined the response of the aluminum cenosphere syntactic foam core stiffened and unstiffened structures subjected to blast load in terms of the peak central point displacement of the back-sheet (opposite to the explosion) of the sandwich structures.

Journal ArticleDOI
TL;DR: In this article, the first attempt to study metal matrix syntactic foam core sandwich composites under quasi-static and high strain rates was made, and the results showed that the fabric had a reinforcing effect under quasistatic conditions.
Abstract: The present work is the first attempt to study metal matrix syntactic foam core sandwich composites. The sandwich is studied for microstructure and compressive properties at quasi-static and high strain rates. Under quasi-static compressive conditions, specimens were tested in the flatwise and edgewise orientations. The compressive strength, yield strength and plateau stress were higher in the flatwise orientation. Furthermore, both orientations for the sandwich composites showed a higher specific compressive strength and specific yield strength than the foam core alone. Failure initiated in the particles in the flatwise orientation, but in the carbon fabrics in the edgewise orientation. The results show that the fabric had a reinforcing effect under quasi-static conditions. The high strain rate (HSR) characterization was conducted in the strain rate range 525–845 s −1 using a split-Hopkinson pressure bar set-up equipped with a high speed image acquisition system. Within this strain rate range, the compressive strength of the sandwich is similar to that of the syntactic foam core alone. Upon review, the syntactic foam core metal matrix sandwich outperforms most of the syntactic foams in terms of energy absorption and compressive strength at comparable density levels.

Journal ArticleDOI
TL;DR: In this paper, the composite action of 46 segments representing precast concrete sandwich panels (PCSPs) using a fiber-reinforced polymer grid/rigid foam as a shear mechanism was investigated.
Abstract: This paper investigates the composite action of 46 segments representing precast concrete sandwich panels (PCSPs) using a fiber-reinforced polymer [FRP; specifically, a carbon fiber–reinforced polymer (CFRP)] grid/rigid foam as a shear mechanism. The experimental aspect of the research reported in this paper examined the effect of various parameters believed to affect the shear flow strength for this CFRP grid/foam system. The parameters that were considered are the spacing between vertical lines of CFRP grids and the thickness of the rigid foam. Results of the experimental aspect of the research reported in this paper indicated that increasing the spacing between vertical lines of CFRP grid increase the overall shear flow strengths due to the increase of the bonded contact area of the rigid foam to the concrete surface. However, the overall shear stresses were decreased due to the increase of this interface surface area. Test results also indicated that increasing the rigid foam thickness decreas...

Journal ArticleDOI
TL;DR: In this article, the authors presented an important experimental fatigue data for honeycomb sandwich panels with artificial defects and without defects, which showed that the presence of defect has no influence on the static behavior of the material and the lifetime of the L configuration is larger than in the W-direction.