Showing papers on "Sandwich panel published in 2016"
TL;DR: In this article, a carbon fiber reinforced composite (CFRC) lattice truss sandwich panel (LTSP) was designed and fabricated to get a strong, stiff and weight-efficient structure.
101 citations
TL;DR: In this article, the impact response of sandwich panels is not only dependent on the facesheet but also on the core material, and the impact properties of the sandwich panels with the five different cores were compared in terms of contact force, energy absorption, depth of indentation, overall bending deflection, etc.
92 citations
TL;DR: In this article, an analytical framework has been proposed to analyze the effect of random structural irregularity in honeycomb core for natural frequencies of sandwich panels, and closed-form formulas have been developed for the out-of-plane shear moduli of spatially irregular honeycombs following minimum potential energy theorem and minimum complementary energy theorem.
Abstract: An analytical framework has been proposed to analyze the effect of random structural irregularity in honeycomb core for natural frequencies of sandwich panels. Closed-form formulas have been developed for the out-of-plane shear moduli of spatially irregular honeycombs following minimum potential energy theorem and minimum complementary energy theorem. Subsequently an analytical approach has been presented for free-vibration analysis of honeycomb core sandwich panels to quantify the effect of such irregularity following a probabilistic paradigm. Representative results have been furnished for natural frequencies corresponding to low vibration modes of a sandwich panel with high length-to-width ratio. The results suggest that spatially random irregularities in honeycomb core have considerable effect on the natural frequencies of sandwich panels.
78 citations
TL;DR: In this article, a two-level numerical optimisation procedure is proposed for the design of a sandwich panel made of carbon-epoxy skins and a metallic cellular core, which does not make use of any simplifying hypothesis to obtain a true global optimum configuration of the system.
Abstract: This work deals with the problem of the optimum design of a sandwich panel made of carbon-epoxy skins and a metallic cellular core. The proposed design strategy is a multi-scale numerical optimisation procedure that does not make use of any simplifying hypothesis to obtain a true global optimum configuration of the system. To face the design of the sandwich structure at both meso and macro scales, a two-level optimisation strategy is employed: at the first level the goal is the determination of the optimum shape of the unit cell of the core (meso-scale) together with the material and geometric parameters of the laminated skins (macro-scale), while at the second level the objective is the design of the skins stacking sequence (skin meso-scale) meeting the geometrical and material parameters provided by the first-level problem. The two-level strategy is founded on the polar formalism for the description of the anisotropic behaviour of the laminates, on the NURBS basis functions for representing the shape of the unit cell and on the use of a genetic algorithm as optimisation tool to perform the solution search. To prove its effectiveness, the multi-scale strategy is applied to the least-weight design of a sandwich plate subject to constraints of different nature: on the positive-definiteness of the stiffness tensor of the core, on the admissible material properties of the laminated faces, on the local buckling load of the unit cell, on the global buckling load of the panel and geometrical as well as manufacturability constraints related to the fabrication process of the cellular core.
74 citations
TL;DR: In this paper, a new composite structure (glass fiber assembly-filled honeycomb sandwich panel) is prepared in order to improve the acoustic properties of a honeycomb panel, and the effect of glass fiber assembly with different filling shapes (random and fiber ball), fiber diameter, fiber content and air-layer on acoustic properties are explored.
Abstract: A new composite structure (glass fiber assembly-filled honeycomb sandwich panel) is prepared in order to improve the acoustic properties. Effect of glass fiber assembly with different filling shapes (random and fiber ball), fiber diameter, fiber content and air-layer on acoustic properties are explored. Sound absorption coefficient (SAC) and sound transmission loss (STL) are determined by a B&K impedance tube. The experiment results indicate that the first resonance frequency of SAC disappears along with the improvement of the second resonance frequency by reducing the fiber diameter or increasing the fiber content. STL can be improved by the increase of the fiber content. Random glass fiber assembly with the fine fibers has the best STL in the all testing samples. The advantage of glass fiber assembly for improving the STL of honeycomb sandwich panel is particularly clear at frequencies below 4.5 kHz. Especially, the STL difference reaches the maximum at around 20 dB at frequencies below 3.0 kHz.
73 citations
TL;DR: In this paper, two types of Arctic GBS structure with flower-conical SCS sandwich shell type and plate type of ice-resistant wall have been developed for the Arctic offshore structure.
63 citations
TL;DR: The composite pyramidal lattice truss core sandwich panel, in which the lattice core is strengthened by end frames between various nodes and the struts are reinforced with unidirectional fibers, is fabricated by the hot-press molding technique and interlocking method.
63 citations
TL;DR: In this article, the results of numerical studies carried out on vibro-acoustic and sound transmission loss behaviour of aluminium honeycomb core sandwich panel with fibre reinforced plastic facings were presented.
62 citations
TL;DR: In this article, an external phase change material (PCM) layer was integrated with an insulated sandwich panel, in order to reduce and displace the heat flux phase caused by the external climatic conditions.
60 citations
TL;DR: In this article, effective approaches to enhance the blast resistance of sandwich structures with corrugated cores were developed by adopting three different strategies to fill the spaces within cores with polymeric foam.
Abstract: Effective approaches to enhance the blast resistance of sandwich structures with corrugated cores were developed by adopting three different strategies to fill the spaces within cores with polymeric foam. The baseline unfilled panels and foam-filled panels were designed and fabricated, and finally subjected to air blast loading generated by detonating cylindrical explosive. Deformation modes and failure mechanisms of tested panels were investigated. Experimental results demonstrated that the panels with back side filling strategy did not show better blast performance compared with the unfilled panels, even though extra weight was expended due to the addition of foam fillers. The panels with front side filling and fully filling strategies encouragingly appeared to possess desirable blast resistance to prevent severe fracture under high intensity blast loading. This benefit should be attributed to the sufficient crushing deformation of foam fillers and the enhanced buckling resistance of core webs. In addition, a preliminary study has been conducted to investigate the effects of front face thickness on the blast performance of foam-filled panel. Attempts of allocating component mass and filling different material have been made to explore the potential of performance improvement.
59 citations
TL;DR: In this article, an experimental and numerical investigation on surface deformation and energy absorption of aluminum honeycomb sandwich panels subjected to low-velocity impact is undertaken, where a high-speed camera system is employed to record the acceleration attenuation process of the impactor, and a projection profile system is introduced to measure the surface profiles of the panel and the depth of the ultimate indentation.
TL;DR: In this article, a three-dimensional phononic crystal whose unit cell has been engineered to obtain a strong wave-attenuation band in the middle of the acoustic frequency range is presented. But the performance of the phononic core is remarkable both in terms of amplitude reduction in the transmissibility and width of the attenuation band.
TL;DR: Based on the yield criteria for the multilayer metal sandwich cross-sections, analytical solutions and bounds of analytical solutions for large deflection of the fully clamped slender sandwich beams are derived, in which interaction of bending and stretching induced by large deflections is considered as mentioned in this paper.
TL;DR: In this paper, the influence of core geometry on vibration and acoustic response characteristics of sandwich panels which are used as aerospace structures is studied. And the results show that for a honeycomb core sandwich panel, the better acoustic comfort can be achieved by reducing the core height and increasing the face sheet thickness.
TL;DR: In this article, a thermal protection system (ITPS) based on the lightweight C/SiC pyramidal core lattice sandwich panel is proposed, which integrates advantages of low areal density and high temperature resistance up to 1600°C.
TL;DR: In this paper, the effect of multi-walled carbon nanotubes (MWCNTs) on the internal and external damages of foam-core sandwich panels with kevlar fiber reinforced epoxy face sheets subjected to a low-velocity impact was studied.
Abstract: This research studied the effect of multi-walled carbon nanotubes (MWCNTs) on the internal and external damages of foam-core sandwich panels with kevlar fiber reinforced epoxy face sheets subjected to a low-velocity impact. The sandwich panels were subjected to six levels of energy. Energy profile diagrams (EPDs) were plotted to determine the rebounding, penetration and perforation thresholds of the sandwich panels. Non-destructive evaluation methods have been employed for detecting and measuring damage size of the sandwich panels using X-ray radiography and active infrared thermography. The results show that MWCNTs can improve the absorbed energy and penetration threshold of the foam-core sandwich panels.
TL;DR: In this article, the deformation/failure modes and dynamic response of peripherally clamped square monolithic and sandwich panels of localized impulsive loading were investigated experimentally by metallic foam projectile impact.
Abstract: The deformation/failure modes and dynamic response of peripherally clamped square monolithic and sandwich panels of localized impulsive loading were investigated experimentally by metallic foam projectile impact. The sandwich panels comprise three different types of cellular metallic cores, i.e., closed-cell aluminum foam core, open-cell aluminum foam core and aluminum honeycomb core. Experimental results show that all the sandwich panels present mainly large global inelastic deformation with obvious local compressive failure in the central area, except for those open-cell foam core sandwich panels. The dynamic response of sandwich panels is sensitive to the applied impulse and their geometrical configurations. Based on the experimental investigation, a theoretical analysis was developed to predict the dynamic response of sandwich panels by employing a comprehensive yield locus and a modified classic monolithic panel theory. A comparison of experimental results and theoretic predictions was made, and a good agreement was then found. These findings are very useful to guide the engineering applications of metallic sandwich structures for the protection purpose.
TL;DR: In this paper, the vibroacoustic behavior of anti-tetrachiral and auxetic hexagonal gradient sandwich panels using homogenized finite element models is described and first-order and random optimization methods are used for the minimization of radiated sound power level of the structures.
Abstract: The work describes the vibroacoustic behavior of anti-tetrachiral and auxetic hexagonal gradient sandwich panels using homogenized finite element models to determine the mechanical properties of the auxetic structures, the natural frequencies and radiated sound power level of sandwich panels made by the auxetic cores. The mechanical properties and the vibroacoustic behavior of auxetic hexagonal sandwich panels are investigated as a benchmark. The radiated sound power level of the structure over the frequency range of 0–1000 Hz is minimized by modifying the core geometry of the gradient auxetic sandwich panels. Several excitation cases are considered. First-order and random optimization methods are used for the minimization of radiated sound power level of the structures. The results of this study present significant insights into the design of auxetic structures with respect to their vibroacoustical properties.
TL;DR: In this paper, 38 push-through tests were performed on a precast concrete insulated sandwich panel design using combined angled and horizontal connectors, and the key parameters were various inclination angles and diameters of connectors; orientation of the diagonal connector relative to loading; and panels with or without an active foam-to-concrete bond.
Abstract: In this study, 38 push-through tests were performed on a precast concrete insulated sandwich panel design using combined angled and horizontal connectors. Basalt fiber-reinforced polymer (BFRP) and steel connectors were tested and compared. The key parameters were various inclination angles and diameters of connectors; orientation of the diagonal connector relative to loading (i.e., tested in tension or compression); and panels with or without an active foam-to-concrete bond. Steel connectors failed by yielding in tension and inelastic buckling in compression. Larger-diameter BFRP connectors usually pulled out under tension and crushed in compression. Smaller-diameter BFRP connectors ruptured in tension and buckled in compression. Strength and stiffness increased with the connector angle and diameter. The insulation foam bond was found to contribute similarly regardless of connector material. An independent theoretical model accounting for material, bond, and stability failure modes, as well as ge...
TL;DR: In this paper, an analytical model was developed to predict the flexural response, and determine the impact of various shear connector parameters on the behavior, of architectural partially-composite precast concrete insulated panels.
TL;DR: In this paper, the authors examined the vibration of fiber-steered laminated plates, such as those used in the skins of a sandwich panel, manufactured by automated fiber placement.
Abstract: This paper examines the vibration of fiber-steered laminated plates, such as those used in the skins of a sandwich panel, manufactured by automated fiber placement. We use third-order shear deformation theory, hybrid Fourier-Galerkin method, and numerical integration technique to predict their vibration responses, and to study the role of manufacturing defects, in particular gaps and overlpas, as well as the parameters representing the stiffness of the sandwich core. With the aim of improving both structural and vibration performance, we first adopt a passive approach to search for optimal fiber paths that can concurrently maximize the undamped dynamic out-of-plane and in-plane stiffness of laminates with gaps and overlaps. To further reduce vibration, we then follow an active approach that uses magnetostrictive layers to suppress the structural vibration of laminates with optimal vibration characteristics. The results of the vibration analysis show that for plates with gaps, as opposed to those with overlaps, the dynamic out-of-plane deflection has a higher amplitude and a lower frequency than that of a defect-free plate. In addition, the results show that magnetostrictive layers with a higher gain control can lead to a lower vibration frequency, and better attenuate the vibration response of the panel.
TL;DR: In this paper, numerical results of optimization of sandwich panel properties were provided for a three-layer sandwich two-phase composite, where the structure of the composite is completely filled with solid materials, hence no voids appear within its whole volume.
Abstract: Optimization of structures with complex shapes is a big challenge for computational physics. Results of numerical calculations show that composite or sandwich panel structures have a great influence on their effective properties. This article presents numerical results of optimization of sandwich panel properties. Calculations were provided for a three-layer sandwich two-phase composite. Optimization techniques were used for minimization of the effective Poisson's ratio of the core. The resultant composite structure exhibits a negative Poisson's ratio (NPR), although all its constituents are characterized by positive values of the Poisson's ratio. The structure of the composite is completely filled with solid materials, hence no voids appear within its whole volume. To find a solution, the finite-element method combined with an optimization algorithm MMA (method of moving asymptotes) was used. For the purpose of analysis, the material parameters were written by means of the shape interpolation SIMP (solid isotropic material with penalization) scheme.
TL;DR: In this paper, a multifunctional hybrid material class in the form of a sandwich panel has been developed towards the combined optimization of mechanical and electromagnetic absorption performance, where the faces of the panel are made of glass fibre reinforced epoxy composites and the core is made of carbon nanotube reinforced polymer foam filling a metallic honeycomb.
TL;DR: In this article, a tube-core sandwich panel was designed to serve as anti-blast panel of blast resistant walls, which can be easily connected with face sheets through welding, and the panel is rigid enough to resist the shock wave.
TL;DR: In this article, a finite element study is conducted to determine optimal geometric parameters of hollow tetrahedral truss cores given height and density constraints, and nodal height truncation is introduced as an additional parameter for this architecture, and demonstrate that nodal truncation can yield further improvements in the shear and compression strength.
TL;DR: The reliability and accuracy of a numerical shell model simulation and its predictive capabilities with existing failure criteria are compared to experiments of a 34-m long blade tested to ultimate failure as mentioned in this paper.
TL;DR: In this paper, the effect of temperature on the shear creep response of a rigid polyurethane (PUR) foam within the scope of sandwich panel application in building floors was investigated.
TL;DR: In this paper, a numerical model was developed to predict the response of partially composite load bearing concrete sandwich panels under axial loads applied to the structural wythe at any eccentricity.
Abstract: This paper presents a numerical model developed to predict the response of partially composite load bearing concrete sandwich panels under axial loads applied to the structural wythe at any eccentricity. The model accounts for material nonlinearity, second-order effects, and cracking of concrete and plasticity of steel reinforcement, and can also model fiber-reinforced polymer (FRP) connectors. The analysis uses a bond-slip model to simulate partial composite action between the two wythes resulting from various configurations of insulation and shear connectors. A variety of failure modes can be detected, including concrete crushing, flexural yielding, connectors yielding, pullout or rupture, and stability failures. Progressive failure of connectors is also modeled. The degree of composite action (κu) can be calculated for a given design. The model was verified against experimental data and used to conduct a comprehensive parametric study. It was shown that κu increases with panel length. Connector...
TL;DR: In this article, a homogenization method for geometric nonlinear analysis of structural core sandwich panels is proposed, which provides high computational performance based on an efficient separation of scales and allows for description of buckling in these two scales and is shown to hold good accuracy with respect to equivalent 3D FEM models.
TL;DR: In this article, the optimal design of a composite sandwich panel with honeycomb core structure using particle swarm optimization (PSO) technique was investigated, where the face sheets of sandwich panel are considered to be thin and the sandwich panel is subjected to a uniformly distributed normal load.