Showing papers on "Sandwich-structured composite published in 2020"
TL;DR: In this paper, the deformation/failure modes of sandwich panels against blast impulse were investigated experimentally, and it was shown that the back facesheet deflection increases linearly with the impulse, apart from the petal-tearing failure of front facesheet.
82 citations
TL;DR: A review of precast concrete sandwich panels can be found in this paper, where the authors evaluate the body of research undertaken and analyse proposed design-solutions and test-results to identify future research focuses.
82 citations
TL;DR: In this article, a numerical model was developed and validated by comparing the simulation results with the experimental results in terms of deformation modes and back facesheet deflection, and an optimization study was performed to improve the blast resistance of graded core sandwich panels.
Abstract: Structural responses, deformation modes, blast resistance and energy absorption of foam core signify some major functional characteristics for design of sandwich panels. This study aimed to address these issues by investigating uniform and graded foam core configurations. First, an experimental study was performed and the testing results of blast-loaded sandwich panels were analyzed. Second, a numerical model was developed and validated by comparing the simulation results with the experimental results in terms of deformation modes and back facesheet deflection. Third, the blast resistance of sandwich panels was comprehensively studied based upon the developed numerical models. Due to the high attenuation ability of the shock induced stress wave, the foam core with descending gradient of layer density across the thickness direction provided the highest blast resistance of all the core configurations considered here and its advantage could be further improved by enlarging the density difference of the core layer. While keeping total facesheet thickness unchanged, a relatively thick back facesheet is beneficial to enhance the blast resistance under relative low blast intensity. Finally, an optimization study was performed to improve the blast resistance of graded core sandwich panels. For the single objective optimization, the maximum back facesheet deflection of the optimum design decreased by 24.58% in comparison with that for the initial baseline design. For the multiobjective optimization, the optimal designs obtained from the Pareto solution can significantly enhance weight efficiency without compromising the resistance.
76 citations
TL;DR: In this article, the authors investigated low-velocity impact responses and crashworthiness of different aluminum foam-core sandwich structures and found that multi-layer sandwich structure had much better performance in the crush force efficiency than those with single-layer foam core.
75 citations
TL;DR: In this article, the effects of the density of honeycomb cores, face-sheet thickness, punch diameter, and impact energy on impact loads and failure modes of Nomex honeycomb sandwich panels were explored.
67 citations
TL;DR: In this paper, the dynamic stability behavior of a nanocomposite sandwich truncated conical shells (NSTCS) is analyzed using the Kelvin-Voigt model.
Abstract: Present research is conducted in order to assess dynamic stability behavior of a nanocomposite sandwich truncated conical shells (NSTCS). In fact, graphene platelets (GPLs)-reinforced as core layer is encompassed through magnetostrictive layers as face sheets. For modeling the core layer and face sheets mathematically, higher order shear deformation theory (HSDT) besides first order shear deformation theory (FSDT) are utilized, respectively. To presume this sandwich structure much more realistic, Kelvin-Voigt model will be used. According to Hamilton's principle with respect to continuity boundary conditions, the governing equations are obtained. Utilizing differential cubature (DC) as well as Bolotin procedures, the governing equations will be solved and the region related to the dynamic instability is achieved. In this novel work, different variables covering various boundary edges, controller, cone's semi vertex angle, damping, feedback gain, proportion of core to face sheets thickness, dispersion kinds of GPLs and its volume percent will be studied. So as to indicate the accuracy of applied theories as well as methods, the results are collated with another paper. It is found that increment of GPLs volume percent leads to rise of excitation frequency.
49 citations
TL;DR: In this paper, two re-entrant hierarchical sandwich panels constructed by substituting the cell walls of reentrant honeycombs with isotropic regular hexagon substructure and equilateral triangle substructure are proposed, and their crashworthiness performance has been investigated systematically.
48 citations
TL;DR: Aluminum foams are known for their unique combinations of physical and mechanical properties, such as, lightweight, higher specific strength & stiffness, improved elevated temperature strength, and excellent energy absorption capacity at very low plateau stress as mentioned in this paper.
43 citations
TL;DR: In this article, the low-energy impact response of woven carbon fibre reinforced plastic (CFRP) composite sandwich panels with thermoplastic honeycomb and reentrant cores was investigated experimentally and numerically under three different impact energies (20,J, 40,J and 70,J).
Abstract: In the present study, the low-energy impact response of woven carbon fibre reinforced plastic (CFRP) composite sandwich panels with thermoplastic honeycomb and reentrant cores was investigated experimentally and numerically under three different impact energies (20 J, 40 J and 70 J). The Acrylonitrile Butadiene Styrene (ABS) honeycomb and reentrant core structures were manufactured in-plane and out-of-plane oriented via 3D printer, and adhesively bonded with two CFRP face sheets. The results indicate that the in-plane reentrant core based composite sandwich panel exhibits better impact strength and energy dissipation behavior than the in-plane and out-of-plane honeycomb core based composite sandwich panels.
42 citations
TL;DR: In this paper, the mechanical behavior of multilayer corrugated core laminated composite sandwich panel subjected to quasi-static three-point bending is investigated experimentally as well as numerically.
39 citations
TL;DR: In this article, the effect of core density on the low-velocity impact response of foam-based sandwich composites was investigated and it was shown that the influence of core densities on the damage resistance of the panels is strongly correlated to the layup of the skin.
TL;DR: In this article, the nonlinear postbuckling behavior of carbon nanotubes reinforced sandwich composite annular spherical (AS) shells supported by elastic foundations in the thermal enviro-graph is investigated.
Abstract: This work presents the nonlinear post-buckling behavior of carbon nanotubes (CNTs) reinforced sandwich composite annular spherical (AS) shells supported by elastic foundations in the thermal enviro...
TL;DR: In this article, the effects of foam core gradation and the locations of UHMWPE laminates on the air blast responses of sandwich panels were analyzed experimentally and numerically.
TL;DR: In this article, an analytical model based on energy approach is developed to predict contact force, contact time, impactor displacement, energy absorption and failure modes for composite sandwich panels with closed-cell foam core.
TL;DR: In this paper, the structural loss factors of two sandwich structures are identified from measurements using modal, energetic and spatial methods, and the results using the space domain definition are in very good agreement with the analytical predictions and the estimations of the modal and energetic methods for both plates for a large frequency band (up to 20 kHz).
TL;DR: In this article, a new composite structure was formed by filling Nomex honeycomb with polyester fiber to achieve the goal of improving its acoustic characteristics by using the impedance tube method.
TL;DR: In this article, a closed-cell aluminum foam was filled into the interspaces of a sandwich panel with corrugated cores to form a composite structure, which was expected to have enhanced performance.
Abstract: In this study, a closed-cell aluminum foam was filled into the interspaces of a sandwich panel with corrugated cores to form a composite structure. The novel structure is expected to have enhanced ...
TL;DR: In this article, the effect of layer numbers and core configurations on failure deformation of TPC CSPs was investigated by experimentally and numerically investigating three configurations: regular, perpendicular and symmetrical.
Abstract: Multi-layered thermoplastic composite (TPC) corrugated sandwich panels (CSPs) were designed and fabricated from glass fiber reinforced polypropylene prepregs by hot-pressing and hot-melting bonding methods. Quasi-static compressive response including failure deformation modes of TPC CSPs were experimentally and numerically investigated to reveal the effect of layer numbers and core configurations namely regular, perpendicular and symmetrical. For two-layered CSPs, core layers of the regular configuration panels were firstly compressed to overlapping and then failed together, core layers of the perpendicular ones failed step by step. But for the symmetrical configuration, assembly deviations were found to affect the deformation modes sensitively by comparing the experimental and numerical results. Among three configurations, the perpendicular one has the optimal specific energy absorption (SEA) and crushing force efficiency (CFE), while the regular one has the biggest peak crushing force (PCF). Increasing layer number can enhance the SEA and MCF due to the bending of the interlayer face sheets.
TL;DR: In this article, bio-based sandwich panels made of fiber-reinforced polymer (FRP) skins and two types of paper honeycomb core (namely, hollow and foam-filled) with three different thicknesses were studied.
Abstract: In this paper, bio-based sandwich panels made of fiber-reinforced polymer (FRP) skins and two types of paper honeycomb core (namely, hollow and foam-filled) with three different thicknesses (namely, 6 mm, 12 mm, and 25 mm) were studied. Flax FRP composites made of a unidirectional plant-based flax fabric and bio-based epoxy resin (30% bio content) were used for the skins. The panels were cut into a total of 36 sandwich beam specimens with the width of 50 mm and tested under four-point bending with two span configurations to characterize the flexural and shear stiffness of the panels. The specimens with foam-filled paper honeycomb cores showed a higher load capacity than those with hollow honeycomb, however their stiffnesses were not fundamentally different. Major non-linearity was observed in the load-deflection and load-strain behavior of the specimens. An analytical model was successfully developed based on the non-linearity of the skins in tension/compression and the core in shear to predict the non-linear behavior of the specimens. A parametric study was performed on different geometrical parameters and it was shown that contribution and bending and shear changes and it can be engineered to achieve desirable strength and stiffness. Overall, the bio-based sandwich panels can be used for interior walls, doors, and furniture in building application with much less impact on the environment in comparison with their synthetic counterparts.
TL;DR: In this paper, the authors investigated thin, lightweight precast concrete sandwich cladding panels that embed high performance insulation between two thin concrete wythes and found that thermal bridging is a major source of heat loss in the thin wall design.
Abstract: Thin, lightweight alternatives to standard precast concrete sandwich panels have received much research and design focus in recent years. Some designs have been structurally tested and validated. Much less focus has, however, been given to their thermal performance. This study thermally investigates thin, lightweight precast concrete sandwich cladding panels that embed high performance insulation between two thin concrete wythes. A sample thin design is experimentally tested using a hot plate apparatus to evaluate its thermal performance. Finite element modelling is then used to further investigate the common features of thin panel designs and potential areas of heat loss. The analysed representative thin sample sandwich panel (150 mm thick) achieves an average U-value of 0.324 W m −2 K−1 ; this is 16% lower than that of a typical 315 mm thick sandwich panel with 100 mm of polystyrene foam insulation. Thermal bridging is identified as a major source of heat loss in the thin wall design, accounting for up to 71% of the total thermal transmittance of the tested thin sandwich panel. In standard walls this is usually less than 20%. Some of the features of the tested design can be improved to significantly reduce the effect of the thermal bridging and reduce the U-value by 59% to 0.13 W m −2 K−1 in an optimised panel design.
TL;DR: In this paper, the vibration and sound properties of a type of metamaterial sandwich panels are investigated and compared numerically, and the reduction on the vibration, sound radiation and sound transmission is studied.
TL;DR: In this paper, a novel approach for the modeling of lattice structures based on beam elements with variable cross-section is proposed. But the authors do not consider the material concentration in the vicinity of the intersecting nodes and general defects in the member struts issued from AM.
TL;DR: An analytical equation describing the plate torsion test taking into account the transverse shear stiffness in sandwich plates is derived and numerically validated and it has been proved that both analytical and numerical formulations lead to an identical result.
Abstract: In the present work, an analytical equation describing the plate torsion test taking into account the transverse shear stiffness in sandwich plates is derived and numerically validated. Transverse shear becomes an important component if the analyzed plate or shell is thick with respect to the in-plane dimensions and/or its core has significantly lower stiffness than the outer faces. The popular example of such a sandwich plate is a corrugated cardboard, widely used in the packaging industry. The flat layers of a corrugated board are usually made of thicker (stronger) material than that used for the corrugated layer, the role of which is rather to keep the outer layers at a certain distance, to ensure high bending stiffness of the plate. However, the soft core of such a plate usually has a low transverse shear stiffness, which is often not considered in the plate analysis. Such simplification may lead to significant calculation errors. The paper presents the generalization of the Reissner's analytical formula, which describes the torsional stiffness of the plate sample including two transverse shear stiffnesses. The paper also presents the implementation of the numerical model of the plate torsion test including the transverse shear stiffnesses. Both approaches are compared with each other on a wide range of material parameters and different aspect ratios of the specimen. It has been proved that both analytical and numerical formulations lead to an identical result. Finally, the performance of presented formulations is compared with other numerical models using commercial implementation of various Reissner-Mindlin shell elements and other analytical formulas from the literature. The comparison shows good agreement of presented theory and numerical implementation with other existing approaches.
TL;DR: In this paper, the compression properties of the SiCp/SiC composite lattice core sandwich panels with three different configurations under room temperature and high temperature were investigated and the room temperature experiment results were compared with the analytical predictions.
TL;DR: In this paper, the compressive behavior of sandwich panels with lattice truss core filled by shear thickening fluid (SPLTC-STF) at high strain-rates is performed analytically and numerically.
TL;DR: In this article, the ballistic limit velocity, energy absorption and the effects of facesheets thickness ratios for three types of sandwich panels consist of titanium facesheet and aluminum honeycomb core were studied experimentally and numerically.
Abstract: The ballistic limit velocity, energy absorption and the effects of facesheets thickness ratios for three types of sandwich panels consist of titanium facesheet and aluminum honeycomb core were studied experimentally and numerically. The tests are carried out by a nitrogen gas gun and 24 g hemispherical steel projectiles with velocity ranges from 100 m/s to 190 m/s. A proper ABAQUS/Explicit model was developed using the experimental data. Results shown the impact energy mainly absorbed by the rear facesheet in symmetrical sandwich panels. The ballistic limit enhanced almost linearly with increasing rear or front facesheet thickness in specimens with the same weight.
TL;DR: In this article, the structural performance of a new type of precast concrete sandwich panels, for which reinforced geopolymer concrete is used as two wythes and connectors made of fiber-reinforced polymer composites are used to realize the composition action, is investigated.
TL;DR: In this paper, a PIP method was used to fabricate C/SiC pyramidal lattice core sandwich panels (LCSPs) and their bending behaviors with different core angles were experimentally studied.
TL;DR: In this article, the structural shear performance of precast concrete sandwich panels with steel plate connectors of various dimensions was analyzed, giving rise to different load capacities, stiffnesses and failure modes.