Showing papers on "Sandwich-structured composite published in 2021"
TL;DR: In this article, the impact behavior of composite sandwich panels with different types of auxetic (negative Poisson's ratio) and non-auxetic prismatic core structures is described.
Abstract: This work describes the low-velocity impact behavior of composite sandwich panels with different types of auxetic (negative Poisson’s ratio) and non-auxetic prismatic core structures Sandwich panels have been manufactured with carbon/fiber epoxy composite face sheets, polyurethane rigid foam core or 3D printed PLA plastic cellular honeycombs head (hexagonal, re-entrant, hexachiral and arrowhead) The material properties of the constituents have been determined via tensile and compression tests The cellular core topologies have the same wall thickness and number of cells (39x4, except for the hexachiral topology) A rigid striker with a hemispherical head tip is dropped on the specimens with a speed of 26 m/s Explicit finite element (FE) models are validated by the experimental results Parametric numerical analyses using the validated FE have been carried out with different impact energies of 10, 20, 30, 40, 50, 60 and 76 J to identify the best core designs The results show that non-auxetic cores could have advantages over the auxetic ones at small deformation (impact energy is equal to 10 J) thanks to the larger contact surface and higher thickness of the cellular structure The auxetic core, however, provides greater impact resistance and energy absorption capability as the impact energy increases due to the larger densification and lower indentation during collapse The arrowhead-based panels in particular possess 25%, 13% and 11% larger crash efficiency than the other samples for impacts with 50, 60 and 76 J The hexachiral lattice provides the best performance at 10, 20 and 30 J, and also possesses advantages over the other cellular configurations (except for the arrowhead core) in the case of 40, 50, 60 and 76 J impact loading As a result, the arrowhead and hexachiral configurations are those mostly recommended for applications involving impacts under large deformations
67 citations
TL;DR: In this paper, a combined experimental and numerical study on the low-velocity impact behavior of honeycomb-core sandwich panels with different structural parameters, including facesheet thickness, core height, honeycomb cell size, and cell wall thickness, is presented.
Abstract: This paper presents a combined experimental and numerical study on the low-velocity impact behavior of honeycomb-core sandwich panels with different structural parameters, including facesheet thickness, core height, honeycomb cell size, and cell wall thickness. Impact tests were conducted at four different energies using a drop-weight impact facility, and the deformation and damage characteristics of the tested sandwich panels were analyzed by microscopic X-ray computed tomography. The experimental results revealed two distinct failure modes of sandwich panels: namely mode A, with localized damage in both facesheets and core, which is dominated by indentation; and mode B, which is characterized by global bending deflection of the facesheets and overall core crushing. It was found that a sandwich panel with thin facesheets and a high-density honeycomb core (e.g. with a small cell size and/or a thick cell wall) tended to fail in mode A, but core height did not influence the failure mechanism notably. Furthermore, finite element modeling was carried out to gain further understanding of the effects of these structural parameters. The perforation resistance and energy absorption capacity were significantly enhanced with increasing facesheet thickness. Whereas reducing the cell size and/or thickening the cell wall resulted in lower perforation resistance. When the total thickness of facesheets remained a constant, the impact behavior of the sandwich structure could be optimized by controlling the thickness ratio of the front to back facesheets. Finally, cost efficiency analysis was performed to achieve a rational design of the sandwich structure considering both the impact performance and cost.
67 citations
TL;DR: In this article, the authors present a challenging task to advance the excellent strength and structural performance of sandwich structures, while continuing to reduce the weight and cost parameters of the sandwich structures.
Abstract: It is a challenging task to advance the excellent strength and structural performance of sandwich structures, while continuing to reduce the weight and cost parameters. Thousands of researchers hav...
65 citations
TL;DR: In this paper, two kinds of meta-lattice sandwich panels consisting of single/double-layer pyramidal truss-cores are designed, and the 3D printing technique of selective laser sintering (SLS) is applied to fabricate the dissipative composite meta-structures.
Abstract: Achieving superior properties of vibration suppression at low-frequency range, yet with high load-bearing capabilities in lightweight structural designs is still a challenge. In this work, we propose a strategy to realize broadband low-frequency vibration bandgaps by combining the design concepts of locally resonant metamaterials and lightweight lattice-truss-core sandwich structures. Two kinds of meta-lattice sandwich panels consisting of single/double-layer pyramidal truss-cores are designed, and the 3D printing technique of selective laser sintering (SLS) is applied to fabricate the dissipative composite meta-structures. The vibration suppression performance and bandgap generation mechanisms are theoretically, numerically, and experimentally investigated. Remarkable vibration suppression within broadband low-frequency bandgaps, stemming from the coupling between the designed secondary structures and host panels, are numerically and experimentally verified in both time and frequency domains. Equivalent mass-spring models are developed to theoretically predict the vibration attenuation ranges. Bandgap merging effects induced by the damping of the 3D printed meta-structures are further investigated, and remarkably enlarged attenuation bands are experimentally captured. The metamaterial-based lattice sandwich structures pave feasible ways for designing vibration shielding systems with both high functional and mechanical performance.
49 citations
TL;DR: In this article, a three-dimensional elastoplastic finite element model of AHSPs under repeated impact loadings is established by using the commercial software ABAQUS Explicit, and the accumulation processes of plastic deformation, the impact force displacement curves as well as the energy absorption performances are numerically calculated.
37 citations
TL;DR: In this article, Biancolini's method was extended to include the possibility of determining, apart from the tensile and flexural stiffnesses, also the transverse shear stiffness of the homogenized corrugated board.
Abstract: Knowing the material properties of individual layers of the corrugated plate structures and the geometry of its cross-section, the effective material parameters of the equivalent plate can be calculated. This can be problematic, especially if the transverse shear stiffness is also necessary for the correct description of the equivalent plate performance. In this work, the method proposed by Biancolini is extended to include the possibility of determining, apart from the tensile and flexural stiffnesses, also the transverse shear stiffness of the homogenized corrugated board. The method is based on the strain energy equivalence between the full numerical 3D model of the corrugated board and its Reissner-Mindlin flat plate representation. Shell finite elements were used in this study to accurately reflect the geometry of the corrugated board. In the method presented here, the finite element method is only used to compose the initial global stiffness matrix, which is then condensed and directly used in the homogenization procedure. The stability of the proposed method was tested for different variants of the selected representative volume elements. The obtained results are consistent with other technique already presented in the literature.
36 citations
TL;DR: In this article, the two-dimensional metallic DAHs were used as the sandwich cores to construct the large-size double arrowhead honeycomb sandwich panels (DAHSPs) and a comprehensive experimental investigation on their dynamic responses under the paper tube-guided air blasts was conducted.
34 citations
TL;DR: In this paper, a review of the evolution of sandwich panels based on recent work and older sources, focusing on the trends concerning sandwich panel achievements and applications, core materials, core designs, types of failure mechanism and factors which contribute to the failure of sandwich panel.
33 citations
TL;DR: In this paper, the failure mechanisms of sandwich panels with multi-layered aluminum foam/UHMWPE laminate cores under combined blast and fragments loading were investigated, where the combined loading was generated by detonating a cylindrical TNT charge whose bottom face was attached with prefabricated fragments.
Abstract: This paper presents an experimental investigation into the failure mechanisms of sandwich panels with multi-layered aluminum foam/UHMWPE laminate cores under combined blast and fragments loading. The combined loading was generated by detonating a cylindrical TNT charge whose bottom face was attached with prefabricated fragments. Attention focused on the effects of UHMWPE laminate location, foam core gradation and refractory interlayer on the dynamic responses of the panels. Multiple failure patterns were observed on the panel components, including the perforations of front face, petalling or cracking of back face, plugging of foam core, scorching, fiber fracture and delamination of UHMWPE laminate, and debonding failure of adhesive. Results indicated that introducing the UHMWPE laminate was beneficial to alleviating the damage state of back face. The foam layers with graded density could further decrease the back face deflection, while the incorporation of a ceramic fiber felt would deteriorate the back face damage. As expected, the sandwich panels suffered much more destructive damage under combined loading than the ones under bare blast loading. The core configuration with the UHMWPE laminate located at the bottom layer was favored by the panels to possess a desirable capacity of comprehensive protection under combined loading and bare blast loading.
33 citations
TL;DR: In this article, the effect of core-layer arrangement on the deformation modes and shock resistance of clamped sandwich panels with layered-gradient aluminium foam cores was studied experimentally and numerically.
Abstract: The blast response of clamped sandwich panels with layered-gradient aluminium foam cores was studied experimentally and numerically. The effective blast impulse acting on specimens in ballistic pendulum tests was first calibrated, and the influences of blast impulse and core-layer arrangement on the deformation modes and shock resistance were revealed. Then, the corresponding numerical simulations were conducted. The finite element model was validated via the displacement–time curves of the ballistic pendulum system and the deformation profile and deflection response of sandwich specimens. The blast pressure, deformation process, energy absorption, strain evolution, and distribution of blast-loaded sandwich panels are discussed. The experimental and numerical results show that all the layered-gradient core sandwich panels have a weaker blast resistance capability than the ungraded sandwich panels because of the reduction in structural integrity of the specimens. For a given effective impulse, the specific energy absorption value of the positive gradient sandwich panels is the largest, followed by that of the ungraded sandwich panels, whereas that of the negative gradient sandwich panels is the lowest.
31 citations
TL;DR: In this article, the effect of short aramid fiber tissue and carbon fiber belt on mechanical properties of carbon fiber/honeycomb sandwich specimens was investigated at different loading rates.
Abstract: The bending performances at different loading rate are studied for carbon fiber/honeycomb sandwich panels toughened by short aramid fiber tissues and carbon fiber belts. The carbon fiber belts are stitched cross the pores of honeycomb core for interfacial improvements. Three-point bending tests at different loading rates are carried out to investigate the effect of short aramid fiber tissue and carbon fiber belt on mechanical properties of carbon fiber/honeycomb sandwich specimens. Experimental results firstly indicate that the short-aramid-fiber interfacial toughening and carbon fiber belts toughening could both enhance the energy absorption and peak load of sandwich specimens at loading rates ranging from 2 mm/min to 500 mm/min. The failure modes and microstructures of toughened specimens are observed to analyse and explain the underlying mechanism of enhancing effect. It is illustrated that crack isolation phenomenon is found to be the main mechanism for avoiding interfacial damage of the sandwich specimen.
TL;DR: In this paper, a novel CFRP tube by reinforced with composite sandwich panels (CSPs) for enhanced energy absorption was investigated, and numerical models were developed, based on the continuum damage mechanic for intralaminar failure and the cohesive zone method for interlaminar damage of CFRP materials with an elastic-plastic model for honeycombs, to predict the progressive failure of the composite tubes.
TL;DR: In this paper, a 2D-based large-scale metallic auxetic double arrowhead honeycomb core sandwich panel (DAHSP) was proposed and its deformation response, energy dissipation characteristics an
Abstract: In the present study, a 2D-based large-scale metallic auxetic double arrowhead honeycomb core sandwich panel (DAHSP) was proposed and its deformation response, energy dissipation characteristics an
TL;DR: In this paper, rectangular metallic sandwich panels with aluminium origami cores were manufactured and three different shapes of indenters were considered: flat-ended, hemispherical-nosed, and conical-nose.
TL;DR: In this paper, an energy-based analytical model for multilayer sandwich panels was developed to predict contact force, impactor displacement and energy absorption, and the predictions were validated by experimental results.
TL;DR: In this article, the bending behavior and energy absorption characteristics of the Nomex honeycomb sandwich panels were analyzed and sufficient data and theoretical support was provided for the practical application of such panels.
Abstract: To provide sufficient data and theoretical support for the practical application of Nomex honeycomb sandwich panels, the bending behavior and energy absorption characteristics of the Nomex honeycom...
01 Jun 2021
TL;DR: The two-dimensional regular hexagonal cell shape is commonly used in automotive, aerospace and marine industries, as they provide adequate functional properties as mentioned in this paper, and they can be constructed in any shape.
Abstract: Sandwich structures are frequently used in automotive, aerospace and marine industries, as they provide adequate functional properties. The two-dimensional regular hexagonal cell shape, i.e. honeyc...
TL;DR: In this article, a finite element model for the prediction of dynamic responses of trapezoi is proposed to improve the blast performance of trapezoidal corrugated core sandwich panel under air blast loading.
Abstract: This research aims to improve the blast performance of trapezoidal corrugated core sandwich panel under air blast loading. A finite element model for the prediction of dynamic responses of trapezoi...
TL;DR: In this article, the effect of multi-layering in sandwich panel composite structures with different configurations of corrugated cores under the effects of quasi-static indentation loading is investigated experimentally and numerically.
Abstract: In this study, the effect of multi-layering in sandwich panel composite structures with different configurations of corrugated cores under the effect of quasi-static indentation loading is investigated experimentally and numerically. Composite plates and corrugated cores with equal weight fraction were manually made using ML506 epoxy resin with 15% hardener and the overall volume fraction of 45% for woven glass fibers. Experiments were performed using a cylindrical indenter with a diameter of 20 mm and a semi-spherical nose shape, and the behavior of the composite structure was evaluated in the case of energy absorption, contact force, and fracture mechanisms for different corrugated cores (rectangular, trapezoidal and triangular). Progressive damage analyses of the composite samples were investigated using well-known 3D failure criteria developed in ABAQUS software, and an acceptable agreement between the experimental and numerical results was observed. Experimental results show that multi-layering of composite sandwich panels not only increases the structural strength in quasi-static indentation process but also increases the energy absorption of specimens by increasing the peak load, instantaneous force, and dislocation displacement up to the complete penetration. By comparing different geometries of the corrugated cores in terms of maximum force, energy absorption, and specific energy, it was shown that the functionality of specimens with rectangular cores is the best. Among the most important damage mechanisms of the examined sandwich panel specimens (visual analysis) in the quasi-static indentation process, matrix cracking, fiber breakage, delamination, cell walls buckling and crushing, face sheets and core debonding, and specimens complete penetration are noticeable.
TL;DR: In this article, the use of honeycomb core sandwich panels filled with a shear thickening fluid (STF) as a component of spacecraft micrometeoroid/orbital debris (MMOD) shielding was investigated using hypervelocity impact (HVI) testing.
TL;DR: In this article, a dual-meta panel functioning as a sacrificial cladding is proposed and its blast mitigation capacity is investigated and validated through numerical simulations, where the proposed panel possesses the potential to generate bandgaps that target at a specific range of frequencies to stop stress wave propagating through the panel, leading to the favorable stress wave mitigation for structural protection.
TL;DR: In this paper, a reduced-scale experiment is employed to perform a parametric investigation of the thermal performance of phase change materials (PCM)integrated wall specimens considering two types of concrete, two type of PCM, and different thicknesses of the concrete and PCM layers.
Abstract: The employment of phase change materials (PCMs) in the construction of concrete building components has engaged many researchers’ interest. In this study, a novel reduced-scale experiment is employed to perform a parametric investigation of the thermal performance of PCM-integrated wall specimens considering two types of concrete, two types of PCM, and different thicknesses of the concrete and PCM layers. Moreover, three different ambient temperature profiles of a summer day in three different cities were considered as the outside ambient temperature to evaluate the performance of each PCM under different temperature conditions. The test procedure is capable of evaluating the thermal performance of different wall configurations under various temperature conditions. The inside temperature variations of the wall specimens were monitored as the thermal performance criteria. In consequence, integrating the PCM layer with normal concrete or with slimmer concrete layers resulted in better thermal performance of PCM in absorbing heat in comparison to lightweight concrete or thicker specimens due to the considerable effect of density and specific heat capacity of different types of concrete. Moreover, the compatibility of the melting temperature of PCMs with the ambient temperature of the considered cities in summer is assessed and discussed.
TL;DR: The final panel design is deemed to achieve both structural and thermal requirements of a high performing cladding element, that was developed at scale in a precast facility for practical implementation on a building in-use.
TL;DR: In this article, the energy absorption characteristics of aluminum sandwich panels with Shear Thickening Fluid (STF) filled 3D fabric cores were investigated under various loading conditions, and the 2Al-5STF specimen showed the highest absorbed energy (3.53 J).
Abstract: In this study, the energy absorption characteristics of aluminum sandwich panels with Shear Thickening Fluid (STF) filled 3D fabric cores was investigated under various loading conditions. The sandwich panel with 5-ply STF-filled 3D fabric (2Al-5STF) showed the highest absorbed energy (3.53 J) in three-point bending test. The 2Al-5STF specimen also demonstrated more resistance under ballistic impact loading than the sandwich panel with 5-ply neat 3D fabric (2Al-5Neat) such that with less average penetration depth presented the highest ballistic resistance. The dynamic compression test showed the STF helped to improve the impact absorption and compressive performance of the sandwich panels. The average peak force applied to the 2Al-5STF sandwich panel (30.5 kN) was 24.5 and 54.6% less than the 2AL-5Neat and 4Al specimens, respectively, and this sandwich panel demonstrated the highest impact absorption (peak force reduction). However, the 2Al-3STF specimen demonstrated the highest peak force reduction per unit areal density, and the 2Al-5Neat specimen demonstrated better reversibility.
TL;DR: In this paper, the mechanical behavior of resin pin-reinforced composite sandwich panels made from polyvinyl chloride core and glass/epoxy face sheets under indentation of a hemispherical inden...
Abstract: This paper reports the mechanical behavior of resin pin-reinforced composite sandwich panels made from polyvinyl chloride core and glass/epoxy face sheets under indentation of a hemispherical inden...
TL;DR: In this paper, a hot-press molding technique was developed to design and manufacture carbon fiber reinforced polymer (CFRP) X-core sandwich panels that allowed both the composite face sheets and its X core to be simultaneously molded together.
Abstract: A hot-press molding technique is developed to design and manufacture carbon fiber reinforced polymer (CFRP) X-core sandwich panels that allowed both the composite face sheets and its X-core to be simultaneously molded together. Compression tests were performed on the sandwich panels to assess the effects of relative density on its compressive properties and the failure mode that it develops. Analytical models were developed to predict the panel stiffness and strength; and a failure map of its deformation mode is generated based on the geometric parameters of the unit cell. Linear and nonlinear finite element analyses were performed to further investigate the effects of initial geometric imperfection and progressive damage on the response of the sandwich panels with different cell wall slenderness. Predictions from analytical and numerical models will be shown to be in good agreement with the experiments. The CFRP X-core sandwich panels will be shown to attain good compressive properties that are comparable to typical high strength cellular materials, which will be potentially useful for lightweighting applications.
TL;DR: In this article, the performance of double-skin composite sandwich panels made of steel sheets and aluminium foam to be used as the deck in civil structures is evaluated. But the application of these materials are mainly limited to aeronautic and mechanical engineering.
Abstract: Metal foams are engineered materials with attractive mechanical properties such as lightness, energy dissipation capacity, high resistance and stiffness. To date, the applications of these materials are mainly limited to aeronautic and mechanical engineering. However, their features can provide significant advantages also for the development of new products for structures and infrastructures in the field of civil engineering. This consideration has motivated the study described in this paper, which is mainly devoted to assessing the performance of double-skin composite sandwich panels made of steel sheets and aluminium foam to be used as the deck in civil structures. To this aim, as the first step of ongoing research activity, both experimental and finite element (FE) simulations are carried out verifying the applicability of the proposed type of sandwich panel. Both tests on material specimens and three-point bending tests on the double-skin composite sandwich panels are performed, and the main results are discussed. FE analyses are carried out enlarging the range of investigated and monitored parameters assessing their influence on the bending and shear response of the panels. The outcomes of the study show the effectiveness of the proposed type of sandwich panel and allow selecting the most effective type of adhesive to bond the steel plates to the aluminium foam core. The obtained results are complemented with simple design equations that allow satisfactorily predicting both stiffness and strength of the sandwich panels.
TL;DR: In this paper, the effects of climate change become more apparent, and it is necessary that environmental impact is considered in every aspect of our society, including the design of new infrastructure.
Abstract: As the effects of climate change become more apparent, it is necessary that environmental impact is considered in every aspect of our society, including the design of new infrastructure. The use of...
TL;DR: In this article, the basic concept of textile-based 3D woven honeycomb composites, engineering design, manufacturing process, structure-properties relationship, and applications of 3D weaving honeycomb fabrics and their composites are discussed in detail.
Abstract: Honeycomb is considered an excellent structural material because of its high strength and shear rigidity, excellent energy absorbing property, high impact strength, lower weight, high crushing stress, and almost constant crushing force. Honeycomb being a cellular solid is a well-known core used to build a sandwich structure while making structural composites. Because of this excellent mechanical performance, honeycombs are frequently used in the aircraft industry as a core of sandwich panels and in the automotive industry as efficient impact attenuators. The hollow spaces in the honeycomb structure reduce weight but also ensure required strength, provided they are designed correctly. 3D woven honeycomb composite has a promising future in the lightweight application areas and can be the real substitutes for aluminum and other metal alloys as these structures provide structural integrity. In this review, the basic concept of textile-based 3D woven honeycomb composites, engineering design, manufacturing process, structure-properties relationship, and applications of 3D woven honeycomb fabrics and their composites are discussed in detail. Geometrical modeling of 3D woven honeycomb fabric and theoretical analysis of impact, flexural, and compression behavior of their composites are summarized to appreciate the potential advantages of textile-based honeycomb structural composites.
TL;DR: In this paper, the results of the development of innovative sandwich panels made by combining wood bio-concretes and long sisal fibers reinforced composites were presented, and the effect of the cement-to-wood ratios on the density, thermal conductivity, compressive strength and elastic modulus of the WBC were also investigated.