Types Of Sandwich Panels Research Articles

Crushing behavior and energy absorption of steel-GFRP-foam sandwich structures under quasi-static compression: Experimental and theoretical study

To overcome the poor energy-absorbing efficiency of existing layered panels, three kinds of novel steel-glass fiber reinforced polymer (GFRP)-foam sandwich structures composed of two steel face sheets and GFRP-foam composite cores were proposed in this paper. The effect of the composite core thickness and GFRP lattice configuration on the energy absorption performance for sandwich structures was studied through quasi-static crushing tests. Considering the role of steel face sheets, a theoretical prediction model was derived to calculate the initial absorbed energy for all types of sandwich panels. Parametric studies were carried out to investigate the influence of five different variables (axial compressive load, steel sheet thickness, GFRP web thickness, GFRP and foam compressive modulus) on the overall energy dissipation for each kind of composite panel. Test results indicated that both the thicker core component and double-layered dislocation GFRP layout could effectively promote the energy consumption property of all the steel-GFRP-foam structures, and the steel face sheet played a crucial role in the proposed sandwich panels due to its excellent absorbed-energy capacity per volume and exceptional ductility. Theoretical results demonstrated that the equivalent energy-absorbing formula was desirable to be used to assess the crushing resistant behavior of each sandwich structure. Parametric analysis results showed that a larger axial compressive load was able to improve the structural initial energy absorption, but the increase of four other structural parameters, especially the thickness of the front (rear) steel sheet, could weaken such an identical performance.

An experimental study of multi-core composite aluminium honeycomb sandwich panels under low-velocity impacts

This paper aims to evaluate the impact response of the multi-core composite sandwich panels from low-velocity experiments. Geometrical parameters of sandwich panels like cell size, cell height, and facesheet thickness are varied and their effect on peak load, energy absorption, and efficiency is reported in this article. The effect of impact energy variation ongraded and non-graded types of sandwich panels is also studied. Based on these experiments suitable recommendations are given for impact energy absorber applications. From a crashworthiness point of view, graded multi-core composite sandwich panels are found to be more effective than non-graded ones.

Static response of synclastic sandwich panel with auxetic wood-based honeycomb cores subject to compression

Only a few research works show a method for creating doubly curved surfaces using single-layer auxetic structures. There are no studies regarding sandwich wood-based synclastic panels with the auxetic core. The main goal of this work was to determine the effect of the thin facings on the stiffness, strength, amount of absorbed energy, and damage of the synclastic panels with an auxetic core subjected to static compression. The facings of sandwich panels were manufactured out of cardboard and a copolyester of polyethylene terephthalate glycol (PETG). WoodEpox® composite was used as a material of the core structure. Synclastic panels were tested experimentally and analyzed using the finite element method. In addition, the damage process of the core and facings was described. The results of studies have shown a significant impact of the facing type of sandwich panel on its overall stiffness and ability to absorb energy. Cardboard panels are significantly more rigid than those made of PETG. Also, cardboard panels show a high ability to absorb energy.

Investigation of the bending and crushing for the light-weight structures used in vehicle's radiator

Sandwich panels are widely used in various industries, including the aerospace industry, where they have long been regarded because of their light-weight and high energy absorption capacity. This research introduces a novel type of sandwich panel whose raw material is widely used in the automotive industry. The materials used for manufacturing the sandwich panels addressed in this research are currently used in the cooling radiator structure for the engine of conventional vehicles. Such a radiator is nothing but a lattice of a set of B-shaped tubes and cooling fins. In this research, the crashworthiness properties of such a lattice are extracted along with various directions (samples A, B, and C). Moreover, the applicability of the considered lattices as the core of sandwich panels was studied. This research showed that the considered structures tend to exhibit maximum strength when the loading plane is parallel to the cooling fins. It was further figured out that the addition of aluminum shells to specimens A, B, and C can increase their energy absorption capacity by 85, 268, and 13%, respectively.

Experimental and numerical study of double-skin aluminium foam sandwich panels in bending

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.

Quasi-static three-point bending of metallic sandwich panels

Sandwich panels become ideal candidates in industry applications due to their excellent energy absorption ability and light weight. The cellular core of sandwich panels may experience large plastic deformation at an almost constant stress, thus the panel has excellent energy absorption capability. The current paper examines and compares the mechanical performance of sandwich panels with three types of cores (corrugated, honeycomb and lattice truss) under quasi-static three-point bending. Finite element analysis (FEA) was performed in this study and the numerical models of each panel were developed using ABAQUS to predict the deformation mode and the bending response of panels (i.e. force-displacement curve and energy absorption) under three-point bending. Two deformation modes are predicted for all three types of sandwich panels. The honeycomb sandwich panel is expected to have the best energy absorption ability among the three types of sandwich panels with the same relative density. The outcomes of the present study will thereby provide useful information for their applications in industry.

A multilayer panel in cork and natural phase change materials: thermal and energy analysis

This paper presents thermal and energy analysis of a multilayer panel in bio-based cork material and natural phase change materials (PCMs) for the development of prefabricated, recyclable and energy-efficient and autonomous building modules. For this purpose, a calculation tool is developed for the dynamic simulation of the thermal and energy behaviour of the sandwich panel. In particular, through an extensive parametric survey, the panel is sized with the identification of the arrangement of the layers, PCM temperature, and layer thicknesses to optimize the insulating and damping properties, considering typical climatic conditions of the Mediterranean climates of Southern Italy. From the conducted simulations, the types of sandwich panels that have the best insulating and storage characteristics for the building module construction were chosen. The results of these simulations will be used in future research for the preliminary design of tests to be carried out in a climatic chamber and to build a building module in real conditions to be constantly monitored through the automatic instrumental survey of internal and external physical quantities such as temperature, humidity and radiant temperature.

Исследование технологии возведения каркасно-панельных и модульных зданий в Арктике

Choosing the technology for the construction of buildings in the Arctic conditions is stipulated by two important factors, namely, the remoteness of the facilities and the short period of the summer season, which actualizes the problem of reducing the mass of structures and making shorter the construction work duration. In addition, one should keep in mind other important factors, such as permafrost, strong winds and low temperatures. Such conditions of construction necessitate the use of building technologies and space-planning solutions using light metal structures and mineral wool slabs, as well as sandwich-type laminated panels. The unified nomenclature, compactness and relative lightness of the parts ensure high efficiency of construction in the remote territories of the Arctic zone of the Russian Federation. The first experimental construction experience in the Arctic has shown not only the comfort of space-planning solutions, but also the manufacturability of installation of load-bearing and enclosing structures of the erected residential and administrative complexes of the Arctic Trefoil type. The block-modular technology for the construction of dormitory buildings in the village of Tiksi (Yakutia), as well as the technology for the construction of buildings of the production and logistics complex «Arkhangelsk», erected using light steel structures, sandwich type panels and other pre-fabricated structures. A comparison analysis of pre-fabricated building systems according to the criterion of manufacturability has been carried out. There are proposed some fundamental solutions aimed at improving the installation technology of buildings in the Arctic conditions.

Experimental evaluation of OSB-faced structural insulated panels subject to blast loads

This paper reports the results of an experimental program to quantify the blast protection provided by as-built and strengthened structural insulated panels (SIP) subjected to short-duration uniform pressure loads in a blast load simulator facility. SIPs are used in residential and light-commercial buildings. The SIPs used in this study had an overall thickness of 117 mm with 11 mm thick oriented strand board (OSB) facers and a 95-mm thick polyurethane closed-cell foam core. This type of sandwich panel provides improved energy efficiency and reduced construction time. A total of eight panels were tested in four different configurations: (1) as-built SIP design with standard connections, (2) as-built SIP design with strengthened roof connection, (3) flexural strengthened SIP using galvanized steel straps with strengthened roof connections, and (4) flexural strengthened SIP using fiber reinforced polymer (FRP) wallboard with strengthened roof connections. Each panel in this experimental program was 1.2 m by 2.4 m and was tested independently. The panels were subjected to two to five incrementally increasing pressure-impulse combinations. The first was a low pressure shot to verify the elastic performance of the SIP. The magnitude of the pressure-impulse combination for the subsequent shots increased until ultimate failure of the panels. By strengthening the roof connection, the as-built panels withstood a 27% larger impulse. The steel strap and FRP flexural strengthening with the strengthened roof connections led to a three-fold and five-fold increase in impulse resisted, respectively, when compared to the as-built SIP with standard connections. The results of the experimental study were validated using single-degree-of-freedom (SDOF) models. The SDOF analysis included an elastic resistance function for each panel configuration. The SDOF analysis estimated displacements 9% larger than the experimental results on average. The analytical model was more conservative for the lower pressure shots indicating that one-way behavior of SIPs subjected to shortduration uniform pressure loads may be reasonably estimated using fundamental bending mechanics. Overall, the results of the experimental and analytical study indicated simple strengthening methods may be used to significantly improve the blast resistance of SIPs.

Experimental and numerical studies on the ballistic impact response of titanium sandwich panels with different facesheets thickness ratios

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.

Flexural properties of sandwich composite panels with glass laminate aluminum reinforced epoxy facesheets strengthened by SMA wires

Sandwich composite panels are widely used and significant in structural applications such as aerospace, shipbuilding and transportation, etc. This is due to their specific properties such as specific stiffness, strength and energy absorption. Still, many innovations are required to develop and upgrade their mechanical properties in various loadings and conditions, specifically in bending loads. One of the methods to enhance the properties of sandwich structures is to employ various advanced materials in these structures to change their acquired properties. In the present research work, sandwich composite panels made by fiber metal laminate like glass laminate aluminum reinforced epoxy (GLARE) as the facesheets and PVC polymer foam as the core material are investigated in flexural (bending) loading condition. To change or enhance the behaviour of sandwich panel in bending loads, shape memory alloy wires are also embedded in between glass fiber reinforced epoxy composite layers in fiber metal laminate facesheets. The shape memory wires are also pre-strained in fiber reinforced epoxy composite in sandwich panels. To study the flexural properties of sandwich panels with fiber metal laminate facesheets, the effect of shape memory alloy wires and also the effect of pre-straining of the wires, three types of sandwich panels are considered and made including panels without shape memory alloy wire, two wires with 0% tensile pre-strain, and two wires with 5% tensile pre-strain for the same cross section. Due to the importance of bending properties in structural applications, the sandwich composite specimens are subjected to flexural test according to ASTM standards. The maximum of 13% increase in maximum bending load and 84% increase in breaking load for the specimens with 0% pre-strained wires are achieved. Also, the maximum displacement and the energy absorption for the specimen with 5% pre-strain was enhanced by 26.5% and 37%, respectively. The energy absorption during the flexural test is greater in case of the specimen with pre-strained wires. Moreover, the specimens with pre-strained wires show better integrity of the structure after the failure in bending. The results represent the advantage effect of shape memory alloy wires on sandwich composite panel's behaviour in bending.

Investigations about periodic design for broadband increased sound transmission loss of sandwich panels using 3D-printed models

Abstract Two types of sandwich panels are designed by using the periodic structure theory. A double-wall panel with mechanical links and a sandwich panel with rectangular core are studied. An oriented optimization of the elastic bending waves’ propagation versus the acoustic wavenumbers is achieved by using shifted core walls and by keeping the mass and stiffness of the system constant. Standard and optimized configurations are 3D-printed and sound transmission measurements are carried out by using a facility with an uncoupled reverberant-anechoic configuration. The experimental evidences of enlarged bending band-gaps and deformation mechanisms are proved using a reverse approach based on the acoustic radiation of the panels.

Damage detection based on vibration for composite sandwich panels with truss core

Composite sandwich panels with truss core have been widely studied for their outstanding characteristics and excellent designable properties, but very little of this work was focused on non-destructive testing (NDT) methods. Based on mode curvatures and a two-dimensional (2D) continuous wavelet transform (CWT), a baseline-free NDT method is proposed for damage identification in these types of sandwich panels. Initially, the 2D CWT is applied to process the mode curvatures from specific mode shapes. Then, considering the structural periodicity of the truss, which is a distinctive characteristic of these sandwich panels, a novel damage index is defined through a combination of the structural periodicity and the coefficients of the CWT. Numerical simulations and experimental tests were conducted to identify damage in the composite sandwich panels with core trusses forming a pyramidal lattice. Results show that the proposed method is efficient and reliable, and has a good resolution in identifying one or more truss bars missing detection without a baseline and thus has the potential in damage detection of composite sandwich panels.

Lightweight construction design with bearing surfaces. Thin-walled structures

This article examines the supporting capacities of the foam-cored metal composites and the assembly methods. The type of sandwich panel chosen is the triple tongue-and-groove refrigeration panel, the operation of which is the basis for calculating its structural capacity. The results of the research on these panels show us conclusions that allow advances in a constructive system demanded in contemporary architectures and markets; Lightweight, pre-industrialized, digitizable, easily assembled and energetically sustainable.

Geometry Strength of Honeycomb Sandwich Panel

The geometry strength of honeycomb sandwich panel with several types of core were investigated. There are four types of sandwich panels; Rectangular Core Sandwich Panel (RCSP), Horizontal Core Sandwich Panel (HCSP), Triangular Core Sandwich Panel (TCSP) and Symmetrical Core Sandwich Panel (SCSP). For all types of panel, the upper and bottom layers and the inner core made from the plywood with different thickness. The performance of the honeycomb sandwich panel subjected to four-point bending test and punching shear test were investigated. The results of flexural test showed that RCSP that having the rectangular core has the highest maximum load of 9.79 kN compared to HCSP and TCSP. The maximum load of RCSP in the punching shear test achieved 34.35 kN which was higher than SCSP. All the specimens having the core shear failure.

Buckling of sandwich panels with transversely flexible core: Correction of the equivalent single-layer model using thick-faces effect

Modeling a periodic structure as a homogeneous continuum allows for an effective structural analysis. This approach represents a sandwich panel as a two-dimensional plate of equivalent stiffness. Known as the equivalent single-layer, the method is used here to analyze bifurcation buckling of three types of sandwich panels with unidirectional stiffeners in the core: truss-core, web-core and corrugated-core panels made of an isotropic material. The transverse shear stiffnesses of these panels can differ by several orders of magnitude, which cause incorrect buckling analysis when using the equivalent single-layer model with the first-order shear deformation theory. Analytical solution of the problem predicts critical buckling loads that feature infinite number of half-waves in the direction perpendicular to the stiffeners. Finite element model also predicts buckling modes that have non-physical, saw-tooth shape with infinite curvature at nodes. However, such unrealistic behavior is not observed when using detailed three-dimensional finite element models. The error in the prediction of the critical buckling load is up to 85% for the cases considered here. The correction of the equivalent single-layer model is proposed by modeling the thick-faces effect to ensure finite curvature. This is performed in the finite element setting by introducing an additional plate with tied deflections to the equivalent single-layer plate. The extra plate is represented with bending and transverse shear stiffness of the face plates. As a result, global buckling is predicted accurately. Guidelines are proposed to identify the sandwich panels where ordinary model is incorrect. Truss-core and web-core sandwich panels need the correction. Corrugated-core panels without a gap between plates in the core have smaller shear orthotropy and do not need the correction. Modeling the thick-faces effect ensures correct results for all cases considered in this study, and thus one should resort to this approach in case of uncertainty whether the ordinary equivalent single-layer model is valid.

Global bending analysis of corrugated sandwich panels with integrated piezoelectric layers

Smart corrugated sandwich panels are special types of sandwich panels which are well suited in advanced devices to provide not only high resistance capability against mechanical loads but also energy harvesting capacity for low power applications. In this paper, analytical solution for corrugated sandwich panels with embedded piezoelectric layers is presented by using three-dimensional theory of elasticity. Energy method in conjugation with homogenization approach is used to determine effective properties of corrugated cores in thickness direction. Due to extreme orthotropic nature of corrugated cores, this method can give an accurate solution by using state-space method. Accuracy of core properties is verified by comparing numerical results with previous investigations. Furthermore, reliability of presented method is guaranteed by comparing the results with finite element analysis. A comprehensive parametric study including influences of geometrical factors such as pitch, height, sheet thickness and corrugation shape is accomplished.

Analysis and parametric optimization of a novel sandwich panel with double-V auxetic structure core under air blast loading

Blast shock wave is a big threat to the military vehicle and may cause vehicle damages and passenger casualties. It is a big issue to balance the protective performance and lightweight property of military vehicle. In these days, many types of sandwich panels with different cores were applied as protective plates in military vehicles. In view of the excellent energy absorption capability of auxetic structure, applying auxetic structure as sandwich panel core for blast protection purpose is a promising field. However, existing in-plane configuration of two-dimensional auxetic honeycomb core always represent anisotropic behaviour. In this paper, a novel sandwich panel with three-dimensional double-V Auxetic (DVA) structure core, which can produce isotropic mechanical behavior, was proposed for air blast protection purpose. Its primary structural parameters and their relations were discussed, and a parametric numerical model was established. In order to reduce both the dynamic response under air blast loading and mass, the design variables and objective function of the DVA core optimization problem were confirmed, then parametric optimization was conducted based on Latin Hypercube Sampling (LHD) method, Gaussian process metamodel (GPM) and multi-objective particle swarm optimization algorithm (MOPSO). Finally, it is proved that the applied optimization process is efficient and can obtain accurate optimum points. The proposed DAV core sandwich panel performed much better both in lightweight and protection than solid plate and has an apparent merit in lightweight aspect compared with square honeycomb core sandwich panel.

Experimental study on the temperature field of ETICS cladding system with finishing colorful steel plate

Colorful steel plate (CSP) is a material characterized with high durability and low maintenance requirement during the service life, especially when it is used as a decoration material in the building exterior wall. This study proposes a new type of sandwich panel for building envelope that is composed of CSP shins and ribs and is infilled with heat-insulating material core. The panel provides many advantages such as durability, corrosion resistance and speed construction. In this study, three rigs of external thermal insulation composite system (ETICS) with three heat-insulating materials, namely, foam glass, foam concrete and rigid polyurethane foam, are tested inside a weathering test chamber. Thermal fields of the rigs are measured using a resistance thermometer, T-type thermocouple and an infrared imaging technology during heat-rain and heat-cold cycles. The results show that the temperatures of the CSP finish and the outer face of the insulation layer change in accordance with the air temperature of the chamber. The temperatures of CSP finish change abruptly (especially near the window) while the temperatures of the bonding layer change slowly. Among the three heat-insulating materials studied, rigid polyurethane foam is the most efficient in energy-conservation. In all three ETICSs, each layer causes a lag in time and reduces the transmission of thermal waves from the exterior to interior parts, these phenomena being more prominent with an increase in the insulating effect of the insulation layer.

Experimental and numerical analyses of the impact response of lightweight sandwich panels

In the present work, experimental and numerical analyses were developed to investigate the particularities of the impact response of lightweight sandwich panels subjected to low velocity impact. Two types of sandwich panels, with aluminum faces and polyurethane or polystyrene core, were tested in impact on an Instron Ceast 9340 drop tower at speeds ranging from 0.77 to 4.5 m/s. Local displacement of the top Al face sheet, contact force and deflection of the sandwich panel were obtained for different impact velocities. It was found that the behavior of the core has a big influence upon the evolution of the force variation during impact. There were noticed differences in the size and shape of the produced penetration of the skins after low-velocity impact. A numerical model was also developed to explore the possibilities of simulating the damage progression in foams. Rather good agreements, in terms of contact-force histories, damage evolution and indentation depths of the sandwich panels, between the experimental and numerical results were observed. A damage criterion should be considered further for simulation.