Types Of Sandwich Panels Research Articles

Properties of multilayered sandwich panels with an agglomerated cork core for interior applications in buildings

Four types of sandwich panels with multilayered designs were produced using wood veneer of Aleppo pine as face and inner sheets, and cork agglomerate as core, intended for use in construction as panelling or partition walls in interior applications. These multilayered sandwich panels were characterized regarding static hardness and dimensional stability when facing changes in relative humidity and when subjected to a deformation. The panels showed a considerable increase in dimensional stability and shear strength with the increase of the number of layers. The results suggest that the correct design choice, for example number of inner wood sheets and thickness of cork core layers, allows these sandwich panels to be used as non-structural construction elements such as partition walls.

Structural Performance of Wood Based Sandwich Panels in Four Point Bending

Current paper describes design, prototyping and experimental tests of wood based sandwich panels with plywood surfaces. In the first case 3D core of the sandwich panel is formed by thermoplastic glass fibre / polypropylene (GF/PP) composite and bonded to plywood in one manufacturing step. Other sandwich panel type consists of plywood skins and stiffeners with additional foam core filler made of environmentally friendly PU foam. Both types of sandwich panels are intended for applications in lightweight fast transformable housing applications.Experimental flexural tests demonstrates that wood based structures are competitive alternative for solid wood based plate materials. Average flexural modulus for sandwich panels with stiffener/foam core is 6.2 GPa and flexural strength 26.1 MPa at density of 325 kg/m3. Thermoplastic composite core allows to reach flexural modulus of 4.18 GPa and strength of 22.6 MPa at the same time maintaining low density magnitude at 235 kg/m3. It has been demonstrated that numerical analysis could be applied as a benchmark tool to evaluate mechanical performance of the panels comparing to idealized design.

Mechanical properties and experimental researches of new CSIPs sandwich panels

The advantages of glass fiber reinforced composites (FRP) and SIPs (structural insulated panels) are combined, and a new type of sandwich panel called composite structural insulated panels (CSIPs) is proposed. Through the adhesive bonding, CSIPs are made of FRP as face sheets and expanded polyethylene foam (EPS) as a core. To master the mechanical characteristics of CSIPs, firstly, adopting the large deflection theory of Reissener in this paper derived the calculation formula of displacement and the stability critical load of CSIPs. Then, ANSYS software was used to carry on the analysis of finite element simulation. Finally, a testing piece of CSIP with length 1000mm and breath 1000mm was made and a test was done. The results show that the theoretical analysis results, finite element simulation results and test results are basically coincide. So the calculating formula of deformation and bearing capacity of CSIPs are correct. And CSIPs have the outstanding advantages of light weight and high strength.

Creep of Sandwich Panels with Longitudinal Reinforcement Ribs for Civil Engineering Applications: Experiments and Composite Creep Modeling

AbstractComposite sandwich panels with reinforcement ribs or webs are being increasingly considered for structural applications in civil engineering. Such panels are prone to creep when subjected to significant permanent loads and therefore the effects of this phenomenon must be duly accounted for in their design. Data regarding the viscoelasticity of sandwich panels and their constituent materials is still scarce and often cannot be directly used for creep predictions in design practice. To address this issue, this paper presents the experimental assessment and the analytical modeling of the viscoelastic response of two types of sandwich panels, with and without reinforcement ribs. Panels comprising glass fiber–reinforced polymer (GFRP) faces, cores of polyurethane (PU) foam, and longitudinal GFRP ribs are considered. The ribs increased the flexural strength and stiffness of the panels by a factor of two, while providing a threefold reduction in their creep compliance. A composite creep modeling (CCM) ap...

Application of dynamic analysis and modelling of structural concrete insulated panels (SCIP) for energy efficient buildings in seismic prone areas

Structural Concrete Insulated Panel is a special type of Sandwich Panel or Structural Insulated Panel (SIP) which is composed of thick layer of foam (polystyrene or polyurethane) and welded GI Wire mesh crossed between the foam sandwiched between two layers of shotcreting (1.5in. thick on each side). Wall panels and Roof Panels are manufactured in 4ft. in width and 8ft. height, available in thicknesses range of 2–6″.The conventional building system take much longer time for construction and also it is very poor in terms of energy conservation as compare to Sandwich Panel of Structural Insulated Panel (SCIP) building. According to a conservative estimate, buildings consume more than 40% of the total electricity produced. The demand of this sector is growing at the rate of almost 14% per annum, the highest among all other sectors. To cope up with the challenges of the construction industry, energy efficient fast construction buildings solution is indispensable. A typical school building using Sandwich Panel Insulated Building was modelled and analyzed using SAP2000 software and its results were analyzed and examined.

Experimental Study of the Bending Properties and Deformation Analysis of Web-Reinforced Composite Sandwich Floor Slabs with Four Simply Supported Edges.

Web-reinforced composite sandwich panels exhibit good mechanical properties in one-way bending, but few studies have investigated their flexural behavior and deformation calculation methods under conditions of four simply supported edges. This paper studies the bending performance of and deformation calculation methods for two-way web-reinforced composite sandwich panels with different web spacing and heights. Polyurethane foam, two-way orthogonal glass-fiber woven cloth and unsaturated resin were used as raw materials in this study. Vacuum infusion molding was used to prepare an ordinary composite sandwich panel and 5 web-reinforced composite sandwich panels with different spacing and web heights. The panels were subjected to two-way panel bending tests with simple support for all four edges. The mechanical properties of these sandwich panels during the elastic stage were determined by applying uniformly distributed loads. The non-linear mechanical characteristics and failure modes were obtained under centrally concentrated loading. Finally, simulations of the sandwich panels, which used the mechanical model established herein, were used to deduce the formulae for the deflection deformation for this type of sandwich panel. The experimental results show that webs can significantly improve the limit bearing capacity and flexural rigidity of sandwich panels, with smaller web spacing producing a stronger effect. When the web spacing is 75 mm, the limit bearing capacity is 4.63 times that of an ordinary sandwich panel. The deduced deflection calculation formulae provide values that agree well with the measurements (maximum error <15%). The results that are obtained herein can provide a foundation for the structural design of this type of panel.

Novel Sandwich Panel with Interlocking Plywood Kagome Lattice Core and Grooved Particleboard Facings

A new sandwich composite structure was prepared that utilizes classic wood-based composites as the core and face materials. Particleboards were used as faces, which covered a plywood-made iso-grid core. A new type of core-face fixation was suggested and assessed. The sandwich panels can be regarded as lightweight, as their density was below 400 kg/m3. Digital image correlation (DIC) was used to determine Poisson’s ratios and obtain additional insight into the deformation behavior of the sandwich panel. DIC was also employed to assess the core-face bonding, which was based on imprinted grooves on one side of the particleboard face. The results include strength in edgewise and flatwise compression and flexural properties. The latter were determined through three-point bending tests. Comparable strength properties were found relative to the literature, which means that this new type of sandwich panel demonstrates a competitive property profile. It was concluded that the developed sandwich panel is versatile, and the hollow spaces in the core can be filled with insulation materials such as fibers or foams. Surfaces can also be covered with some overlay, delivering improved bending performance.

Improvements to the procedure for flexural testing, on two spans, of full wood-based sandwich panel subject to uniform load

This work presents a detailed procedure for flexural testing, on two spans, of simply supported full wood-based sandwich panel subject to uniform load. This procedure improves the test described sparsely in the Annex C1 of EOTA-ETAG 016-Part 1: Guideline for European Technical Approval of Self-supporting Composite Lightweight Panels.To show the validity of the method, several tests were carried out in accordance with this procedure and the results were compared with analytical models. It was observed that the analytical models fit the experimental results with different accuracy on the prediction of the load at maximum allowed deflection, provided that the mechanical parameters of the constituent materials of sandwich panel are known accurately.It was also found that, in this type of sandwich panel, the thicknesses of the faces are not negligible, and therefore the shear stiffness of the sandwich should not be simplified in the equations.Additionally, it is included a simple method to estimate the uncertainties of some of the outcomes obtained in the test.

Modeling and simulation on the performance of a novel double shape-stabilized phase change materials wallboard

The structure of a new wall system was that of a three-layer sandwich-type panel with external/internal layer consisting of shape-stabilized phase change material (SSPCM) wallboard and middle layer consisting of conventional concrete. The external layer was active in hot seasons and the internal layer was active in cold seasons. An office room integrated with the novel double SSPCMs wallboard with a splitting air-conditioner was used for modeling and simulation test platform. Studies were conducted to investigate the effects of the novel double SSPCMs and different parameters on the energy and thermal performance in typical climate area with hot summer and cold winter (Wuhan city, China). Test results showed that the recommended thicknesses of external and internal SSPCM wallboard were 30–60mm. With the recommended thickness, the annual energy savings for cooling were 3.4–3.9%. The peak load reductions for cooling were 3.1–3.8%. The annual energy savings for heating were 14.8–18.8%. The peak load reductions for heating were 8.6–11.3%. The external layer was effective on reducing annual energy demand and peak load of cooling in hot seasons. The internal layer was effective on reducing the indoor temperature fluctuation in cold seasons.

Influence of reinforcement structure on the flexural properties of sandwich composite panels

New types of sandwich panels were built by filling foam in woven spacer fabric and combining the epoxy resin on the surface. To investigate the effect of the fabric structure on the flexural property of panels, different types of spacer fabrics were woven with reinforcing material, technical polyester filaments. Then the new types of composite panels were built, and the flexural property of each type of sandwich composite panels was tested. The analysis indicated that the flexural strength first increased and then decreased with increase of the bonding yarn density showing parabola tendency. It was proved that the flexural strength reached the maximum when the binding yarn density rose to 1·99 ends cm−2 by regression analysis. The flexural load of the panels increased with the increase of the bonding yarn height. Different failure behaviours were found for different type of composite panels.

CHARACTERIZATION OF LOW VELOCITY LOCAL IMPACT OF SANDWICH PANELS

The present paper deals with analysis of local indentation and their energies in point loading of sandwich panel with thin orthotropic composite faces and honeycomb core as an introduction for low velocity impact loading and energy absorbing in sandwich structures. Energy is consumed in two stages: local indentation of sandwich panel skin and bending of sandwich panel. If the impact is located near support or clamping only first stage (indentation of sand-wich panel) will be presented. Here the analytical model has been used assuming a rigid-perfectly plas-tic compressive behaviour of the honeycomb core and membrane behaviour of orthotropic skin for large indentation of sandwich panel. In experimental work were investigated two types of sandwich panels, which consisted of different laminated skins: cross-ply of unidirectional CFRP and AFRP (aramid fabric reinforced plastic) and core honeycomb materials (impregnated paper like Nomex and one layer of glass fabric reinforced plastic). Length of cell side is 2.5 mm. Skins were made with symmetrical lay-ups [0/90]s and [45/-45]s. For indentation test we used steel balls with radius 5-30 mm, speed of loading was 2 mm/min. The experimental results are in good agreement with the analysis. These results can be used in impact loading and energy absorption studies of laminated structures by integrating of “local load vs deflection” curve.

Flatwise compression and flexural behavior of foam core and polymer pin-reinforced foam core composite sandwich panels

The behavior of foam core sandwich (FCS) and polymer pin-reinforced foam core sandwich (PRFCS) panels was experimentally explored for flatwise compression and flexural loadings. The FCS and PRFCS panels were made of chopped strand mat glass/polyester as face sheets and polyurethane foam as core material using a vacuum infusion process. The aim of the study is to determine the effect of the polyester pin reinforcement in the foam core when the panels are subjected to flexural and flatwise compression loadings. Moreover, the effects of different loading rates on the flexural response of glass/polyester laminate and both types of the sandwich panels were determined. It was found that by reinforcing the foam core with cylindrical polymer pins, the flatwise compression and flexural properties of panels were increased significantly. Furthurmore, it was found that the diameter of polymer pins had a large influence while the loading rate had a moderate influence on the flexural stiffness of both types of the composite sandwich panels.

Deformation and impact energy absorption of cellular sandwich panels

The response and energy absorption capacity of cellular sandwich panels that comprises of silk-cotton wood skins and aluminum honeycomb core are studied under quasi-static and low velocity impact loading. Two types of sandwich panels were constructed. The Type-I sandwich panel contains the silk-cotton wood plates (face plates) with their grains oriented to the direction of loading axis and in the case of Type-II sandwich panel, the wood grains were oriented transverse to the loading axis. In both of the above cases, aluminum honeycomb core had its cell axis parallel to the loading direction. The macro-deformation behavior of these panels is studied under quasi-static loading and their energy absorption capacity quantified. A series of low velocity impact tests were conducted and the dynamic data are discussed. The results are then compared with those of quasi-static experiments. It is observed that the energy absorption capacity of cellular sandwich panels increases under dynamic loading when compared with the quasi-static loading conditions. The Type-I sandwich panels tested in this study are found to be the better impact energy absorbers for low velocity impact applications.

Damping evaluation on eco-friendly sandwich panels through reverberation time (RT60) measurements

Problems involving vibrations occur in many fields of engineering. Thus, it is necessary to increase the knowledge of the damping, offered by new structural configurations and materials in order to reduce the vibration levels. The present paper focuses its attention on the measurements of the structural loss factor of different types of sandwich panels made of eco-friendly materials. The interest in natural materials, for structural applications, has considerably increased in the last years thanks to the growing environmental concerns. The influence on the loss factor of face sheet materials, core types and configurations is experimentally evaluated by means of measurements of the reverberation time (RT60). The reported data represent a good initial database for more detailed analyses of these new materials.

A simplified dynamic model of double layers shape-stabilized phase change materials wallboards

A simplified dynamic building model was proposed and validated in this study. The structure of the new wall system is that of a three-layer sandwich-type panel with outer layers consisting of SSPCM wallboards and middle layer consisting of conventional brick. Each layers of the composite wall have different functions: the external layer connected to outside has a higher PCM melting temperature used in summer and the internal layer connected to indoor with a PCM melting temperature near indoor set point used in winter. The middle layer is brick for insulation. Few studies have involved simplified dynamic models of building structures integrated with double layers SSPCMs. The simplified dynamic model represents the brick layer by three resistances and two capacitances (3R2C) and the SSPCM layer by four resistances and two capacitances (4R2C) while the key issue is the parameters identification of the model. The parameters of the simplified model are identified using genetic algorithm (GA) on the basis of the basic physical properties of the brick and SSPCM layer. Validation results show that the simplified dynamic model can represent light weight walls and median weight walls integrated with double layers SSPCMs with good accuracy.

Experimental studies on thin sandwich panels under impact and static loading

Several thin sandwich panels (thickness close to 3 mm) of different configurations were studied to explore an alternative material for the outer body of various machines and appliances such as automobile, refrigerator, washing machine, lathe machine, drill press, cupboards, light furniture, etc. Three types of sandwich panels with the outer face sheets made of glass fabric/epoxy were fabricated for the present study: (1) XM-Core panel was made of polyester foam Coremat XM/epoxy as core material, (2) Xi-Core panel was made of polyester foam Coremat Xi/epoxy as core material, and (3) J-Core Panel was made of layers of Jute fabric/epoxy as core material. A very thin transition layer of glass chopped strand mat/epoxy was provided between the face sheets and the core to improve their bonding strength. The sandwich panels were analyzed for low velocity normal impact loading under a drop weight impact test set up and transverse static loading under universal testing machine. Damage area, indentation depth and permanent depression over damage area, and failure modes were observed under incident impact loading. The transverse static test was performed to observe load versus deflection relation and to characterize the flexural strength and stiffness.

Numerical study of lightweight sandwich panels under explosion using rigid polyurethane foam and vulcanized rubber

AbstractStructural weight reduction is one of the main design objectives in structural engineering.Various concepts have been proposed to reduce weight of military tunnels protecting layers andarmored doors. Among them, application of sandwich sheets which comprise of two face sheetsand low-density core materials which offers a significant weight reduction, high resistance againstblast loads, and the ability to withstand repetitive blast loa ds.In this paper, numerical investigations were conducted using 3D nonlinear finite elementsimulations with commercial ANSYS AUTODYN software. A number of peripherally simplysupported (from all sides) nonmetallic core sandwich panels with either rigid p olyurethane foam(RPF) or vulcanized rubber (VR) cores were studied. A parametric study was carried out to studythe behavior of these types of sandwich panels against blast load. Different thickness for differentcore materials were tested namely 5, 10, 15, and 20 cm. Sandwich Panels were subjected todifferent blast charges of 1, 5 and 10 kg TNT at fixed standoff distance 1 meter.It was concluded that the behavior of high density RPF sandwich panel is better than that ofVR sandwich panel. Using rigid polyurethane foam instead of vulcanized rubber as a core materialdecreases the maximum displacement by an average value 48.67 %, for the three different blastloads, which is good displacement reduction.

Physical and mechanical properties of particleboard laminated with thermally compressed veneer

The aim of this study was to investigate the effects of thermally compressed veneer laminating on some of the physical and mechanical properties of particleboard. Oriental beech (Fagus orientalis Lipsky)veneers were compressed under various press conditions. Commercially produced particleboard samples were laminated with such compressed veneer sheets. The density, 2-h and 24-h water absorption (WA) and thickness swelling (TS), bending strength (MOR), and modulus of elasticity (MOE) in the parallel and perpendicular directions to grain orientation were measured. The results showed that all of the particleboards laminated with compressed veneer had higher MOR and MOE values compared to unlaminated particleboard and particleboard laminated with non-compressed veneer. In the sandwiched panels, particleboards laminated with veneer sheets and compressed at a pressure of 4 MPa and a temperature of 150 oC had the highest MOR and MOE values. The MOR and MOE values decreased with increasing temperatures higher than 150 oC. The TS value for 2-h and 24-h immersion times decreased with increasing press temperature. The findings of this work could provide some insight in producing sandwich-type panels with improved properties. It appears that compressed veneer using different press temperatures and pressures could be considered as an alternative way of developing sandwich-type products with satisfactory structural properties.

Flexural creep behavior of sandwich panels containing Kraft paper honeycomb core and wood composite skins

Flexural creep behavior is an important performance related characteristic for sandwich panels used as products, such as kitchen bench tops, table legs, and bookshelves. In order to characterize the creep behavior of the sandwich panels with Kraft paper honeycomb core and wood composite skins, a series of creep tests were carried out under a constant three-point bending. The sandwich panels contained different types of core and skin materials as well as various core and skin thicknesses. The flexural creep deflection as a function of time for each type of sandwich panel was measured. The results show that the flexural creep behavior of the sandwich panel is affected by honeycomb core shape, core and skin thickness, and skin material type.

The Low-Velocity Impact Response of Sandwich Panels

The low velocity impact response of sandwich panels at different energy levels has been investigated by conducting drop-weight impact tests using an instrumented falling-weight impact tower. Impact parameters like maximum impact force and the extent of the damage were evaluated and compared for different types of sandwich panels. Finite elements simulations have been undertaken using the LS-DYNA software; the results of FE simulations have a good agreement with the experiments. It shows that, the impact force increased with thickness of face-sheets and foam core, the extent of the damage increased with the impact energy, sandwich panels with steel face sheet has a good impact resistance in comparison with sandwich panel with aluminum face sheets.