Showing papers on "Sandwich panel published in 2011"
TL;DR: In this article, the structural behavior of a composite panel system consisting of two outer skins of profiled thin-walled steel plates with lightweight foamed concrete (LFC) core under axial compression was investigated.
Abstract: This paper presents the results of an experimental and analytical investigation on the structural behaviour of a composite panel system consisting of two outer skins of profiled thin-walled steel plates with lightweight foamed concrete (LFC) core under axial compression The gross dimensions of the test specimens were 400 mm×400 mm×100 mm A total of 12 tests were carried out, composed of two duplicates of 6 variants which were distinguished by two steel sheeting thicknesses (04 mm and 08 mm) and three edge conditions of the sheeting The density of LFC was 1000 kg/m 3 Experimental results include failure modes, maximum loads and load-vertical strain responses In analysis, full bond between the steel sheets and the concrete core was assumed and the LFC was considered effective in restraining inward buckling of the steel sheets Using the effective width method for the steel sheets, the load carrying capacities of the test specimens were calculated and compared with the experimental results It was found that a combination of the Uy and Bradford plate local buckling coefficients with the Liang and Uy effective width formulation produced calculation results in good agreement with the experimental results Finally, a feasibility study was undertaken to demonstrate the applicability and limit of this new composite walling system in low rise construction
133 citations
TL;DR: In this article, small scale explosive loading of sandwich panels with low relative density pyramidal lattice cores has been used to study the large scale bending and fracture response of a model sandwich panel system in which the core has little stretch resistance.
114 citations
TL;DR: In this paper, high-speed photography, with digital image correlation (DIC), was employed to monitor the deformation of glass-fibre reinforced polymer (GFRP) sandwich structures during the blasts.
Abstract: Glass-fibre reinforced polymer (GFRP) sandwich structures (1.6 m × 1.3 m) were subject to 30 kg charges of C4 explosive at stand-off distances 8–14 m. Experiments provide detailed data for sandwich panel response, which are often used in civil and military structures, where air-blast loading represents a serious threat. High-speed photography, with digital image correlation (DIC), was employed to monitor the deformation of these structures during the blasts. Failure mechanisms were revealed in the DIC data, confirmed in post-test sectioning. The experimental data provides for the development of analytical and computational models. Moreover, it underlines the importance of support boundary conditions with regards to blast mitigation. These findings were analysed further in finite element simulations, where boundary stiffness was, as expected, shown to strongly influence the panel deformation. In-depth parametric studies are ongoing to establish the hierarchy of the various factors that influence the blast response of sandwich composite structures.
93 citations
TL;DR: In this article, the compressive properties of lattice structures based on a body-centered cubic and a similar structure with vertical pillars were investigated at quasi-static rates of strain.
Abstract: Lattice structures based on two simple architectures have been manufactured from 316L stainless steel using the selective laser melting process. The compressive properties of structures based on a body-centered cubic (BCC) and a similar structure with vertical pillars (BCC-Z) were initially investigated at quasi-static rates of strain. Blast tests were subsequently performed on the lattice structures as well as on lattice sandwich structures with CFRP skins. When subjected to quasi-static compression loading, the BCC structure exhibited a progressive mode of failure, whereas the BCC-Z lattice deformed in a buckling-dominated mode of collapse. The blast response of the lattice cubes exhibited a linear dependency on the applied impulse up to the threshold for material densification. Relationships between the blast resistance and both the yield stress and energy absorption characteristics of the lattices have been established and an examination of the failed samples indicated that the collapse modes were sim...
89 citations
TL;DR: In this paper, the structural performance of steel-concrete-steel (SCS) sandwich composite system subject to impact and blast load was investigated and an ice caisson protective offshore structure was proposed based on the curved sandwich panel.
Abstract: This paper investigates the structural performance of steel-concrete-steel (SCS) sandwich composite system subject to impact and blast load. Novel J-hook shear connector was invented to prevent the separation of face plates from the concrete core. SCS sandwich specimens subject to 100 kg TNT blast a 5 m standoff distance were tested. The test results are reported and the factors affecting the blast resistance of SCS sandwich structures are discussed. Finite element analysis was carried out and the numerical results are verified against the blast test results. Parametric study of sandwich core strength and plate thickness is presented. Due to the superior impact performance of the proposed SCS sandwich structures, an ice caisson protective offshore structure is proposed based on the curved sandwich panel. The ultimate strength behavior of curved SCS sandwich panels is tested. The effect of arch effect is studied both experimentally and numerically.
87 citations
TL;DR: In this article, the authors present experimental studies on the quasi-static indentation of a rigid indenter into sandwich panels with carbon fibre-reinforced polymer face and polymeric foam core and find that both nose shape and foam core density have large influence on the indentation response of the sandwich panels in terms of absorbed energy, indentation at failure and damage area.
Abstract: This paper presents experimental studies on the quasi-static indentation of a rigid indenter into sandwich panels with carbon fibre-reinforced polymer face and polymeric foam core. It was found that both nose shape and foam core density have large influence on the indentation response of the sandwich panels in terms of absorbed energy, indentation at failure and damage area. A dependency of the indentation load on the supporting condition was observed. It was also found that the difference in indentation resistance between the sandwich panel and its corresponding core material depends on the core density.
85 citations
TL;DR: In this article, the estimation of static and eigenvibration properties of honeycomb sandwich reinforced by polymeric foam was investigated, and a new real microstructure model was proposed for the analysis in which the face materials and the honeycomb were modeled by shell elements, whereas filling foam was modelled by solid elements.
64 citations
TL;DR: In this article, an infinite sandwich panel reinforced by orthogonal rib-stiffeners is theoretically formulated for harmonic point force excitation and the response of the sandwich is determined by employing the Fourier transform technique and considering the periodical nature of the structure, which is numerically solved by truncating two infinite sets of simultaneous equations.
59 citations
TL;DR: In this article, a combination of experimental and modeling methods was used to investigate the mechanical response of edge-clamped sandwich panels subject to the impact of explosively driven wet sand.
59 citations
TL;DR: In this paper, the authors investigated large-scale sandwich panels (9,145×2,440×78 mm) subjected to out-of-plane loading and found that they failed at 7.5 kPa, 2.6 times the factored design pressure for the windiest region in Canada.
Abstract: This paper investigates large-scale sandwich panels (9,145×2,440×78 mm) subjected to out-of-plane loading. The panels comprise glass-fiber-reinforced polymer (GFRP) skins connected by orthogonal GFRP ribs and a polyurethane foam core. The lightweight insulated panel is supported at three levels along its 9,145-mm height and is proposed for cladding of buildings, where the main loading is caused by wind. A full-scale panel was tested under uniform air pressure by using a specially designed setup equipped with pressure load actuators. The panel failed at 7.5 kPa, 2.6 times the factored design pressure for the windiest region in Canada. Failure occurred by outward wrinkling and crushing of the GFRP compression skin near the middle supports. The deflection under the maximum design service wind pressure did not exceed span/360. Another test was carried out on a different specimen by using conventional mechanical loading. It confirmed the ultimate strength of the panel and also revealed a successive failure re...
49 citations
TL;DR: In this paper, a micro-architected multifunctional structure, a sandwich panel heat pipe with a microscale truss core and arterial wick, is modeled and optimized.
TL;DR: In this paper, a curved sandwich panel with two aluminium face sheets and an aluminium foam core under air blast loadings was investigated experimentally and numerically, and the deformation/failure modes of specimens were classified and analyzed systematically.
Abstract: Curved sandwich panels with two aluminium face sheets and an aluminium foam core under air blast loadings were investigated experimentally and numerically. Specimens with two values of radius of curvature and different core/face sheet configurations with the same projected area were tested for three blast intensities. All four edges of the panels were fully clamped. The experiments were carried out by a four-cable ballistic pendulum with corresponding sensors. The impulse acting on the front face of the assembly, the deflection history at the center of the back face sheet, and the strain history at some characteristic points on the back face were obtained. Then the deformation/failure modes of specimens were classified and analyzed systematically. The commercial software LS-DYNA was employed to simulate those physical processes. The finite-element (FE) model was validated by the data from experiments. Detailed deformation and energy dissipation mechanisms were further revealed by the FE models. The valuable experimental data and results from FE models show that the initial curvature of a curved sandwich panel changes the deformation/collapse mode with an extended range for bending-dominated deformation mode, which suggests that the performance of the sandwich shell structures slightly exceeds that of both their equivalent solid counterpart and a flat sandwich plate in certain blast intensity ranges.
TL;DR: In this paper, a 3D elasticity analysis for a sandwich panel with stiffness of the core graded in the thickness direction is presented, on the basis of the recently developed elasticity solution.
TL;DR: In this article, the authors explored concepts to enhance the ballistic resistance without changing the volumetric efficiency of the panels by filling the spaces within the core with combinations of polyurethane, alumina prisms, and aramid fiber textiles.
Abstract: Previous studies have shown that while stainless-steel sandwich panels with pyramidal truss cores have a superior blast resistance to monolithic plates of equal mass per unit area, their ballistic performance is similar to their monolithic counterparts. Here, we explore concepts to enhance the ballistic resistance without changing the volumetric efficiency of the panels by filling the spaces within the core with combinations of polyurethane, alumina prisms, and aramid fiber textiles. The addition of the polyurethane does not enhance the ballistic limit compared with the equivalent monolithic steel plate, even when aramids are added. This poor performance occurs because the polymer is penetrated by a hole enlargement mechanism which does not result in significant projectile deformation or load spreading and engagement of the steel face sheets. By contrast, ceramic inserts deform and erode the projectile and also comminute the ceramic. The ceramic communition (and resultant dilation) results in stretching of both steel face sheets and leads to significant energy dissipation. The ballistic limit of this hybrid is about twice that of the equivalent monolithic steel plate. The addition of a Kevlar fabric to the ceramic hybrid is shown to not significantly change the ballistic limit but does reduce the residual velocities of the debris.
TL;DR: In this paper, the effect of additional core interlayers on blast resistance enhancement of circular sandwich panels was investigated using numerical finite element (FE) models to assess the existing blast resistance capacity, increase the dynamic energy absorption, improve the stress distribution through plastic deformation, and ensure sacrificial damage to the additional core layers.
TL;DR: In this article, the behavior of sandwich panels with TRC faces is studied and several models are used in a finite element analysis and their advantages and disadvantages are discussed, and the calculated nonlinear behavior of the panels is compared to experimental observations.
Abstract: Textile-reinforced concrete (TRC) is a composite material that recently gained renewed interest. Due to an improved durability, the usage of this composite in lightweight constructions becomes possible. In this article, the behavior of sandwich panels with TRC faces is studied. In the first part, several models are used in a finite element analysis and their advantages and disadvantages are discussed. In the second part, the calculated nonlinear behavior of the panels is compared to experimental observations.
TL;DR: An analytical study of sound transmission through all-metallic, two-dimensional, periodic sandwich structures having corrugated core is presented in this article, where an equivalent structure containing one translational spring and one rotational spring per unit cell is proposed to simplify the analysis of the vibroacoustic problem.
Abstract: An analytical study of sound transmission through all-metallic, two-dimensional, periodic sandwich structures having corrugated core is presented. The space-harmonic method is employed, and an equivalent structure containing one translational spring and one rotational spring per unit cell is proposed to simplify the analysis of the vibroacoustic problem. It is demonstrated that the core geometry exerts a significant effect on the sound insulation performance of the sandwich, so that one may tailor the core topology for specified acoustic applications. Subsequent analysis of the sound transmission loss (STL) and dispersion curves of the structure leads to fundamental insight into the physical mechanisms behind the appearance of various peaks and dips on the STL versus frequency curves. As the weight, stiffness, and acoustic property of the sandwich structures all change with the alteration of core configuration and geometry, it is further demonstrated that it is possible to explore the multifunctionality o...
TL;DR: In this paper, the authors used the finite element method to evaluate the dynamic response of a submerged cylindrical foam core sandwich panel subjected to underwater shock loading, where the composite plies were presented in graphical form and the effects of core type on circumferential stress and velocity of stand-off point were also investigated.
TL;DR: In this paper, a finite element method has been used to develop collapse mechanism maps for the shear response of sandwich panels with a stainless steel core comprising hollow struts, and the dependence of the elastic and plastic buckling modes upon core geometry is determined, and optimal geometric designs are obtained as a function of core density.
25 May 2011-Materials Science and Engineering A-structural Materials Properties Microstructure and Processing
TL;DR: In this paper, the authors used the Finite Element Method (FEM) to study the brazing residual stresses in a stainless steel X-type lattice truss sandwich structure, and the nanoindentation experiment was used to verify the validity of FEM.
Abstract: The lattice truss sandwich structures are considered as the most promising advanced lightweight materials used in modern industries and aircrafts. Most sandwich panel structures are fractured at brazed joints named node failure during static and dynamic testing, which is mainly influenced by brazing residual stresses. Finite element method (FEM) was used to study the brazing residual stresses in a stainless steel X-type lattice truss sandwich structure. And the nanoindentation experiment is used to verify the validity of FEM. The effects of braze processing parameters including applied load, face sheet thickness, truss thickness and truss length on residual stresses have been investigated. It is shown than the residual stresses are concentrated on the brazed joint, which has a significant effect on node failure. As the applied load increases, the residual stresses decrease first and then remain unchanged, and the optimal applied load is around 1 MPa. As the face sheet thickness increasing, the residual stresses are increased. Too thin face sheet can cause large residual stresses on the top surface of face sheet. With truss thickness and truss length increase, the residual stresses are decreased first and then increased. The optimized face sheet, truss thickness and truss length are found to be 2 mm, 1 mm and 26 mm.
TL;DR: In this paper, the effect of the core triangle geometry and the core material of sandwich panels on the performance of T-joints was investigated by numerical analysis, and the results showed that by changing the core materials of the sandwich panel, the joint failure load is also changed.
TL;DR: In this article, a steel hexagonal honeycomb core concept was proposed to increase the stiffness of a commercial GFRP honeycomb sandwich panel through the inclusion of steel within the cross section.
TL;DR: In this paper, the structural behavior of precast lightweight foamed concrete sandwich panel, PLFP, subjected to eccentric loading was investigated and the results showed that panel with symmetrical double truss connectors, PE-2, is able to sustain higher load compared to panel with single shear truss connector.
Abstract: This paper reports the structural behavior of precast lightweight foamed concrete sandwich panel, PLFP, subjected to eccentric loading. An experiment was conducted to investigate the structural performance of PLFP under this load. Two PLFP panels, PE-1 and PE-2 were cast with 2000 mm in heights, 750 mm in width and 100 mm in thickness. The thickness of the wall is actually a combination of three layers. Skin layers were cast from lightweight foamed concrete while the core layer is made of polystyrene. The skin layers were connected to each other by 9 mm steel shear truss connector which were embedded through the layers. Panel PE-1 was strengthened with single diagonal shear truss connectors made of 6 mm steel rebar while panel PE-2 was strengthened with symmetrical diagonal shear truss connectors of similar steel diameter. Both panels were tested under eccentric load till failure. The results showed that panel with symmetrical double truss connectors, PE-2, is able to sustain higher load compared to panel with single shear truss connector. The load-deflection profiles indicate that both panels achieved certain degree of composite action especially during the later stage of loading where the wythes tend to move in the same direction until they reached failure. The load-strain curves for both panels highlight the inconsistent distribution of surface strain along the height of panels. The overall trend of the strain curves show that they are under compression.
TL;DR: In this article, the Young's modulus in the thickness direction of the honeycomb core of a sandwich panel was determined by experimental methods, an analytical approach and by the finite element method.
25 Jun 2011-Materials Science and Engineering A-structural Materials Properties Microstructure and Processing
TL;DR: In this article, a series of creep tests were carried out under a constant three-point bending, and the results showed that the flexural creep behavior of the sandwich panel is affected by honeycomb core shape, core and skin thickness, and skin material type.
Abstract: 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
01 May 2011
TL;DR: In this article, a Precast Lightweight Foamed Concrete Sandwich Panel (PLFP) was developed for axial load test and the results are presented here, which include the ultimate load capacity, crack pattern and failure mode, strain distribution and load-deflection curve of the panels.
Abstract: A study is carried out to develop a Precast Lightweight Foamed Concrete Sandwich Panel, PLFP, as a new and affordable building system. Experimental investigation to study the behaviour of the panel under axial load is undertaken. The panel consists of two lightweight foamed concrete wythes and a polystyrene insulation layer in between the wythes. The concrete panels are reinforced with 9mm diameter high tensile steel bars. The rebars are tied to each other through the insulation layer by shear connectors which are made of 6mm mild steel bars bent to 45o angle. Total number of four specimens was tested with one specimen; PA1 was cast without capping at both ends. It was used as a pilot test. The other three specimens are capped with normal concrete at both ends to avoid end crushing during axial loading. Axial load test was conducted and the results are presented here, which include the ultimate load capacity, crack pattern and failure mode, strain distribution and load-deflection curve of the panels. The experimental ultimate strength achieved recorded lesser percentage difference with the formulae by Pillai and Parthasarathy when compared to formulae in BS8110. It is also observed that the strength of the panels are affected by the compressive strength of the foamed concrete forming the wythes, the presence of concrete capping at panel’s ends and the slenderness ratio, H/t. Specimens with capping at both ends recorded higher ultimate loads with no premature crushing. Failure of panels with slenderness ratio, H/t < 18 were by premature buckling near the supports whereas for panels with higher H/t ratio, slight bending was observed in the middle zone. The results also indicate that a certain degree of compositeness is achieved between the wythes.
Patent•
21 Dec 2011
TL;DR: In this paper, a composite XPS sandwich panel is made by selecting and manufacturing dies of components and materials; then carrying out machining and forming; and tightly adhering the machined and formed components and material, thus forming a composite xPS composite panel, which has the advantages of being low in water absorption and heat conductivity coefficient, high in tensile strength, good in frost and melting resistance.
Abstract: The utility model belongs to the technical field of preparing sandwich panels, and relates to a composite sandwich panel which is made of extruded polystyrene foam panels (XPS). The composite sandwich panel comprises flanging steel plates, polyurethane adhesive, an XPS and a sandwich layer, wherein multiple layers are compounded into a staggered layer which can be meshed with mutually, the flanging steel plates are arranged at two sides of the sandwich layer, thus breaking through the limit on the thickness of the sandwich panel under low-temperature condition; the sandwich layer consists of an upper XPS, a middle XPS and a lower XPS which are adhered by the polyurethane adhesive, the middle XPS of the sandwich layer and the upper XPS and the lower XPS are staggered, one side of the staggered layer is in a groove shape, and the other side is in a raised shape; the sandwich panel is made by the following steps: first selecting and manufacturing dies of components and materials; then carrying out machining and forming; and tightly adhering the machined and formed components and materials, thus forming a composite XPS sandwich panel. The composite sandwich panel has the advantages of being low in water absorption and heat conductivity coefficient, high in tensile strength, good in frost and melting resistance, good in heat insulation performance, environment-friendly in materials and the like.
TL;DR: In this paper, the effect of continuously grading fiber orientation face sheets on free vibration of sandwich panels with functionally graded core using generalized power-law distribution is investigated and presented useful results arising from symmetric, asymmetric and classic profiles.
Patent•
19 Oct 2011
TL;DR: In this article, a method for preparing a continuous fiber multiaxial fabric reinforced thermoplastic composite material is presented, which can be used for producing composite materials for different industries.
Abstract: The invention discloses a method for preparing a continuous fiber multiaxial fabric reinforced thermoplastic composite material. The prepared continuous fiber multiaxial reinforced thermoplastic preconsolidating material is taken as a base material of the composite board, and combined with other functional materials for forming a novel material system which can be used for producing multiaxial fabric reinforced thermoplastic composite materials for different industries and solving the technical bottleneck that different materials have different composite bonding difficulties. According to the invention, the prepared composite material is constructed by continuous fiber multiaxial direaction; materials have the characteristics of resilience and uniform stressing on different directions. In addition, light sandwich panel formed by a honeycomb core material provides higher impact strength of materials, which is suitable for preparing structural parts and interior decorative parts in the field of railway car containers of navigation and aviation. The product of light-weight flame retardant can be recovered and used, and is more suitable for industrialization scale production of the warp knitting industry organization.
TL;DR: In this paper, the out-of-plane shear behavior of a hollow core is analyzed and the expressions for the failure loads are developed, and a strength-based optimisation problem is formulated for predicting the optimum values of the panel dimensions that would produce minimum panel weight when subjected to bending.