Sandwich-structured composite

About: Sandwich-structured composite is a research topic. Over the lifetime, 5853 publications have been published within this topic receiving 101126 citations.

The impact response of aluminum foam sandwich structures based on a glass fiber-reinforced polypropylene fiber-metal laminate

Abstract: The fracture properties and impact response of a series of aluminum foam sandwich structures with the glass fiber–reinforced polypropylene-based fiber-metal laminate (FML) skins have been studied. Initially, the manufacturing process for producing the FML skins was optimized to obtain a strong bond between the composite plies and the aluminum layers. The degree of adhesion between the composite plies and the aluminum was characterized by conducting single cantilever beam tests. Here, it was found that the composites could be successfully bonded to the aluminum using a simple short stamping procedure. A detailed examination of the fracture surfaces indicated that crack propagation occurred within the composite ply in the fiber-metal laminates and along the composite-aluminum foam interface in the sandwich structures. The low velocity impact response of the FMLs and the sandwich structures was investigated using an instrumented drop-weight impact tower and a laser-Doppler velocimeter. The energy absorption characteristics of the sandwich structures were investigated along with the failure processes. Finally, a series of tensile tests on the damaged FMLs and thermoplastic sandwich structures showed that both systems offer promising residual load-bearing properties. Here, shear failure in the aluminum foam was observed in the sandwich structures, indicative of a strong bond between the FML skins and the aluminum core. Polym. Compos. 25:499–509, 2004. © 2004 Society of Plastics Engineers.

Three-layered sandwich plate: Exact mathematical model

Abstract: The subject of this paper is the plate composed of two relatively stiff outer layers (skins) and a more compliant inner layer (soft interlayer, called core), i.e., three-layered (sandwich) plate. This system may represent composite and laminated plates, e.g., sandwich panels and decks. This paper presents a model that describes the behavior of three-layered plate by a system of exact analytical (explicit) equations, derived from the Kirchhoff–Love plate assumptions. Accordingly, this system of equations corresponds to the Kirchhoff–Love equation of the plate. The pie-chart of research on sandwiches allots only a slight slice to analytical modeling, while it allots the largest slice to approximate prediction methods. In particular, the three-layered plate lacked the two-dimensional governing equations. Empirical or semi-empirical formulations, finite element models, a priori formulas based on simplified or rough theories may represent more accessible research topics; however, they suffer from high layer-to-interlayer stiffness ratios, which impinge on their results. Thus, these approximate prediction methods provide unsatisfactory results for the continuously increasing ratios that the industry is developing, and will be developing, to increase ever more the stiffness-to-density and strength-to-density ratios of the sandwiches. Conversely, this model, whose formulation is exact, does not suffer whatsoever from high skin-to-core elastic modulus ratios, and therefore it is specifically dedicated to modern, advanced, and innovative sandwich plates. To apply this exact model is less time consuming than to generate any finite element mesh or to apply any approximate method. Consequently, approximate methods become completely unnecessary for the three-layered plates that comply with Kirchhoff–Love plate assumptions. On the contrary, for the three-layered plates that do not comply with these assumptions, the finite element models continue to represent a viable means, provided that beforehand their reliability is checked and their free parameters are calibrated. To facilitate check and calibration, exact results from the model are provided in the paper, which finite element results can be compared to.

Analysis of large scale cladding sandwich panels composed of GFRP skins and ribs and polyurethane foam core

Abstract: This paper addresses the numerical modeling of lightweight sandwich panels intended for cladding of buildings. The proposed sandwich panels are composed of woven glass fiber reinforced polymer (GFRP) skins and ribs and soft polyurethane foam core, which provides excellent insulation. The panels are designed to resist wind loading. A robust 3D FE model was developed for the large scale panels (9145×2440×78 mm3) tested under transverse loading. The model accounts for material nonlinearities; most pronounced in the soft polyurethane core and in the [0/90] GFRP ribs under shear, as well as geometric nonlinearities in the form of a reduction in panel thickness due to the soft core. The model captures both stability and material failure modes, essentially skin wrinkling and crushing in compression. It was then successfully validated using experimental results. Failure of the tension skin never occurred in this type of panels as compression skin wrinkling and crushing consistently governed. The cladding panel was shown to satisfy design code requirements in terms of strength and stiffness.