Behavior of Sandwich Composites under Edgewise and Flatwise Compression; Effect of Variation of Fibre Architecture and Core Density

Abstract

The present paper is focused on the fabrication of foam–cored sandwich composites using manual hand layup technique and testing under in-plane compression. The sandwich construction comprises of polyurethane foams of five varied densities with E-glass fibre in vinylester resin as face sheets. Four different varieties of E-glass fibre are used. As compression properties are of critical importance during the design of lightweight structures, an attempt is made to study the behavior of sandwich composites under edgewise and flatwise compression modes. The tests are conducted in accordance with ASTM (American Society for Testing and Materials) standards. The experimental results showed that the core-facesheet interface plays a major role in contributing to compressive strength. Compressive strength increases with the increase in density of foam core. It is observed that woven roving (WR) and stitch bond mat (SBM) type fabric possess better strength in edgewise and flatwise compression than other fabrics. Edgewise compressive strength of sandwich composites is influenced by fibre architecture, where as flatwise compressive strength is independent of fibre architecture. The failure mode observed is facesheet wrinkling in low density sandwich composites and facesheet compression followed by core cracking in high density sandwich composites under edgewise compression. In flatwise compression, the failure mode is core crack followed by core crushing.