Flexural Analysis of Balsa Core Sandwich Composite

A comprehensive investigation was undertaken to study failure mechanisms of sandwich composites and their influence on flexural behavior. Sandwich composite panels were cured from compression thermoforming of E-glass/epoxy skin and low density balsa wood core. Balsa core grain orientation is found to have major effect on flexural response and failure modes. Flexural behavior, failure mode and its sequence varies with different core grain orientations. Indentation, skin failure, core shear failure were dominant failure modes observed for various cases. Indentation of skin is a major concern under localized loading, as the skin failure is premature as compared to its normal compressive strength. Hence, the effect of padding on sandwich beam with soft core was also completed as part of this work. Finite element analysis for modeling this type of sandwich composite beam is studied and correlated. Several material parameters required for finite element analysis were determined from extensive testing and data from literature. Composite failure model and wood material model available in LS-Dyna were applied for skin and core of sandwich beam and analyzed under three-point flexural tests.