Design bio-inspired composite structure subjected to blast loading

Abstract

This paper investigates the behaviour of a bio-inspired finite element composite model (that mimics the structure of nacre, the inner layer of molluscan shells) under blast loading. Nacre, which has attracted the attention of researchers over the past few decades, comprises 95% aragonite, brittle voronoi-like polygonal tablets that are joined by an organic matrix and arranged in a brick and mortar type structure. The best attempt made thus far in mimicking such complex geometry involved rebuilding the tablet contours via optical imaging. This method, which practically copies the nacreous structure, offers no control over the geometry, making it difficult, if not impossible to eventually develop composites that mimic nacre. To this end, the finite element model developed herein was constructed using voronoi diagrams and geometric algorithms capable of automatically generating staggered layers of voronoi-like aluminium tablets bonded together by a vinylester adhesive layer. Many studies have led to the belief that the magnificent toughness of nacre is mainly attributed to the inter-platelet adhesive bonds. Results obtained from the finite element analysis show that this is indeed true, and it is imperative that the adhesive bond exhibits adequate toughness in order to be able to spread damage across the entire composite, thereby delaying localised failure. KEYWORDSNacre, composite panel, blast loading, voronoi structure, bio-inspired structure.