Three-dimensional Voronoi model of a nacre-mimetic composite structure under impulsive loading

Nacre, the inner layer of mollusk shells holds the key to the development of an effective composite system for protecting structures from extreme loads due to its superior fracture toughness, despite its brittle constituents. It is known that the hard mineral tablets provide structural rigidity, while the soft organic polymer matrix provides the mechanisms to mitigate damages and dissipate energy uniformly across the structure. Nacre's composite structure is arranged to have multiple laminates and three dimensional polygonal tablets bonded with organic adhesives to maximize its load sharing capability. This paper presents a novel 3D Voronoi model of an Aluminum/Vinylester composite structure that closely mimics multilayer nacre's tablet. Vinylester cohesive and adhesive layers are introduced between nacre-mimetic polygonal Aluminum tablets and layers, respectively, to simulate the bonding and delamination process. The performances of nacre-like composite structures under blast loading are evaluated in terms of maximum deformation, damage distributions as well as dissipated energy. The influences of size and shape of the nacre-mimetic tablets, as well as the number of composite laminates on the blast resistance of the composite are also investigated. Results reveal the importance of tablet size and number of laminates as opposed to the insignificant influences of tablet overlapping.