Hierarchical materials with enhanced fracture toughness

Jian Zhang (PhD candidate) and Alejandro M. Aragón (supervisor)

Composite materials with high fracture toughness have been widely explored in aerospace and automotive industries. While the performance of these composites greatly depends on constituent properties, the volume and distribution of constituents also have a significant effect on composite behaviour. Instead of changing composition, we aim to explore the optimal material layout to design a composite with enhanced fracture toughness.

First, the Discontinuity-Enriched Finite Element Method (DE-FEM), which was proposed for analysing 2-D problems in elastostatics, is extended to handle 3-D problems containing weak and strong discontinuities. A robust geometric engine that handles the interactions between the background (original) mesh and material interfaces and/or cracks is essential. Once this engine is in place, we will use topology optimization to find a composite material micro-structural design with enhanced fracture toughness in the context of linear elastic fracture mechanics. The topology optimization approach in this work uses a level set to represent topology and the Interface-enriched generalized FEM (IGFEM) to obtain the structural response. This methodology was recently proposed to solve compliance minimization problems. Once optimum material layouts are obtained, they will be validated through fracture experiments