Unfolding the role of topology-driven toughening mechanisms in nacre-like composite design through XFEM

Biological materials have evolved through thousands of years, adapting, morphing, and optimizing to their particular function. One of the many natural materials that are widely studied is nacre, an elegant merge of stiff (mineral) and soft (biopolymer) components with extremely high mechanical properties, which are highly desired for structural applications. Naturally, nacre has been a source of inspiration for developing artificial composites with different levels of intrinsic designs. Some of these designs exploit the microstructures of the materials, such as the connection between the composite stiffer parts, known as mineral bridges. To develop an eXtended Finite Element Method (XFEM)-based model of a biphasic composite inspired by the nacreous brick-and-mortar morphology, initially, we evaluate the use of XFEM on single materials models, including a hyperelastic material. Then, simulation of complex bioinspired materials shows that structures mimicking mineral bridges considerably improve composites' mechanical properties such as strength and toughness. The influence of the biomimetic mineral volume fraction on the overall toughening mechanisms, particularly crack arresting, is demonstrated. Our results provide a numerical approach to simulating biphasic materials with hyperelastic components and contrasting material properties (e.g., stiff and ductile) that have potential applications in complex composite structural designs.