Phase-field study of crack behaviors in nacre-like materials

Hua-Chuan Tsai^1*, Chih-Hung Chen¹, Yi-Chung Shu¹

¹Institute of Applied Mechanics, National Taiwan University, Taipei, Taiwan

* Presenter:Hua-Chuan Tsai, email:r07543095@ntu.edu.tw

It is known that biological materials such as nacres, bones, and teeth exhibit excellent mechanical toughness and strength. Experimental studies found these materials share similar hierarchical arrangement that stiff blocks are embedded in a soft matrix. The arrangement of microstructural is considered to greatly affect the mechanical properties. Although extensive studies have been done attempting to understand the toughening of the nacre-like materials, the underlying mechanisms associated with crack behaviors are not fully clear yet.

This study proposes a phase-field method for modeling the crack propagation inside nacre-like materials made of two different materials. We investigated the behavior of crack for a range of structural parameters relevant to nacres, including the aspect ratio, volume fraction of mineral, elastic modulus mismatch and fracture resistance mismatch. Then we obtained a phase diagram summarizing four different modes of crack growth: straight crack, interface crack, branching, and crack arrest. Our results clarify the relation between the complex hierarchical microstructure and the toughening mechanisms, such as crack bridging, microcracking and tablet sliding.

Keywords: phase-field method, nacre-like materials, cracks behaviors, elastic mismatch, hierarchical structure