Session: 03-05-01: Bioinspired materials

Paper Number: 158483

158483 - How Crack Twisting in Bouligand Structures Lead to Damage Delocalization and Toughening 

Fiber-reinforced composites with Bouligand structures exhibit exceptional mechanical properties due to their intricate and hierarchically organized fiber arrangements. These biomimetic architectures, inspired by natural systems such as the mantis shrimp’s dactyl club, are renowned for their outstanding resistance to fracture. In this study, we introduce an advanced coarse-graining (CG) model meticulously designed to capture the complex behavior of Bouligand structures. The model incorporates bonded interactions that simulate fiber cohesion and a double-well potential to represent the nuanced non-bonded interactions within the composite matrix. This innovative framework enables a comprehensive examination of the fracture mechanics specific to these structures, with a focus on the formation and propagation of helicoidal cracks.

The study’s central hypothesis posits that helicoidal cracks, aligned with the fiber orientation, act as precursors to localized hardening mechanisms. These mechanisms hinder the propagation of individual cracks while promoting the nucleation and simultaneous growth of multiple cracks. This behavior facilitates a delocalization effect, where damage is distributed across a larger material volume. Through extensive computational simulations and rigorous analyses, our findings validate this hypothesis. Twisting cracks trigger localized hardening, effectively redistributing mechanical stresses and enhancing the material’s energy dissipation capacity. This delocalization phenomenon mitigates damage concentration, significantly increasing the toughness and durability of the structure.

These findings offer valuable insights into the fracture behavior and mechanical resilience of Bouligand structures. Additionally, the CG model demonstrates its efficacy as a powerful and efficient tool for exploring the fracture mechanics of complex fiber-reinforced composites. By simulating and analyzing helicoidal crack behavior, this research aligns with several focal areas within SSDM’s Materials Track, such as Damage and Fracture, Bioinspired Materials, and Micromechanics and Multiscale Modeling. It paves the way for the development of next-generation materials with improved toughness and damage resistance.

Presenting Author: Alvaro Garnica Kairos Power

Presenting Author Biography: Alvaro holds a PhD and MS degree in Civil Engineering from Purdue University and University of Illinois Urbana-Champaign, respectively. Since he has joined Kairos Power in Spring 2023 as a FEA Engineer, Alvaro has been applying his Computational Fracture Mechanics background to graphite core components of Kairos Power Fluoride salt-cooled, High temperature demonstration Reactor (KP-FHR), called Hermes.