Crack deflection in liquid crystal elastomers determined by energy release rate maximization: Experiments and simulations

This study investigates crack deflection in monodomain liquid crystal elastomers (LCEs) using a combined experimental and numerical approach. Fracture tests were performed on pure shear specimens with various initial mesogen orientations. Despite the pronounced anisotropy in stress–stretch behavior when mesogens are aligned parallel or perpendicular to the loading direction, the measured fracture toughness exhibits only a moderate dependence on orientation. Crack deflection was also characterized experimentally, revealing the influence of mesogen alignment on crack path deviation. To interpret the experimental observations, a finite element model incorporating the anisotropic constitutive behavior and mesogen reorientation of LCEs was developed to compute the energy release rate in cracked specimens. The model successfully predicted crack deflection by assuming propagation along the path of maximum energy release rate. These results provide critical insights into the fracture behavior of LCEs and offer guidance for the design of more robust LCE-based structures for diverse applications.