Transonic and supershear crack propagation driven by geometric nonlinearities

TL;DR

This paper demonstrates that geometric nonlinearities in materials can enable tensile cracks to exceed the Rayleigh wave speed, leading to supershear crack propagation, challenging classical fracture mechanics predictions.

Contribution

It reveals that geometric nonlinearities are sufficient to allow cracks to propagate at supershear speeds, providing new insights into dynamic fracture behavior.

Findings

Cracks can surpass Rayleigh wave speed due to nonlinear effects

Geometric nonlinearities alter crack-tip singularity and energy flow

Supershear crack propagation observed in simulations and theory

Abstract

Linear elastic fracture mechanics theory predicts that the speed of crack growth is limited by the Rayleigh wave speed. Although many experimental observations and numerical simulations have supported this prediction, some exceptions have raised questions about its validity. The underlying reasons for these discrepancies and the precise limiting speed of dynamic cracks remain unknown. Here, we demonstrate that tensile (mode~I) cracks can exceed the Rayleigh wave speed and propagate at supershear speeds. We show that taking into account geometric non-linearities, inherent in most materials, is sufficient to enable such propagation modes. These geometric non-linearities modify the crack-tip singularity, resulting in different crack-tip opening displacements, cohesive zone behavior, and energy flows towards the crack tip.