Roughening and pinning of interface cracks in shear delamination of thin films

TL;DR

This paper studies how interface disorder causes shear cracks in thin films to become rough and pin, using analytical models validated by simulations to understand the critical crack behavior.

Contribution

It introduces a theoretical framework linking interface disorder to crack roughening and pinning, validated through simulations, advancing understanding of shear delamination.

Findings

Interface fluctuations induce self-affine roughening of cracks.

Disorder affects the pinning force and shape of critical cracks.

Analytical predictions agree with simulation results.

Abstract

We investigate the roughening of shear cracks running along the interface between a thin film and a rigid substrate. We demonstrate that short-range correlated fluctuations of the interface strength lead to self-affine roughening of the crack front as the driving force (the applied shear stress/stress intensity factor) increases towards a critical value. We investigate the disorder-induced perturbations of the crack displacement field and crack energy, and use the results to determine the crack pinning force and to assess the shape of the critical crack. The analytical arguments are validated by comparison with simulations of interface cracking.