Tuning load redistribution and damage near heterogeneous interfaces

TL;DR

This paper explores how heterogeneous interfaces in model materials influence failure modes, revealing that microstructure design can control crack propagation without sacrificing strength.

Contribution

It introduces a theory of network Green's functions to explain how hierarchical microstructures confine failure and alter crack surface correlations.

Findings

Hierarchical microstructures confine failure near a surface.

Failure mode is controlled by local anisotropy of elastic interactions.

Strength and work of failure are unaffected by microstructure design.

Abstract

We investigate interface failure of model materials representing architected thin films in contact with heterogeneous substrates. We find that, while systems with statistically isotropic distributions of impurities derive their fracture strength from the ability to develop rough detachment fronts, materials with hierarchical microstructures confine failure near a prescribed surface, where crack growth is arrested and crack surface correlations are suppressed. We develop a theory of network Green's functions for the systems at hand, and we find that the ability of hierarchical microstructures to control failure mode and locations comes at no performance cost in terms of peak stress and specific work of failure and derives from the quenched local anistotropy of the elastic interaction kernel.