Patterns of load, elastic energy and damage in network models of architected composite materials

TL;DR

This paper explores how architected thin films in bi-layer composites influence failure and toughness, revealing hierarchical patterns can localize failure and dissipate energy to prevent crack growth using a novel network formalism.

Contribution

It introduces a network formalism combining discrete differential geometry and spectral graph theory to analyze load redistribution and damage mechanisms in architected composite materials.

Findings

Hierarchically patterned layers localize failure and enhance interface toughness.

Graded structures do not significantly improve fracture toughness.

Elastic energy dissipation occurs through diffuse damage in buffer regions.

Abstract

We investigate the role of architected thin films in the interfacial failure properties of bi-layer composites. Our results show that, while graded structures can be used to prescribe failure at the interface, they do not offer significant advantages in terms of fracture toughness. Hierarchically patterned layers can localize failure at the interface and simultaneously enhance interface toughness, by enforcing a buffer region where elastic energy is dissipated in the form of diffuse damage, so that no stress concentration can drive crack growth. To analyze these mechanisms, the associated patterns of local load redistribution and the soft deformation modes, we develop a network formalism that brings together concepts of discrete differential geometry and spectral graph theory.