Coupled Large Deformation Phase-Field and Cohesive Zone Model for Crack Propagation in Hard-Soft Multi-Materials

Abstract

This work presents a unified large deformation constitutive framework that couples the phase-field approach for bulk fracture with the potential-based Park-Paulino-Roesler cohesive zone model (PPR CZM) to study crack propagation in hard-hard and hard-soft multi-materials with weak interfaces. The phase-field component is aimed at capturing crack initiation and propagation within the bulk constituents, whereas the PPR CZM is intended for capturing failure mechanisms at interface regions. The proposed unified framework is implemented via a user-element subroutine (UEL) within the finite element software Abaqus, and incorporates a large-deformation extension of the PPR CZM. The coupled nature of the framework allows for accurate capturing of the theoretically expected fracture phenomena (deflection vs. penetration) in hard-hard brittle layered materials (with dissimilar properties) containing weak interfaces in accordance with the LEFM. Furthermore, the framework provides a numerical tool for probing the underlying toughening mechanisms in hard-soft tri-layer multi-material assemblies relative to their monolithic counterparts. Results demonstrate that the proposed framework is successful in capturing both (i) crack deflection and crack penetration in hard-hard bi-layer assemblies, and (ii) crack bridging by the soft layer in hard-soft tri-layer assemblies as an emerging toughening mechanism characterized by a post-peak hardening in the force-displacement response. The framework can be used to inform the design of similar/dissimilar hard-hard brittle materials (e.g., layered materials) and hard-soft architected composites.

Keywords: Phase-field, Cohesive Zone Model, Large deformation, LEFM theory, Fracture, Finite-element