# Revisiting the problem of a crack impinging on an interface: a modeling framework for the interaction between the phase field approach for brittle fracture and the interface cohesive zone model

## TL;DR

This paper introduces a combined phase field and cohesive zone model to study crack interaction with interfaces, revealing complex phenomena like simultaneous penetration and deflection, and transitions influenced by model parameters.

## Contribution

A novel integrated modeling framework that couples phase field brittle fracture with cohesive zone interface modeling, providing new insights into crack-interface interactions.

## Key findings

- The model captures classical fracture mechanics criteria for crack behavior.
- Increasing process zone size leads to complex crack phenomena.
- Parameter variations induce transitions between crack penetration and deflection.

## Abstract

The problem of a crack impinging on an interface has been thoroughly investigated in the last three decades due to its important role in the mechanics and physics of solids. In this investigation, this problem is revisited in view of the recent progresses on the phase field approach to brittle fracture. In this concern, a novel formulation combining the phase field approach for modeling brittle fracture in the bulk and a cohesive zone model for pre-existing adhesive interfaces is herein proposed to investigate the competition between crack penetration and deflection at an interface. The model, implemented within the finite element method framework using a monolithic fully implicit solution strategy, is applied to provide a further insight into the understanding of the role of model parameters on the above competition. In particular, in this study, the role of the fracture toughness ratio between the interface and the adjoining bulks and the characteristic fracture-length scales of the dissipative models are analyzed. In the case of a brittle interface, the asymptotic predictions based on linear elastic fracture mechanics criteria for crack penetration, single deflection or double deflection are fully captured by the present method. Moreover, by increasing the size of the process zone along the interface, or by varying the internal length scale of the phase field model, new complex phenomena are emerging, such as simultaneous crack penetration and deflection and the transition from single crack penetration to deflection and penetration with subsequent branching into the bulk.