Applications of phase field fracture in modelling hydrogen assisted failures

TL;DR

This paper demonstrates the use of phase field fracture models to simulate hydrogen embrittlement and stress corrosion cracking, enabling realistic predictions of defect evolution and failure in engineering components.

Contribution

It introduces a coupled multi-physics phase field model for hydrogen-assisted fracture, including inertia effects and various constitutive choices, with implementation in 2D and 3D.

Findings

Captures complex fracture phenomena like crack branching and void interactions.

Simulates standard tests for critical components such as bolts.

Enables realistic structural integrity assessments through defect geometry modeling.

Abstract

The phase field fracture method has emerged as a promising computational tool for modelling a variety of problems including, since recently, hydrogen embrittlement and stress corrosion cracking. In this work, we demonstrate the potential of phase field-based multi-physics models in transforming the engineering assessment and design of structural components in hydrogen-containing environments. First, we present a theoretical and numerical framework coupling deformation, diffusion and fracture, which accounts for inertia effects.Several constitutive choices are considered for the crack density function, including choices with and without an elastic phase in the damage response. The material toughness is defined as a function of the hydrogen content using an atomistically-informed hydrogen degradation law. The model is numerically implemented in 2D and 3D using the finite element method. The resulting computational framework is used to address a number of case studies of particular engineering interest. These are intended to showcase the model capabilities in: (i) capturing complex fracture phenomena, such as dynamic crack branching or void-crack interactions, (ii) simulating standardised tests for critical components, such as bolts, and (iii) enabling simulation-based paradigms such as Virtual Testing or Digital Twins by coupling model predictions with inspection data of large-scale engineering components. The evolution of defects under in-service conditions can be predicted, up to the ultimate failure. By reproducing the precise geometry of the defects, as opposed to re-characterising them as sharp cracks, phase field modelling enables more realistic and effective structural integrity assessments.