Open-Source Implementation of Classical and Micromorphic Phase-Field Fracture Models in Code_Aster

Abstract

Phase-field fracture provides a flexible framework for simulating complex crack processes, but implementations in open-source finite element solvers with structural-analysis capabilities remain limited. This technical note presents an implementation of phase-field fracture models in Code_Aster, with the aim of documenting how established formulations can be realised within its existing solver architecture without modifying the source code. Two complementary strategies are developed. Classical AT1 and AT2 models are implemented through a heat-transfer analogy and solved using a staggered coupling scheme with a bound-constrained phase-field solver. A micromorphic formulation is implemented using an existing gradient-enhanced internal-variable framework, enabling phase-field cohesive-zone models through constitutive behaviours written in MFront. Two benchmark problems are used to verify the implementations against FEniCSx reference solutions. Close agreement is obtained in both force-displacement response and crack path, demonstrating that the considered phase-field fracture models can be implemented consistently in Code_Aster. This provides a reproducible basis for phase-field fracture simulations in Code_Aster as an open-source structural-mechanics environment.