Ductile fracture has been studied over the years at different scales. For metallic materials, ductile damage results from nucleation, growth and coalescence of microvoids at the micro-scale. At the macro scale, these mechanisms induce a progressive degradation of the material’s mechanical properties, finally leading to fracture. Many theoretical models and numerical approaches have been presented to study ductile fracture phenomena at both scales. However, due to the complexity of these phenomena, many theoretical and numerical issues remain to be addressed.

This symposium aims to take a step forward in comprehending the physical mechanisms of ductile damage under complex loading paths and discussing the computational challenges associated with ductile damage modelling, both at the micro and macro scales. 

Special attention will be paid to:

• Ductile fracture micromechanisms: Recent advances in experimental observations have improved our understanding of ductile damage micro-mechanisms under different loading conditions. Based on these observations, new models are defined to simulate the stages of nucleation, growth and coalescence of microvoids. Challenges remain in the numerical model representation of microstructures, including grains and particles and their behaviour/evolution for large plastic strain applications or thermomechanical loading conditions.
• Influence of stress triaxiality ratio and Lode angle parameter on ductile fracture: It has been shown that simplistic representations of damage growth at the macro scale are not always accurate when dealing with complex loading conditions. The influence of stress triaxiality ratio and Lode angle on damage nucleation, growth, and coalescence needs further study.
• Analysis and modelling of damage to fracture transition: The transition from continuous damage mechanics to discrete fracture mechanics is still an issue regarding physical modelling and numerical representation of fracture initiation and propagation. Numerical solution strategies for continuous/discontinuous transition, phase–field methods, XFEM, and GFEM-type approaches still have a significant ground to evolve in the application to ductile fracture modelling.
• Regularization techniques to deal with ductile damage localization issues: Coupled damage models give rise to softening mechanical behaviour at the macroscopic scale. From a numerical point of view, this softening can induce spurious numerical dependencies such as damage localization or mesh sensitivity. Many different non-local approaches, such as those derived from nonlocal continua or micromorphic theories, have been proposed to circumvent these pathologic aspects. Typically, those approaches require length scale parameters whose physical meaning and theoretical justification are not always straightforward. Advances in these aspects and thorough research and discussion of their evidence are still required.
• Methods based on Data Science: Data-driven methods based on machine learning models, departing mainly from experimental data, are giving new approaches to characterise ductile fracture behaviour at different scales, allowing for better model parameter identification, a better understanding of void and crack evolution aspects, unveiling patterns that deepen our knowledge of this phenomenon and the improvement of existing models.