Particle-induced void growth under shear loading revealed by 3D X-ray laminography and finite element modeling

We present a quantitative, multiscale, four-dimensional study of ductile damage evolution during a “tension-to-shear” load path change in a recrystallized AA2198-T851 alloy sheet. Significant strain and damage develop under tension, and their subsequent evolution under shear is quantified. Damage mechanisms are characterized using synchrotron-based in situ 3D X-ray laminography, complemented by correlative surface imaging. Mesoscale strain fields, measured via projection digital image correlation and validated through simulations, guide the selection of representative regions of interest and their boundary conditions for detailed microscale analysis within the sample bulk. Damage features are either grain-related or intermetallic particle-induced. Grain-related damage shows only moderate evolution under shear, with volume increases of a factor one and a half, whereas intermetallic particle-induced voids exhibit pronounced growth, with volume increases up to factor of six. To elucidate the underlying mechanism, experimentally observed particle–void clusters are investigated using three-dimensional finite element modeling initialized with measured boundary conditions. The simulations reproduce the strong shear-driven void growth via a void-locking mechanism associated with stiff intermetallic particles. In their absence, simulations predict a strongly reduced void growth under shear, confirming the critical role of intermetallic particles in shear-driven damage evolution.