Crystal plasticity finite element simulation: Factor dominance and micromechanical analysis of void evolution under uniaxial tension

Void evolution is the microscopic process governing ductile fracture in metallic sheets, yet the relative dominance of the multiple microstructural and geometric factors that regulate it remains unclear. In this study, a crystal plasticity finite element (CPFE) model embedded with elliptical voids is constructed for 2219 aerospace aluminum alloy based on real electron backscatter diffraction (EBSD) microstructures. Five factors: grain size, grain orientation, initial void size, void aspect ratio λ = b/a, and void azimuth angle β are systematically examined under uniaxial tension. To rank their dominance objectively, a maximum deviation metric δmax,i(X)=(Xmax,i−Xmin,i)×100% is defined for each void evolution indicator X ∈ {f/f0, a/a0, b/b0, (b/a)/(b0/a0)}. The results show that β and λ are the two dominant factors: at a macroscopic strain ε = 8%, β yields δmax = 34% for f/f0 and 91% for the aspect-ratio indicator (b/a)/(b0/a0), while λ yields 21% for f/f0; grain size, void size and texture produce δmax for all indicators below 16%. Because a multiplicative correction F(λ)·g(β) cannot capture the λ-β coupling, an equivalent aspect ratio λeq(λ,β)=λ2cos2β+sin2βλ2sin2β+cos2β is derived through an equal moment of inertia mapping, and a modified Rice-Tracey growth law V˙V=C·exp(D·η)·F(λ‾)·ε‾˙ is established with C = 2.03 and D = 1.5. Validated against CPFE simulations and 100× scaled uniaxial tensile experiments, the model predicts f with a maximum deviation of 8.8% and b/a with 13.7%. Micromechanical analysis reveals that β and λ govern void growth by reconstructing the local hydrostatic stress triaxiality field and altering the Schmid-factor distribution and slip-system activation around the void. The findings provide a quantitative basis for multi-factor damage assessment and an efficient analytical model for ductile fracture prediction in aluminum alloy sheets.