Fracture toughness in thin metallic sheets is strongly thickness dependent which is not yet fully explored, while the coupled roles of strain hardening, plastic anisotropy, and stress state remain also important. In this study, fracture toughness of thin metallic sheets is investigated through a combination of targeted experiments and micromechanics based simulations to map thickness effects and the conditions that modulate them. Double edge notched tension (DENT) specimens spanning 0.5 to10 mm are fatigue precracked and tested; crack-tip opening displacement (CTOD) and J are extracted as indicators of fracture toughness, and a systematic increase in fracture toughness with decreasing thickness is revealed. Modeling is conducted in two stages: (i) J2 elastoplastic analyses are employed to isolate strain hardening contributions without crack growth; and (ii) a GTN–Thomason framework, augmented with Hill48 anisotropy and a physically motivated hardening law (Kocks Mecking), is used to capture void growth, and coalescence. The combined findings quantify how anisotropy and hardening capacity jointly govern resistance, and actionable guidance is provided for heat treatment strategies and processing routes aimed at tuning hardening and maximizing damage tolerance in advanced aluminum sheets.
Javangorouh et al. (2025) studied this question.