Unified wrinkling limit diagram for sheet metals under entire in-plane stress domain

The Wrinkling Limit Diagram (WLD) is crucial for applying wrinkling instability research to engineering. However, existing WLD frameworks lack robust theoretical foundations, and their empirical construction under diverse experimental conditions compromises generality. This study introduces a novel Unified Wrinkling Limit Diagram (Uni-WLD) theory applicable to entire in-plane stress domain by establishing a coupled analytical framework integrating nonlinear elastoplastic constitutive modeling with wrinkling instability criteria to address these limitations. This study innovatively designs a Large-hole Yoshida buckling test (YBT-H) to characterize wrinkling behavior in the whole stress domain effectively and constructs a finite element model containing material anisotropy based on the Hill48 and Hill90 yield criterion. Uni-WLDs for four types of anisotropic plates, employing the principal stress ratio-principal strain ratio coordinate system, are developed through two distinct methodologies: theoretical derivation and test and simulation combination verification. Key findings include: (1) When loading along the rolling direction, the Hill90 criterion demonstrates superior performance over conventional Hill48 in reconstructing wrinkling morphology and predicting z-direction displacement; (2) Uni-WLDs constructed through different methodologies exhibit remarkable consistency, obeying an inverse function characteristic equation; (3) Principal stress ratio and principal strain ratio (K_ss) of non-wrinkling nodes evolve along the Uni-WLD trajectory, while that of wrinkled nodes deviate from the trajectory. This work advances fundamental theories in sheet metal plasticity and provides theoretical guidelines for optimizing forming process parameters under complex stress states.