ارزيابي معيار آسيب ويرزبيكي در فرآيندهاي شكل‌دهي ورق‌هاي فلزي به روش اجزاء محدود

eva‎luation of Wierzbicki Damage Criterion of Sheet Metal Forming by Finite Elements

مهندسي مكانيك

In recent decades, significant research has been conducted on ductile damage and fracture. This topic has gained attention due to its potential to reduce production and maintenance costs by improving the understanding of ductile failure, which necessitates overcoming traditional approaches. The introduction of new materials or technologies in the market also requires novel strategies for modeling material behavior. Damage mechanics, as a branch of fracture mechanics, focuses on studying defect growth and its impact on material strength. Simulating damage growth and predicting failure locations are among the key objectives in metal forming processes. Bai-Wierzbicki proposed a new concept of damage for ductile metals by considering the effects of hydrostatic pressure and deviatoric stress invariants, in contrast to classical theories. The Bai-Wierzbicki damage model is a robust tool for predicting failure in ductile metals due to its ability to cover a wide range of triaxiality stresses. Using governing equations, a subroutine was developed in VUMAT for 3D simulations and extended to 2D (plane stress) cases. To validate the developed 3D subroutine, several models made of aluminum 2024-T351 and two tensile sheet specimens of aluminum 2024-T351 and DP600 steel were tested. The plane stress results for both sheets showed excellent agreement with the 3D simulations. After verifying the subroutine, the Bai-Wierzbicki damage parameters were extracted for SS-304 steel in the plane stress condition. Finally, numerical simulations of the Erichsen test were performed to eva‎luate the damage model in sheet metal forming processes, and the results were compared with experimental data, demonstrating the effectiveness of this criterion in metal sheet forming applications.

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