Analysis of wrinkling in deep drawing processes

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2019
Dal, Saniye Rabia
Wrinkling, observed due to compressive instability, is one of the main failure modes in deep drawing processes. The prediction and prevention of wrinkles are critical for production of stamping parts which require good surface quality. In the current work, the occurrence of wrinkling in square and cylindrical cup deep drawing processes are investigated considering various constitutive models; formed by using CPB06ex2, Hill’48, BBC2008-8p, BBC2008-16p, and von Mises yield criterion with isotropic, kinematic and combined hardening. Numerical simulations were performed by implementing CPB06ex2, BBC2008-8p and BBC2008-16p models to a commercial finite element code through user subroutines. In the simulations, AA5042-H2 aluminum alloy with 1 mm thickness were employed. First a comparison is made between the predictions of the constitutive models and the experimental results of the previous works to evaluate the accuracy of the developed models. It was found that the predictions of all constitutive models for the number of wrinkles are in good agreement with experimental data. The CPB06ex2 model gives closer numerical results with experiments for the wrinkling profile and the punch force evolution comparing to the other models. Moreover, square cup drawing process needs higher blank holding forces to prevent wrinkling than cylindrical cup drawing at the same punch travel.