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COMPUTER AIDED MODELING OF WRINKLING AND ITS PREVENTION PiSKiN, Mehmet Ali M.S., Department of Mechanical Engineering Supervisor: Prof. Dr. Bilgin KAFTANOgLU September 2005, 111 Pages Deep-drawing operations are performed widely in industrial applications. It is very important for efficiency to achieve parts with no defects. Wrinkling is a kind of defect caused by stresses in the flange part of the blank during metal forming operations. It is required that the flange of a workpiece in deep drawing operation should deform in its plane without wrinkling otherwise it will impair the quality of the product. To avoid wrinkling appropriate blank-holder force or drawbead can be applied. In this work, finite element method is used to obtain the wrinkling behavior. A four nodded five degree of freedom shell element is formulated. Isotropic elasto-plastic material model with Von Mises yield criterion is used. By using this shell element, the developed code can predict the bending behavior of workpiece besides membrane behavior. Simulations are carried out with four different element sizes and two different shapes (circular and rectangular). The thickness strain and nodal displacement values obtained are compared with results of a commercial finite element program and results of previously conducted experiments.