유한요소법을 이용한 다단인발과 냉간전방압출 시 발생하는 중심파괴 현상에 관한 비교 연구

In this paper, central bursting defects occurring in multi-pass drawing and cold forward extrusion are investigated by finite element method and the distinctive characteristics are revealed. The previous experimental researches are examined and discussed to figure out the shape of the central bursting defects in the qualitative manner. An elasto-plastic finite element method is employed for this study, which supplies the crack prediction algorithm based on element removal scheme after separating or cracking the damaged neighboring elements along the element boundary. The comparative study shows that the shape of the typical chevron crack (i.e., an obtuse V-shape defect) occurs in cold extrusion while the U-shape central bursting defect that is hard to be called chevron crack occurs in multi-pass drawing, which is in good agreement with the experimental evidences found in the literatures.