本研究採用Prandtl-Reuss塑流法則和von Mises的降伏條件，結合有限變形理論及Updated Lagrangian Formulation (ULF)的觀念建立一增量型彈塑性大變形有限元素分析模式，再應用退化殼元素所推導之形狀函數偶合入剛性矩陣中，組成有限元素之分析模式，並以此程式模擬孔凸緣成形之製程。本研究將模擬圓柱形與半球形沖頭孔凸緣成形的沖頭負荷與衝程之關係、料片厚度分佈、擴孔半徑與卸載後板片之最終變形，而模擬之沖頭負荷及厚度分佈與實驗結果有良好的一致性，故本彈塑性大變形有限元素分析程式可合理的模擬金屬板材孔凸緣成形之製程。 A methodology for formulating an elasto-plastic finite element model, which is based on an Updated Lagrangian Formulation (ULF), Prandtl-Reuss flow rule, and von Mises yield criterion is developed. The shape function derived from degenerated shell element is associated into the stiffness matrix to constitute the finite element model, which is used to simulate the hole-flanging process. The study discussed the simulation on relationship between the punch load and punch displacement, the variation of sheet thickness, the radius of hole expansion, and the final shape of the workpiece after unloading in the hole-flanging process of cylindrical and hemispherical punches. It shows good agreement between the simulated results and experiment outcomes. Therefore, the elasto-plastic large deformation finite element program can reasonably simulate the hole-flanging process.
關聯:
中華民國力學學會90年度年會暨第25屆全國力學會議=Proceedings of 25 National Conference of Theoretical and Applied Mechanics，12頁
