本文採用動顯函有限元素法，發展增量型彈塑性大變形三維動顯函有限元素分析程式，模擬方孔凸緣之製程，並設計一組方型模具加以實驗。經數值分析得到方孔凸緣成形之變形歷程、厚度分佈，及沖頭負荷和衝程之關係，再和實驗結果比較得知，擴孔成形後，工件沿沖頭角隅相接觸之區域，因承受極大之拉伸應力，造成擴孔周緣之厚度明顯變薄，而厚度最小值和破裂處皆發生在工件與沖頭角隅所接觸之區域。由於執行動態程式並沒有Newton-Raphson的疊代收斂之問題，和執行靜態程式相比下，可大幅縮短求解時間，顯示動顯函有限元素法有其應用優勢。 The objective of this study was to analyze the square hole-flanging process of sheet metal by using the 3-D dynamic explicit finite element program based on elasto-plastic large deformation. A set of tools is designed for experiments to verify the reliability of the program. Simulation results include the deformation history, the distribution of the workpiece thickness, and the relationship between punch load and punch stroke. According to the simulation and experiment results, the minimum thickness and the fracture site occurred at the contact regions between workpiece and punch corners. After comparison the execution time of the dynamic and static program, we found that executing the static program would spend much more time than the dynamic program, so the dynamic explicit program will be useful in the application of sheet-metal forming process.
