本研究係採用等應變三角形(3-CST)及四邊形四節點等數種有限元素剛性法則,在軸對稱之條件下,分析半球頭板金拉伸成形製程,以探討適用於此製程之最佳剛性法則。同時設計一組拉伸模具,在板金成形機上加以實驗以驗證理論及程式之正確性。由分析結果可瞭解穩定矩陣(SM)法則以及由四個等應變三角形(3-CST)構成的四邊形元素,在沖頭負荷與沖程關係、成品厚度分布上與實驗結果相當一致,然而在不影響計算精度之情況下,穩定矩陣(SM)法則所須之CPU時間約較等應變三角形(3-CST)節省60%的時間。同時用來處理彈塑性狀態和工具與材料界面間之接觸問題的擴張r/sub min/方法,亦證明可正確追蹤整個製程之變形履歷。 This study uses the 3-CST and four different stiffness schemes for the four-node quadrilateral element to investigate the most adequate element scheme on the axisymmetric hemispherical cup sheet stretching process. Meanwhile, a set of stretching die was designed to perform experiments in the sheet forming machine to verify the accuracy of the theory and computer code. Form the results of the FEM and experiments, the stabilization-matrices scheme and 3-CST schemes showed good agreement with the experiments, especially in the relation of punch load versus stroke, and thickness variation of the workpiece. Most of all stabilization-matrices scheme saved 60% CPU time when it compared with the 3-CST scheme. Furthermore, the technique for the extended r/sub min/ was also proved adequate to trace the whole deformation history on the sheet stretching process.
關聯:
中華民國力學學會第二十屆全國力學會議論文集(二)=Proceedings of the 20th National Conference on Theoretical and Applied Mechanics (II)，頁299-304
