[[alternative]]Study of Thickness and Grain Size Effects on Cylindrical Micro Cup Drawing

[[abstract]]在金屬成形中，縮小料片尺寸越來越受到重視，為了尋求最適化的加工方式，需廣泛應用有限元素法來分析模擬，由於傳統的應力應變曲線構成式只適合大面積與較厚的料片，不足描述微小料片厚度及晶粒尺寸影響效應，因此發展一個有效率且實際可行的數學模型是有必要的。本文首先利用Nelder-Mead最小值搜尋法獲得含有料片厚度及晶粒尺寸參數之應力應變構成式，可透過此單一構成式即能準確描述不同料片厚度及晶粒大小之應力應變曲線。其次透過FEM 模擬微小圓杯引伸成形，探討料片微小化後之厚度及晶粒尺寸大小對成形的影響，模擬結果顯示，成形後之厚度變化與應力分佈情形皆能合理呈現，故本研究成果可提供微成形相關研究之參考。[[abstract]]It is more and more important to reduce blank size in metal forming. In order to find optimal forming process, finite element analysis is broadly used for simulation in forming process. The traditional stress-strain curve formulation is only suited to large and thick blanks. It is not enough to described the effects of thickness and grain size to micro blanks. It is necessary to develop an effective and practicable mathematical model. At first, this paper obtains a new stress-strain formulation including the parameters of the thickness and grain size by Nelder-Mead method. This curve equation can describe the material behavior of any thickness and any grain size. Next, the cylindrical micro cup drawing is analyzed by dynamic finite element method. The results show that thickness variety and stress distribution are reasonable after FEM simulation. The paper can be reference to the relative research in micro forming.[[sponsorship]]中華民國力學學會[[conferencetype]]國內[[conferencedate]]20061215~20061216[[conferencelocation]]臺北市, 臺