限定型高压扭转变形分析

Deformation analysis of copper samples subjected to destined high pressure torsion

利用量纲分析研究限定型高压扭转(HPT)变形的相关因素,在此基础上用有限元分析不同侧边摩擦条件和不同径厚比和不同侧面摩擦约束大小对纯铜试样角位移场的特点,讨论理想高压扭转公式适用的范围。量纲分析揭示,试样上变形与几何位置、径厚比、施加压力、材料弹性参数以及模具侧面的摩擦状况相关。有限元分析结果表明,可用幂函数形式的角位移约束来简化侧面摩擦,当幂指数不小于8时,试样上非HPT变形区域大小趋于稳定;当径厚比不小于5时,试样中心存在一个可用纯扭转变形描述的区域,非理想HPT区域大小不超过试样厚度尺寸;当径厚比不大于2时,试样上不存在理想HPT区域。

Dimensional analysis was employed to analyze the factors related to the deformation characteristic due to destined high pressure torsion （HPT）. And finite element method was applied to calculate angular displacements of copper specimens with different states of side surface friction and different values of diameter-thickness ratio. Then the validity range of the expression for ideal HPT was discussed. Dimensional analysis shows that the shear deformation is correlated with its position, diameter-thickness ratio applied pressure, elastic modulus, Poisson＇s ratio, and side friction condition with apparatus. FEM results reveal that angular displacement by power function can he used to describe friction constraint on side faces, and zone of no ideal HPT tend to stable when exponent is not less than 8. When diameter-thickness ratio is not less than 5, an ideal HPT region on center of copper specimens exists, and no ideal HPT region size is less than its thickness on samples margin. While diameter-thickness ratio is not greater than 2, no ideal HPT deformation region exists.