Finite element method is widely used to simulate bulk metal forming processes in recent years . though finite element method is maturing in the simulation of metal forming processes , it has been a difficulty to deal with frictional conditions at the tool - workpiece interface . the frictional condition is usually simplified according to reality 近年来采用有限元技术对金属体积成形过程进行数值模拟得到了广泛的应用,但在用有限元模拟金属体积成形过程时,工件与模具摩擦边界条件的处理,一直被认为是一个难点,常常是通过一系列简化来处理,常用的方法有常摩擦模型和反正切摩擦模型。
Now autosomal and y - chromosomal strs are widely researched and applied , while the x - str markers are not . because x chromosome has the character that the male transmits his x chromosome only to his daughter ( s ) , it can provide more information than the autosomal does , particularly in complex cases of kinship testing 而在解决一些复杂的亲缘关系案件(如单亲父女关系的鉴定和缺乏双亲的姐妹亲缘关系的鉴定)时,由于父亲的x染色体具有只传给他的女儿(们)的遗传特性,因此在解决此类案件时有常染色体所无法比拟的优点。
