The atan ( ) function returns the arctangent of a number as a numeric value between-pi / 2 and pi / 2 radians 函数的作用是:返回一个指定数值参数的反正切值。
Friction models normally applied in finite element analyses for bulk metal forming are the constant friction model and arctangent friction model . however frictional conditions are often variational in realistic metal forming processes 而在实际成形过程中,摩擦的状态是不断变化的,因此,摩擦问题是影响有限元分析精度的一个重要因素。