Analys is on the Geometric Unlinear Finite Element of Sheet Metal

In drawing up the large-sized calculation program of sheet metal, the basic theory of unlinear has been analysed by the tensor theory based on minimum potential energy principle. During the formation of rigidity matrix, it is necessary to avoid the direct alternative of unlinear and those strees and deformation that are not easy to get in the increment of liner pattern in order to derive the rigidity matrix directly.