Method for calculating forming limits during expansion of a pipe blank taking into account nonlinear plasticity

A method for determining the limiting expansion coefficient of cylindrical pipes using conical equipment is considered which allows a fairly accurate calculation of the moment of fracture of a workpiece taking into account the nonlinear plasticity of the material and the change in thickness. The method is based on the use of forming limit diagrams to predict the fracture of the workpiece and the method of variable elasticity parameters to determine the stress-strain state.