Load bearing capacity of thin shell structures made of elastoplastic material by direct methods

A method is introduced to determine the limit load of thin shells using the finite element method. The method is based on an upper bound limit and shakedown analysis with the elastic-perfectly plastic material model. A nonlinear constrained optimisation problem is solved by using Newton’s method in conjunction with a penalty method and the Lagrange dual method. The numerical investigation of a pipe bend subjected to bending moments proves the effectiveness of the algorith