A formulation is presented for the static and transient analysis of sheet metal structures involving very large displacements and rotations and elastoplastic material behavior. The geometrical nonlinearity can be treated by the decomposition of the element displacements into rigid body and deformation displacements. The elastoplastic formulation is based on the Mises yield criterion with isotropic strain hardening. The equations of motion are integrated by either the explicit or implicit schemes. Elements employed include the spring, three-dimensional beam, and plate element. Internal force or moment releases and rigid links are provided for beams.