Theoretical Analysis and Finite Element Simulation of Autofrettage for Extrusion Die

The design of extrusion die has been investigated by autofrettage technique considering the characteristics of the extrusion die. Ideal elastoplastic autofrettage model was established and the stress formulae of three loading procedures were derived and the theoretical calculation method of the maximum autofrettage pressure and working load was put forward. The simulations of stress distribution and the inwall displacement of the autofrettaged extrusion die were performed using MARC finite element software, and the results coincided well with the theoretical derivations. It was observed that the autofrettaged extrusion die can raise the elastic loading capacity under the inner displacement limit, without the appearance of reverse yielding and reyielding under the working load. The results show that the autofrettage technique is appropriate for the design of extrusion die.