Strengthening and design of the linear hardening thick-walled cylinders using the new method of rotational autofrettage

Abstract

The new approach introduced for the autofrettage called the rotational autofrettage is applied here for thick-walled cylinders made of materials with linear strain hardening behavior. The concept of the rotational autofrettage originates from the fact that large enough angular velocity in a thick-walled cylinder causes beneficial residual stress which is the prerequisite of the autofrettage process. For this purpose, elasto-plastic stress distribution in a rotating thick-walled cylinder are obtained analytically for both loading and unloading phases using Tresca's yield criterion and considering the bauschinger effect. In the following, the residual stress distribution are obtained to determine the best level of autofrettage for strengthening and design of thick-walled cylinder prior to industrial use with the aim of increasing strength-to-weight ratio. It is concluded that rotational autofrettage causes better results in comparison with the conventional method, pressure autofrettage. Moreover, rotational autofrettage method is used to obtain the best dimensionless thickness for a cylinder to withstand high internal pressure.