The Change in Overstrain Level Resulting From Machining of an Autofrettaged Thick-Walled Cylinder

Abstract

An analytical model for predicting the level of autofrettage following either inner, outer, or combined machining of a gun barrel is developed based on Hill’s (Hill, R., 1950, The Mathematical Theory of Plasticity, Clarendon Press, Oxford, U.K.) solution for the autofrettage residual stress field. The analysis results in very simple algebraic expressions for the post-machining level of autofrettage in terms of the original level induced in the blank tube. In parallel, a finite element analysis of the machining process is performed in which the residual stress field is simulated by an equivalent thermal load. The numerical results are found to be in excellent agreement with the analytical ones. Thus, as an equivalent thermal load can always be determined, either analytically or numerically, for any other approximations to the residual stress field due to autofrettage (Perl, M., 1988, ASME J. Pressure Vessel Technol., 110 , pp. 100–102), the foregoing methodology can be readily applied, enabling the determination of post-machining autofrettage level in these cases. [S0094-9930(00)00501-1]