An analytical procedure for estimating residual stresses in blocks containing crossbores

Intersecting bore geometries are used in a number of industrial application s such as the fluid ends of reciprocating pumps and have regions with high stress concentration. To increase the fatigue life of a fluid end, a reduct ion in the operating mean stress is helpful. This can be achieved with the introduction of compressive residual stresses in these critical regions by means of proof loading or autofrettage. Accurate estimation of fluid end fa tigue lives necessitates accurate evaluation of the residual stresses induc ed by autofrettage. In this paper, finite element models were used to obtai n hoop stress to pressure ratios, at the most highly stressed plane, in blo cks of different sizes and bore ratios. The hoop stress to pressure ratios were used along with Neuber's rule and kinematic hardening to select an aut ofrettage pressure and to estimate the elastoplastic residual stresses on t his plane. The suggested method estimates residual stress magnitudes close to finite element solutions, and eliminates the need for a lengthy and cost ly elastoplastic finite element analysis. (C) 2001 Elsevier Science Ltd. Al l rights reserved.