Application of an Equivalent Temperature Field for Emulating Thermal Autofrettage-Induced Residual Stresses in Thick-Walled Cylinder

Abstract

The equivalent temperature field of residual stresses induced by autofrettage of thick-walled cylinders and spheres have been successfully implemented in a finite element method framework to study the crack growth in autofrettaged components. Thermal autofrettage is a potential alternative method for strengthening hollow cylinders against internal pressurization. The assessment of service life of thermally autofrettaged cylinders containing cracks is imperative when they are subjected to high pressure static or cyclic in-service loading. There the equivalent temperature field replicating the thermal autofrettage-induced residual stresses will serve as the input to the finite element method analysis to evaluate the important fracture parameters such as static fracture endurance and the rate of crack growth for predicting service life. This work presents evaluation of an equivalent temperature field by establishing an equivalence between the thermoelastic stress field and thermal autofrettage-induced residual stress field in a cylinder obtained from either an analytical or a numerical model. The evaluated equivalent temperature field is then used in a finite element method analysis to exemplify the replication of the original residual stresses generated by thermal autofrettage in SS304, aluminum cylinders and electroslag refined (ESR) steel gun barrel. It is found that the finite element stress solution due to the application of equivalent temperature field and the original analytical or numerical thermal autofrettage residual stress solution are in good agreement with less than 5% deviation in the case of SS304 and aluminum cylinders, and that in ESR steel barrel with less than 1% deviation.