Abstract: The optimum autofrettage pressure of the thick wall cylinder under thermo-mechanical loadings is analyzed. The theoretical solutions are compared with those numerical results obtained by optimization analysis based on ANSYS. Furthermore, the effect of autofrettage on shakedown behavior of a thick-walled cylinder under constant internal pressure and cyclic thermal load is also investigated. The results indicate that the theoretical solutions of the optimum autofrettage pressure are in good agreement with the numerical solutions and the maximum error is not greater than 1% when normalized temperature tn is  0.75, while autofrettage processing is not necessary when tn is  0.75 and 1.00 due to the small equivalent stress difference between the inner and outer walls. Moreover, without considering the effect of thermal load, autofrettage may increase the difference of the equivalent stress between the inner and outer walls, which decreases the fatigue strength of the thick cylinder subjected to thermo-mechanical loadings. In addition, autofrettage has little influence on shakedown behavior under cyclic thermo-mechanical loadings.

Key words: ANSYS, Autofrettage, Shakedown, Thick cylinder