On autofrettage of cylinders by limiting circumferential residual stress based on Mises yield criterion

The autofrettage technique is an effective and important measure to improve load-bearing capacity and safety and to even distributions of stresses for pressure vessels. Based on the classical fundamental theory on autofrettage and by theoretical analysis of residual stresses, the total stresses, the overstrain and the load-bearing capacity, etc., in view of the cylindrical pressure vessels with outside-to-inside radius ratio larger than the critical ratio, the laws contained in the autofrettage theory are revealed, the essential cause and reason for the obtained laws are analyzed, the inherent and meaning relations between various parameters in the autofrettage theory are brought to light, and the safe depth of the plastic zone (overstrain) as well as the conditions of loading or optimum operation conditions are found out. It is shown that under the optimum operation conditions, pressure vessels are not only safe but also economic, and the equations of the autofrettage theory are simplified greatly and are quite terse, as a result, the essential relations between various parameters in the autofrettage theory are distinct, and these equations are convenient for application in engineering practice.