Patent ID: 7739059

Claim:
A computer readable storage medium encoded with instructions which, when executed by a computer, cause a processor to execute a method for determining a residual stress state of two elastoplastic cylinders coldworked by expansion, said method comprising: calculating whether applying an internal expansion load to an inner cylinder that is concentrically arranged within an outer cylinder will result in the interference of the inner cylinder with the outer cylinder, wherein an outer radius of the inner cylinder is smaller than an inner radius of the outer cylinder such that there is a clearance between the outer radius of the inner cylinder and the inner radius of the outer cylinder prior to applying the internal expansion load to the inner cylinder; calculating whether unloading the internal expansion load will result in assembly of the inner cylinder with the outer cylinder; calculating residual stresses, residual displacement and residual strains in the inner cylinder and the outer cylinder, wherein the residual stresses, the residual displacement and the residual strains in the inner cylinder and the outer cylinder are stresses, displacement, and strains in the inner cylinder and the outer cylinder after the internal expansion load has been unloaded; and recording said residual stresses, residual displacement and residual strains of the inner cylinder and the outer cylinder for use in selecting a ring that is to be initially clearance fitted in a receiving part and then involved in a loading-unloading process so as to install the ring in the receiving part by cold expansion.