A program for the residual stress analysis of an autofrettaged compound cylinder is designed using a Matlab graphical user interface (GUI) and program design technique. The high-pressure vessels are autofrettaged in order to increase their operating pressure and fatigue life. An autofrettage process causes plastic expansion of the inner section of the cylinder, adding residual compressive stress to the bore after relaxation. Such a compound cylinder is produced via a shrink-fit procedure that incorporates a monobloc tube that has previously undergone autofrettage. This paper presents a simple and visual tool to calculate the residual stress and describe the distribution of residual stress for both the elastic-perfectly plastic model and the strain-hardening model.

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Manufacturing of precise couples is the most important key technology for hydraulic products. The hydraulic characteristics are not only strongly correlated with their geometric elements, but also associated with the surface qualities of the couples, including surface roughness and surface texture, and which primarily influence the dead zone, lag rings and friction of the couples. In order to get better surface machining quality of the precise hydraulic couples, the process of surface grinding and polishing was researched. Through process test, the optimum parameters of grinding and polishing processing were found, which made the surface roughness achieved Ra 0.031μm.

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