Residual Stress of Thin-Wall Pipe Subjected to Axisymmetric Plastic Expansion

A straight pipe was expanded at one end by inserting a rigid disk. The residual stress measured at the inner surface shows a strong tensile peak beyond the region where the pipe was directly expanded by the insertion of the disk. The reason the residual stress reaches its peak at a location further into the pipe is discussed based on a FE analysis. The residual stress was found to reach its tensile peak at the plastic region front that was developed during the pipe expansion. A simple formula for identifying the tensile peak location is also proposed.