Although tube cracking has been discussed extensively in the literature, roll expanded plugs and their associated stress corrosion cracking (SCC) have yet to be fully addressed. In addition, roll plugs present a different set of loads, expansionregions, discontinuities, and displacement boundary conditions. The method of solution to the subject roll expansion problem uses a general purpose finite element program to mathematically simulate the expansion process. The simpler problem of expanding a 0.750" plug with hydraulic pressure was previously presented in part 1 of this paper (Williams, 1996). In part 2, a 3-D finite element model that was developed to simulate the rolling process used to form the plug-to-tube frictional joint, is discussed.The mechanical expansion simulation is accomplished by replicating the final displacements of an installed plug for which field measurements are available. Because of the absence of symmetry in the geometry and loading, a 3-D solution is required. Theresulting stress field throughout the plug, and in particular, in the rolled transition region, is calculated. In addition, of critical importance are the orientations of the tensile residual stresses that may be used as a predictor of future crackpotential and undesirable failure.
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