Obtaining Residual Stresses in Metal Forming After Neglecting Elasticity on Loading

A methodology for computing residual stresses in forming operations is examined in which the elasticity is neglected during the loading phase of the operation. The elastic response is recovered on unloading through the analysis of an initially-stressed body. Two examples are presented which provide a quantitative assessment of the accuracy of the approach. The first is the axisymmetric expansion of a thick-walled tube. In this case the residual stresses are compared to those computed with an elastic-plastic analysis for both the loading and unloading phases. The second example is a ring upsetting application that has been analyzed using a finite element formulation and for which there are experimental data available for comparison.