Elasto-plastic finite-element analysis of the cold expansion of adjacent fastener holes

This investigation is devoted to the modelling and simulation of the residu al stress field resulting from the cold expansion of two adjacent fastener holes. In this two-dimensional elasto-plastic analysis, the development and growth of the plastic zone and unloading residual stresses were examined u sing the finite-element method. Attention was devoted to two related issues . The first is concerned with the effect of the separation distance between the two holes, the mechanical properties of workpiece and the expansion le vel upon the field variables; and the second with the effect of the order o f cold working of the two holes upon the residual stress field. The results reveal the important role played by the geometry of the workpiece and the expansion parameters upon the quality of the treatment, as measured by the mechanically-induced residual stresses. The shortcomings of the two-dimensi onal analysis are highlighted and compared with the results of a three-dime nsional model. (C) 1999 Elsevier Science S.A. All lights reserved.