The modelling of residual stresses due to surface peening using eigenstrain distributions

Abstract

The beneficial effect of surface peening (including shot peening, laser shock peening, low plasticity burnishing, etc.) on fatigue resistance of structural alloys is well documented and widely used in industry to improve component life. It is perhaps the most widely used technique that relies on the introduction of residual stresses into the component by direct mechanical means. The resulting stress states are usually evaluated experimentally by X-ray diffraction or other stress measurement techniques. In order for shot peening operations to be effective and reliable, the process of introducing residual stresses and strains into peened components must not only be controlled but also be predictable and quantifiable. The present paper establishes a framework for predictive modelling of the residual stress states due to surface peening. Firstly, uniform (within planes parallel to the surface) plastic deformation of the surface layer taking place during shot peening of a thin plate is simulated using the concept of eigenstrain. As a further demonstration of the capabilities of the proposed approach, flexible plate theory is applied to the analysis of stresses and deformations arising due to local peening within a circular area. The results are of considerable use and significance for the analysis of shot peening and peen forming operations.