Fatigue performance of shot-peened gears investigated by experimental and numerical methods

In the last fifty years many theories have been developed with the aim of investigating the fatigue performance of mechanical components. On the basis of experimental results, mathematical models were developed to simulate the fatigue life of shaped components under different load cycles. Such models can be used to study local fatigue properties at most critical points, i.e. notches or edges. However, such models were generally not applied to shot-peened components, even if many papers were published on fatigue behaviour improvement by shot-peening treatments. In this study, case-hardened and shot-peened gears were tested in order to evaluate their fatigue limit and the local S-N curve at the tooth root. Residual stress distribution was also investigated by diffractometric analysis. The same problem was approached from the numerical point of view. The process of shot-peening was simulated by a finite element model and the stress distribution was numerically determined and compared to the measured one. This result was then processed and a methodology was devised to numerically evaluate the fatigue behaviour of the component. The present paper discusses the simulation accuracy, emphasizing the generality of proposed methodology.