A geometry-based method for prediction of shot-peening coverage

Shot-peening is the process of repeatedly hitting the work piece surface with small balls, making overlapping indentations on the surface. This process is extensively used on shafts, gears, springs, and jet engine parts because it imparts compressive residual stresses on the surface, thus improving the fatigue life of components. Under-peening does not give a sufficient fatigue life while over-peening induces cracking and reduces fatigue performance. Hence, determining optimal peening conditions such as peening time is very important. In general, optimal peening conditions are experimentally determined by measuring arc-height using Almen-strip or calculating coverage using microscope images. Shot-peening coverage is defined as the proportion of the exposed surface that has been impacted in a given time of shot-peening. To save the time and effort spent in repeating experimental measurement needed whenever the geometry of a work piece and peening conditions change, this paper presents a computer simulation algorithm for the prediction of shot-peening coverage, which is based on the geometry of a work piece. An example is presented to validate the proposed method.