Cyclic modelling of the mechanical state produced by shot-peening

During low cycle fatigue of shot-peened parts, the competition between the compressive residual stresses and the hardening damage, both of which are p roduced by cumulated plastic strains, is of major importance for lifetime i mprovement. In order to take into account these effects in life prediction, the shot-peening treatment must be considered as a first step in the servi ce life of the studied part. The predicted residual stresses provided by th e existing shot-peening models are not sufficient when taking account of th e induced mechanical state. The proposed methodology in this paper describe s the shot-peening process by a new cyclic approach where the Chaboche cons titutive equations, commonly used in the aircraft industry, show the best p romise. A reversed method is employed to quantify, after shot-peening, the complete mechanical state in line with commonly used life-prediction algori thms. Computations are carried out for a shot-peened TiAl6V4 titanium alloy as used in the low pressure stage compressor of turbo-engine discs.