An analytical approach to relate shot peening parameters to Almen intensity

Shot peening is widely used in the automotive and aerospace industries to improve the fatigue strength of metal components by introducing near-surface plastic strains and compressive residual stresses. This mechanical treatment is primarily controlled by monitoring Almen (peening) intensity, which corresponds to the arc height at saturation of standardized test strips exposed to the shot stream. However, the same Almen intensity may be obtained by using small shots impacting the surface at high velocity or by using large shots impacting the surface at low velocity. This paper describes a model for predicting Almen intensity based on an analytical model for shot peening residual stresses. Theoretical results for different sets of peening parameters were consistent with published experimental results and revealed that although different combinations of shot peening parameters can produce the same Almen intensity, each combination resulted in a different through thickness residual stress distribution.