Discrete element-periodic cell coupling model and investigations on shot stream expansion, Almen intensities and target materials

A. Bag, C. Bianchetti, D. Delbergue, F. Tu, H. Miao, M. Brochu, M. Levesque, P. Bocher, T. Klotz
International Journal of Mechanical Sciences
300M steel, Aluminum alloy AA7050, Discrete element method, Nickel super alloy IN718, periodic cell, Shot peening, Shot stream expansion

Shot peening is a cold-working process widely used to enhance the fatigue life of metallic components. This process consists of propelling thousands of spherical particles onto a ductile metallic surface. This paper presents a sequential coupled discrete element (DE)-periodic cell based finite element (FE) model to predict the shot peening effects, in terms of residual stresses and surface roughness. Shot stream expansion was accounted for and distribution of shots impacting velocities was extracted in discrete element model (DEM). Shot peening effects were computed on an impacting zone represented by a periodic cell. A cyclic material model was used to describe the plastic properties of the targets. Shot peening on IN718, 300M and AA7050 with CW14, S230 and Z425 shots at 4A and 8A Almen intensities were simulated to investigate their influences on the distribution of shot impacting velocities, residual stress profiles and surface roughness at full coverage. Numerical results show that accounting for shot stream expansion leads to residual stress profiles that are closer to those experimentally measured than assuming a cylindrical shot stream. The predicted residual stress profiles and surface roughness are comparable to the experimentally measured values, for the three materials studied.

Keywords: Shot peening, Discrete element method, Periodic cell, Shot stream expansion, Nickel super alloy IN718, 300M steel, Aluminum alloy AA7050, 

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