Numerical Simulation of Shot Dynamics and the Material Surface Condition of IN718 After Ultrasonic Shot Peening

Author:  Jan Schubnell, Andreas Maciolek, Paul Lefevre, Majid Farajian
Source:  ICSP-13
Doc ID:  2017129
Year of Publication:  2017
Abstract:  
Abstract: Ultrasonic shot peening (USP) is a mechanical surface treatment process used to enhance the fatigue life of high-added value components. During the process the shots are accelerated by a mechanical actor stimulated with a frequency between 15-40 kHz. In contrast to conventional shot peening (CSP) the shot velocities are lower and the mass of the shots are higher. For optimization of the process parameter without large experimental effort it is necessary to describe the condition in the surface layer (residual stress, surface topology) after the process depending on the process parameter. For this it is essential that the stochastic distribution of the shots and their impact velocities are known. During this work a multiple-step numerical simulation was performed to calculate first the distribution and velocity of the shots and use this information in the second step to apply an FE-analysis on a limited area to calculate the surface characteristics. An advanced hardening model was implemented to describe the effect of nonlinear combined isotropic-kinematic hardening and strain rate dependent yield at once. Subsequently, the numerically determined residual stresses were compared with experimental measurements by X-ray and synchrotron diffraction. Specimen