• Transactions of the Korean Society of Mechanical Engineers A
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• v.34 no.3
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• pp.323-331
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• 2010

In this study, we propose a 3D finite element (FE) model for the residual stress under oblique shot peening. Using the FE model for an oblique impact, we examine the effects of factors on the residual stress such as the Rayleigh damping in the material, dynamic friction, and the rate dependency of the material and systematically integrate the effects. The plastic deformation of the shot is also emphasized. Then, the FE model is used to study oblique multi-impacts. The results obtained using the FE model are compared with experimental x-ray diffraction (XRD) results; in contrast to the rigid and elastic shots, plastic shots are found to produce residual stresses similar to that shown in the XRD results. Thus, the 3D FE models with integrated factors and plastically deformable shots are validated. The proposed model will serve as a basis for the 3D FE model for multi-impacts with different impact angles to simulate the actual phenomenon of shot peening.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.36 no.2
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• pp.125-135
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• 2012

The FE model for shot peening often assume that shots impact vertically on the engineering parts to generate compressive residual stresses. However, the shots obliquely impact on the surface in actual peening. In this work, we propose a 3D finite element (FE) model for evaluation of residual stress under angled shot peening. Using the FE model for angled multi-impact, we examine the effects of factors such as impact angle, impact pattern and the number of shots. Plastic deformation of shot is also considered. To validate the model, we then compare the FE solution with experimental result by X-ray diffraction (XRD). The proposed model will be a base of 3D multi-impact FE model with diverse impact angles.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.33 no.4
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• pp.310-320
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• 2009

In this paper, we estimate area-averaged solution of peening residual stress using a 3-D multi-impact symmetry-cell FE model. The symmetry-cell model includes factors reflecting peening phenomena and plastic shot. Area-averaged solution is much closer to XRD experimental solution than 4-node-averaged solution in plastic shot FE model. We then obtain FE Almen saturation curve corresponding to experimental Almen curve based on area-averaged solution. Using the curve, we obtain FE area-averaged solution in major peening materials, and compare the FE solution with experimental solution. In peening materials, surface, maximum compressive residual stress and deformation depth reach experimental solutions. Thus, FE Almen curve is useful for estimation of residual stress solution and could improve the efficiency of peening process. Consequently, it is confirmed that concept of area-averaged solution is the realistic analytical method for evaluation of peening residual stress.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.32 no.8
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• pp.642-653
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• 2008

In this paper, we propose a 3-D finite element (FE) analysis model with combined physical behavior and kinematical impact factors for evaluation of residual stress in multi-impact shot peening. The FE model considers both physical behavior of material and characteristics of kinematical impact. The physical parameters include elastic-plastic FE modeling of shot ball, material damping coefficient, dynamic friction coefficient. The kinematical parameters include impact velocity and diameter of shot ball. Multi-impact FE model consists of 3-D symmetry-cell. We can describe a certain repeated area of peened specimen under equibiaxial residual stress by the cell. With the cell model, we investigate the FE peening coverage, dependency on the impact sequence, effect of repeated cycle. The proposed FE model provides converged and unique solution of surface stress, maximum compressive residual stress and deformation depth at four impact positions. Further, in contrast to the rigid and elastic shots, plastically deformable shot produces residual stresses closer to experimental solutions by X-ray diffraction. Consequently, it is confirmed that the FE model with peening factors and plastic shot is valid for multi-shot peening analyses.