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Wei X.L.,Jiangsu Key Laboratory of Process Enhancement and New Energy Equipment Technology | Wei X.L.,Nanjing University of Technology | Ling X.,Jiangsu Key Laboratory of Process Enhancement and New Energy Equipment Technology | Ling X.,Nanjing University of Technology
Procedia Engineering | Year: 2015

In this paper, residual stress and plastic damage in the welded joint processed by laser shock processing are investigated. Plastic damage during laser shock processing (LSP) is modeled combined with Gurson-Tvergaard-Needleman (GTN) plastic damage constitutive equations. In order to verify the FEA model, benchmark simulations are performed and verified with available experimental results. Results show that predicted residual stresses agree well with the experimental data. It is very interesting that welding tensile residual stress can be modified and changed into compressive residual stress due to laser shock processing. Simulations reveal that void volume fraction (VVF) referring to ductile damage of materials is approximately constant and decaying sharply at the edge of the impact zone in radial direction. A point can be noted that the magnitude of surface void volume fraction (VVF) increases with increasing power density.


Wei X.-L.,Jiangsu Key Laboratory of Process Enhancement and New Energy Equipment Technology | Wei X.-L.,Nanjing University of Technology | Zhou J.-X.,Jiangsu Key Laboratory of Process Enhancement and New Energy Equipment Technology | Zhou J.-X.,Nanjing University of Technology | And 2 more authors.
Lasers in Engineering | Year: 2014

In this paper, a material ductile model induced by laser shock processing was developed to predict the ductile damage of materials, which refers to carrying capacity reduction of materials during a laser shock processing treatment. Ductile damage of 35CD4 30HRC induced by laser shock processing was investigated by finite element analysis (FEA) method combined with Gurson-Tvergaard-Needleman (GTN) ductile damage constitutive equations. The effects of power density, spot size and full width at half maximum (FWHM) on ductile damage had been discussed respectively. In order to verify the FEA model, benchmark simulationwas performed coupled with experiments. The results of the benchmark simulation show similar residual stress magnitude and distribution compared with experimental data. Results reveal that void volume fraction (VVF) in relation to ductile damage of materials is approximately constant, decays sharply at the edge of the impact zone in radial direction and only exists in hundreds of micron near surface in depth. Furthermore, the results demonstrate magnitude of VVF rises with increasing power density or decreasing FWHM, while magnitude of void volume fraction VVF is almost the same when spot size changes. ©2014 Old City Publishing, Inc.


Wei X.L.,Jiangsu Key Laboratory of Process Enhancement and New Energy Equipment Technology | Wei X.L.,Nanjing University of Technology | Ling X.,Jiangsu Key Laboratory of Process Enhancement and New Energy Equipment Technology | Ling X.,Nanjing University of Technology
Applied Surface Science | Year: 2014

Laser shock processing (LSP) is proving to be a competitive technology to traditional surface enhancement techniques in engineering products. The LSP develops a significant residual compressive stress deep into the surface of a metal alloy, which is beneficial for fatigue, wear and corrosion. In this paper, a comprehensive three-dimensional model is presented to predict the development, magnitude and distribution of residual stress field induced by LSP. In order to verify the FEA model, a benchmark simulation is performed verified with available experimental results. The predicted residual stress field for single laser shock processing is well correlated with experimental data. With the aid of the model, the influences of LSP parameters such as full width at half maximum (FWHM), power density, spot size, number of shots and overlapped shots have been analyzed. Some optimized parameters of LSP can be made by employing the presented models and results of the parametric investigations. © 2014 Elsevier B.V. All rights reserved.

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