基于有限元仿真与机器学习的GH4065A高温合金喷丸强化工艺多目标优化

    Multi-objective Optimization of Shot Peening Process for GH4065A Superalloy Based on Finite Element Simulation and Machine Learning

    • 摘要: 航空发动机涡轮盘常用的GH4065A镍基变形高温合金,在高温、离心和交变应力耦合作用下易萌生疲劳裂纹。喷丸强化技术可在合金表层引入残余压应力并改善表层组织,从而提升疲劳性能。通过ABAQUS与Python二次开发建立随机多弹丸喷丸模型,并基于Box-Behnken响应面法设计试验,系统研究弹丸材质(陶瓷丸、铸钢丸、玻璃丸)、直径、喷射速度及覆盖率对表面粗糙度、表面残余压应力和总体残余压应力层深的影响。采用相关性分析和方差分析研究工艺参数的影响规律及交互作用,构建XGBoost代理模型,并通过10次重复的5折交叉验证方法评价模型预测性能;进一步分析各输入特征的重要性,并开展多目标Pareto优化。结果表明:在所研究参数范围内,弹丸直径与喷射速度是影响粗糙度和层深的核心因素,而弹丸覆盖率对表面残余压应力的影响最为显著;相较于铸钢丸、玻璃丸,陶瓷丸处理后试件的残余压应力分布均匀性与综合强化效果更优。优化获得313组Pareto非支配候选组合,筛选得出最优折中候选方案为陶瓷弹丸、弹丸直径0.42 mm、喷射速度80 m/s、喷丸覆盖率200%。该方案预测表面粗糙度22.351 μm、表面残余压应力-981.457 MPa、总体残余压应力层深0.3309 mm。通过独立有限元仿真回代验证,三项指标的仿真结果与代理模型预测结果的相对误差分别为10.71%、2.38%和4.38%,且各指标的绝对误差均均小于模型重复交叉验证的均方根误差(RMSE),表明代理模型与有限元计算结果总体具有一致性。该研究结果可为GH4065A高温合金涡轮盘构件的喷丸工艺参数优化提供参考。

       

      Abstract: GH4065A, a wrought nickel-based superalloy commonly used for aero-engine turbine disks, is susceptible to fatigue crack initiation under elevated-temperature, centrifugal, and cyclic loading conditions. Shot peening can improve fatigue performance by introducing residual compressive stress and modifying the near-surface microstructure. A random multi-shot peening model was developed using ABAQUS and Python scripting, and a simulation scheme based on the Box- Behnken response surface methodology was employed to systematically investigate the effects of shot material (ceramic, cast steel, and glass), shot diameter, impact velocity, and coverage on surface roughness, surface residual compressive stress, and the overall residual compressive stress layer depth. Correlation analysis and analysis of variance were conducted to examine the effects and interactions among the process parameters. An XGBoost surrogate models were constructed, and its prediction performance was evaluated using ten repetitions of five-fold grouped cross-validation. Analysis of feature importance was performed, and multi objective Pareto optimization was further implemented. The results show that, within the investigated parameter range, shot diameter and impact velocity are the primary factors affecting surface roughness and residual compressive stress layer depth, whereas coverage has the greatest influence on surface residual compressive stress. Ceramic shot exhibits favorable residual compressive stress uniformity and overall strengthening performance. A total of 313 Pareto-nondominated candidations are identified. The compromise candidate employs ceramic shot with a diameter of 0.42 mm, an impact velocity of 80 m/s, and a coverage of 200%. The predicted surface roughness, surface residual compressive stress, and overall residual compressive stress layer depth are 22.351 μm, -981.457 MPa, and 0.3309 mm, respectively. The relative errors between the independent finite element back-analysis results and the surrogate-model predictions are 10.71%, 2.38%, and 4.38%, respectively. Moreover, the absolute errors of all three responses are lower than the corresponding root mean square errors(RMSE) obtained from repeated grouped cross-validation, which demonstrates reasonable agreement between the surrogate-model predictions and the finite element results. These findings provide a reference for optimizing shot peening process parameters for GH4065A superalloy.

       

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