高温合金激光冲击强化数值模拟及其疲劳寿命预测

Numerical Simulation of Laser Shock Peening for Superalloy and Fatigue Life Prediction

建立了激光冲击强化宏观有限元数值模型和细观参量演化数值模型,提出了激光冲击强化三维多尺度模拟方法,分析了激光冲击强化后Inconel 718高温合金残余应力、位错密度、晶粒尺寸的分布规律;考虑激光冲击强化所致残余应力和晶粒细化对疲劳寿命的影响,对Sines疲劳寿命准则进行修正,并进行了试验验证。结果表明:模拟得到试样表面光斑冲击范围内形成了不小于550 MPa的残余压应力,表层区域存在明显的位错增殖,局部晶粒尺寸可细化25%左右,模拟结果与试验结果基本吻合;采用修正Sines准则预测得到的疲劳寿命在3倍分散带内,说明该模型能够较好地预测激光冲击强化后Inconel 718高温合金的疲劳寿命。

The macroscopic finite element numerical model and the mesoscopic parametric evolution numerical model of laser shock peening were established.A three-dimensional multi-scale simulation method for laser shock peening was proposed.The distribution law of residual stress,dislocation density and grain size of Inconel 718 superalloy after laser shock peening was analyzed.The Sines fatigue life criterion was modified considering the influence of residual stress and grain refinement caused by laser shock peening on fatigue life,and was verified by tests.The results show that residual compressive stresses no less than 550 MPa within the impact range of the light spot on the sample surface were obtained by simulation;significant dislocation proliferation existed in the surface area,and the local grain size could be refined by about 25%;the simulation was basically consistent with the test results.The fatigue lives predicted by the modified Sines criterion were within 3 times the dispersion band,indicating that the model could predict the fatigue life of Inconel 718 superalloy after laser shock peening.