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基于Cosserat连续体理论建立考虑应变梯度效应的粉末高温合金弹塑性模型.该模型考虑微尺度长度效应,并能消除缺陷局部化问题求解时的网格依赖性.基于参变量变分原理提出一种高效的求解方法,该方法将原非线性问题转化为互补问题求解,可大大提高求解效率和收敛性.针对一种假想涡轮盘模型,将Cosserat尺度参数和Basquin斜率作为随机变量,分别采用蒙特卡洛法与二阶矩法进行疲劳寿命概率可靠度计算.结果表明二阶矩法在保证精度的情况下具有较高的效率.
Based on the theory of Cosserat continuum, the elastic-plastic model of powder superalloy considering the effect of strain gradient is established. The model considers the microscale length effect and can eliminate the grid dependency when the defect localization problem is solved. Based on the parametric variational principle Which can transform the original nonlinear problem into the complementary problem solving, which can greatly improve the efficiency and convergence of the solution.For an imaginary turbine disk model, the Cosserat scale parameters and the Basquin slope are taken as random variables, and Monte-Carlo Lofa method and second-order moment method are used to calculate the probability of fatigue life, and the results show that the second-moment method has higher efficiency with guaranteed accuracy.