移动荷载下三维半空间动力安定性下限分析

Dynamic shakedown lower-bound analysis of three-dimensional half-space under moving load

针对交通移动荷载,基于第一动力安定性理论预测了弹塑性半无限空间动力安定性下限值。通过建立无限元边界的三维动力有限元模型,研究了移动荷载作用下弹塑性半无限空间的动应力分布,构造了稳态动应力下的残余应力场,基于残余应力场的构造提出了动力安定性下限值的预测方法,分析了交通动应力下的安定性下限值以及车辆移动速度对安定性的影响,同时分析了均布荷载和Hertz荷载分布对动力安定性下限值的影响。当荷载移动速度低于Rayleigh波速时,安定性极限值随着速度的增加而增加,而当速度超过Rayleigh波速时,随着速度的增加而减小。研究还发现,当荷载和总重相等时采用圆形均布荷载和Hertz荷载的安定性极限值较为相似。

This paper predicts the lower-bound shakedown limit of an elastoplastic half-space under traffic loads based on the first dynamic shakedown theory. A three-dimensional finite element model with infinite element boundaries is built. And then the model is used to analyze the dynamic elastic stress under different speed moving loads, and a steady residual stress field is constructed through the dynamic elastic stress. A method to predict the dynamic shakedown limits through analyzing the residual stress is proposed as well. Then the lower-bound shakedown limits of half-space under dynamic traffic load and the influence of speed on shakedown limits are discussed. Meanwhile, the difference of shakedown limits between uniform load and Hertz load are studied. In addition, the shakedown limits will increase with the growth of moving speed when the load speed is lower than Rayleigh wave speed, otherwise the shakedown limits will decrease with the growth of moving speed when the load speed is faster than Rayleigh wave speed. It is also found that shakedown limits of uniform load and Hertz load are similar when the total weight load of this two load manners are the same. © 2016, Science Press. All right reserved.