预应力硬态切削加工中残余应力的数值模拟

航空轴承外圈的疲劳裂纹分析表明,套圈表面的残余压应力分布致使轴承表面接触疲劳寿命降低。预应力切削是一种能主动控制加工表面的残余应力状态的方法,它是通过预先给工件施加一个弹性范围内的张应力后再进行切削加工。针对预应力硬态切削的特点,建立了切削模拟的三维热力耦合模型;分析研究了材料本构方程、任意拉格朗日-欧拉方法以及刀屑接触面的摩擦模型等切削模拟中的关键技术。最后,通过切削实验和有限元模拟,比较和分析了预应力硬态切削对加工表面应力状态的影响,证明了预应力切削方法能在加工表面产生残余压应力,从而提高加工表面的接触疲劳寿命。

Simulation of Residual Stress States in Pre-stress Hard Machining

The analysis on fatigue cracks of the outer race of aero-bearing shows that the distribution of residual tensile stress on race surface could reduce its contact fatigue life. The method of pre-stress hard machining, which is a process that imposes a tensile stress to work piece within elastic limit beforehand and then exerts machining, can actively control the residual stress states of machined surface. Based on the characteristics of pre-stress hard machining, a 3D coupled thermo-mechanical model is constructed. Several key numerical techniques, such as the constitutive equation of material, the Arbitrary Lagrangian Eulerian (ALE) method and the friction law along the chip-tool interface have been analyzed and implemented. In the end, through combining cutting experiments and numerical simulations, the residual stress states of machined surface in pre-stress hard machining are compared and analyzed. Simulation and experiment results indicate that this method can acquire residual compressive stress on machined surface and prolong the contact fatigue life.