钢轨螺栓孔冷扩张过程弹塑性分析及其模拟计算

Elastoplastic Mechanics Analysis and Computer Simulation for Rail Bolt Hole Cold Expanding Process

对钢轨螺栓孔冷扩张过程进行了弹塑性力学分析。通过简化的无限大平板的单孔模型的弹塑性理论计算，得出了冷扩张后的残余应力分布情况，证实冷扩张确实可产生预加压应力。为确定合适的扩孔率，分析多孔同时扩孔时塑性区的相互影响，建立了基于实际钢轨扩孔条件的轨端弹塑性有限元分析模型，对冷扩张过程的钢轨螺栓孔周边应力及变形情况进行了模拟计算。并结合对钢轨螺栓孔冷扩张及其加工过程的分析，考虑实测的钢轨螺栓孔没扩孔前的残余拉应力区的存在，以及扩孔过程的弹塑性分析及加工间隙的配匹，分析了适合我国６０ｋｇｍ－１钢轨轨材的钢轨螺栓孔冷扩张的扩孔率范围，并得到了疲劳试验的验证。

With a simplified elasto plastic mechanics model of a single hole in a infinite plate, the residual stress distribution after cold expanding is calculated.The result confirms theoretically that a pre stress in compression can be produced through the cold expanding process To determine the appropriate hole expanding rate and to investigate the mutual influence in the plastic deformation zone between holes in multi hole cold expanding process,an elasto plastic finite element for rail end model is established based on the actual condition of rail bolt hole expansion process.With this model,simulation is carried out of the peripheral stress and deformation of the rail bolt hole during the cold expanding process,the Tskinh into consideration of a residual tension stress zone in rail before cold expanding and hole dimension tolerance, as well as elastoplastic analysis results of the expansion process, suggests the proper hole expansion rate range suitable for our domestic 60kg·m -1 rail material, and the result is proved to be practical and effective by the simulation fatigue test