高频振动下无砟轨道扣件疲劳破损研究

Ballastless track fastener is long-term directly borne the effect of rail vibration, with the rapid increase of train operating speed, disturbing frequency is sharply increase, and high frequency vibration of rail is also produced, the complex process of fastener is accompanied by high strain, high overload, and enormous energy is released and converted instantaneously, so a new situation of fastener fatigue characteristics is appeared. In order to research the fatigue damage mechanism of ballastless track fastener under high frequency vibration, structural vibration, fracture mechanics theory, numerical analysis and calculation technique, which is combined with indoor test, will be used in the application. According to the actual situation of the contact connection between the fastener components, the fatigue damage model of rail under high-frequency vibration of ballastless track fastener will be established, the characteristics of high frequency and low frequency vibration on the fatigue failure of fasteners will be also studied. The fatigue test will be designed and assembled according to the research and theoretical calculation, the mechanism of ballastless track fastener fatigue damage under high-frequency vibration will be investigated and the design parameters of fastening system will be optimized in combination with theoretical research and experimental analysis, then reasonable measures to suppress high frequency vibration and the reasonable service period of the ballastless track fastener will be put forward. The project has good theoretical significance and engineering application value to improve the ballastless track fastener fatigue durability, and reduce high-frequency vibration hazards.

无砟轨道是高速铁路的主要轨道结构形式，扣件技术是无砟轨道结构关键技术之一。无砟轨道扣件长期直接承钢轨振动作用，列车运营速度大幅提高后，激扰频率急剧增加，钢轨普遍产生高频振动，扣件也伴随着高应变、高过载、巨能瞬间释放、能量转换极快等复杂过程，扣件疲劳特性出现了有别以往的新情况。项目运用结构振动、断裂损伤力学理论、数值分析与计算技术，结合室内试验，研究高频振动下无砟轨道扣件的疲劳破损机理。基于扣件各部件之间接触连接的实际情况，建立钢轨高频振动下无砟轨道扣件疲劳破损模型，研究高频与中低频振动对扣件疲劳破损的特点。根据理论研究与计算，设计组装室内疲劳试验，结合理论研究与试验分析，探讨高频振动下无砟轨道扣件疲劳破损机理，优化扣件系统设计参数，提出无砟轨道扣件合理的服役期限。项目对提高无砟轨道扣件疲劳耐久性、减少高频振动危害具有良好的理论意义和工程应用价值。

无砟轨道是高速铁路的主要轨道结构形式，扣件技术是无砟轨道结构关键技术之一。高速列车运营条件下，钢轨振动频率普遍达300Hz以上。扣件也伴随着高应变、高过载、巨能瞬间释放、能量转换极快等复杂过程。项目运用结构振动、断裂损伤力学理论、数值分析与计算技术，建立钢轨高频振动下无砟轨道扣件疲劳破损模型，结合室内试验，研究高频振动下无砟轨道扣件的疲劳破损机理，优化扣件系统设计参数，得出如下结论：（1）通过静力拉伸试验得到W1型弹条（即60Si2MnA）的屈服强度为1600 MPa，抗拉强度为1900 MPa；（2）W1型弹条在不同循环位移载荷作用下的疲劳寿命随循环位移载荷的增大而减小，循环位移载荷越小，弹条疲劳寿命越大，7.5 kN位移载荷作用时弹条疲劳寿命均值为157128 次；（3）W1型弹条在不同循环位移载荷作用下的疲劳寿命与扣压力呈反向关系，即弹条扣压力随循环位移载荷值的增大而减小，直至弹条断裂；（4）通过最小二乘法对W1型弹条在不同可靠度下的lgFa-lgN曲线进行直线拟合，可以得到弹条在不同可靠度下的拟合公式，可为以后从事铁路扣件工作人员预测不同可靠度下弹条的疲劳寿命提供参考；（5）使用电镜扫面议对W1型弹条断口进行扫描分析得出弹条的断裂性质为弯曲-扭转复合型断裂，且弹条断裂位置均在弹条后端大圆弧靠外侧。. 项目对提高无砟轨道扣件疲劳耐久性、减少高频振动危害具有良好的理论意义和工程应用价值。