高速铁路无砟轨道扣件系统弹性垫板力学性能的温变试验

Experimental Study on Temperature-dependent Mechanical Property of Rail Pads Used in Non-ballasted Track of High-speed Railway

以我国高速铁路无砟轨道WJ-7B、WJ-8B与Vossloh 300扣件系统内的弹性垫板为研究对象,利用配有温度控制箱的万能试验机,测试-60℃～70℃时3类扣件弹性垫板随温度变化的静态力学特征与0.3 Hz动态力学特征。然后,应用高分子材料的温频等效原理与WLF方程,预测-60℃～70℃时3类扣件弹性垫板随频率变化的动态力学参数。研究结果表明：WJ-7B、WJ-8B及Vossloh 300扣件弹性垫板的静刚度与动刚度均具有显著的低温敏感性,且其损耗因子在玻璃区转化温度（-45℃左右）达到最高;与低温静刚度的变化情况相比,3类扣件弹性垫板动刚度的低温变化幅度更大;在轨道振动1～10 000Hz,3类扣件弹性垫板动参数随低温与频率的变化均较显著。因此,在轮轨系统动力响应及环境振动、辐射噪声的预测中,应考虑扣件弹性垫板等高分子材料的温变与频变动态力学特征。

With the elastic pads in WJ-7B,WJ-8Band Vossloh 300 rail fasteners used in the non-ballasted track of Chinese high-speed railway as the object of the study,the temperature-dependent static mechanical characteristics of the elastic pads and their temperature-dependent dynamic mechanical features at a frequency of 0.3Hz were measured by the universal testing machine equipped with temperature control box in the temperature range of-60 ℃~70 ℃.After that,Time-Temperature Superposition(TTS)of high polymer materials and WLF formula were applied to predict the frequency-dependent dynamic parameters of the three kinds of elastic rail pads at-60 ℃~70 ℃.The research results showed that the static and dynamic stiffness of all the elastic pads in WJ-7B,WJ-8Band Vossloh 300 rail fasteners were provided with significant low-temperature sensitivity,and their loss factors reached the highest at about-45 ℃ where the glassy state of rail pads began to transform into their rubbery state.Compared with the changes of the static stiffness of the three kinds of elastic pads in low temperatures,their dynamic stiffness had a greater variation with decrease of low temperatures.In railway track vibration frequencies of 1~10 000 Hz,the variation of dynamic parameters of the three kinds of elastic pads with decease of low temperatures or increase of frequencies was significant.Therefore,the temperature-dependent and frequency-dependent dynamic mechanical characteristics of high polymer materials used in track,such as elastic rail pads,should be considered in the prediction of the wheel/rail coupled vibration responses,the train-induced environment vibration and the corresponding radiated noise.