轮轨高频动力作用模拟中接触模型的影响分析

Influence of Contact Modeling on Numerical Analyses of High Frequency Wheel-rail Interactions

轮轨高频动力分析模型目前多沿用了传统的赫兹接触模型,其在高速轮轨系统上的适用性尚未得到验证。针对赫兹接触工况,建立基于多体动力学的车轮-轨道耦合动力学和车辆动力学模型,其中轮轨法向接触由赫兹弹簧表征,作为对比也建立基于显式有限元的三维高速轮轨瞬态滚动接触有限元模型,采用可考虑三维接触几何的"面-面"接触算法精确求解轮轨接触。对比150~500km/h速度范围内典型钢轨短波波磨(波长20~140mm、波深0.01~0.20mm)激励下的高频轮轨力结果,发现三种模型预测的幅值存在显著差异,但未发生轮轨脱离时(波磨尚浅),三种模型预测的幅值均与波深线性正相关。具体而言,相较于瞬态滚动接触模型,车轮-轨道耦合动力学和车辆动力学模型预测的垂向轮轨力更大,其特征幅值的最大差值分别为静轮重的39.2%和88.4%,三种模型预测波长30mm波磨的临界波深(恰好发生轮轨脱离)相应地高于0.2mm、0.14mm和0.05mm。开展高速、高频轮轨动力分析时,传统的赫兹接触弹簧会带来不可忽略的计算误差。

Hertzian spring is widely used today in many dynamics models of high frequency wheel-rail interaction,but its applicability to high speed railways has not been validated.For cases of Hertz contact,two multi-body dynamics based models,a wheel-track coupled dynamics model and a vehicle dynamics model,are developed,in which Hertzian springs are employed to represent the normal contact.Meanwhile,a 3-D transient rolling contact model is developed for reference using the explicit finite element method,in which the rolling contact is solved by a surface-to-surface algorithm in the consideration of actual contact geometries.High-frequency normal contact forces calculated at 150-500 km/h and in the presence of typical corrugation(wavelength 20-140 mm and depth 0.01-0.20 mm)show that significant difference exists among the contact forces predicted by the three models,but for relatively shallow corrugation(no contact loss occur)a linear relationship has been obtained between the corrugation depth and the amplitude of the contact force by all three models.In detail,the normal contact forces predicted by the wheel-track coupled dynamics and the vehicle dynamics models are significantly higher than those by the transient rolling contact model,their maximum over-estimations are 39.2%and 88.4%of the static load,respectively,and the obtained critical depths,at which wheel and rail lose contact during rolling,deviate significantly with the employed models,being greater than 0.2 mm,0.14 mm and 0.05 mm for the three model,respectively,when the wavelength of 30 mm is taken.In a word,significant errors exist in predictions of high-speed and high frequency wheel-rail interactions if the traditional Hertzian spring is employed.