钢轨底部动力吸振器对钢轨振动与噪声的影响

为分析钢轨底部动力吸振器对钢轨振动特性和声辐射特性的影响,建立钢轨振动-声辐射模型.首先,根据铁路板式轨道实际拓扑结构建立三维实体有限元模型,采用直接法求解钢轨结构的特征值问题;其次,计算分析了钢轨在垂向单位力激励下的导纳特性与振动衰减率;再次,利用轮轨滚动噪声预测模型计算分析了动力吸振器对钢轨声辐射功率的影响;最后,对轨底动力吸振器的参数影响进行了分析.结果表明:轨底动力吸振器的减振频段为750～1 650 Hz,降噪频段为800 Hz以上;吸振器的质量比越大其减振降噪水平越高,但减振降噪水平的提高效率越低;在一定范围内适当增大吸振器刚度可略微提高降噪水平,但是刚度过大会加剧钢轨的振动及其纵向传播;阻尼系数影响减振降噪作用频率的带宽,需要保证足够大且与吸振器质量、刚度相匹配.对钢轨底部动力吸振器减振降噪作用和参数影响的计算分析可以为钢轨轨底动力吸振器的参数设计以及低噪声钢轨的选型提供一定的参考.

Influence of dynamic vibration absorber beneath rail base on rail vibration and noise

To analyze the influence of dynamic vibration absorber beneath rail base on the sound radiation characteristics of the rail, a vibration-acoustic radiation model for rails was established. First, three-dimensional solid finite element model was established according to the actual topological structure of the railway slab track, and the eigenvalue problem of the rail structure was solved by the direct method. Next, the admittance characteristics of the rail and the decay rate on the track under vertical unit force excitation were calculated and analyzed. Then, the wheel-rail rolling noise prediction model was used to calculate and analyze the influence of rail vibration absorber on the sound radiation power of the rail. Finally, the influence of the parameters of dynamic vibration absorber beneath rail base was analyzed. Results show that the vibration reduction effects of the dynamic vibration absorber beneath rail base were at the frequency band of 750 Hz to 1 650 Hz, and the noise reduction was above 800 Hz. The larger the mass ratio of vibration absorber was, the higher the level of vibration reduction and noise reduction was, while the lower the efficiency improvement of vibration reduction and noise reduction was. Increasing the stiffness of the vibration absorber in a certain range could slightly improve the noise reduction level, whereas too large stiffness could aggravate rail vibration response and its longitudinal propagation. The damping coefficient could affect the frequency bandwidth of vibration reduction and noise reduction, so it needs to be large enough to match the mass and stiffness of the vibration absorber. The calculation and analysis in this paper can provide certain reference for the parameters design of rail dynamic vibration absorbers and the selection of low-noise rails.