钢轨波磨水平对轮轨噪声影响研究

[目的]针对国内某地铁线路运营过程中频繁出现噪声超标现象,研究钢轨波磨水平对轮轨噪声的影响,以解决线路的波磨不平顺导致轮轨匹配度下降、波磨导致轮轨噪声增大的问题。[方法]根据实测不同区段波磨特征及噪声情况,建立了波磨不平顺下的噪声发展预测模型;分析了波磨1/3倍频程特征与产生噪声主频率,得出了易激发噪声波磨波长特征;分析了钢轨质量和列车运行速度与钢轨噪声间的关系。[结果及结论]轮轨噪声由钢轨噪声和车轮噪声叠加构成。频率在2000 Hz以内时,轮轨噪声由钢轨噪声主导;频率在2000 Hz以上时,轮轨噪声由车轮噪声主导。波磨不平顺会加剧轮轨噪声,轮轨噪声的敏感波长为25~55 mm,波谷越大则噪声越大,打铣磨可以降低轮轨噪声。轨道质量对轮轨噪声的影响较小,但列车运行速度对轮轨噪声有着显著的影响,车速越快则轮轨噪声越大,因此,在居民区等公共场合,可以通过适当限速来降低噪声对周边环境的影响。

轨面短波不平顺时域反演算法研究

轨面短波不平顺对轮轨噪声、车辆轨道各部件的动力学破坏作用巨大,为得到其具有代表性的时域波形,并进一步研究轮轨振动噪声和轨面状态仿真分析提供基础,提出一种基于轨面粗糙度水平谱反演短波不平顺时域波形的算法。由于反演过程中相位的随机性,使该算法在保证代表性的同时又具备一定随机性。在此基础上,用该算法实现了ISO3095标准谱与上海轨道交通实测谱的反演,结果表明反演算法可行且正确,反演得到的轨面短波不平顺时域波形可作为轮轨动力学仿真模型的激励输入,也可为预测轨面不平顺发展提供初始数据。

Preliminary Study on the Seizure Trend of a MOM-THP with Self-directed Balls

This work continues the approach of one of our topics relating to a MOM-THP （metal on metal-total hip prostheses） with self-directed movement balls. Experiments revealed a certain seizure in some strain conditions. Laboratory trials for balls/plane Hertzian contacts have been restarted in order to determine seizure behaviour depending on the roughness of the flat area. The trials have been carried out in BSF （body simulated fluid） lubrication conditions, much closer to the real operating conditions up against the initial tests with distilled water. Seizure burdens to different loadings and contact surfaces roughness influence over the seizure burden have been determined. Even though the minimum value of the wear must be the same with the minimum value of the surfaces roughness, given the experimental conditions, it came out from the trials results on wear that the lowest level of wear is acquired at a certain value of roughness, not at the lowest level of roughness.