Abstract: In order to study the vibration characteristics of rails in ballastless railroad, a P60 typical rail with unit length was tested with the impulse hammering excitation method. The force and acceleration responses of the rail were measured, and the frequency response was obtained by analyzing the rail admittance using DASP software. The frequency response graph of acceleration admittance was plotted. The vibration characteristics below 10000Hz frequency of the rail-top, the rail head side and the rail waist at the midpoint of the rail-specimen were given. The results show that the vibration response of the rail- waist at the midpoint of the rail specimen decreases gradually when the location of excitation translates from the midpoint to both ends of the rail. Since track admittance analysis is the basis of noise analysis, and is helpful for detecting the location and mechanism of noise sources, these results may provide the experimental data for theoretical analysis of the high-frequency admittance performance of the rail in ballastless railroads and the determination of the frequency-range for noise reduction and the location of the noise sources.

Key words: vibration and wave, rail, admittance, spectrum analysis

摘要： 为研究无砟轨道钢轨的振动特性，以1 m长P60标准钢轨为研究对象，采用脉冲锤击激励法在实验室内进行试验。通过测量力响应及加速度响应，及运用DASP软件分析得出钢轨导纳（传递函数）的频响数据，计算得出钢轨在不同位置激励时跨中各拾振点的加速度导纳频响图。实验结果给出钢轨跨中截面轨顶、轨头侧面、轨腰、轨底各位置在10 000 Hz以下的振动特性。对不同位置激励时，跨中轨腰处振动响应受力的影响从跨中到两端效果逐渐减弱。轨道导纳分析是噪声分析的基础，有助于探明轨道噪声源产生的主要位置及其产生机理。该结果为无砟轨道钢轨的高频振动导纳特性的理论分析及其减振降噪频域范围和发声源位置的确定提供实验依据。

关键词: 振动与波, 钢轨, 导纳, 频谱分析