Based on the generalized principle of resonance, resonance demodulation method is used to transform the analysis on low frequency periodic impact of rail welded joints on the vehicle-track system into the analysis of high-frequency resonance. The envelope of the measured vertical acceleration of the axle-box preprocessed by band-pass filter is extracted by use of Hilbert transform, and discrete time Fourier transform is applied to calculate its refined envelope spectrum. The percentage ratio of the energy corresponding to the first dominant frequency of the envelope spectrum to its partial energy sum within 0~ 5 Hz is presented to describe the periodic impact characteristics of the rail welded joints on the vehicle-track system. The curve of the percentage ratio in terms of filtering frequency is calculated, and that which corresponds to the peak of the curve is chosen as the cutoff frequency of the band-pass filter. Then the frequency range 20~450 Hz of the band-pass filter for the vertical acceleration of the axle-box is obtained. By combining the position information of the rail welded joints with large RMS value of vertical acceleration and the property that their periodic spacing is approximately 100 m, a detailed algorithm is introduced to precisely determine the position of the rail welded joints with small RMS value of vertical acceleration. According to the probability distribution RMS value of the vertical acceleration of the rail welded joints of high speed railway within 300 km ? h-1, the value 50 m ? s-2 is chosen as the threshold for evaluating the status of rail welded joints. On this basis, the dynamic evaluation and implementation method for rail welded joints of high speed railway within 300 km ? h-1 is given.%基于广义共振原理,利用共振解调方法将钢轨焊接接头对车辆—轨道系统的低频周期性冲击特征的分析转换为对其高频共振的分析.对轴箱垂向加速度实测数据进行带通滤波,然后利用希尔伯特变换得到轴箱垂向加速度包络,并采用离散时间傅里叶变换对包络进行分析得到细化包络谱.利用细化包络谱第1主频能量与其0～5 Hz内的总能量之百分比反映钢轨焊接接头对车辆—轨道系统的周期性冲击特性,并根据该百分比与滤波频率的关系曲线的峰值确定带通滤波截止频率,由此得到带通滤波的频率范围是20～450 Hz.结合钢轨焊接接头处轴箱垂向加速度有效值出现大值的位置和钢轨焊接接头周期性间距近似为100 m的性质,对钢轨焊接接头进行精确定位.根据300 km·h-1速度级高速铁路钢轨焊接接头处轴箱垂向加速度移动有效值的分布规律,确定其阈值为50 m·s-2,依此作为评判钢轨焊接接头状态的依据.在此基础上,给出了300 km·h-1速度级高速铁路焊接接头状态动态评判方法和实现方式.
展开▼
