基于运用条件和频域特征的动车组转向架构架疲劳损伤规律研究

Research on Fatigue of Bogie Frame of EMU Based on Running Conditions and Frequency Domain Characteristics

转向架作为动车组车辆的关键部件,担负着承载与走行等多种任务,传递不同形式的动态载荷,有必要对其疲劳问题进行研究。以某型城际车动车和拖车转向架构架为研究对象,在对构架疲劳关键点动应力进行线路实测基础上,依据速度、航向角以及部分线路参数,提取到直线、不同半径曲线、启动牵引、混合制动以及低速过站等不同工况下各测点的动应力数据,分析和比较各测点在不同运用条件下的疲劳损伤特点。通过时-频变换方法,得到不同速度下动车和拖车各主要测点动应力幅频特征,进而分析各测点动应力峰值频率所对应的系统固有频率和外界激励频率,探讨不同频率成分的动应力对各关键点损伤的贡献情况。研究发现,相同速度和曲线半径下,多数动车疲劳关键点的等效应力大于拖车。在车辆接近停止时,抗蛇行减振器座和横侧梁连接处的动应力会存在一个大幅值循环,这与车体惯性力对抗蛇行减振器的作用有关。中低速过道岔时,各测点的动应力变化范围均有一定程度的增大,以横侧梁连接处和抗蛇行减振器座处变化最为明显,其他疲劳关键位置的动应力变化相对较小。达到相同损伤占比时,绝大多数动车构架测点的动应力频带比同速度下拖车构架更宽。

As the key component of the EMU vehicle,the bogie is taking on the tasks such as carrying,running,and transferring different forms of dynamic forces,therefore,it is very necessary to study its fatigue problems.In this research,the bogie frames of a certain intercity EMU motor car and trailer car are chosen as the research object.Based on the measurement of the bogie frame on the high-speed line,the dynamic stress of the key point on the frame is acquired.Combining with the signals such as speed,heading angle and some line parameters,the working condition such as straight lines,curves with different radius,traction process,hybrid braking process and passing stations with a low speed are differentiated,and the dynamic stress referring to these working conditions are extracted.Then the fatigue characteristics of each measuring point under different working conditions are analyzed and compared.Through time-frequency transform,the amplitude-frequency characteristics of dynamic stress at the main measuring points of the motor car and trailer under different speeds are obtained,and then the system natural frequency and the external excitation frequency corresponding to the peak frequency of the dynamic stress at each measuring point are analyzed.Furthermore,the contribution of the dynamic stress with different frequency component to the damage of each measuring point are discussed.The results show that with the same speed and curve radius,the equivalent stress at most key point of motor car is greater than that of the trailer.When the speed is closing to zero,there will be a large-magnitude cycle of the dynamic stress at the hunger of anti-hunting damper and the connection of lateral beam and side beam,which is associated to the action from the inertial force of the car body to the anti-hunting damper.When crossing a turnout at a low speed,the range of dynamic stress at each measuring point is increased to a certain level,the most obvious change is at the hanger of anti-hunting damper and the connection of lateral beam and side beam,and relatively smaller change can be seen at other key points.With the same speed,when the equal damage ratio approaching,the frequency band of the dynamic stress at most key points of the motor car’s bogie frames is wider than that of the trailer car.