地铁车辆转向架天线梁模态与疲劳寿命分析

国内某地铁车辆转向架的ATP天线梁频繁出现断裂,为探寻天线梁断裂的原因,对其进行现场试验分析。依据实测的天线梁约束模态及有限元软件计算的整备状态下模态结果,分析天线梁实测动应力频谱的主频及振型,并利用IIW-1823《焊接接头与部件的疲劳设计标准》计算天线梁上测点的等效应力范围和疲劳寿命。结果表明,天线梁的1阶垂弯、1阶横弯及与构架八字变形的耦合振型(75 Hz)均对天线梁的疲劳寿命造成较大的影响;在随机振动疲劳分析下,天线梁上大部分测点的等效应力都已经超过焊缝的疲劳极限80 MPa,尤其是位于天线梁横梁中部支座上的T4测点,等效应力为214.4 MPa,已经极大地超过焊缝的疲劳极限,而且疲劳寿命也远远达不到设计要求。

Modal analysis and fatigue life analysis of antenna beam on metro vehicle bogie

ATP antenna beam on metro vehicle bogie often breaks in some China metros.In order to identify the cause of the break,the field test analysis is conducted.Based on the measured constrained mode of the antenna beam and the modal results calculated by the fi nite element software under the servicing state,this paper analyzes the dominant frequency and mode vibration pattern of the measured dynamic stress spectrum of the antenna beam,and calculates the equivalent stress range and fatigue life of the measuring points on the antenna beam by using IIW-1823 Recommendation for Fatigue Design of Welded Joints and Components.The results show that the first-order vertical bending,the fi rst-order transverse bending and the coupled mode shape(75 Hz)of the antenna beam have a great impact on the fatigue life of the antenna beam.Under the random vibration fatigue analysis,the equivalent stress of most measuring points on the antenna beam has exceeded the fatigue limit of 80 MPa,especially T4 on the middle support of the antenna beam and the equivalent stress is 214.4 MPa,which has greatly exceeded the fatigue limit of the weld,and the fatigue life fails the design requirements by big margin.