Stress response and fatigue damage assessment of high-speed train gearbox

A high-speed train line test was carried out, the GPS signal and mechanical characteristics of gearbox structure were researched, and the stress-time history curves under torque load and vibration load were obtained.The stress response characteristics of gearbox under the action of torque load and vibration load were analyzed, and the stress spectrum was compiled.The influencing parameter of fatigue damage was used to reflect the effect degrees of torque load and vibration load on the fatigue damage of gearbox.Research result shows that under torque load, the alternative change between train traction and braking can cause greater stress response of gearbox, and the maximum stress amplitude is 25.80 MPa.In the braking condition, the stress of gearbox fluctuates like ladder wave.The frequency of high stress amplitude at the end of gearbox hanger seat is higher at low speed than at high speed, and the influencing parameter of fatigue damage declines by 60.0% from 0.20 to 0.08.Under vibration load, when train speed drops from 350 km·h^-1 to 200 km·h^-1, the stress response strength at the end of gearbox hanger seat declines by 53.4% from 2.08 MPa to 0.97 MPa.The gearboxstress amplitude is lower at the front of train than at the tail at the same speed level.When the train transforms from traction state to inert operation, the stress response strength decreases by70.6%from 3.4 MPa to 1.0 MPa.When the train transforms from low speed to high speed, the influencing parameter of fatigue damage at the end of gearbox under vibration condition increases by 27.9 times from 0.009 to 0.260.