The Analysis of the First Order Bending Stiffness of Vehicle Body in Different Loading Conditions

The first order vertical bending mode of vehicle and its stiffness are very important to the dynamic characteristics. A high-speed vehicle body was selected to study on, the differences of the sections stiffness features were considered, with the unknown sections geometry sizes, mass and mass distribution. Under the different load, the first order bending stiffness of the seven sections and the equal bending stiffness of the vehicle body was calculated only using the modal test data. The result was validated by the tested mode frequency. The research showed that the sections upon air-spring have lower stiffness, and the rice loading on the vehicle body would reduce the vehicle body bending stiffness. However, the middle section stiffness would increase with fixed number of passengers on the vehicle.