Modal Analysis for Rear Torsion Beam on Car

The inherent vibration characteristic of rear torsion beam was used to analyze for revealing the mechanism easy to appear vibration fatigue when the car was suffered from actual road excitation.In order to get more accurate inherent vibration characteristic of the rear torsion beam,the suspension position,excitation position and the measuring point of modal test were firstly focused and optimized according to actual situation.Secondly,the structural natural frequency and vibration mode characteristics were achieved by using the optimal modal test method to identify modal parameters of rear torsion beam under free-free conditions.By contrasting with the finite element analysis results,the FE analysis for first-ten free modal frequencies matched with test,and the error was in 6%.It has verified that the optimization of the modal test scheme could acquire more accurate to identify the modal frequency of structure,and get structural inherent vibration characteristic.