扭力梁式后悬架模态与疲劳实验研究

摘要

扭力梁式后悬架是汽车行驶系统中重要的承重构件,在不同的行驶工况下,会受到不同幅值和不同频率的激励.在激励频率和扭力梁式后悬架固有频率接近或相同时,会产生共振,进而发生疲劳断裂.通过对扭力梁式后悬架进行模态实验,获得该结构的固有频率和模态振型.对同一型号的扭力梁式后悬架进行弯曲、扭转疲劳实验,得到其疲劳破坏的具体形式.对产生破坏的扭力梁式后悬架进行模态实验,对未损坏和损坏的扭力梁式后悬架各自的固有频率和模态振型进行对比分析,发现产生疲劳破损的扭力梁式后悬架在某一阶频率下的模态振型有较大变化,结构的固有频率值和固有频率分布的变化并不很大.%Torsional beam rear suspension is an important load-bearing component in automobile's driving system. It is subjected to the excitations with different amplitudes and different frequencies under different driving conditions. When the excitation frequency and the natural frequency of the torsional beam rear suspension are close each other, the torsional beam rear suspension resonates, and then the fatigue fracture may occur. In this paper, through the modal test, the natural frequencies and the modal shapes of the torsional-beam structure are obtained. Then, bending and torsion fatigue tests of the torsional beams of the same type are carried out to get the specific forms of the fatigue damage. Finally, the modal experiments are carried out on the damaged torsional beam rear suspension. The natural frequencies and modal shapes of the healthy torsional beam rear suspension and the damaged one are mutually compared and analyzed. It is found that the torsional beam rear suspension with fatigue damage has a great change in the modal shapes comparing with the healthy suspension, but the frequencies and the frequency distributions of both structures are essentially the same.