Abstract: Exhaust pipe clamp on one certain heavy-duty vehicle experienced failure during use. After microscopic morphological observation, the fracture surface shows the hint of fatigue failure. The operating conditions of heavy duty vehicles include motor transport and in situ load. Firstly, experiments aiming at studying the vibration conditions of exhaust pipe clamp under these two working conditions are arranged and the two measuring points vibration acceleration values near fracture surface are get. The experiments results shows that exhaust pipe clamp occurred abnormally vibration when the vehicle works at power take-off condition and the engine works full load at 1 700 r/min. The modal simulation is done and the comparison between simulation results and experiment data frequency domain signal leads to the resonance occurred around 138 Hz. To avoid the failure happening again, the redesign of exhaust pipe clamp is done. The redesigned structure improves its modal frequency and can effectively avoid resonance. Finally, the experiments on redesigned structure find that the measuring points vibration acceleration decreased when the engine works at lower speed and increased when engine works at high speed. The redesigned structure doesn′t lead to significantly change of main frequencies, but the failure doesn′t happen in the course of subsequent use.

Key words: electro driven heavy-duty; exhaust pipe clamp; model simulation; design improvement

摘要： 某重载车辆排气管夹在使用过程中发生了断裂失效现象，经过微观形貌观察，断口呈 疲劳裂纹。所研究的重载车辆使用工况包括机动运输和原地取力，首先，针对排气管夹在这 两种工况下的振动情况进行试验研究，获取断口处两测点位置的振动加速度值。试验结果表 明，在原地取力且发动机 1 700 r/min 满负荷情况下，排气管夹测点加速度值异常，通过模态 计算并与该工况下的频域振动信号进行对比发现，共振主要发生在 138 Hz。为了避免排气管 夹再次出现失效现象，对其进行了设计改进。改进后的结构提高了自身的模态频率，能有效 避免发生共振。最后针对改进设计再次进行试验发现，在发动机低转速工况下管夹测点位置 振动加速度有所下降，但是发动机高转速工况下测点的振动加速度有所上升。改进后的设计 并未使主频成分发生明显改变，但是在车辆的后续使用过程中未再出现失效现象。

关键词: 电驱重载；排气管夹；模态分析；设计改进