基于均方根值法的排气系统吊钩位置设计

Design of hook position for the exhaust system based on the RMS value

以某轿车排气系统为研究对象,阐述了均方根值(RMS)法在汽车排气系统吊钩位置优化设计上的应用。基于壳体简化的方法建立了有限元模型并进行了自由模态分析,结合锤击模态试验方法验证了有限元模型的准确性;通过频响分析得到排气系统的频率响应曲线,利用均方根值法设计吊钩位置;采用约束模态分析、静力分析与动态分析全面验证吊钩位置设计方案。结果表明,系统固有频率避开了发动机激振频率,橡胶吊耳疲劳寿命可以得到保证,且吊钩传递力较小,设计方案合理。该方法能够简单快速设计吊钩位置,验证排气系统的动力学性能与设计方案的合理性,为轿车排气系统减振设计提供理论依据。

This article,with the focus on the car’s exhaust system,expounds the application of RMS value in the optimal design of hook position.Based on the method of shell simplification,the finite-element model is set up and the free-modal analysis is carried out;the hammer modal test is conducted to verify that the finite-element model is accurate.The frequency-response curve of the exhaust system is identified by the RMS value,in order to make clear the hook position;the constrained modal analysis,static analysis and dynamic analysis are conducted to fully verify the design scheme of hook position.The results show that the natural frequency of the system avoids the excitation frequency of the engine,the fatigue life of the rubber-based hanging ear is ensured,the hook’s transfer force is small,and the design scheme is reasonable.With the aid of this method,the hook position is identified easily and quickly,and both the dynamic performance of the exhaust system and the rationality of the design scheme are verified.Therefore,this method provides theoretical basis for the design of the car’s exhaust system.