形貌优化在驾驶室支架NVH设计中的应用研究

Study on the application of topography optimization in the NVH design of cab bracket

形貌是零部件的关键特征,它不仅影响零部件的质量,更影响零部件的动态特性,如NVH(噪声、振动、声振粗糙度)特性。为了提高驾驶室的NVH性能,提出将形貌优化技术应用到驾驶室支架的NVH设计中,通过改变支架的形貌,提高其动态特性,降低支架上端振动加速度,从而提高驾驶室的舒适性。在Hyperworks建立支架有限元模型,再根据试验测试的数据分析了当前驾驶室支架的NVH传递特性,并进行有限元模型校正。在二阶频率处,仿真结果为10.23 m/s^2,试验结果为9.79 m/s^2,相对误差为4.49%;在三阶频率处,仿真结果为4.24 m/s^2,试验结果为4.48 m/s^2,相对误差为5.35%,各阶相对误差均小于5.5%,表明模型具有较高的准确性。再以支架本体为设计变量,以支架上端振动加速度最小值为优化目标,进行形貌优化,得到三种优化方案。最后根据优化方案进行CAD(计算机辅助设计)建模,对新建模型进行模态频率响应分析,选取较优方案。结果表明,支架加强筋的分布方式对其模态频率及刚度有较大影响,三种优化方案均达到了不同程度的优化效果,其中方案三优化效果较为明显,第二、三阶的振动加速度降低幅度达到59.7%、61.2%,关键频率避开了激励较大的频率区域。优化结果表明,通过合理的设计零件的形貌能够达到改善汽车NVH的性能,为类似汽车零部件NVH性能的改善提供一种新的思路与方法。

Topography is the key feature of parts. It affects the quality and dynamic characteristics of components, such as NVH （noise vibration harshness）. In order to improve comfortable perform- ance of the cab, topography optimization Changing the shape bracket can improve technology is applied to the its dynamic characteristics, design of the cab NVH stent. reduce vibration acceleration,and improve NVH performance of the cab. Finite element model of cab bracket is designed in the Hyper-works. According to the test data, the NVH transfer characteristics of the cab bracket are an- alyzed to ensure the model correctness. The simulation results and the test results are 10.23 m/s2 , 9.79 m/s2 in the second order frequency, which the relative error is 4. 49% ; in the third-order fre- quency simulation results are 4.24 m/s2, test results are 4.48 m/s2, relative error is 5.35%. Each order relative error is less than 5.5 percent, which indicates that the model has a high accuracy. According to the optimization results with the bracket body as design variables, the vibration acceleration minimum as optimization objective, three CAD models of the cab bracket schemes are redesigned to comparing modal frequency response analysis results and to determine a best scheme. The results show strengthening ribs layout has a greater effect on the modal frequencies and stiffness. The vibration acceleration of the bracket is significantly reduced. The third optimization is most obvious, the vibration acceleration are reduced 59. 7% , 61.2% in the second and third order, and the key frequencies are avoided the excitation frequencies. The optimization results show that rational design of parts topography can improve vehicle NVH performance, the application of this method will provide a new way for improving the performance of NVH in similar parts.