Abstract
Combining substructure and power flow theory, in this paper an external program is written to control MSC. Nastran solution process and the substructure frequency response are also formulated accordingly. Based on a simple vehicle model, characteristics of vibration, noise, and power flow are studied, respectively. After being compared with the result of conventional FEM (finite element method), the new method is confirmed to be feasible. When it comes to a vehicle with the problem of low-frequency noise, finite element models of substructures for vehicle body and chassis are established, respectively. In addition, substructure power flow method is also employed to examine the transfer characteristics of multidimensional vibration energy for the whole vehicle system. By virtue of the adjustment stiffness of drive shaft support and bushes at rear suspension lower arm, the vehicle interior noise is decreased by about 3 dB when the engine speed is near 1050 rpm and 1650 rpm in experiment. At the same time, this method can increase the computation efficiency by 78%, 38%, and 98% when it comes to the optimization of chassis structure, body structure, and vibration isolation components, respectively.
Highlights
IntroductionWith the continuous enhancement of life quality of human beings, consumers’ requirements of vehicle NVH (noise, vibration, and harshness) performance become more stringent
With the continuous enhancement of life quality of human beings, consumers’ requirements of vehicle NVH performance become more stringent
The power flow at the 20 locations shown in Figure 10 is quantified, and the first 3 locations in which most energy is input to the body structure are found, which are connecting points at transmission shaft support bushing, rear suspension lower arm bushing, and rear suspension lower arm bushing, all considered as the risky transmission path of interior noise
Summary
With the continuous enhancement of life quality of human beings, consumers’ requirements of vehicle NVH (noise, vibration, and harshness) performance become more stringent. The NVH performance is mainly measured based on two indicators, body vibration and interior noise. Through chassis components and isolation components, the energy is transferred in multiple directions and eventually input to the body structure, leading to vibration of thin plate parts. As a result, reducing the vibration energy input to vehicle body and controlling vibration of thin plate parts are two effective ways to make the enhancement of vehicle NVH performance [1]. Through using a simple vehicle model, the characteristics of vibration, noise, and power flow are, respectively, investigated. A kind of vehicle model with low-frequency noise problem is studied in this paper, and the transfer characteristics of vehicle system multidimensional vibration energy are obtained by virtue of substructure power flow analysis method. An improved proposal is made, which is verified to be useful through experiments
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