Zuo Shuguang

Analysis of noise and vibration for a new pure electrical vehicle

In the four-wheel tumbler test bench of semi-freedom noise elimination chamber,test the noise and vibration characteristics of a new pure electrical automobile (PURE EV), and collect noise and vibration signals of moving parts in different speeds. Analyze the frequency distribution of internal noise and vibration. The signal analysis shows noise sources of interior are change as the increase in speeds. At low speeds, the noise radiated by differential is the main source; while at the high speeds, noise radiated by motor is the main source. And the vibration sources of interior are derived from the motor and wheels vibration respectively when at low and high speeds. Finally, present vibration and noise reduction methods according to the structure features of passenger car.

Studies of band gaps in flexural vibrations of a locally resonant beam with novel multi-oscillator configuration:

To realize a broadened band gap as a potential application of vibration control in the electric vehicle powertrain system requires, a novel configuration of locally resonant (LR) beam with multi-oscillators attached is proposed, in which two types of oscillators are periodically and alternately attached at identical intervals. An analytical model is proposed based on transfer matrix method, which is validated by a finite element simulation. The band gaps in flexural vibration generated by this novel structure are investigated by the analytical model. The band gap coupling effect is observed and the influence of the intervals and oscillator parameters are discussed. The novel configuration effectively enlarges the range of band gaps in flexural vibrations.

Bifurcation and factors influence analysis on self-excited vibration of tire tread:

The purpose behind this work is to discuss dynamic stability when self-excited vibration occurs on tire tread. First of all, a suspension-tire-tread model has been built for simulation, and the result shows the existence of self-excited vibration on tire tread under particular conditions. A six-component test of the wheel indicates that self-excited vibration often takes place on tire tread when the vehicle travels straightaway at high speed. Then, through bifurcation analysis of tire tread, we found that the speed of the vehicle and slip angle of the wheel play significant roles in vibration generation. Within the lateral speed component caused by the tiny slip angle, equivalent damping of system turns to negative and thus provides enough energy to be consumed by obstructions. In order to investigate the influence of this self-excited vibration on the system, the system model has been simulated with different parameters, such as vehicle speed, vertical load, and tire pressure. The result explains different wear characteristics from the driven wheel to the driving wheel, which provides the basis of polygonal wear calculation.

The Neural Network Direct Inverse Control of Four-wheel Steering System

The motorcycle model which has two degrees of freedom (2-DOF for short) is adopted to study the characteristics of four-wheel steering (4WS for short) vehicle, and the linear 2-DOF dynamic equation of 4WS vehicle is constructed in this paper. A neural network direct inverse controller is designed to control the steering system of 4WS through the offline identification and online learning processes. In contrast to other control methods, the neural network direct inverse controller is more effective in controlling the steering angle of rear wheel to actualize the slip angle minimization and to improve both the mobility at low speed and the handling stability at high speed.

Modeling and simulation analysis of rear axle with multi-degree-of-freedom

A dynamic vibration model of suspension-tire-tread four degree-of-freedom theoretical vibration model, taking time-delay into account, is established to study the range of speed to motivate self-excited vibration and the relationship of vibration character and speed. The numerical simulation of bifurcation is applied to the four degree-of-freedom system, and the vehicle speed range which can generate self-excited vibration of tire tread is found. The dynamic differential equations in the theoretical model can be used to further research.

Hopf bifurcation and stability analysis of a non-linear model for self-excited vibration of tire

This work explains the hopf bifurcation and stability of self-excited vibration with the variety of vehicle velocity. Polygonal wear of tire is one of the most pressing problems to be solved in the process of a vehicles research and design. Based on the non-linear character of friction coefficient, which combines the concept of static and kinetic friction, a model of tread-pavement, taking time-delay into account, is built. The phenomenon of hard self-excited and hopf bifurcation is proved after simulating in matlab.

Transfer path analysis of fuel cell vehicle interior air-borne noise

Taking fuel cell vehicle as an example, this paper carried out interior noise transfer path analysis. The application of the traditional method of transfer path analysis, the acoustic reciprocity law, proposed path contribution calculation method under single-frequency and the main frequency band. Through transfer path test of interior noise of fuel cell vehicle, acoustic transfer functions of different paths were measured and calculated, and interior air-borne noise was synthesized with actual excitation data. The contribution of different paths is analyzed, and the main transfer path was identified, which would be useful for fuel cell vehicle noise reduction.

A finite element analysis of the barrel-shaped helical spring on the vehicle rear suspension

It can improve the stability of the vehicle by using non-linear spring, such as barrel-shaped helical spring, in vehicle suspension. The barrel-shaped helical spring on the rear suspension of PASSAT B5 was analyzed is this paper. Firstly, the accurate physical model of the spring is built by 3D scanning and post-process. Then the stiffness of the spring was calculated by finite element analysis, and the influences of the major structural parameters on the springs stiffness were obtained. Finally, the FE model of the barrel-shaped helical spring was validated with experiment results.

Reverse modeling and CFD simulation of vortex blower used in fuel cell cars

One application of vortex blowers is to provide compressed air for fuel cell stack in fuel cell cars developed by Tongji University. However, it produces too much noise; therefore, it needs to analyze its flow field to study the mechanism of noise generation. In this article a complete CAD model of the vortex blower was first established by means of reverse engineering and its basic geometric parameters of the flow channel was obtained. Then the CAD model was processed and a suitable flow field mesh model for CFD simulation was established. By setting reasonable boundary conditions, the flow distribution and pressure fluctuations in the channel were obtained and the harmonic frequencies of noise were analyzed.