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.

To achieve a wider band gap and a lower cut-on frequency, a locally resonant phononic crystal (LRPC) with a dual-base plate is investigated in this paper. Compared with the LRPC with a single plate, the band structure of the LRPC with a dual-base plate is calculated using the method of plane wave expansion and verified by the finite element method. According to the analysis of the band curves of the LRPC with a dual-base plate, the mechanisms are explained. Next, the influences of the thickness of the plates, the stiffness of the springs, the mass of resonators, and the lattice constant are also investigated. The results show that the structural asymmetry between the upper and the lower plate is conducive to reducing the cut-on frequency and broadening the band gap effectively. The results indicate a different approach for the application of LRPC in vibration and noise control.

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.

Polygonal wear seriously decreases the lifespan of a tire of a passenger car and adversely affects vehicle dynamic safety. The present paper builds a model that reflects the dynamic contact characteristics of the tire and reveals the mechanism and conditions of polygonal wear of a tire. The model describes the dynamic contact behavior of the tread block and considers the characteristics of dynamic friction between the road and tread of a rolling tire. Conducting numerical bifurcation analysis, the paper reveals the conditions for self-excited vibration of the tread, i.e., the improper combination of the vertical load, wheel slip angle, tire pressure and vehicle speed considerably strengthen the lateral self-excited vibration of the tread, which is the direct vibrational source of abnormal circumferential polygonal wear. The polygonal wear of a tire occurs when a vehicle travels for a certain long distance at a so-called polygonal wear speed. The polygonal wear speed should induce lateral self-excited vibration on the contact tread of the tire and the frequency of the lateral self-excited vibration should be divisible by the rolling frequency of tire that is determined by the polygonal wear speed. Visible polygonal wear requires that the vehicle travels at a certain polygonal wear speed for a minimal distance to produce a stably developing polygonal wear pattern even for subsequent driving at variable speed.