Search

Tire wear negatively affects vehicle safety and riding comfort. Abnormal wear is more dangerous and wears tires out more quickly. In this paper, numerical and sensitivity analyses of polygonal wear caused by unstable vibration are presented. The model used for this study was based on the works of Sueoka. Tread self-excited vibration was analyzed in a quantitative sense, which was qualitatively different from the work of Sueoka. Wear was plotted on tire circumference visually. The mechanism governing polygonal tire wear was investigated as that both the polygonal wear and the standing wave are caused by two types of tread vibrations that only differ in the extent of the tread vibration. Sensitivity analysis shows that decreases in tread mass and stiffness and increases in tread damping lead to noticeable reductions in tire wear. This information could help tire manufacturers produce tires that exhibit less wear caused by tread vibration. [ABSTRACT FROM AUTHOR]

Abstract: This paper presents an overview of the vibration problems which are experienced in running gas turbines, and other high-speed machinery. The primary problem is that of resonance, where response levels under dynamic loading can be 100 or 1000 times greater than the levels resulting from static loading of the same magnitude. These resonances can be caused by steady, non-oscillatory, forces being applied to a rotating disc and their prediction and observation from measurement under running conditions are essential capabilities for the machinery dynamics engineer. Additional problems can arise if instabilities are encountered, either from aerodynamic sources (flutter) or from rotor dynamics. In all cases where severe vibrations are encountered, they must be controlled by the introduction of extra damping to the critical components, usually by incorporating friction devices. The use of visual displays to illuminate and help to understand the complexities of vibration in rotating machinery structures is presented. [Copyright &y& Elsevier]

In general, asymmetrical shaft-disk systems have been investigated where unstable vibrations may occur. Most studies have treated a single resonance case for the linear system, and we have previously treated a single resonance case for the nonlinear system. However, when natural frequencies have a simple integer ratio relation in a nonlinear asymmetrical shaft-disk system, an internal resonance may occur and the vibration phenomena change remarkably compared to the characteristics of a single resonance case (the case without internal resonance). In this study, the internal resonance phenomena of an asymmetrical shaft are investigated theoretically and experimentally in the vicinities of the major critical speed, and twice and three times the major critical speed. We clarify that the shape of the resonance curves changes, almost periodic motions occur, and, especially, the occurrence of unstable vibration at the rotational speed of twice the major critical speed is extremely affected by the internal resonance. Further, we show the change of nonlinear phenomena between the systems with and without internal resonance. [ABSTRACT FROM AUTHOR]