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When we acquire tactile sensation, contact and relative motion are necessary between our bodies and objects. This implies that the tactile sensation is produced by friction phenomena. The present paper describes the sliding test for estimating the tactile sensation associated with cosmetic foundation. When the cosmetic foundation is rubbed with an apparatus that imitates a human finger, two types of time-evolving signals-normal and tangential-are obtained as the source of the tactile information. In the sliding test with the apparatus under the frictional condition of humans acquiring the tactile sensation, frictional vibration is observed in the tangential signals, which should be related to the tactile sensation associated with the cosmetic foundation. When a surface with a grooved pattern that imitates fingerprints is used in the sliding test, two types of frictional vibrations are observed. If an adequate sliding velocity is selected, the slight difference between the four types of commercial cosmetic foundations is discriminable by using the signals of these vibrations.

As the herringbone-grooved journal gas bearing can rotate silently at high speed with low friction, and moreover it can be small-sized, it is used a lot in the fields such as information appliances. In this paper, the equation of motion of the herringbone-grooved journal gas bearing is derived using the gas force which can be obtained by applying the Navier-Stokes equation for the grooved and the ridged parts of a journal. The stability analysis can be performed when a journal rotates with a high speed by using the stability analysis method of Routh-Hurwitz, the root locus of complex eigenvalue analysis, and the time history analysis due to transient response vibration. Comparing with the already published analytical results, the physical meanings which have not been clarified in the conventional study are reported as for the stability of herringbone-grooved journal gas bearing. The stability chart is shown to be determined by considering the forward whirl and the backward whirl. In addition, it is reported that the present analysis results show a good agreement with the already reported experimental results. Furthermore, the parameters study as for the specification of gas bearing is performed, and it is shown that the stability chart changes due to the influence of specifications complicatedly.

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]