Analysis of the Gyroscopic Stability of the Wheelset

Abstract

The wheelset of the railway vehicle is a rotor which itself has gyroscopic effect. Nowadays, the rolling stock has entered the era of high speed, and the wheel rotates faster than in the past. The influence of gyroscopic effect on stability is little understood. Metelitsyn’s inequality theorem for asymptotic stability has some advantages to analyze this problem although this method is sufficient but not necessary condition. Based on its deduction, the extremal eigenvalues criterion and compared with Routh-Hurwitz criterion, both are applied to solve the critical value of speed. Further, according to the instability criterion, gyroscopic contributory ratio is derived to study how the role the gyroscopic effect plays in stability. Moreover, the effect of gyroscopic matrix or gyroscopic terms pitch rotor inertia Iy on stability coefficient is investigated. The results show that Iy is a key factor to wheelset gyroscopic stability. The gyroscopic effect becomes significant, and the stability increases with increasing Iy. The results also indicate that the critical value of speed solved by Metelitsyn theorem is more conservative than the one it solved by Hurwitz criterion, which proves that Metelitsyn inequality theorem for asymptotic stability is a sufficient but not necessary condition in the way of attaining the numerical simulation result. Finally, the test for the influence of gyroscopic effect on stability needs to be further studied.

Carbody vibrations of high-speed train caused by dynamic unbalance of underframe suspended equipment

“…Lightweight can effectively reduce the interaction forces between wheels and rails, save energy, and lower the production costs. [1][2][3] However, it may result in the decrease of structural rigidity of the body, increase of flexible vibrations and worsen the passenger ride comfort. Therefore, the issues of carbody vibrations considering the carbody elasticity have been paid much attention by researchers, especially for high-speed electric multiple units (EMUs).…”

On the Critical Speed, Supercritical Bifurcation, and Stability Problems of Certain Type of High-Speed Rail Vehicle

“…Since the nonlinear bifurcation theory is utilized in solving nonlinear vehicle problems [1][2][3], the study on the calculation of critical speed gets a great deal of achievements [4,5]. The right way for calculating the critical speed refers to the path following (continuation) or ramping method [6].…”