Vibration Characteristics Of Gear System Research Articles

Vibration characteristics of gear system with a cracked-gear tooth: modeling and experiments

Gear tooth crack failure is a cruel problem in the gear transmission system. The research on the simulation and experiment is the hotpots in the field. The theoretical and experimental investigations on the vibration characteristics of a gear system with a cracked gear tooth are carried out in this study. A finite element (FE) model is built to predict the crack propagation path in a gear tooth and determine the time-varying mesh stiffness (TVMS) of gear pairs. A dynamic model of the gear system is developed using the lumped-mass model. The established models are validated by comparing the computing results with experimental ones. The influences of crack length on TVMS and vibration characteristics of the gear system are analyzed in detail. The proposed methods can provide useful guidance for fault diagnosis and dynamic performance evolution prediction of a gear system.

Nonsmooth Vibration Characteristic of Gear Pair System with Periodic Stiffness and Backlash

As the most widely used power transmission device in mechanical equipment, the vibration characteristics of gears have a very important influence on the working performance. It is of great theoretical and practical significance to study the vibration characteristics of gear system. In this paper, a gear transmission system model is set up in a forcefully nonlinear form; the continuity mapping and discontinuity mapping are utilized to analyze the nonsmooth vibration. Then, the sliding dynamics of separation boundaries is studied by using the perturbation method and the differential inclusion theory. In addition, the periodic response of gear pair system is illustrated and Floquet’s theory is presented to confirm the stability and bifurcation of periodic response. Concurrently, the maximal Lyapunov exponent is obtained to accurately determine the chaotic state in gear pair system, which is consistent with the bifurcation diagram and Poincare section. Finally, a reasonable explanation is given for the jump phenomenon in bifurcation diagram.

Dynamic Analysis of Spiral Bevel Gear Pair under Time-Varying Backlash

Neglecting the influence of static transmission error, a non-linear dynamic model of spiral bevel gear pair with time-varying backlash was presented. Through the simplification of above model, the dimensionless form of gear system was obtained. Then, the dynamic characteristics of gear system were acquired by using Runge-Kutta method under the influence of time-varying backlash and torque. The results showed primary harmonic amplitude of gear backlash and torque had a significant effect on the non-linear and vibration characteristics of gear system. With the change of that, bifurcation phenomenon, quasi periodic motion and chaotic motion were detected. In addition, the variation and fluctuation of amplitude, containing displacement amplitude and velocity amplitude, were analyzed detailedly.

Dynamic simulation of spur gear with tooth root crack propagating along tooth width and crack depth

Gear tooth crack will cause changes in vibration characteristics of gear system, based on which, operating condition of the gear system is always monitored to prevent a presence of serious damage. However, it is also a unsolved puzzle to establish the relationship between tooth crack propagation and vibration features during gear operating process. In this study, an analytical model is proposed to investigate the effect of gear tooth crack on the gear mesh stiffness. Both the tooth crack propagations along tooth width and crack depth are incorporated in this model to simulate gear tooth root crack, especially when it is at very early stage. With this analytical formulation, the mesh stiffness of a spur gear pair with different crack length and depth can be obtained. Afterwards, the effects of gear tooth root crack size on the gear dynamics are simulated and the corresponding changes in statistical indicators – RMS and kurtosis are investigated. The results show that both RMS and kurtosis increase with the growth of tooth crack size for propagation whatever along tooth width and crack length. Frequency spectrum analysis is also carried out to examine the effects of tooth crack. The results show that sidebands caused by the tooth crack are more sensitive than the mesh frequency and its harmonics. The developed analytical model can predict the change of gear mesh stiffness with presence of a gear tooth crack and the corresponding dynamic responses could supply some guidance to the gear condition monitoring and fault diagnosis, especially for the gear tooth crack at early stage.