Dynamic modeling of gearbox faults: A review

Meshing and dynamic characteristics analysis of spalled gear systems: A theoretical and experimental study

Time-varying mesh stiffness calculation of spur gears with spalling defect

Time varying mesh stiffness calculation of spur gear pair considering sliding friction and spalling defects

A “slice method” is adopted to calculate the time-varying mesh stiffness (TVMS) of helical gear pairs, where the tooth is divided into many individual sliced spur gears along the tooth width, and the TVMS of helical gear pairs is obtained by accumulating the TVMS of the sliced spur gear pairs. Based on the slice method, an improved analytical method (IAM) is proposed to calculate TVMS of the helical gear pairs. The proposed method is also verified by comparing TVMS obtained from IAM with that obtained from references and the finite element method. Based on the proposed IAM, the effects of the helix angle, gear width, modification coefficient and friction coefficient on mesh characteristics are also discussed. The results show that the total contact ratio of helical gear changes under different helix angles and gear tooth widths, and the fluctuation of mesh stiffness will reduce when the overlap contact ratio approaches an integer. Meanwhile, addendum modifications can not only change the total contact ratio but also affect the mean mesh stiffness of gear pairs. Furthermore, not only will the friction coefficients affect the mean mesh stiffness, and it can lead to an abrupt change of TVMS in double-teeth engagement region.

An improved analytical method for calculating time-varying mesh stiffness of helical gears

Dynamic characteristics of helical gears under sliding friction with spalling defect

Due to either elastic deformations or errors in the manufacturing or assembling of gears, shafts, bearings and their housings, it is an inevitable consequence that mesh misalignment between teeth occurs. The change in length of the contact line or the change in load distribution along the length of the contact line induced by mesh misalignment causes changes in the dynamic characteristics of helical gears. There is currently no satisfactory solution for the modeling and calculation of the internal excitation in helical gears with mesh misalignment and sliding friction that would reveal the changes in the dynamic characteristics. In this study, an improved calculation method of friction excitation is proposed based on the time-varying length of the contact line and the time-varying friction coefficient model in helical gears. By considering the change in the mesh position and the change in the length of the contact line or the change of the displacement error along the contact line induced by mesh misalignment, the time-varying sliding friction force and the dynamic mesh force may be obtained. An eight degree-of-freedom analytical helical gear pair model is developed by incorporating the time-varying sliding friction force and dynamic mesh force and considering the mesh misalignment. By assuming a constant mesh stiffness density along the contact line, the rules governing the variation of the dynamic response are obtained using simulations of helical gear pair examples with different friction coefficient models and mesh misalignment. The developed analytical model provides a new method for the study of excitation characteristics in helical gears with mesh misalignment.

https://link.springer.com/content/pdf/10.1007%2Fs12206-015-1001-5.pdf

The influence of mesh misalignment on the dynamic characteristics of helical gears including sliding friction

Dynamic characteristics of helical gears incorporating the effects of coupled sliding friction

The speed ratio parameters of transmission are crucial factors that affect a vehicle’s power, economy, and comfort. Due to the complex working conditions, multiple working modes, and wide range of speed ratios of agricultural tractors, designing and optimizing speed ratio parameters in power-shift transmissions is a challenging task. This paper proposes a transmission speed ratio optimization method based on the life cycle speed utilization rate of general-purpose agricultural tractors. The speed ratio parameters are optimized and solved using the genetic algorithm, with multi-gear power-shift transmissions in agricultural tractors as the research subject. The optimization results and simulation analysis show that the optimized speed ratio has more and denser gears in the common operating speed range while ensuring the general-purpose agricultural tractors’ use requirements. Compared to commonly used geometric series speed ratios, tractors using the optimized speed ratio parameters in this paper can significantly improve fuel economy. Most importantly, this provides a practical method reference for optimizing speed ratios in multi-gear gearboxes with complex structures.

/pdf/optimization-method-of-speed-ratio-for-power-shift-fo5ovbdd.pdf

Hanjun Jiang

Papers

Dynamic characteristics of helical gears under sliding friction with spalling defect

The influence of mesh misalignment on the dynamic characteristics of helical gears including sliding friction

Dynamic characteristics of helical gears incorporating the effects of coupled sliding friction

Optimization Method of Speed Ratio for Power-Shift Transmission of Agricultural Tractor

Dynamic analysis of spur gears system with dynamic force increment and velocity-dependent mesh stiffness