Haozhong Huang

Analysis of lubricating performance for spur gear pairs applying tribo-dynamic model

A tribo-dynamic model for spur gear pairs combined dynamic loading with elastohydrodynamic lubrication theory is proposed in this paper. The integrated model incorporates a transverse-torsional dynamic model and a mixed elastohydrodynamic lubrication model to predict the dynamic behavior and lubricating performance of a spur gear pair under typical operating conditions. The dynamic model considering time-varying mesh stiffness, backlash as well as friction force generated from contact surfaces is built up to predict the dynamic tooth forces and surface velocities for the elastohydrodynamic lubrication model. In return, the elastohydrodynamic lubrication model taking into account the transient effect provides the dynamic model with viscous damping, friction forces and moments that play a non-negligible role in free and forced vibrations. In view of the convergence and efficiency, an iterative calculation program combined Runge-Kutta method and the multigrid method is developed to implement the tribo-dynamic model orderly to investigate the mutual relationship between the two models. The elastohydrodynamic lubrication predictions of the proposed model under dynamic conditions are compared to those obtained from a quasi-static elastohydrodynamic lubrication model to demonstrate the influence of the coupling effect on the elastohydrodynamic lubrication behavior. Simulation results indicate that the vibration caused by time-varying gear mesh force may enhance the friction coefficient at high speed.

Biodiesel preparation from Jatropha oil catalyzed by KF/Red mud catalyst

ABSTRACT Biodiesel preparation from Jatropha oil catalyzed by KF/Red mud (KF/RM) was studied. The optimum values of parameters for preparation of Jatropha oil biodiesel were obtained. The conversion rate of transesterification reached 92.2% under the optimum conditions, and the used KF/RM could be regenerated. Catalyst characterization showed that KOH and KFeF4 were produced in KF/RM catalyst, which was crucial for the transesterification of Jatropha oil with methanol. Red mud was a good support to prepare KF-loaded catalyst, and prepared KF/RM was an excellent catalyst for biodiesel synthesis from Jatropha oil via transesterification reaction.