Triacetin as Lubricant Additive: Slipping Friction between Metal Pairs under Boundary Lubrication

Friction between rubbing pairs plays a key role in operating machines in an efficient approach. In some intended works or occasional circumstances, slipping friction may occur during dry or boundary lubrication. Lubricating mechanical equipment using proper and efficient lubricant agents is tremendously necessary. This work explores the synthesized triacetin as an additive for lubricant under slipping friction between steel rollers and aluminum, brass, copper, and stainless-steel rods under boundary lubrication. The metal surface morphology under the lubricant with 10% triacetin additive covering roughness periphery is investigated by Field Emission Scanning Electron Microscope imaging. In the dry slipping condition, the friction coefficient is lower for the copper-steel pair compared to the aluminum-steel combination. Compared to the absence of triacetin additive, the steel roller combinations with the rod metal specimens undergoing boundary lubrication with 10% triacetin additive in the lubricant can reduce the slipping friction coefficient by up to 49.2% in the case of steel roller and brass rod pair. The quantitative influences of triacetin additive on metal rubbing pair friction coefficients under boundary lubrication are inversely exponential correlated to triacetin additive, varying in the range of 0 to 10% v/v.

A Transient Dynamic Model of Brake Corner and Subsystems for Brake Creep Groan Analysis

To improve the understanding of brake creep groan, both experimental and numerical studies are conducted in this paper. Based on a vehicle road test under the condition of downhill, complicated stick-slip type motion of caliper and its correlation with the interior noise were analyzed. In order to duplicate these brake creep groan phenomena, a transient dynamic model including brake corner and subsystems was established using finite element method. In the model, brake components were considered to be flexible body, and the subsystems including driveline, suspension, tire, and vehicle body were considered to be rigid body. Simulation and experimental results of caliper vibration in time and frequency domains were compared. It was demonstrated that the new model is effective for the prediction and analysis of brake creep groan, and it has higher accuracy compared to the previous model without the subsystems. It is also found that the lining and caliper not only have stick-slip motion in each coordinate direction but also have translational and torsional movements in plane, which relate to the microscopic sticking and slipping, friction coefficient, and forces, as well as the contact status at the friction interface.

Research about FPS Seismic Isolating System on Bridges

A numerical model was established for a continuous beam bridge with FPS bearings. It started from Lagrange equation in dynamic mechanics. The software for its numerical solution was presented with Newmark-β method. Computation results show that efficiency of the seismic isolation system is closely related to slipping friction factor on the contacting surface and slide radius. The internal forces (shear forces) for piers exhibit a significant reduction under an optimum combination of friction factor and slide radius. For friction factor being in the range of 0.1-0.2 and slide radius 1.5m, the shear force could be decreased by more than 50%, and the drift of beam would be less than 2cm in horizontal direction and less than 0.1cm in vertical direction respectively.

A Test Study of Wet Dual Clutch Transmission during Vehicle Launch

This paper focuses on the model and analysis of wet dual clutch transmission (DCT) during vehicle launch. Two evaluation indexes, slipping friction work and degree of jerk, is presented, and a single clutch control strategy is established and has been validated after applied for an experimental vehicle equipped with a wet dual clutch transmission.