In a marine environment, the working conditions for carbon brush and slip-ring system are complicated, leading to carbon brush abrasion and a shortened replacement cycle. A research and experiment platform using a salt spraying tester has been established to study abrasion on the carbon brush and slip-ring system of a Doubly-fed machine. We conducted tests on the carbon brush and slip-ring system contact current, contact pressure, concentration of salt spray, and the experimental temperature. The improved Coulomb-viscous friction model was adopted for modelling the carbon brush abrasion. The contact current, contact pressure, salt spray concentration and temperature were introduced as the test conditions for the forecast model, and the unknown model parameters were identified through the least square method. MATLAB was utilized to fit the nonlinear model parameters using the carbon brush abrasion prediction model results. The residual error plot and test data fitting indicated that the prediction model could effectively forecast the carbon brush abrasion loss under various conditions.INDEX TERMS Carbon brush and slip-ring system; salt spray test; prediction of abrasion; contact friction
This article proposed a novel friction stir rivet welding process to join aluminum alloy 6061-T6 sheets in lap configuration with threaded rivet employed. The material flow behavior and temperature distribution of FSRW process are analysed using Simufact Forming 15.0 software, and joints have been obtained on the modified CNC machine with 1200rpm rotational speed and 10s dwell time. Rotational speed and dwell time are important factors which affecting mechanical properties of FSRWed joints. The welding heat input is determined by the rotation speed, while the heat time of plasticized materials is controlled by dwell time during FSRW process. In order to obtain FSRWed joints with excellent mechanical properties, welding heat input is taken as measurement standard, and the reasonable range of rotational speed and dwell time have been investigated by numerical simulation and statistics. The macroscopic morphology of 3 mm and 4 mm thick aluminum alloy 6061-T6 FSRWed joint we obtained shares uniform characteristic with the numerical simulation forming appearance whose upper surface tests smooth but exists "flash", and stir zone, heat affected zone, thermo-mechanically affected zone and base metal four distinct zones can be observed in transverse section. The results of numerical simulation and experimental study show that the potential process we proposed takes advantages of solid-state welding and riveting technology. Not only metallurgical bonding can be obtained between upper and lower sheets, but also mechanical properties will be strengthened by riveting.
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