Showing 3 results for Friction
H. Pashazadeh, A. Masoumi, J. Teimournezhad,
Volume 3, Issue 1 (3-2013)
Abstract
The objective of this study was to develop a numerical model for the prediction of temperature distribution,
effective plastic strain distribution, and especially material flow in friction stir welding of copper plates.
The DEFORM-3D software was used by incorporating a lagrangian incremental formulation. Threedimensional
results of the material flow pattern which were extracted using the point tracking are in good
agreement with the experiment. It was shown that the main part of material flow occurs near the top
surface. Material near the top surface at the behind of tool stretches from retreating side towards advancing
side which leads to non-symmetrical shape of the stir zone. The stir zone shape in FSW of copper alloys,
which was predicted by simulation, does not lean completely towards any sides of welding line.
Ah Kakaee, Anvar Ahmadkhah,
Volume 11, Issue 3 (9-2021)
Abstract
Surface texturing modifications improve the tribological performance parameters. In parallel slider bearings with a micro-grooved textured surface, the effects of the Reynolds number and the texture aspect ratio at constant texture density have been studied; however, the texture density variation's effects on the tribological performance have not been investigated yet. The focus of this study is on the texture density variation in micro-grooved parallel slider bearings. The numerical analysis approach was utilized to perform a more in-depth understanding of texture density variation on the two-dimensional pressure distribution, skin friction coefficient, and recirculation zones in micro-grooves and the objective of flow functions such as load-carrying capacity and friction coefficient. In order to validate using the current CFD model for analyzing hydrodynamic bearings, a comparison with the published theoretical paper results was presented. The results were in good agreement with the published theoretical predictions. In a variety of aspect ratios, the texture densities led to an upgrade tribological performance. Results showed remarkable improvements in frictional response with texture density, and an optimal texture density exists. Finally, it was observed that the optimal micro-grooves texture density depends on the texture aspect ratio, while it is independent of the sliding velocity.
Dr. Abbas Soltani, Mr. Milad Arianfard,
Volume 13, Issue 2 (6-2023)
Abstract
In this study, an adaptive sliding mode controller (ASMC) based on estimation of tire-road friction coefficient is proposed for engagement control of automotive dry clutch. The control of clutch engagement is one of the most important parts of gear-shift process for automated manual transmission. Accurate amount of drive shaft torque in modelling of powertrain system is essential to guarantee smooth engagement of the clutch and rapid response of the control system. As the tire-road friction coefficient has significant influence on drive shaft torque, an estimator is designed to calculate this parameter. The ASMC is proposed for the clutch control to overcome the system uncertainties and a proportional integral (PI) controller is adopted to engine speed control. In addition, a nonlinear estimator utilizing unscented Kalman filter is applied to estimate the state variables that are measured hardly such as wheel slip and longitudinal vehicle velocity. The simulation results demonstrate the high effectiveness of the combined use of presented controller and road friction coefficient estimator for improving the smooth clutch engagement in comparison to the control system without estimator.
