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Friction

Keywords

friction coefficient, Coulomb friction force, drum brakes, contact force.

Abstract

The suitable brake torque at the shoe–drum interface is the prerequisite of the active safety control. Estimation of accurate brake torque under varying conditions is predominantly the function of friction coefficient at the shoe–drum interface. The extracted friction coefficient has been used in the antilock braking system (ABS) algorithm to plot the µ–slip curve. The longitudinal forces like Coulomb friction force, contact force and actuating forces at the shoe ends are resolved under the equilibrium condition. The computation of the friction coefficient is presented for the symmetric and asymmetric length of the drum shoes to track the variations in the longitudinal forces. The classical mechanics formulae considering friction are simulated using virtual environment in Matlab/Simulink for the distribution of the Coulomb force. The dual air braking system set up operated at the 8 bar pressure is used to acquire data for the input parameters like distance of Coulomb friction force, distance of pivot point, and contact force applied. The evolved estimation algorithm extracted the maximum friction coefficient of 0.7 for the normal force arrangement of the contact force at the symmetric shoe length, while friction coefficient in the range of 0.3–0.7 is obtained at the asymmetric shoe length.

Publisher

Tsinghua University Press

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