The effect of longitudinal tangential vibrations on friction and driving forces in sliding motion

The main purpose of the work has been to qualitatively and quantitatively analyse the influence of longitudinal tangential vibrations on friction and driving forces in a sliding motion. Computational models were developed and implemented in a combined Matlab-Simulink environment. Both the dynamic Dahlʹs and the Dupontʹs and classical Coulombʹs friction models were used. The influence of vibration velocity amplitude on the friction force in the presence of tangential longitudinal vibrations and on reduction of the driving force in sliding motion was analysed. It revealed that the commonly accepted view that the reduction of the average friction force is a consequence of cyclic changes in the sign of the friction force vector, only when the amplitude of vibration velocity is greater than the sliding motion velocity, is erroneous. The phenomenon was also observed without any changes in the sign of friction force vector. The results of simulations were compared with experimental data obtained with the use of a test rig specifically designed for the work. The Dahlʹs friction model led to the best correlation.