Impact friction test for friction materials

Abstract
Friction material is widely used for conveyances, detents and clutches in machines. The friction materials must be qualified with high friction coefficient, heat exchange coefficient and stress strength. In many braking processes, the friction layers undergo impacting at quite high strain rate. The present paper presents a new design of modified Split Hopkinson Bar suitable for the investigation of the dynamic friction, and experiments carried on the friction layers, which are made of fibers reinforced ceramic matrix composite. The innovative system, named Split Hopkinson Pressure and Shear Bar (SHPSB), can apply both compressive and shear loadings on the specimen. We can attain the information of the two profiles of loadings with different methods according to the simulation of this system by ANSYS/LS-DYNA. We embedded quartz piezoelectricity crystal wafer in the transmitted bar at the side near the specimen to obtain the tangential loading information, and got the dynamic compression response of the specimen in the same way as traditional SHPB. At normal temperature, the experimental results show that the dynamic coefficient of friction varies from 0.15 to 0.23 due to different loading amplitude.