Abstract
A mathematical model is developed for a dynamometer for testing a two-disk friction brake system. The model accounts for the compressive shear properties of the friction disks as well as stiffness and inertial characteristics of the dynamometer. Friction coefficient/velocity relations are established using the measurement data and employed in the mathematical model to perform simulations of the dynamometer’s vibration response and instability.
Five different simulations are performed. The first four employ a fifth order polynomial fit from the coefficient friction measured experimentally. One of these four simulations uses data from noisy test while the other three utilize relatively low-noise tests. The fifth and last simulation is carried out using a theoretical coefficient of friction, being assumed to experience certain sinusoidal variation. Such function is used to study the effect of variability in kinetic coefficient of friction of the experimental data.
In the first four simulations (i.e. the experimental cases), it is observed that the simulations turn unstable when the friction-velocity slope becomes negative. That phenomenon is alleviated when higher damping is used. In the fifth simulation (i.e. the sinusoidal case), variation in the coefficient of friction is found to increase vibration in the dynamometer system.
