Characterisation of a Carbon/Carbon Multi-Plate Clutch for a High Energy, Race Car Application

The torque output of a carbon/carbon multi-plate Formula One clutch during race starts has proved to be both unstable and inconsistent. A specially designed single clutch-plate interface dynamometer (SCID) showed the formation of narrow (~2 mm), high-temperature (1300-1650°C) hot bands during tests replicating race start conditions, suggesting that less than 15% of the full friction surface areas were in contact. A thermomechanically coupled finite element analysis (TCFEA) was developed to simulate the thermomechanical behaviour of the clutch plates during SCID testing. With allowance for wear, the TCFEA closely replicated the SCID results. Both the SCID and TCFEA demonstrated no radial movement of the hot bands during single engagements indicating that torque instability is due to surface morphology effects alone. The hot band migration observed between successive SCID engagements indicated that torque inconsistency is due to both surface morphology and hot band migration effects.