Influence of Clutch Output Shaft Inertia and Stiffness on the Performance of the Wet Clutch

Being a part of the complex mass, spring, and damper system in a driveline, the choice of design factors such as output shaft stiffness and inertia of a wet clutch system can influence its performance. The effects of these parameters were experimentally evaluated. Widely used commercial paper-based friction plates with standard steel reaction plates were tested with four different stiffness and inertia combinations in a recently developed wet clutch test rig. A low inertia system in general showed a faster degradation and shorter clutch life for high torsional oscillation. In addition, the system became more shudder sensitive for lower natural frequency in the case of a less stiff system. The less stiff output shaft with low inertia showed the highest shudder tendency among the four conditions. The differences in performance for different output shaft conditions were noticeable for numerous clutch engagements or a degraded system. The effect of different shaft design conditions was also illuminated in the topographical analysis of the separators’ surfaces and morphological study of the frictional surfaces. This study revealed the influence of both inertia and stiffness not only on shudder sensitivity of the system but on the clutch frictional performance as well as the overall clutch life.