From investigating the porosity and graphite effects on sintered bronze for wet clutch applications, it is clear that elasticity, as determined by the porosity and the graphite content, is important for both the friction coefficient and the power absorbing capacity.
The apparent elastic modulus values, measured by a compression test of clutch disks, show a very good correlation with performances of various wet friction materials (sintered bronze, paper, graphitics and elastomerics) in both an inertia-brake type clutch testing machine and also on the full-size powershift transmission bench. The lower elastic modulus material has the higher friction coefficient and the better energy/power absorbing capacity.
Effects of the material pores, the oil-groove patterns and also the material deterioration on friction performances and hot-spot size are discussed in conjunction with apparent elastic modulus.