The total normal force (F) acting on the area of contact of disc clutch (Assuming uniform distribution of interface pressure) is:
(Where P is the intensity of pressure, r0 and ri outer and inner diameter of disc respectively)1
\(F = \pi P\left( {r_0^2 - r_i^2} \right)\)
2
\(F = \pi P{\left( {r_0^4 - r_i^4} \right)^{1/2}}\)
3
\(F = 2\pi P{r_i}\left( {{r_0} - {r_i}} \right)\)
4
\(F = 2\pi P{r_0}\left( {{r_0} - {r_i}} \right)\)