M. Whittle et al., FLUID DYNAMIC LIMITATIONS ON THE PERFORMANCE OF AN ELECTRORHEOLOGICALCLUTCH, Journal of non-Newtonian fluid mechanics, 57(1), 1995, pp. 61-81
We examine flow in a cylindrical electrorheological clutch and discuss
the fluid dynamic and inertial effects which limit the speed of opera
tion. Time-dependent solutions of the equation of motion are developed
in which the fluid is treated as a homogeneous continuum obeying the
Bingham plastic constitutive equation. Some approximations have to be
made but the results give a realistic description of the acceleration
in clutches of practical dimensions. The problem is also approached in
an entirely different way by direct numerical integration using an al
ternative time-dependent model. There is agreement between the two met
hods and the results show that the fluid density and viscosity place a
n upper limit on the acceleration of the output rotor. This is only re
ached if very low moment of inertia rotors are used, otherwise the out
put hardware inertia is the limiting factor. Design formulae are devel
oped to give a rough estimate for the fluid limited acceleration and t
o define the minimum output moment of inertia that can usefully be emp
loyed to give maximum available acceleration.