
68 Magnetorheological Fluid Technology: Applications in Vehicle Systems
where τ
y
is the yield stress of the MR uid induced by the applied magnetic
eld, η is the eld-independent plastic viscosity (the base viscosity), L is the
length of the inner cylinder, t
g
is the gap of the annular duct between the inner
and outer cylinder, R
1
and R
2
are the average radii of the intermediate pole
and the annular duct, respectively, L
m
is the length of the magnetic pole, t
m
is
the gap of the orice of the MR valve structure, and c is the coefcient, which
depends on ow velocity prole and has a value range from a minimum of 2.07
to a maximum of 3.07. Th ...