The fluid dynamics of dampers is investigated for the case where the damping fluid flows through passages in which a magnetic field is applied. This is a specific case of a new and promising field of applications that has emerged through the design of devices that take advantage of some properties of the so-called electrorheological fluids and magnetorheological fluids (ERF and MRF). These fluids are created when a base fluid is seed with very small dielectric or iron particles, so that it reacts to electric or magnetic fields by developing some non-Newtonian characteristics, most prominently a yield stress, viscosity change, and also viscoelasticity. These fluid properties can be controlled through control of the electric or magnetic fields’ strength. In this paper, a typical damping load is modeled and related to the required flow of a MRF inside the damper. To this end the fluid is modeled as a Bingham fluid with time-varying yield-stress. The analysis here developed makes it possible to determine the magnetic field variation necessary in order to achieve a specific displacement of the damper’s piston. The flow equations are analytically solved for any time-history of the dimensionless fluid’s yield-stress. Main results are some simplified relationships that correlate damping load and magnetic field time-variations. These results aim at providing analytical tools that may facilitate dampers’ design.

1.
Nakamura
T.
,
Norihiko
S.
and
Nakazawa
M.
(
2004
). “
Variable viscous control of a homogeneous ER fluid device considering its dynamic characteristics
,”
Mechatronics
,
14
, pp.
55
68
.
2.
Lee
H-G.
and
Choi
S-B.
(
2002
). “
Dynamic properties of an ER fluid under shear and flow modes
,”
Materials and Design
,
23
, pp.
69
76
.
3.
Jolly
M. R.
,
Carlson
J. D.
and
Mun˜oz
G. C.
(
1996
). “
Model of the behavior of magnetorheological materials
,”
Smart Mater. Struct.
,
5
, pp.
607
614
.
4.
Weiss
K. D.
,
Carlson
J. D.
and
Nixon
D. A.
(
1994
). “
Viscoelastic properties of magneto- and electrorheological fluids
,”
J. Intell. Mater. Syst. Struct.
,
5
, pp.
772
775
.
5.
Norris, J.A., and Ahmadian, M. (2003), “Behavior of magneto-rheological fluids subject to impact and shock loading,” Proceedings of IMECE03, American Society of Mechanical Engineers, paper 42891.
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