<title>Effective design strategy for a magneto-rheological damper using a nonlinear flow model</title>

Abstract

This paper presents an effective design strategy for a magnetorheological (MR) damper using a nonlinear flow model. The MR valve inside a flow mode MR damper is approximated by a rectangular duct and its governing equation of motion is derived based on a nonlinear flow model to describe a laminar or turbulent flow behavior. Useful nondimensional variables such as, Bingham number, Reynolds number, and dynamic (controllable) range are theoretically constructed on the basis of the nonlinear model, so as to assess damping performance of the MR damper over a wide operating range of shear rates. First, the overall damping characteristics of the MR damper are evaluated through computer simulation and, second, the effects of important design parameters on damping performance of the MR damper are investigated. Finally, the effective design procedure to meet a certain performance requirement is proposed. A high force-high velocity damper is fabricated and tested, and the resulting model and design procedure are experimentally validated.

Experimental validation of a magnetorheological energy absorber design analysis

“…However, at a speed of 6.6 m/s (260 in/s), the dynamic range reduced nominally to D ≈1. They hypothesized that the transition from controllable ( D > 1) to uncontrollable behavior ( D ≈1) is related to the transition of fluid flow from laminar to turbulent, which is supported by the analysis of Mao et al (2005). Browne et al (2009) conducted impact tests of an MREA at stroking velocities ranging from 1.0 to 10 m/s and showed that the MR damper force could be tuned by adjusting the magnetic field.…”

“…A schematic diagram of annular duct type MR valve in a typical flow-mode MREA (or interchangeably called MR damper in this study) is presented in Figure 2. According to the BP nonlinear flow model, which considers laminar and turbulent flows (Franzini and Finnemore, 1997; Mao et al, 2005; White, 1986), the damping force, F , of the MR damper is given by…”

“…To do so, we developed a strategy to determine design variables numerically. Unlike the strategy in our prior work (Mao et al, 2005), this strategy applies to MREA designs with minor loss factors due to velocity squared effects for both laminar and turbulent flows. The procedure that was used is given below…”

“…Recently, magnetorheological energy absorbers (MREAs) have been proposed as stroking elements because they possess adaptive force capability needed for systems that require control of impact or shock loads for varying payload masses (Hiemenz et al, 2007; Mao et al, 2005, 2007a, 2007b). MREAs can provide adaptive vibration and shock mitigation capabilities to varying payloads, vibration spectra, and shock pulses for varying duration and/or magnitude (Choi and Wereley, 2008; Wereley et al, 2011), as well as other environment factors in a rapid manner (typically 5–10 ms) during the impact event.…”

“…Nevertheless, pilot studies on MREAs under impact conditions have so far been conducted on the basis of BP linear flow model (Dyke et al, 1996; Gavin et al, 1996; Peel et al, 1996; Wereley and Pang, 1998; Yang et al, 2004) and BP nonlinear flow model (Mao et al, 2005). In addition, it was shown that such BP linear and nonlinear flow models are not adequate to describe MREA behavior under high-speed impact loadings.…”