This paper presents the study of a field-controllable, semi-active magneto-rheological fluid (MRF) shock absorber for high-payload, off-highway vehicles. A MRF damper is developed that is tailored for ground vehicles which undergo a wide range of dynamic loading. The MRF damper also has the capability for different rebound and compression characteristics. The new MRF shock absorber emulates the original equipment manufacture shock absorber behavior in its passive-off mode. Theoretical and experimental studies are performed to examine this MRF damper. The Bingham Plastic theory is employed to model the nonlinear behavior of the MRF. A fluid-mechanics-based theoretical model along with a three-dimensional finite element electromagnetic analysis is utilized to predict the MRF damper performance. The theoretical and experimental results are demonstrated to be in good agreement.

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As technologies for magnetorheological (MR) fluid hardware further evolve towards commercial adoption, the appeal for simpler, more cost-effective solutions becomes evident. While the skills involved in methods of manufacturing and costreduction efforts for mass production lie with the manufacturing community, practical and cost-effective MR technologies must first exist. As part of a 'whole approach' MR solution, the MR damper technology presented in this paper illustrates the development of a fast-response, low-power, cost-effective solution. Fundamentally, a competitive 'whole approach' active or semi-active MR solution can be viewed as system of separate components: parameter sensing, intelligent control, power delivery, and MR hardware technology. The development of any one single component should not successfully evolve without the addressing the cost efficiency and commercialization concerns of the other three. The MR hardware component should be predictable in performance behavior, capable of high damping force at minimal power, and fast in time response to complement simplified control schemes. The design effort is further challenged to meet these requirements within a simple, cost-effective package that holds commercial development appeal.This research includes the characterization of a new prototype MR damper including a description of the device technology, characterization test results and current work. It is evident by these results that this MR technology, comprising simple, commercial-off-the-shelf (COTS) components where possible, presents an attractive, practical and cost effective component of the 'whole approach' MR solution.

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Precision controlled vibration isolation utilizing magnetorheological (MR) fluid technology for potential space optical applications, such as surveillance and directed energy, is addressed. This research includes the design, development and preliminary testing of a semiactive, proof-of-concept, MR vibration isolator. Base disturbances designed to produce payload vibration responses were employed in a single degree-of-freedom test apparatus. The MR vibration isolator served as the load-coupling element between the payload and the base disturbance input. The three-parameter isolator consists of two passive spring elements combined with one MR damping element. The MR damper control algorithm uses relative rate between damper cylinder and piston to dynamically vary the effective coefficient of damping. The result of this technology is ability to tune isolation frequency within a given range. Through intelligent modulation of the damping element alone, dynamic changes in both apparent stiffness and damping of the isolator are achieved. For applications where the ability to vary stiffness and damping would improve pointing accuracy and jitter control, this technology holds great appeal.