Controlled deformation of critical truss members using magnetorheological dampers with reversed power requirements

Abstract

A magnetorheological (MR) damper exhibits a variable damping coefficient depending on the strength of an accompanying magnetic field. A high magnetic field creates a nearly unyielding damper filled with a semi-solid fluid while no magnetic field produces an ordinary viscous damper. Presently, these dampers are being used in a variety of ways by supplying power to an electromagnet that causes stiffening of the damper. Reversing these power requirements allows development of new and innovative applications for MR dampers. For example, ephemeral deformation of critical truss members may be controlled through a reverse MR damper. The goal is to provide protection to truss structures during severe loading events. Implementation of a reverse damper for an application such as this presents two major tasks: (1) development of a control algorithm and (2) design of an MR damper with reverse power requirements. A control algorithm for dynamic response that uses fuzzy logic and neural networks is presented. A potential design for a reverse MR damper utilizing a combination of permanent magnets and electromagnets is also presented. It is further shown that design for MR dampers with reverse power requirements will be governed by minimization of detrimental effects due to creep of the damper under sustained static loading.