Quasi-steady Bingham plastic analysis of an electrorheological flow mode bypassdamper with piston bleed

Abstract

We present an improved experimental validation of our nonlinear quasi-steadyelectrorheological (ER) and magnetorheological damper analysis, using anidealized Bingham plastic shear flow mechanism, for the flow mode of damperoperation with leakage effect. To validate the model, a double-acting ER valve orbypass damper was designed and fabricated. Both the hydraulic cylinder and thebypass duct have cylindrical geometry, and damping forces are developed in theannular bypass via Poiseuille flow. The ER fluid damper contains a controlledamount of leakage around the piston head. The leakage allows ER fluid to flowfrom one side of the piston head to the opposite side without passing through theER bypass. For this flow mode damper, the damping coefficient, defined asthe ratio of equivalent viscous damping of the Bingham plastic material,Ceq, to the Newtonianviscous damping, C,is a function of the non-dimensional plug thickness only. The damper was testedfor varying conditions of applied electric field and frequency using a mechanicaldamper dynamometer. In this analysis, the leakage damping coefficient withincorporated leakage effects, predict the amount of energy dissipated for acomplete cycle of the piston rod. Measured force verses displacement cycles formultiple frequencies and electric fields validate the ability of the non-dimensionalgroups and the leakage damping coefficient to predict the damping levels for anER bypass damper with leakage. Based on the experimental validation of themodel using these data, the Bingham plastic analysis is shown to be an effectivetool for the analysis-based design of double-acting ER bypass dampers.