Characterization and Analysis of Magnetorheological Damper Behavior Under Sinusoidal Loading

The hysteresis behavior of a linear stroke magnetorheological damper is characterized for several magnetic fields and sinusoidal excitations over a nominal operational frequency range of 1.0-3.0 Hz. The behavior of the damper is inadequately modeled using the equivalent viscous damping and the complex modulus. Therefore, four different nonlinear modeling perspectives are discussed for purposes of system identification procedures, including the 1) nonlinear Bingham plastic model, 2) nonlinear biviscous model, 3) nonlinear hysteretic biviscous model, and 4) nonlinear viscoelastic plastic model. The first three nonlinear models are piecewise continuous in velocity. The fourth model is piecewise smooth in velocity. The parameters for each model are identified from an identification set of experimental data; these parameters are then used to reconstruct the force vs displacement and the force vs velocity hysteresis cycles for the respective model. Model performance is evaluated by calculating equivalent viscous damping and force time history errors between the model fit and the experimental data. In addition to the identification study, a validation study was done. Model parameters were calculated for offset values of current and frequency. These intermediate parameters were used to calculate hysteresis cycles, which were compared with a second set of experimental data, a validation data set. Identification and validation study results including damping levels and force time history errors.