To increase the output damping torque of a rotary magnetorheological (MR) damper with limited geometrical space, a novel rotary MR damper based on helical flow is proposed. A new working mode, helical flow mode, is discussed and applied to enlarge the flow path of MR fluids. The helical flow can improve the performance of the rotary damper by enlarging the length of the active region. Based on the idea, a rotary MR damper is designed. The rotary MR damper contains a spiral piston, dual-coilcore, a rotating cylinder and a stator cylinder. Based on the Bingham model, the output damping torque of the damper is analytically derived. The finite element method (FEM) is applied to calculate the magnetic field of the active region. The multi-objective optimal design method is adopted to obtain the optimal geometric parameters. A prototype is fabricated based on the optimal results. To validate the proposed rotary MR damper, two types of experiments including the low rotation speed and the high rotation speed are investigated. The results show that the proposed rotary MR damper has high torque density and compact structure. The helical flow mode can increase the output damping torque with limited space.

Due to the complex nonlinearity of magnetorheological (MR) behavior, the modeling of MR dampers is a challenge. A simple and effective model of MR damper remains a work in progress. A novel model of MR damper is proposed with force-velocity hysteresis division method in this study. A typical hysteresis loop of MR damper can be simply divided into two novel curves with the division idea. One is the backbone curve and the other is the branch curve. The exponential-family functions which capturing the characteristics of the two curves can simplify the model and improve the identification efficiency. To illustrate and validate the novel phenomenological model with hysteresis division idea, a dual-end MR damper is designed and tested. Based on the experimental data, the characteristics of the novel curves are investigated. To simplify the parameters identification and obtain the reversibility, the maximum force part, the non-dimensional backbone part and the non-dimensional branch part are derived from the two curves. The maximum force part and the non-dimensional part are in multiplication type add-rule. The maximum force part is dependent on the current and maximum velocity. The non-dominated sorting genetic algorithm II (NSGA II) based on the design of experiments (DOE) is employed to identify the parameters of the normalized shape functions. Comparative analysis is conducted based on the identification results. The analysis shows that the novel model with few identification parameters has higher accuracy and better predictive ability.

A novel scissor-type magnetorheological seat suspension with self-sustainability which integrated self-powered, self-sensing, and self-adaptability is proposed in this study. The adaptive rotary damping system consisted of the rotary magnetorheological damper, and rotary permanent magnet direct current generator is designed to realize the self-sustainability. Effects of damping force and isolation object mass are analyzed for further designing and testing based on the dynamic model. The rotary magnetorheological damper and the electrical part are designed and analyzed theoretically. Series of experimental tests are conducted to verify the feasibility and control performances. The experimental results show that the on–off balance control algorithm based on the self-sensing signals can improve the comfort than the directly and supply-with-rectifier control modes.

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This research investigates the design, modeling, and control of an improved magnetorheological rotary damper for seat suspension. A magnetorheological damper with optimized flux path is developed to improve the distribution of magnetic field. Its dynamic damping characteristics are tested by MTS machine under sinusoidal excitations. To describe the nonlinear damping characteristics of magnetorheological damper, a hysteretic model based on backbone curve is selected by comparing with other models. To verify the feasibility of seat suspension with the proposed magnetorheological damper, the simulated analysis and experimental tests are conducted. A dynamic model of scissor seat suspension with rotary damper is constructed and simplified. The performances of semi-active system show that the seat suspension with the proposed damper can reduce vibration efficiently.