Papers by Author: Jin Huang

Abstract: A magneto-rheological (MR) fan clutch is a device that transmits torque by the shear stress of the MR fluids. In this paper, the torque transmitted by MR fluids is analyzed to compute the torque transmission ability in the disk-type MR fan clutch. The results show that with the increase of the applied magnetic field, the torque developed by MR fluids goes up rapidly. The driven speed of the fan clutch can be adjusted continuously by changing the applied magnetic field.

Abstract: A magnetorheological (MR) rotary brake is a device that transmits torque by the shear stress of the MR fluids. In this paper, Bingham model is used to describe the constitutive characteristics of MR fluids subject to an applied magnetic field. The operational principle of the MR rotary brake is introduced. The torque transmitted by MR fluids is analyzed to compute the torque transmission ability in the MR rotary brake.

Abstract: A magnetorheological (MR) valve is a device that uses the MR fluid flowing through a cylindrical orifice. In this paper, based on volumetric flow rate equation in the cylindrical MR valve, the necessary active MR fluid volume and the thickness between two cylinders of the valve are carried out. They are the minimum active fluid volume and gap of MR fluid exposed to the magnetic field. The equations for the volume and the gap derived to provide the theoretical foundation for the key geometric design in the valve. The results indicate that the volumetric flow rate can be continuously adjusted by an external magnetic field. The thickness and the volume for the cylindrical MR valve can be calculated based on MR fluid properties, the desired control pressure ratio, and the pressure of the valve.

Abstract: This paper presents a cylindrical Shape memory alloy (SMA) fan clutch for automobile cooling system application. The resilience of pre-strain 2% SMA alloy wire is analyzed in the processes of heating and cooling. The Design method of SMA helical spring is described. The expression of transmission torque provided by SMA spring is established. The relationship between transmission torque and temperature is analyzed in detail. The results indicate that the transmission torque increases gradually with the increasing of airflow temperature and decreases with the decreasing of airflow temperature, respectively. The cylindrical SMA fan clutch has the property that its transmission torque changes rapidly according to the temperature of airflow from radiator.

Abstract: Magnetorheological (MR) dampers are the semi-active control devices that use MR fluids to produce controllable dampers. In this paper, the design method of the cylindrical MR damper is established. Bingham model is used to describe the constitutive behavior of MR fluids subject to an applied magnetic field. The equation for the damping force is derived to provide the theoretical foundation for the design of the damper. Based on this equation the engineering expressions for the gap and effective length of the annular MR fluid between the piston and the outer cylinder are derived. The result shows that with the increase of the applied magnetic field strength, the damping force is increased. The dimensions of the gap and length can be calculated when the required damping force, the velocity of the piston, and the desired control damping force ratio are specified.

Abstract: Magnetorheological (MR) fluids are materials that respond to an applied magnetic field with the change of their yield and rheological behaviors. In this paper, the yield and rheological behaviors of MR fluids are discussed. Based on the microstructure of magnetic chain a theoretical model is developed to analyze the effect of an applied magnetic field on the yield stress of MR fluids. Bingham model is used to describe the rheological behaviors of MR fluids subject to an applied magnetic field. The results show that altering the strength of an applied field can control the yield stress of MR fluids. The shear stress increases as the strength of an applied magnetic field increases, and it hardly changes with the increase of shear strain rate. MR fluids exhibit Bingham plastic model.