Analysis and design of device of electrorheological magnetorheological fluid with variable stiffness

According to the properties of Electro-Rheological / Magneto-Rheological Fluid (ER/MR Fluid), a device whose stiffness can be adjusted by electric field and / or magnetic field was designed. The basic mechanical properties were analyzed theoretically. The relation of resistance of piston movement to speed of piston movement is discussed, especially asymptotically relation of slow moving and to fast moving was given. And the basic mechanical properties was tested actually. The stiffness of element combined a device with a spring was characterized with accumulation of energy of the unit in vibration. And then the character of stiffness change of the device element with change of yield stress of ER/MR fluid was discussed. The method of optimizing parameters to improve control capability for some condition was discussed. The results indicate that the device is an effective controllable stiffness element. For a controllable stiffness element, its best working state is that its critical resistance is nearly equal to vibration force. For the device used for high frequency, the duct with larger width and gap is recommended. But for the device demanding large critical force, as used in civil engineering, the duct with larger length and smaller gap is recommended.