Friction Damper using magnetorheological elastomer in Stick/Slip Condition

초록

The magnetorheological elastomer (MRE) is the material composed of rubber-like base matrix with iron particles. The material properties such as Young’s modulus and friction coefficient can be changed with varying magnetic field strength. In this study, novel friction damper using magnetorheological elastomer (MRE) is designed where the control performance is validated by experiment. With the benefits of property changing characteristics, the magnitude of energy dissipation due to the shear deformation and surface friction of MRE can be controlled. As sliding friction force is utilized as the energy dissipation maneuver, the closed area of force-displacement hysteresis loop becomes larger compare to devices that only using shear deformation. In order to control MRE damper, the Improved LuGre model is incorporated to identify the response of shear force as well as the surface friction force. The Improved LuGre model precisely reflects the response of MRE such as strain stiffening, Stribeck friction and stick/slip behavior. Each parameter of the model is determined as the function of magnetic field strength and utilized to enable semi-active vibration control. Variations of parameters are highly nonlinear both with velocity and magnetic field. Considering nonlinear characteristics of the model, the nonlinear controller such as Lyapunov controller is recommended and adopted in order to attenuate the vibration. To investigate the performance of the damper, power spectrum density variations of acceleration and displacement are observed and compared while adopting random input vibration condition. As the MRE friction damper enlarge energy dissipation with sliding friction, it is expected to effectively broaden frictional application area of MRE.