A New Semi-Active/Passive Isolator

This paper presents a novel semi-active Variable Stiffness and Damping Isolator (VSDI) for vibration mitigation of structures. The proposed VSDI system consists of a traditional steel-rubber vibration absorber, as the passive fail-safe element, and a magneto-rheological elastomer (MRE) with a controllable (or variable) stiffness and damping behavior, as the passive-active element. MRE is a type of material whose stiffness and damping properties can be altered by a magnetic field. In this study, a small scale prototype of this device is designed, fabricated and tested. A typical MRE material is implemented into the device with a built-in electromagnetic system for activation. The magnetic field of the system is numerically analyzed to show the efficiency of the design. Dynamic shear tests in passive and active state are carried out experimentally to demonstrate the VSDI’s ability in stiffness change and eventually shift in natural frequency, while at the same time in damping increment, resulting in vibration reduction.