State-switched absorber for semi-active structural control

A system that has the capability to make instantaneous changes in its mass, stiffness, or damping may be termed a state-switchable dynamical system. S uch a system will display different dynamical responses dependent upon its current state. For example, state-switchable stiffness may be practically o btained through the control of the termination impedance of piezoelectric s tiffness elements. If such a switchable stiffness element is incorporated a s part of the spring element of a vibration absorber, the change in stiffne ss causes a change in the resonance frequencies of the system, thereby inst antaneously "retuning" the state-switched absorber to a new frequency. This paper briefly develops the fundamental analysis tools for a Single-Degree- of-Freedom state-switchable device, and then considers the application of s uch a device for the purpose of vibration control in a 2-DOF system. Simula tion results indicate that state-switched vibration absorbers may be advant ageous over classical passive tuned vibration absorbers under certain condi tions.