Experimental Evaluation of the Smart Spring Impedance Control Approach for Adaptive Vibration Suppression

Most active vibration suppression approaches have attempted to suppress structural vibration by incorporating active material actuators, such as piezoceramic, within the structure to act directly against vibratory loads. These approaches require the piezoceramic actuators to generate significant force to effectively counteract the vibratory forces. Unfortunately, successful implementation of these approaches has been hindered by the limited displacement capabilities of piezoceramic actuators. The Smart Spring concept is a unique approach to actively control combinations of dynamic impedance characteristics of a structure, such as the stiffness and damping, to suppress vibration in an indirect manner. The piezoceramic actuators employed in the Smart Spring concept are not used to directly counteract excitation loads but rather adaptively vary the effective impedance properties of the structure. This study demonstrates the ability of the Smart Spring concept to control dynamic impedance characteristics of a structure through experimental investigations. Mechanical shaker tests using the proof-of-concept hardware verify the controllability of the impedance properties using the Smart Spring device and its ability to suppress vibration. More importantly, the tests conducted in a wind tunnel demonstrate the performance of the Smart Spring under highly varying unsteady excitation conditions. These experimental investigations confirm the capability of the concept that can easily be implemented as an adaptive mount system to suppress undesired vibration generated by mechanical systems.