Active control of compressional constrained layer damping treatments using electromagnetic actuation.

摘要

A new class of structural damping treatments is introduced. This class is the Active Compressional Constrained Layer Damping (ACCLD) treatment which relies in its operation on a viscoelastic damping layer sandwiched between an electromagnet and a permanent magnet. Interaction between the magnets generates magnetic forces that enhance the compressional damping mechanism of the viscoelastic layer. With proper tuning of the magnetic forces, in response to the structural vibration, undesirable resonances and catastrophic failures can be avoided. The fundamentals and the underlying phenomena associated with the ACCLD are investigated theoretically and experimentally. Finite element models are developed to describe the interaction between the dynamics of flexible plates, the visco-elastic damping layer and the electro-magnetic actuators. Expressions for the strain, potential and kinetic energies for the plate/ACCLD system will be derived. Hamilton's principle is utilized to formulate the stiffness and mass matrices of the new plate/ACCLD element. These matrices will account for the coupling between the base structure and the electro-magnets in the presence of the visco-elastic damping. The validity of the developed finite element model is checked experimentally using thin aluminum plates, which are, treated with single and multiple ACCLD patches. The plate/ACCLD system is subjected to sinusoidal excitations and its multi-mode response is monitored when the electro-magnetic actuator is activated or not. Several control strategies are considered to activate the electro-magnetic actuator including simple PD controllers. The performance of the uncontrolled and controlled system is determined at various operating conditions. Comparisons with conventional Passive Constrained Layer Damping (PCLD) treatments emphasize the potential of the ACCLD treatment as an effective means for controlling structural vibrations.