Comparison of Damping Augmentation Mechanisms with Position and Velocity Feedback in Active Constrained Layer Treatments

Abstract

In active constrained layer damping treatments there are two distinct physical mechanisms that contribute to vibration damping - increased passive damping due to increased shear in the viscoelastic material (VEM) layer, and damping due to transmission of active forces to the host structure. The present study demonstrates that the first mechanism is dominant when proportional feedback is used while the second mechanism is dominant when derivative feedback is used. In the case of proportional feedback, the shear in the VEM increases considerably so that the passive damping is significantly larger than that obtained for the zero-voltage case, but the active action is actually detrimental. In the case of velocity feedback, the shear strain levels in the VEM are virtually unchanged, and all of the damping augmentation is due to the active action. It is also seen that if position feedback is used, moderate values of VEM shear modulus that provide optimal passive damping, are best. On the other hand, if velocity feedback is used, high values of VEM shear modulus that allow best transmission of active forces from the active piezoelectric layer to the host structure, provide maximum augmentation in damping, with the maximum total damping depending on the feedback gain used.

Keywords

Active Constrained Layer Damping Treatments

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