Quantification of damping mechanisms of active constrained layer treatments

In order to implement the approach, a wave approach model of beams treated with ACL is selected from the literature and is experimentally validated. The model is used to find numerically the control voltage optimising the efficiency of the active action, and to calculate the resulting quantification indices for the six first modes of partially or fully treated beam. Results indicate that with a high shear modulus of the viscoelastic material, the optimum control voltage is lower and less sensitive to changes of the stiffness that might occur with temperature variations. A high shear modulus also leads to a better complementarity between the active and passive frequency of the ACL treatment, resulting in a broader effective frequency range. The effect of the forces applied to the structure is to minimise the total input power rather than to maximise the absorption of power by the actuator, suggesting that control laws ensuring absorption of energy by the actuator (and thus the stability of the control) might be suboptimal in terms of vibration reduction. It can be concluded that the quantification indices presented in this work are a powerful tool to get insight into the damping mechanisms of ACL.