Abstract
In this work, we present a novel concept of adaptive friction damper based on electrostatic adhesion and we characterize its performance under quasi-static conditions. The concept is based on a stack of circular electrodes structurally coupled to different ends of the damper, separated by a thin dielectric film and hinged around a common axle. When an electric potential is applied, the electrodes experience an attractive force, which is used to control the transfer of shear stress between electrodes and thus the resistive torque of the assembly and the amount of energy dissipated. However, imperfections on the contact surfaces and air gaps have a strong detrimental effect on the resistive torque.
A prototype of the damper was manufactured and the resistive torque was measured as a function of applied voltage. Theoretical and experimental results were compared to estimate the average thickness of the air gap. The surface roughness of the electrodes and of the dielectric was measured before and after the mechanical test. Moreover, the surface of an entire electrode was scanned to measure its planarity. Then, the results were compared with the value of the air gap previously estimated.
The maximum resistive torque measured was constant over five actuation cycles for constant values of the voltage applied and, as expected, increased quadratically with the voltage. The estimated value of the air gap amounted to 38 μm. Both the electrodes and the dielectric showed an increase in average surface roughness after the mechanical test; however, the surface roughness was lower than 1 μm in both cases and could not justify the estimated air gap. On the other hand, we observed a large inhomogeneity in the planarity of the electrode, which was comparable with the thickness of the air gap previously estimated.
The results obtained demonstrated the possibility to adapt the resistive torque of the damper using an electrical input and proved the feasibility of the concept. Further work has to focus on the design of the electrodes and on the operating life of the damper. We envisage that the concept could replace traditional, semi-active dampers in automotive or in aerospace applications.
