Développement d'un dispositif semi-actif pour la réduction des vibrations des structures mécaniques par dissipation d'énergie par frottement sec
Buaka Muanke, Paulin
This thesis presents the development of a semi-active device for the reduction of mechanical structure vibration through energy dissipation by dry friction contact surfaces. The prototype presented incorporates two piezoelectric stack actuators used to apply a normal force between a mobile inertial component and two friction pads.This force is controlled so that the distance between the two surfaces is neither too small (to avoid shock and stiction that can cancel the slip between the two surfaces and then the friction effect) or too large (loss of contact surfaces). Second order mass-spring-damper system is adopted as friction device dynamic model and LuGre friction model as friction force model. So, semi-active friction device characteristics, friction model parameters and stack actuator characteristics are experimentally identified. Two control strategies are used in order to maximize the energy dissipated by the device. The first one is the Lyapunov method leading to the nonlinear bang-bang controller law, and the second is the feedback linearization approach leading to the derivative feedback gain controller equivalent with the viscous friction. Both bang-bang and feedback linearization controllers laws are based on the mobile inertial component velocity for piezoelectric stack actuators command signal synthesis. A compensator, consisting of a filter with narrow band and a dephasor of the mobile inertial component velocity is used to compensate delays of the closed-loop scheme and in order to keep the fundamental sine in the excitation force. The approaches are experimentally assessed using a clamped-free beam with semiactive device attached to the beam. The experimental control results show the influence of controller laws parameters on the energy dissipation and the vibration of the beam. Optimal controller parameters lead to a gain on energy dissipation in comparison with the case where the normal force is constant. An improper choice of controller parameter can lead to the instability of the piezoelectric stack actuators command signal. That issue is solved by a proper choice of the parameters for the compensator on the mobile inertial component velocity.
- Génie – Thèses