Piezoelectric damping for mitigation of flow-induced vibrations – HYDRAVIB

The HYDRAVIB project proposes to use «piezoelectric shunts« to couple the mechanical structure to an electrical circuit intended to modify its vibratory dynamics. Thin layers of piezoelectric material can be integrated on the surface of the structures subjected to flow and the control circuit can be relocated at the foot of the blade or even inside the ship. This technique has already been validated during laboratory experiments, but it still demonstrates some weaknesses including the lack of robustness in the event of variation of certain parameters. Adaptive solutions exist but they are not designed to handle the high voltage levels encountered during tests under hydrodynamic flow. In addition, the diversity of fluid-structure interaction phenomena requires reconsidering the tuning strategies for piezoelectric shunts, that are often limited to optimizations under broadband excitations. Although currently almost non-existent in the scientific literature, models taking into account the fluid, structure and coupling to an electrical circuit are necessary in order to design, develop and then experiment new techniques for reducing vibrations of lifting surfaces.

Ongoing project

The potential industrial impact is not limited to the naval sector but extends to the energy sector and the aeronautics which share many similar issues in terms of vibrations of rotating blades.

Ongoing project

Acoustic signature is a major concern for naval platforms whose deterrence or projection missions can be compromised by passive sonars. Unlike electromagnetic waves, acoustic waves propagate very well underwater and noise can be detected more than one hundred kilometers away. Acoustic emissions come from various sources, including propeller cavitation, hydroacoustic noise and noise generated by vibrations. The HYDRAVIB project aims to reduce vibrational noise with innovative solutions for controlling structural resonances under hydrodynamic flow. These techniques will also contribute to an increase of the lifespan of blades, hydrofoils or fins that experience fatigue in a vibrating environment. The potential industrial impact is not limited to the naval sector but extends to the aerospace and the energy industry which share many common issues in terms of vibrations of rotating blades.

The HYDRAVIB project is based on the use of « piezoelectric shunts » to couple the mechanical structure to an electrical circuit intended to modify the vibration dynamics. Thin layers of piezoelectric material can be integrated on the surface of structures subjected to external flow and the control circuit is then relocated at the foot of the blade or even inside the ship. This technique has already been validated in laboratory experiments but demonstrates some weaknesses including the lack of robustness in the event of parameter variations. Adaptive solutions does exist but they are not designed to respond to the high voltage encountered during tests under hydrodynamic flow. Moreover, the diversity of fluid-structure interaction phenomena require to reconsider the classical tuning strategies of piezoelectric shunts, whose optimization is often limited to broadband excitations. Although almost non-existent in the scientific literature, models taking into account the both fluid, structure and coupling to an electrical circuit are necessary in order to design, develop and then experiment new techniques for reducing vibrations.

The scientific program of this project that includes Cnam, ENSAM and the French Naval Academy begins with the identification and modeling of vibratory configurations that occur under hydrodynamic flow. The targeted configurations will be those encountered in the hydrodynamic tunnel of the Naval Academy Research Institute which will be used for the test campaigns. These fluid-structure interaction models will then be supplemented by the coupling to a piezoelectric shunt in order to design several vibration mitigation strategies. Reduction factors around 10 are expected for structures in water without flow and around 3 for structures under flow. In order to make the system adaptive and robust to high voltages, the practical implementation requires a significant investment in the design and assembly of electrical circuits. These will be based on switching amplifiers, a technology never used in the context of piezoelectric shunts. Another innovation involves the application of these techniques to a composite hydrofoil that will be instrumented with piezoelectric patches. These will be integrated into the profile during the manufacturing phase, which also opens up new perspectives for the health monitoring of structures during the different phases of their lifecycle. Fully multidisciplinary, the HYDRAVIB project will therefore provide new tools to address numerous challenges related to both the understanding and the mitigation of flow-induced vibrations.