Dynamics of gas-turbine blades are particularly aero-elastic coupling sensitive. These aerodynamic limits can be
pushed away by adding extra damping to the structure in order to reach even better compressor performance.
However nowadays design and manufacturing techniques in aero-mechanics are achieving their maximum of
As in many fields active control would solve easily this kind of instability. But the diffculty remains in the
needed energy supply for actuators whereas these components are aimed to be bonded on rotating structures.
The capacity of different auto-supplied devices using shunted piezoelectric circuits had been studied here to
prevent turbomachine bladed from fluttering.
Before realizing the study on complex turbomachine geometries, the presented technique uses a numerical
development thanks to a 1D Euler-Bernoulli beam model combining both mechanical and electrical coupling
parameters. A second development thanks to a 3D model had been made using a commercial tool, Comsol
software. These approximate models are used to optimize electrically the shunted piezoelectric element and its
localization. The results, verified experimentally, let suppose that vibrations can be reduced signiffcantly when
shunted piezoelectric circuits are mounted on a real structure.
This paper presents some preliminary results concerning semi-active vibration isolation of a spacecraft during
its launch using Magneto-Rheological (MR) dampers. In order to evaluate the isolation performance of such
smart structures, a single degree of freedom isolation system was studied and the extension to a soft hexapod
configuration is currently carried out. Semi-active isolation is known to offer appreciable improvement over
passive isolation for tonal vibration. As regards broadband vibration, semi-active control leads to a conflict
between the demand for damping, which induces less good isolation performance than for tonal vibration. This
paper focuses on semi-active isolation of broadband vibration. In the single degree of freedom configuration,
it is demonstrated experimentally that, for an example of broadband disturbance, band-passed white-noise,
semi-active isolation using MR dampers performs better than passive isolation for various damping, when using
a clipped-continuous skyhook control scheme. Then, a semi-active hexapod prototype using MR dampers is
shown. The dynamic modelling of the hexapod as well as the investigated control strategy, a clipped-continuous
version of the integral force feedback law are presented. Finally, some preliminary open-loop transmissibilities
for a piston motion are measured.