The Use of PVDF Strain Sensing in Active Control of Structural Intensity in Beams

An investigation of structural intensity control associated with flexural vibration in beams using strain sensing is presented in this paper. The instantaneous intensity is completely taken into account in the control algorithm, i.e., all the terms are considered in the real-time control process and, in particular, the evanescent waves are considered in this approach. Previous work has shown the validity of the approach using an array of accelerometers to measure structural intensity. It is the purpose of this paper to present results on the use of strain sensing in the control of structural intensity. A finite difference approach using discrete PVDF strain sensors provides the structural intensity sensing scheme. A feedforward filtered-X LMS algorithm is adapted to this energy-based control problem, involving a nonpositive definite quadratic form in general. In this respect, the approach is limited to cases where the geometry is such that the intensity component will have the same sign for the control source and the primary disturbance. Experimental validation of the approach is conducted on a free–free beam covered with viscoelastic material and excited harmonically by a shaker. A comparison is made between classical acceleration control and structural intensity control and the performance of both approaches is presented. These results tend to indicate that intensity control allows the error sensors to be placed closer to the control source and the primary disturbance, while preserving a good control performance.