ROBUSTNESS OF OPTIMAL DESIGN SOLUTIONS TO REDUCE VIBRATION TRANSMISSION IN A LIGHTWEIGHT 2-D STRUCTURE, PART III: USING BOTH GEOMETRIC REDESIGN AND THE APPLICATION OF ACTIVE VIBRATION CONTROL

Abstract

In Parts I and II of this series of papers, geometric optimization (Anthony et al. 2000Journal of Sound and Vibration229 , 505–528 [1]), and the application of active vibration control (AVC) techniques with optimally placed actuators (Anthony and Elliott 2000 Journal of Sound and Vibration229, 529–548 [2]) were both used to reduce the vibration transmission of a lightweight cantilever structure. Two further strategies are reported here combining these techniques: (1) the application of AVC using optimal actuator positions placed on the geometrically optimized structures reported in Part I; and (2) the simultaneous optimization of the structure geometry and the AVC actuator positions.For both strategies even better vibration reductions were found than in references [1,2]. The application of AVC is seen to be more efficient (reduction per AVC control effort) if the structure geometry is also optimized. Slightly better reductions were found with the simultaneous optimization strategy. The change in the performance of the optimal structures due to small geometric perturbations, representing manufacturing tolerances for example, is investigated by a robustness analysis. It was found, as before, that the selection of the best practical structure is not necessarily the same structure ranked on nominal performance, and the AVC control effort can also increase dramatically in the face of such geometric perturbations.Finally, a comparison of the average success of using all the optimization strategies considered in Parts I and II, and in this paper are compared for both the performance and control effort required (where applicable), for both nominal and perturbed structure geometries.