9. Sensing and Control of Cylindrical Shells

In this chapter, distributed sensors and actuators for cylindrical shells were designed and their spatially distributed sensing/control effects were analyzed. Mathematical model and analytical solutions suggest that the fully distributed shell sensor is sensitive only to all odd modes and insensitive to all even modes. This is due to signal cancellations of positive and negative signals in opposite strain regions. The diagonal stripe sensor is sensitive only to the m = n modes and insensitive to the m ≠ n modes. Three sensor sensitivities, i.e., transverse, in-plane longitudinal x and in-plane circumferential θ, were defined for each sensor and their normalized sensitivities evaluated. It was observed that the in-plane sensitivities are insensitive to thickness variations of elastic shells because the in-plane strains remain identical regardless of the thickness change. However, the transverse sensitivity increases as the shell becomes thicker due to an increase of bending strains. Furthermore, control effects of a fully distributed actuator and a diagonal strip actuator are evaluated.