Micro-control actions of actuator patches laminated on hemispherical shells

Spherical shell-type structures and components appear in many engineering systems, such as radar domes, pressure vessels, storage tanks, etc. This study is to evaluate the micro-control actions and distributed control effectiveness of segmented actuator patches laminated on hemispheric shells. Mathematical models and governing equations of the hemispheric shells laminated with distributed actuator patches are presented first, followed by formulations of distributed control forces and microcontrol actions including meridional/circumferential membrane and bending control components. Due to difficulties in analytical solution procedures, assumed mode shape functions based on the bending approximation theory are used in the modal control force expressions and analyses. Spatially distributed electromechanical actuation characteristics resulting from various meridional and circumferential actions of segmented actuator patches are evaluated. Distributed control forces, patch sizes, actuator locations, micro-control actions, and normalized control authorities of a free-floating hemispheric shell are analyzed in case studies. Parametric analysis indicates that (1) the control forces and membrane/bending components are mode and location dependent, (2) actuators placed near the free boundary contributes the most significant control actions, and (3) the meridional/circumferential membrane control actions dominate the overall control effect. r 2003 Elsevier Ltd. All rights reserved.