Active shape control of composite structures under thermal loading

Abstract

Maintaining the shape of high-precision structures such as space antennas and opticalmirrors is still a challenging issue for designers. These structures are subjected to varyingtemperature conditions which often introduce thermal distortions. The development ofsmart materials offers great potential to correct the shape and to minimize thesurface error. In this study, shape control of a composite structure under thermalloading using piezocomposites is investigated. The composite structure is made ofa foam core and two carbon–epoxy face sheets. Macro-fiber composite (MFC™)patches are bonded on one side of the structure. The structure is subjected to athrough-the-thickness temperature gradient which induces thermal distortion,essentially in the form of bending. The objective is to apply electric potential tothe MFC™ actuators such that the deflection can be minimized. Finite-elementanalyses are conducted using the commercial software ABAQUS. Experimentsare performed to study thermally induced distortion, piezoelectric actuation,and compensation of thermal distortion using MFC™ actuators. Numerical andexperimental results are compared. A control loop based on strain measurements isused to actively control the structure. The results show that MFC™ actuators cancompensate thermal distortion at all times, and that this is an efficient methodology.