Up to now experimental and theoretical research on active structures for aerospace applications has put the focus mainly on surface bonded actuators. Simultaneously piezoceramics became the major type of actuating device being investigated for smart structures. In this context various techniques of insulating, bonding and operating these actuators have been developed. However, especially with regard to actuators, only a few investigations have dealt with embedding of these components into the load bearing structure so far. With increasing shares of fibre-reinforced plastics applied in aerospace products the option of integrating the actuation capability into the components should be reconsidered during the design process. This paper deals with different aspects related to the integration of piezoceramic actuators into fibre reinforced aerospace structures. An outline of the basic possibilities of either bonding an actuator to the structure's surface or embedding it into the composite is given while the emphasis is put on different aspects related to the latter technology. Subsequently, recent efforts at DaimlerChrysler Aerospace Dornier concerning aircraft components with surface bonded actuators are presented. Design considerations regarding embedded piezoceramic actuators are discussed. Finally, some techniques of nondestructive testing applicable to structures with surface bonded as well as embedded piezoelectric actuators are described.

Currently, scientific space missions based on interferometric optical and infrared astronomical instruments are under development in the United States as well as in Europe. These instruments require optical path length accuracy in the order of a few nanometres across structural dimensions of several metres. This puts extreme demands on static and dynamic structural stability. It is expected that actively controlled, adaptive structures will increasingly have to be used for these satellite applications to overcome the limits of passive structural accuracy. Based on the evaluation of different piezo-active concepts, analysis and design of an adaptive lightweight satellite mirror primarily made of carbon fibre reinforced plastic with embedded piezoceramic actuators for shape control is described. Simulation of global mirror performance takes different wavefront sensors and controls for several cases of loading into account. Extensive finite-element optimization of various structural details was performed while testing of active sub-components served as a basis for a final update of finite-element models. Local material properties of sub-assemblies or geometry effects at the edges of the structure were investigated with respect to their impact on mirror performance. The major result of the analysis was the lay-out of the adaptive mirror and the specific design of embedded piezoceramic actuators. Manufacture of structural components and successfully completed mirror integration is described. The paper concludes with an outline of testing, and space qualification of the demonstrator of an actively controllable lightweight satellite mirror currently under way.

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