Integration of piezoceramic actuators in fiber-reinforced structures for aerospace applications

Abstract

Up to now experimental and theoretical research on active structures for aerospace applications has put the focus mainly on surface bonded actuators. Simultaneously piezoceraniics 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'9 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 Daimler-Benz Aerospace Domier 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.

Analysis of the deformational behaviour of a bimorph configuration with piezoelectric actuation

“…Substrate (steel) d 1 = 1.35 l meas = 105 a E (1) = 220 ν (1) = 0.29 Piezoelectric ceramic (PZT Sonox P53) d 3 = 0.2 L = 20 E (3) x = E (3) y = 66.7 ν (3) xy = 0.358 d (3) 31 = d (2) 32 = −0.287 × 10 by Volkswagen AG (VW) and the German Aerospace Center (DLR). The piezoceramic plates are cut into smaller pieces (area: 20 × 10 mm 2 , thickness: 200 µm) and provide a surface uniformly covered with electrodes to take advantage of the 'd 31 -effect'.…”

“…the piezoceramic, is equal to the free piezoelectric strain, γ s, (3) x , at this position, while the substrate has not been able to gain any strain there. The resulting misfit u x between the opposite faces of piezolayer and substrate causes a shear deformation γ (2) xz of the adhesive layer that, on the other hand, induces a shear stress τ adh . The shear stress is responsible for a stress transfer from the piezolayer to the substrate, resulting in a gradual compensation of the misfit with increasing distance from the edge position.…”

“…The development of active materials or components that are able to adapt to varying conditions represents a challenging task for modern engineering (see [1][2][3]). Examples for this new technological concept, commonly characterized by the term 'Adaptronics', can be found in vibration damping and stiffness or deformation control, which are especially important in automotive and aerospace applications.…”

Development and manufacture of an adaptive lightweight mirror for space application

“…Since it had already been shown that, depending on the specific configuration, higher efficiency can be obtained by embedding actuators rather than bonding them to a surface [39], the initial design of the CFRP mirror comprised piezoceramic actuators embedded holohedrally into the face-sheets. This initial design for the CFRP mirror gave a total thickness of 54 mm while mass was calculated to be 5.3 kg (18.7 kg m −2 ).…”