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Morphing skins as structural component in shape adaptive wings are still in their early development phase, as they need to combine contradicting requirements, such as extreme anisotropic mechanical behaviour, low structural thickness and air-tightness. Various morphing skin approaches have been designed for confined problems such as camber morphing and low load scenarios. However, to expand the applicability of morphing wings, a morphing skin with full in-plane deformability and an out-of-plane stiffness suitable for manned aircraft is necessary. In this work, a novel, elastomer free layered morphing skin is designed, manufactured, applied to a camber morphing transition region for small aircraft and analysed. The layered morphing skin is based on stacked, stiff platelets contributing to the out-of-plane stiffness, while compliant ligaments connecting the platelets provide in-plane compliance. Therefore, the layered morphing skin shows extreme orthotropy and can independently deform in both in-plane directions with an initial modulus of 198 kPa. Deformation analysis of the layered morphing skin on the camber morphing transition region confirms the bi-axial deformability and shows strains in span and chord up to 10% and 16%, respectively. Conducted pressure tests indicate an out-of-plane stiffness high enough for small aircraft, despite the demonstrator being manufactured from a polymer. The layered morphing skin concept is a promising base for bi-directionally deformable morphing skins., Aerospace Science and Technology, 120, ISSN:1270-9638

Bi-stable composites have been considered for morphing applications thanks to their ability to hold two statically stable shapes with no energy consumption. In this paper, the modelling of the dynamic response of cantilevered wing-shaped bi-stable composites is presented. To this end, an analytical model approximating the dynamic response about each statically stable shape of wing-shaped bi-stable composites is derived. Theoretical modal properties are obtained to attain or stabilise a desired configuration following a previously introduced resonant control strategy. The resonant control technique is evaluated for a wing-shaped bi-stable composite subject to aerodynamic loads. Wind tunnel experiments are conducted on a wing-shaped specimen showing the ability of the control strategy to stabilise or attain a desired stable shape under aerodynamic loads., Aerospace Science and Technology, 29 (1), ISSN:1270-9638

Two new concepts for supporting CAD of repetitively stiffened structures are presented. The two concepts are called D-operator and K-operator, respectively. They have been developed to support preliminary aircraft design and are therefore illustrated by using typical aircraft structures. However, the methods could be applied to any repetitive CAD structure. Cooperation with the software supplier made it possible to implement the K-operator professionally. Sample structures generated with this concept will be illustrated and the results of a CAD based optimization using dynamic objects will be discussed. An outlook will give some ideas for further development and improvements of the method.

Aircraft manufacturers are facing several challenges in the pre-design of aircraft structures. This early stage of the aircraft design has a very multi-disciplinary character. Different competence centres need input data, which is at this point in time to a large extent undefined. Therefore, a large variety of specialised tools is used in order to estimate and predict the required data. If these tools are not compatible, interface problems are the consequence. A permanent improvement of the applied processes with regard to the informal value as well as the applicability remains a continuous challenge. The objective of a collaboration project between Airbus Germany GmbH, the DLR Braunschweig, and the ETH Zurich is to find new methods and approaches to improve accuracy, efficiency, and flexibility of data prediction for primary aircraft structures. The use of modern CAE systems together with the integration of finite element methods into the early pre-design process is a very promising approach [F. Bianconi, P. Conti, N. Senin, D.R. Wallace, CAE systems and distributed design environments, in: XII ADM International Conference, Italy, 5–7 September, 2001 [2] ; M. Pellicciari, G. Barbanti, A.O. Andrisano, Functional requirements for a modern CAD system, in: XII ADM International Conference, Italy, 5–7 September, 2001 [9] ; T. Richter, H. Mechler, D. Schmitt, Integrated parametric aircraft design, in: ICAS 2002 Congress, Institute of Aeronautical Engineering, TU Munich]. The modular and knowledge-based architecture of modern CAE systems allows to represent complex assemblies like aircraft structures by parametric associative and very dynamic models. Design knowledge can be integrated into the modelling [M. Mantyla, S. Finger, T. Tomiyama, Knowledge Intensive CAD, vol. 2, Chapman & Hall, 1997 [8] ] and different characteristics or individuals of the same structure can be mapped through parameters. This document presents concepts, which allow to design comprehensive digital models of novel aircraft structures whereas the level of the modelling detail shall be variegated flexibly [D.E. Whitney, R. Mantripragada, J.D. Adams, S.J. Rhee, Designing assemblies, Res. Engrg. Design 11 (1999) 229–253 [11] ; P. Aspettati, S. Barone, A. Curcio, M. Picone, Parametric and feature-based assembly in motorcycle design: from preliminary development to detail definition, in: XII ADM International Conference, Italy, 5–7 September, 2001]. The strongly parameterised structures allow calculating and assessing different individuals of a given structure in a very efficient and automated way. This makes parametric associative structures very suitable for optimisation. After structural optimisation tasks have successfully been performed with parametric models [U.M. Fasel, O. Konig, M. Wintermantel, N. Zehnder, P. Ermanni, DynOPS – an approach to parameter optimization with arbitrary simulation software, Centre of Structure Technologies, ETH Zurich; O. Konig, R. Puisa, M. Wintermantel, P. Ermanni, CAD-entity based evolutionary design optimization, Centre of Structure Technologies, ETH Zurich, and VGTU, Faculty of Mechanics, Vilnius, Lithuania; U.M. Fasel, O. Konig, M. Wintermantel, P. Ermanni, Using evolutionary methods with a heterogeneous genotype representation for design optimization of a tubular steel trellis motorbike-frame, Centre of Structure Technologies, ETH Zurich], multi-disciplinary optimisations are gaining importance, since they have the potential to find global optima instead of the discipline-dependent optimal configurations and solutions.