Compliant structures-based wing and wingtip morphing devices

Abstract

Purpose The purpose of this paper is to provide an overview of the design and experimental work of compliant wing and wingtip morphing devices conducted within the EU FP7 project NOVEMOR and to demonstrate that the optimization tools developed can be used to synthesize compliant morphing devices. Design/methodology/approach The compliant morphing devices were “designed-through-optimization”, with the optimization algorithms including Simplex optimization for composite compliant skin design, aerodynamic shape optimization able to take into account the structural behaviour of the morphing skin, continuum-based and load path representation topology optimization methods and multi-objective optimization coupled with genetic algorithm for compliant internal substructure design. Low-speed subsonic wind tunnel testing was performed as an effective means of demonstrating proof-of-concept. Findings It was found that the optimization tools could be successfully implemented in the manufacture and testing stage. Preliminary insight into the performance of the compliant structure has been made during the first wind tunnel tests. Practical implications The tools in this work further the development of morphing structures, which when implemented in aircraft have potential implications to environmentally friendlier aircrafts. Originality/value The key innovations in this paper include the development of a composite skin optimization tool for the design of highly 3D morphing wings and its ensuing manufacture process; the development of a continuum-based topology optimization tool for shape control design of compliant mechanisms considering the stiffness and displacement functions; the use of a superelastic material for the compliant mechanism; and wind tunnel validation of morphing wing devices based on compliant structure technology.

Design of compliant mechanism-based variable camber morphing wing with nonlinear large deformation

“…Wing level Maute and Reich 21 Material-based topology optimization 12.3 2.1 Simulation Vasista et al 29 Load-path topology optimization method 10.1 À6.8 /þ8.0 Wing level Smart Droop Nose 26 Traditional rigid-body mechanisms 20 -Wing level DARPA 51 Eccentuator and piezomotor-based actuation -+20…”

Design, Manufacturing and Wind Tunnel Validation of a Morphing Compliant Wing

“…The model was designed and tested at Politecnico di Milano during the final part of NOVEMOR project which is one of the many projects promoted by the 7th European Framework Programme. Starting from the so called Reference Aircraft (RA), developed inside NOVEMOR project for the regional aviation segment, and used as a benchmark in order to evaluate the potential benefits that morphing devices can bring in terms of global performances [20], a small scale wing has been derived for the experimental validation of the proposed morphing concept [21].…”

Lessons learned from wind tunnel testing of a droop-nose morphing wingtip

“…The structural design chain starts with the skin design and the results at the end of this stage are transferred to the design domains of the compliant mechanisms which are designed via gradient-based topology optimization. The processes are briefly explained here and the reader is referred to Vasista et al 6 for more details.…”

“…However, finite element analysis results of the structure under design flight loads (to be reported at a later stage) showed that the strains due to flight-aerodynamic loads still remained low. The reason for this imbalance may be attributed to the topology optimization problem formulation, which as presented in Vasista et al 6 was to maximize stiffness in the clean configuration subject to the shape control displacement constraints of the droop configuration. A problem formulation based on strain energy may lead to a better stiffness-flexibility balance.…”