Distributed compliance systems with integrated variable stiffness elements show great promise for reconciling the conflicting requirements of morphing. The distinct structural properties of each equilibrium configuration allow bi-stable laminates to provide stiffness variability in a purely elastic, energy-efficient manner. This article presents a novel morphing concept based on a distributed arrangement of embeddable variable stiffness bi-stable composites inside a 500 mm chord NACA 0012 profile (where ‘NACA’ is the National Advisory Committee for Aeronautics). The structural response of the aerofoil is assessed numerically and experimentally, with a particular focus on the global stiffness modification potential via the snap-through of the component laminates. Extending the validated finite element models to include a weak static aeroelastic coupling permits evaluation of the aerodynamic adequacy of the final, passively morphed shapes. This concurrent aero-structural methodology is finally employed to develop an improved design. The results allow for assessing the feasibility and potential of the innovative morphing approach exploiting selective compliance provided by the stiffness variability of the integrated bi-stable elements.
AjajRMKeaneAJBeaverstockCS. (2013) Morphing aircraft: The need for a new design philosophy. In: 7th Ankara international aerospace conference, Ankara, Turkey, 11–13 September 2013.
3.
AmacherRCugnoniJBotsisJ (2013) Thin ply composites: Experimental characterization and modeling. In: 19th international conference on composite materials, Montreal, Canada, 28 July–2 August 2013.
4.
ArrietaAFBilgenOFriswellMI. (2013a) Modelling and configuration control of wing-shaped bi-stable piezoelectric composites under aerodynamic loads. Aerospace Science and Technology29(1): 453–461.
ArrietaAFBilgenOFriswellMI. (2013b) Dynamic control for morphing of bi-stable composites. Journal of Intelligent Material Systems and Structures24(3): 266–273.
ArrietaAFKuderIKWaeberT. (2013c) Embeddable variable stiffness multi-stable composites. In: ICAST2013: 24th international conference on adaptive structures and technologies, Aruba, 7–9 October 2013.
9.
ArrietaAFKuderIKWaeberT. (2014b) Variable stiffness characteristics of embeddable multi-stable composites. Composites Science and Technology97: 12–18.
10.
BaierHDatashviliL (2011) Active and morphing aerospace structures – A synthesis between advanced materials, structures and mechanisms. International Journal of Aeronautical and Space Sciences12(3): 225–240.
11.
BakerDFriswellMI (2009) Determinate structures for wing camber control. Smart Materials and Structures18(3): 035014.
12.
BarbarinoSBilgenOAjajRM. (2011) A review of morphing aircraft. Journal of Intelligent Material Systems and Structures22(9): 823–877.
13.
BilgenOArrietaAFFriswellMI. (2013) Dynamic control of a bistable wing under aerodynamic loading. Smart Materials and Structures22(2): 025020.
14.
CampanileLF (2003) Smart shape control: Using compliant and active materials to adapt structural geometry. Challenges and good reasons. In: 14th international conference on adaptive structures and technologies (ICAST), Seoul, South Korea, October2003.
15.
CampanileLF (2005) Initial thoughts on weight penalty effects in shape-adaptable systems. Journal of Intelligent Material Systems and Structures16(1): 47–56.
16.
CampanileLF (2007) Lightweight shape-adaptable airfoils: A new challenge for an old dream. In: WaggDIan BondIWeaverP. (eds) Adaptive Structures: Engineering Applications. New York, NY: John Wiley & Sons, Ltd, pp. 89–135.
DiaconuCGWeaverPMMattioniF (2008) Concepts for morphing airfoil sections using bi-stable laminated composite structures. Thin-Walled Structures46(6): 689–701.
19.
DrelaM (1989) XFOIL: An analysis and design system for low Reynolds number airfoils. In: MuellerTJ (ed.) Low Reynolds Number Aerodynamics (Lecture Notes in Engineering, vol. 54). Berlin/Heidelberg: Springer, pp. 1–12.
20.
DrelaMYoungrenH (2001) XFOIL 6.9 user primer. Massachusetts Institute of Technology, Cambridge, MA.
21.
GandhiFAnusonti-InthraP (2008) Skin design studies for variable camber morphing airfoils. Smart Materials and Structures17(1): 015025.
HufenbachWGudeMKrollL (2002) Design of multistable composites for application in adaptive structures. Composites Science and Technology62(16): 2201–2207.
24.
KotaSHetrickJLiZ. (1999) Tailoring unconventional actuators using compliant transmissions: Design methods and applications. IEEE/ASME Transactions on Mechatronics4(4): 396–408.
KuderIKArrietaAFErmanniP (2015) Design space of embeddable variable stiffness bi-stable elements for morphing applications. Composite Structures122: 445–455.
27.
KuderIKArrietaAFRaitherWE. (2013) Variable stiffness material and structural concepts for morphing applications. Progress in Aerospace Sciences63: 33–55.
28.
LachenalXDaynesSWeaverPM (2013) Review of morphing concepts and materials for wind turbine blade applications. Wind Energy16(2): 283–307.
29.
MattioniF (2009) Thermally induced multi-stable composites for morphing aircraft applications. PhD thesis, Faculty of Engineering, University of Bristol, UK.
30.
MolinariGArrietaAFErmanniP (2014) Aero-structural optimization of three-dimensional adaptive wings with embedded smart actuators. AIAA Journal52(9): 1940–1951.
31.
MolinariGArrietaAFErmanniP (2015) Numerical and experimental investigation of aero-structural characteristics and performance of distributed compliance morphing wings. In: 23rd AIAA/AHS adaptive structures conference, Kissimmee, FL, 5–9 January 2015, pp. 1–14.
32.
North Thin Ply Technology (2013) M40J/736 Property Data Sheet.
33.
PortelaPCamanhoPWeaverP. (2008) Analysis of morphing, multi stable structures actuated by piezoelectric patches. Computers & Structures86(3–5): 347–356.
34.
PotterK (2006) Measurements of the snap-through behaviour and snap-through fatigue performance of bistable unsymmetric composite structures. In: 3rd international conference on composite testing and model identification, Porto, Portugal, 10–12 April 2006.
35.
SchultzMRHyerMW (2003) Snap-through of unsymmetric cross-ply laminates using piezoceramic actuators. Journal of Intelligent Material Systems and Structures14(12): 795–814.
36.
SoflaAYNMeguidSATanKT. (2010) Shape morphing of aircraft wing: Status and challenges. Materials & Design31(3): 1284–1292.
37.
StanewskyE (2000) Aerodynamic benefits of adaptive wing technology. Aerospace Science and Technology4(7): 439–452.
ValasekJ (2012) Morphing Aerospace Vehicles and Structures (Aerospace Series). New York, NY: John Wiley & Sons.
40.
VasistaSTongLWongKC (2012) Realization of morphing wings: A multidisciplinary challenge. Journal of Aircraft49(1): 11–28.
41.
WaggDJBondIPWeaverPM. (2007) Adaptive Structures: Engineering Applications. New York, NY: John Wiley & Sons, Ltd.
42.
WeisshaarTA (2006) Morphing aircraft technology – New shapes for aircraft design. In: Proceedings of multifunctional structures/integration of sensors and antennas, Neuilly-sur-Seine, France.
43.
WinklerM (2012) Analysis of corrugated laminates. PhD thesis, ETH Zürich, Zürich, Switzerland.
44.
WrightJRCooperJE (2008) Introduction to Aircraft Aeroelasticity and Loads. New York, NY: John Wiley & Sons.
45.
ZündelM (2013) Experimental investigation of morphing airfoils with variable-stiffness skin. Semester thesis 13-004, Centre of Structure Technologies, ETH Zürich, Zürich, Switzerland.
