See discussions, stats, and author profiles for this publication at: https://www.researchgate.net/publication/341504684
Aircraft morphing systems: elasticity of selected components and modelling
issues
Conference Paper · May 2020
DOI: 10.1117/12.2560161
CITATIONS
READS
3
173
4 authors:
Antonio Concilio
CIRA Centro Italiano Ricerche Aerospaziali
Ignazio Dimino
106 PUBLICATIONS 664 CITATIONS
173 PUBLICATIONS 1,402 CITATIONS
SEE PROFILE
SEE PROFILE
Rosario Pecora
Maurizio Arena
University of Naples Federico II
University of Naples Federico II
97 PUBLICATIONS 1,194 CITATIONS
65 PUBLICATIONS 385 CITATIONS
SEE PROFILE
Some of the authors of this publication are also working on these related projects:
AirGreen2 View project
MASTRO View project
All content following this page was uploaded by Maurizio Arena on 17 July 2020.
The user has requested enhancement of the downloaded file.
SEE PROFILE
PROCEEDINGS OF SPIE
SPIEDigitalLibrary.org/conference-proceedings-of-spie
Aircraft morphing systems: elasticity
of selected components and
modelling issues
Concilio, A., Dimino, I., Pecora, R., Arena, M.
A. Concilio, I. Dimino, R. Pecora, M. Arena, "Aircraft morphing systems:
elasticity of selected components and modelling issues," Proc. SPIE 11376,
Active and Passive Smart Structures and Integrated Systems XIV, 113760M
(19 May 2020); doi: 10.1117/12.2560161
Event: SPIE Smart Structures + Nondestructive Evaluation, 2020, Online
Only, California, United States
Downloaded From: https://www.spiedigitallibrary.org/conference-proceedings-of-spie on 04 Jun 2020 Terms of Use: https://www.spiedigitallibrary.org/terms-of-use
Aircraft Morphing Systems:
Elasticity of Selected Components and Modelling Issues
A. Concilio*a, I. Diminoa, R. Pecorab, M. Arenab
a
CIRA, The Italian Aerospace Research Centre, Adaptive Structures Division, 81043 Capua, Italy;
b
Univ. of Napoli “Federico II”, Industrial Engineering Dept., Aerospace Div., 80125 Naples, Italy
ABSTRACT
Morphing is an increasingly investigated topic in aeronautics due to the performance improvements brought by
aerodynamic shapes adaptivity on large aircraft. Being aerodynamics mainly driven by geometry, a structure that can
modify its shape may achieve tremendous capability enhancement, especially if its operating scenario is wide. However,
the implementation of morphing structures leads to many issues that still need to be properly solved to make the technology
fully operative in real application scenarios. For instance, additional DOFs generate systems with increased modal density
and then with more complex aeroelastic behaviour, and premature onset of dynamic instabilities. The authors of the present
paper have dealt with this problem in other publications, in cooperation with several colleagues, and interesting results are
available in literature, to some extent.
In this general framework, there are peculiar aspects that only recently have started to catch the attention of the scientific
community. Among those, a particular one is the objective of the present work, referring to the numerical simulation
strategy of adaptive devices. The kinematic system at the basis of a wide class of morphing structures is driven by an
actuation chain, which gives an important contribution to the already cited aeroelastic behaviour. For safety-critical
embedded subsystems, it is crucial to detect potential failures and predict their impacts since the early design stages. Now,
kinematic components significantly affecting the structural dynamics, as torsion bars and bearings, are assumed rigid in
the traditional simulation strategy. If such a concept may be supposed valid for standard layouts (as in the case of flap,
ailerons and other moveable systems), it cannot be held for architectures integrating hundreds of those mechanical parts.
This work addresses preliminary investigations on systematic analyses carried out on detailed simulations of selected
components of aircraft morphing structures, trying to evaluate the effects of elasticity of bearings and hinged connections
on the global dynamic response.
Keywords: morphing systems, adaptive structures, embedded kinematics, mechanisms elasticity, finger-like tabs, nonlinear modelling.
1. INTRODUCTION
Adaptive structural technology is an effective way to increase aircraft performance and has been widely studied in the
research community, which devotes to this thematic ever-growing attention, [1]. Born with the first gliders, [2], and
continued with the first engine aircraft, [3], the willingness of realizing bird-like wings is simply intrinsic to the common
vision of futuristic airplane machines, [4]-[5]. However, as the technology progress led to higher and higher speeds, the
increase of loads forced the engineers towards rigid components, more suitable to face the growing operation forces.
Investigations, luckily, did never stop, [6]: a huge quantity of examples could be extracted from all-time scientific
literature. Because adaptive technology applied to aircraft is basically meant to change its geometry, and therefore its shape
or form, it is used to be recalled as “morphing”.
Morphing systems may be structured in two wide classes, basically, compliant, [7]-[8], and kinematic, [9], mechanisms.
There are many advantages that can be associated to the first or the second, and both of them are currently being
investigated by the world scientific and technological community. For instance, in a non-exhaustive list, kinematic systems
may be considered an evolution of well-assessed and known concepts, since long-time embarked on-board of aircraft.
Flaps, slots, ailerons, rudders, are classical examples. Those devices do not then involve the concretization of novel
concepts, but the adaptation of former ideas into novel, more compact and efficient architectures. On the other side, in
order to attain the distributed characteristics that are necessary to apply the “smart structure paradigm”, they shall be made
of many parts, even resulting different from each other, with a dramatic impact on manufacturing, assembly, maintenance,
*
a.concilio@cira.it; phone 39 0823 623342; fax 39 0823 623515
Active and Passive Smart Structures and Integrated Systems XIV, edited by Jae-Hung Han, Gang Wang, Shima Shahab,
Proc. of SPIE Vol. 11376, 113760M · © 2020 SPIE · CCC code: 0277-786X/20/$21 · doi: 10.1117/12.2560161
Proc. of SPIE Vol. 11376 113760M-1
Downloaded From: https://www.spiedigitallibrary.org/conference-proceedings-of-spie on 04 Jun 2020
Terms of Use: https://www.spiedigitallibrary.org/terms-of-use
and even operation costs. Complaint systems are different. They move from the idea that the structure may be designed
“flexible” enough to comply with the current necessities without needing a network of actuation systems running along
the aircraft. Such a flexibility is attained through the introduction of “elastic hinges”, i.e. the weakening of some specific
points that becomes the “center” of the structural system displacement. This tremendous advantage is however
compensated by excessive and concentrated stress distribution on those parts, with unfavorable consequences on aging
(performance degradation) and fatigue life (collapse of the skeleton). It should be also remarked that both the concepts
need internal actuation system to work, so that a kinematic chain is their common base. It is believed that the current
evolution of those layouts will finally merge into a single one that can outstand the benefits and overcome the detriments
of both.
Many peculiarities characterize those systems behavior, so different conceptually. Compliant mechanisms have the strong
need to be modelled with large details, above all concerning the issue of a continuous structural network that is addressed
at guaranteeing necessary motion while taking under control the arising stresses and strains. Kinematic systems are instead
easier to replicate into a classical FE construction, but on the other side require the inclusion of many parts, very different
the one from the other. For instance, they have to combine classical structural elements with proper mechanic components,
like gears, motors and bearings. The extent these latter portions are modelled may be essential in correctly characterizing
their behavior. The almost standard way to consider them fully rigid, so to reply an ideal constraint may give rise to
peculiarities in the performance of the overall system that may lead in turn to significant differences from the real response,
either static or dynamic. Indeed, for smart adaptive kinematic architectures, the type and number of components is
increased if compared to other existing devices like ailerons or rudders; moreover, each part is considerably smaller than
the ones present in the mentioned objects, [10]. That claimed increase is necessary because it is widely demonstrated that
the number of segments is somehow proportional to the attained benefits: for instance, performance increase by a factor 2
by moving from a plain to a 3-segment finger-like flap, [11]-[12].
Another essential point to be considered is that the actuation system, with all its segments, and the main structural skeleton
make up a single, complex system, where the single contribution in bearing the external load are hard to be separated. For
instance, if in a standard movable surface it is easy to differentiate, the stiff actuation bar pushing or pulling the selected
aerodynamic surface, the motor itself and the object undergoing the desired movements, when dealing with adaptive
structural systems, this distinction is not viable anymore. All the pieces contribute to the response of the assembly and its
performance to resist the action of the external and internal forces even if to a different extent, of course, [13]. Distributed
actuation chains cannot be extracted so easily from the rest of the configuration: they are essential part to the operation of
the whole aircraft. In simple words, should each element be rigid, every segment would absorb loads equally, irrespectively
of actual size, current position, local elasticity, and so on, within an architecture that continuously changes its shape. This
last consideration makes it clear that is not just a matter of statics; the modification of geometry shall lead to different
dynamics, being modal characteristics directly affected. The same change of outline leads to a change in aerodynamics,
being the concerned field essentially driven by geometry. Since aero-structures are governed by aeroelastic phenomena,
the impact is even more complex and important, [14]-[15]-[16]. So, it is correct to question about what could be the effect
of modelling differently, in a more sophisticated way the elements that are instead traditionally supposed to be rigid.
In order to verify the appropriateness of those considerations, and to check their actual importance when applied to a real
system, the authors chose to perform an investigation on a reference adaptive winglet system, they had large experience
with, [17]-[18]. That device is fully representative of an aircraft morphing architecture, yet simple enough in terms of
constitutive elements number and parts type. This fact allows taking under control the number and range of involved
variables that have ultimate effects in performing modelling modifications, then reducing the number of uncertainties
within such an innovative study. Already object of preliminary researches by the authors, [19]-[20], the referred apparatus
is made of the skeleton body, a couple of actuators each driving a specific fingered aerodynamic surface, placed at the
trailing edge of the winglet. In detail, this paper deals with an innovative method in modelling the static and dynamic
characteristics of implemented joints. Numerical simulations were performed to assess the rationality of the proposed
design method. The equivalent stiffness aimed at simulating radial bearing was assessed by a linearized approach, namely
the harmonic balance method. Parametric analysis was carried out by changing the hinge radial bearings stiffness: dynamic
parameters and static stress were therefore assessed. Subsequently, starting from the radial stiffness value of a steel pin, its
different percentage values were considered in the numerical simulations. In addition to the case of an infinity rigid
connection (RBE2) used extensively and traditionally in the modelling of mechanical joints, the value of the equivalent
stiffness was decreased up to 20% in order to simulate an extreme free-play condition.
Proc. of SPIE Vol. 11376 113760M-2
Downloaded From: https://www.spiedigitallibrary.org/conference-proceedings-of-spie on 04 Jun 2020
Terms of Use: https://www.spiedigitallibrary.org/terms-of-use
2. REFERENCE MODEL
In order to check the validity of these considerations, the authors chose as reference model a pair of moveable tabs of an
adaptive winglet system, shown in Figure 1, specifically designed and modelled to serve as benchmark test-bed to evaluate
the identified simulation strategies and associated effects. Such a “finger-like” concept was already developed by the
authors and successfully validated on full-scale morphing wing trailing edge and aileron devices in the past, [21]-[23]. The
authors consider such a reference model as fully representative of a generic morphing architecture equipped with a fingerlike mechanism and driven by an electromechanically-based actuation, still not exaggeratedly complex in terms of parts
and components. In fact, with the aim of understanding how the behavior of the structural system may vary with respect
to certain modelling variations, it is useful to reduce the number of uncertainties as the most in order to concentrate the
attention on a small number of variables.
Hinged mechanisms are considered at the trailing edges to realize the morphing layout of two tabs, which can be
independently deployed both upward and downward. The morphing mechanism consists of three consecutive hingeconnected blocks (B0, B1, B2), whose relative rotations enable the trailing edge camber morphing. Each block consists of
a pair of segments connected by a spar box. An inner actuator (not shown in the figure) forces the block B1 to rotate around
its hinge system through a namely rigid rod. This element is particularly important (and critical) in this kind of architecture,
bearing the great part of the external loads. The resulting system is a 1-degree-of-freedom architecture (SDOF), where the
different blocks rotate according to a specific gear ratio. B0 block is rigidly connected to the rear spar of the winglet
structure and makes the so-called “dead box”, i.e. the part of the active system that is adherent to the non-morphing
structure. The skin of the winglet trailing edge, shown in Figure 2 is divided into separate plates, two for each block, a
lower and an upper skin, attached to the respective edges of the ribs and along the associated spars.
Figure 1. Finger-like mechanism of the morphing winglet trailing edge.
Figure 2. Segmented skin of the morphing winglet trailing edge.
Proc. of SPIE Vol. 11376 113760M-3
Downloaded From: https://www.spiedigitallibrary.org/conference-proceedings-of-spie on 04 Jun 2020
Terms of Use: https://www.spiedigitallibrary.org/terms-of-use
As shown in Figure 3, the mechanism of the reference morphing structure was firstly FE modelled by rigid links. The sole
purpose of these elements was to transfer the loads between the grid points in such a way that all the slave (dependent)
nodes have zero relative deformation after the load application. A spider connection to the pin was modelled by releasing
the rotational degree of freedom activated by morphing. In such a way, one cannot observe any oval effect of hole or any
bearing loaded pattern on the holes. This approach is usually considered as the simplest way to simulate morphing
mechanisms at the preliminary stages of the design.
elastic elements
Figure 3. FE modelling of 1D elements.
As preliminary check, the normal modes were computed by neglecting the actuation chain of the morphing mechanism. A
rigid rotation mode was obtained by neglecting the entire actuation system stiffness consisting of the EMA and the
actuation transmission line. Such motion occurs when the actuator rotates with zero moment due to some internal failure.
An example of this failure is the actuator loss causing it to move freely without producing any effective moment along the
main hinge axis. Such a condition, occurring at 0.9 Hz for the considered kinematics, is usually referred to as morphing
mode since it is fully representative of the morphing aero-shape achieved by the designed non-actuated mechanism, Figure
4. Theoretically, that value should be equal to zero; this deviation is due to the coarse mesh that turns into an imperfect
alignment of the hinges whose effect is to rise the first “rigid” mode to a non-null value (addition of a constraint). The
mode shape of the kinematic system is also shown in Figure 4 along with the non-deformed model.
Figure 4. Free play floating mode of the upper morphing tab (frequency= 0.9 Hz)
In a second step, an equivalent torsional spring was added to the hinge line to replicate the stiffness of the whole actuation
transmission line due to both actuator and actuation line. In such a more realistic condition, the natural frequency of the
mechanical system, usually referred to as operative morphing mode of the device, increased to 13.48 Hz, being totally
Proc. of SPIE Vol. 11376 113760M-4
Downloaded From: https://www.spiedigitallibrary.org/conference-proceedings-of-spie on 04 Jun 2020
Terms of Use: https://www.spiedigitallibrary.org/terms-of-use
driven by the actuation kinematics, Figure 5. Apart from the design challenges, not addressed in this work, that may be
encountered to accommodate a suitable actuator in such a confined space, focus is here given to the study of the structural
behavior sensitivity to the mechanism hinges flexibility for the given torsional stiffness of the whole actuation chain. Such
an approach assumed that, in principle, a flight-worthy actuator of adequate size, weight, and power is available and can
be integrated into the mechanism to counteract aerodynamic loads during system operation.
Figure 5. Detail of the morphing kinematics extracted by normal mode analysis
After that, a parametric analysis was built up by changing the stiffness of hinge radial bearings. An equivalent stiffness
was assessed by a linearized approach, i.e. the harmonic balance method. Starting from the radial stiffness of the steel pin,
different percentage values were considered in the numerical simulations. In addition to the case of an infinity rigid
connection (RBE2) used extensively in the modelling of mechanical joints, the value of the equivalent stiffness was
decreased up to 20% in order to simulate an extreme free-play condition (Figure 6).
Figure 6. Degradation of bearing radial stiffness.
Proc. of SPIE Vol. 11376 113760M-5
Downloaded From: https://www.spiedigitallibrary.org/conference-proceedings-of-spie on 04 Jun 2020
Terms of Use: https://www.spiedigitallibrary.org/terms-of-use
Harmonic Balance methods: Theory
The harmonic balance method allows for analyzing in the frequency domain the steady-state fundamental harmonic nonlinear structural response due to harmonic excitation. It is based on Fourier descriptive function, used to investigate the
limit cycle oscillations of systems with concentrated nonlinearities. The theory is discussed in the following on a single
degree of freedom system, whose non-linear equation of motion can be written in a very general form as:
mu(t )  f R (u, u, t )  f (t )
(1)
where f R (u, u , t ) is a non-linear restoring force function due to friction, clearance, etc., that may contain the contribution
of a viscous damper also. The fundamental assumption behind the Harmonic Balance method is that the total response of
a non-linear system due to harmonic excitation is dominated by the fundamental harmonic response:
 u(t )  uˆ sin(t ) 


ˆ
f (t )  f sin(t   ) 
  u (t )  uˆ cos(t )  .
u(t )   2uˆ sin(t ) 


(2)
If this assumption is fulfilled, the non-linear restoring force functions such as friction, clearance or contact can be
approximated by equivalent spring and damper forces:


f R (u, u, t )  kequ(t )  cequ (t )  kequ sin(t )  cequ cos(t )
where
(3)
keq and ceq can be calculated from the Fourier series decomposition of:
f R (u, u, t ) a0  a1 sin(t ) b1 cos(t )
(4)
 a
keq (u )  1
u
(5a)
b

ceq (u )  1
u
(5b)
as following:
with:
1
2
a0 
a1 
b1 
f
R
(u, u, t )d (t )
(6a)
0
2
1
f

R
(u, u, t ) cos(t )d (t )
(6b)
R
(u, u, t ) sin(t )d (t )
(6c)
0
1

2
2
f
0
3. NUMERICAL RESULTS
Sensitivity Dynamic analysis
The theoretical methodology illustrated in the previous paragraph was applied to assess the influence of the hinge stiffness
on the dynamic performance of the winglet. In particular, the harmonic balance technique was implemented to simulate
Proc. of SPIE Vol. 11376 113760M-6
Downloaded From: https://www.spiedigitallibrary.org/conference-proceedings-of-spie on 04 Jun 2020
Terms of Use: https://www.spiedigitallibrary.org/terms-of-use
the radial free-play of the bearings. The frequency response (Figure 7) was useful for estimating the amplitude of structural
oscillation: in the present case, the mode shapes in the [0; 150 Hz] bandwidth were analyzed. As summarized in Table 1,
the first two modes which represent respectively the morphing motions of the tabs have no null frequency: theoretically,
in the assumption of actuation system full failure and hence, in total absence of dry friction in the hinges, this motion
would be representative of a rigid mode (f = 0 Hz), evolving according to specific gear ratios among each structural block.
In this case, the intrinsic stiffness is associated to the internal actuation leverages. The numerical study allowed to
characterize the deviation of this approach from a standard modelling strategy based on perfectly rigid elements (RBE2).
With particular reference to the first four modes (highlighted in Figure 8 and Figure 9) of greater interest for aeroelastic
concerns, a reduction resonance frequency values with the increase in the free-play level is observed. An increasingly
emphasized free-play leads basically to a lower generalized stiffness with consequent larger modal displacements
associated to hinges distribution. Figure 8(b) confirms this point: a very low bearing stiffness induce to a remarkable and
sudden oscillation. As hinge rigidity approaches to zero, it may be seen as a local failure and revealing how the structure
evolves as it approaches a malfunction is definitely interesting. Therefore, the harmonic balance technique allowed for
predicting a reasonable range of radial flexibility for the hinges between the rib blocks.
Figure 7. Spectral response [0, 150 Hz].
Table 1. Degradation of bearing radial stiffness: parametric normal modes analysis.
RBE2
ID Mode
1
2
3
4
5
6
7
8
9
10
100% 80%
f [Hz]
f [Hz] f [Hz]
13.99 13.48 13.35
20.55 22.27 22.04
29.96 29.95 29.95
42.01 41.78 41.70
70.33 70.33 70.33
86.87 87.93 87.61
88.81 89.16 89.05
91.11 93.19 93.13
120.57 121.95 121.77
129.77 134.89 133.34
Kbearing
60%
f [Hz]
13.18
21.75
29.95
41.61
70.33
87.13
88.96
93.06
121.53
131.43
40%
f [Hz]
12.95
21.36
29.95
41.48
70.33
86.35
88.89
92.95
121.19
128.83
Proc. of SPIE Vol. 11376 113760M-7
Downloaded From: https://www.spiedigitallibrary.org/conference-proceedings-of-spie on 04 Jun 2020
Terms of Use: https://www.spiedigitallibrary.org/terms-of-use
20%
f [Hz]
12.63
20.80
29.95
41.28
70.33
85.10
88.84
92.80
120.68
125.26
Keq
modal overshoot
(a) Mode I
(b) Mode II
(c) Mode III
(d) Mode IV
Figure 8. Zoom on resonance peaks.
(a) Mode I: outer TE harmonic
(b) Mode II: inner TE harmonic
(c) Mode III: first bending mode
(d) Mode IV: second bending mode
Figure 9. Mode shapes of baseline configuration.
Proc. of SPIE Vol. 11376 113760M-8
Downloaded From: https://www.spiedigitallibrary.org/conference-proceedings-of-spie on 04 Jun 2020
Terms of Use: https://www.spiedigitallibrary.org/terms-of-use
Static stress analysis
A greater structural yielding was assessed from a purely static standpoint too. A trial pressure load, i.e. 1 Pa, was uniformly
applied on the winglet surface in order to characterize its static state in terms of displacements (Figure 10) and strains.
These values at the most deformed point are reported as function of the stiffness percentage in Figure 11: as expected, the
drop in local stiffness due to the free-play (/reduced radial stiffness of the bearings) is the cause of a greater displacement
(Figure 11(a)) as well as a greater strain condition, Figure 11(b). As in the case of dynamic analysis, the connections
modelling was carried out in the first instance according to a “rigid” procedure. However, this approach which leads to
introduce an “infinite” stiffness may not be representative of the actual physical behavior of the structure underestimating
the stress level where there may be a not negligible concentration. The strain close to areas such as holes, with a high
concentration factor kt, can significantly impact on the sizing criteria especially for the fatigue life of articulated
mechanisms i.e. morphing systems. The contours in Figure 12 show the same strain distribution with respect to the
infinitely rigid joints but of increasing scale as the free-play increases. In reality, the bolt tends to overload just a portion
of the hole in which it is housed: moreover, the contact stress should be asymmetrical, and its value should increase with
magnitude of free-play of the pin (/reduction of equivalent radial stiffness of the bearing).
At very low levels of bearing stiffness (20% of Keq), a nonlinear analysis was also carried out to deeply characterize the
contact stress. In this case, a one-sided gap element is certainly the most suitable to describe the bolt behavior with great
level of mobility into the joint. Actually, the strain peak at the hinge decreases drastically, Figure 13. However, the local
variation of structural rigidity is a phenomenon responsible for the redistribution of stress path in the model. As the bearing
flexibility increases, the load is carried onto the more rigid elements in the proximity causing therefore an overload of
these parts. As can be seen from the same Figure 13, the maximum strain moves towards the rear region of the rib.
Figure 10. Static displacement under pressure loads.
(a) Maximum displacement trend
(b) Maximum strain trend
Figure 11. Static analysis results close to the hinge.
Proc. of SPIE Vol. 11376 113760M-9
Downloaded From: https://www.spiedigitallibrary.org/conference-proceedings-of-spie on 04 Jun 2020
Terms of Use: https://www.spiedigitallibrary.org/terms-of-use
(a) RBE2 model
(b) 100% stiffness
(c) 80% stiffness
(d) 60% stiffness
(e) 40% stiffness
(f)
20% stiffness
Figure 12. Strain distribution next the flap hinge.
Proc. of SPIE Vol. 11376 113760M-10
Downloaded From: https://www.spiedigitallibrary.org/conference-proceedings-of-spie on 04 Jun 2020
Terms of Use: https://www.spiedigitallibrary.org/terms-of-use
contact stress
Figure 13. Strain distribution next the flap hinge (20% bearing stiffness - nonlinear simulation).
4. CONCLUSIONS
As expected the actual stiffness value of the joints may have a disruptive effect on the dynamic behaviour of the reference
system, in this case a morphing winglet based on a kinematic core. The peculiarity of this kind of architectures is to present
a large number of parts, so that a small change in their characteristics could have important consequences on the overall
device. The reported preliminary application is limited to a first overlook of the modal variations linked to a parametric
modification of the rigidity of some bearings, connecting different segments of a finger-like mechanism. Moreover, the
analysis is also concentrated to the first frequencies, up to 50 Hz. Therein, four modes are well identified, all involving
movements of the adaptive segments, i.e. the parts of the winglet trailing edge that are designed to implement camber
variations. This basic choice it is a simple starting point, and does not establish a preference for the ranges. What is clear
from the graphs is that all the modes are affected, some in a relevant, some others in a confined manner. In the specific,
because selected hinges were chosen to implement controlled stiffness variations, the main influences manifest at the first
and the fourth mode, the ones involving the largest spanwise segment placed at the tip of the reference structure. In that
case, FRF curves show remarkable deviations in the range between 5 and 10% of the natural frequencies. The implemented
excitation field does affect only partially even the second and the third mode. Therefore, it would be necessary to extend
the analysis towards other kind of impinging forces; that is an objective of the authors for further works and further
exploitation of the addressed concept. It is worth to note that frequency variations are evident for Mode 2, but the numbers
are too small to track any kind of conclusions. In the case of the third mode, apparently well excited, it does appear only a
modification in the amplitude of the response; it could be then guessed that stiffness variation affects the disturbance
“transmissibility” along the structure, for the specific case. In the frequency interval immediately further the one considered
and up to 150 Hz, other modes are significantly modified at level of eigenvalues and should deserve some more attention,
investigations, and comments. In further studies, damping factor should be taken into account as well as the effects due to
an overall distribution of these intimate modifications of the connecting elements, to have an estimate of how much the
whole system dynamics is actually modified. Furthermore, aeroelastic analyses are envisaged, to appreciate the effects of
the proposed modelling alternatives on aircraft clearance from static and dynamic instabilities.
REFERENCES
[1] Concilio A., Dimino I., Lecce L., Pecora R., (Editors) Morphing Wings Technology for Large Commercial
[2]
[3]
[4]
[5]
Aircraft and Helicopter Scenario, 2017, ISBN: 978-0-08-100964-2, 978 pages, Publisher: ButterworthHeinemann (UK), doi: 10.1016/B978-0-08-100964-2.09993-7.
Raffel, M. & Wienke, Felix & Dillmann, Andreas. (2019). Flight Testing Stability and Controllability Otto
Lilienthal’s Monoplane Design from 1893, AIAA Aviation 2019 Forum, doi: 10.2514/6.2019-2815.
G. D. Padfield, B. Lawrence, The birth of flight control: An engineering analysis of the Wright brothers’ 1902
glider, The Aeronautical Journal, 2003, pp.697-718, Vol.107, Issue 1078, doi: 10.1017/S0001924000013464.
Holle A. A., Plane and the Like for Aeroplanes, United States Patent N.1225711, Priority Date, Dec. 22nd, 1916;
Publication Date, May 8, 1917.
Parker H. F., The Parker variable camber wing, Report No. 77, National Advisory Committee for Aeronautics
(NACA), Washington Government Printing Office, Washington, DC, 1920.
Proc. of SPIE Vol. 11376 113760M-11
Downloaded From: https://www.spiedigitallibrary.org/conference-proceedings-of-spie on 04 Jun 2020
Terms of Use: https://www.spiedigitallibrary.org/terms-of-use
[6] Hardy R., “AFTI/F-111 mission adaptive wing technology demonstration program,” Proceedings of the 1983
AIAA Aircraft Prototype and Technology Demonstrator Symposium, Air Force Museum Dayton, OH, March 2324, 1983.
[7] Sridhar Kota, Russell Osborn, Gregory Ervin, Dragan Maric, Peter Flick, Donald Paul, Mission Adaptive
Compliant Wing – Design, Fabrication and Flight Test, RTO-MP-AVT-168, Research and Technology
Organization, Applied Vehicle Technology Panel Symposium, Evora, Portugal (P), April 20-24, 2009.
[8] Dean Ninian, Sam M. Dakka, Design, Development and Testing of Shape Shifting Wing Model, MDPI Aerospace
2017, Vol.4, Issue 52, doi: 10.3390/aerospace4040052.
[9] Dimino I., Flauto D., Diodati G., Concilio A., Pecora R., “Actuation System Design for a Morphing Wing Trailing
Edge”, Recent Patents on Mechanical Engineering, Volume 7, Issue 2, 2014, pp.138-148, Publisher: Bentham
Science, doi: 10.2174/2212797607666140429005538.
[10] Miguel A. Castillo Acero, Federico Martın de la Escalera, Yasser Essa, Morphing Technology for Advanced
Future Commercial Aircrafts, In Concilio A., Dimino I., Lecce L., Pecora R., (Eds.) Morphing Wings Technology
for Large Commercial Aircraft and Helicopter Scenario, 2017, ISBN: 978-0-08-100964-2, 978 pages, Publisher:
Butterworth-Heinemann (UK), doi: 10.1016/B978-0-08-100964-2.00019-8.
[11] Woelcken P. C., Papadopoulos M. (Eds.), “Smart Intelligent Aircraft Structures (SARISTU)—Proceedings of the
Final Project Conference,” Springer International Publishing, Cham, Switzerland, 2016, ISBN 978-3-319-224138.
[12] Diodati G., Concilio A., Ricci S., De Gaspari A., Huvelin F., Dumont A., Godard J.-L., “Estimated Performances
of an Adaptive Trailing Edge Device Aimed at Reducing Fuel Consumption on a Medium-Size Aircraft”, SPIE
20th Annual Symposium on Smart Structures and Materials, San Diego (CA-USA), 10-14 March 2013.
[13] Amendola G., Dimino I., Amoroso F., Pecora R., Concilio A., “Preliminary Design of an Adaptive Aileron for
Next Generation Regional Aircraft”, Journal of Theoretical and Applied Mechanics, Volume 55, Issue 1, 2017,
pp.307-316, Publisher: Ptmts, doi: 10.15632/jtam-pl.55.1.307.
[14] Maurizio Arena, Rosario Pecora, Francesco Amoroso, Maria Chiara Noviello, Francesco Rea, Antonio Concilio,
Aeroelastic analysis of an adaptive trailing edge with a smart elastic skin, AIP Conference Proceedings, Vol.1884,
Issue 1, doi: doi.org/10.1063/1.5002521.
[15] Suwin Sleesongsom, Sujin Bureerat, Effect of Actuating Forces on Aeroelastic Characteristics of a Morphing
Aircraft Wing, Applied Mech. and Mat., Vol.52-54, pp.308-317, doi: 10.4028/www.scientific.net/AMM.5254.308.
[16] Senthil Murugan, James H. S. Fincham, M. I. Friswell, D. J. Inman, Aeroelastic Modeling of Morphing Aircraft
Wings, 4th Aircraft Structural Design Conference, Belfast (UK), October 7-9, 2014.
[17] Amendola G., Dimino I., Concilio A., Andreutti G., Pecora P., Lo Cascio M., “Preliminary Design Process for an
Adaptive Winglet”, International Journal of Mechanical Engineering and Robotics Research, Volume 7, Issue 1,
2018, pp.83-92, Publisher: Ijmerr, DOI: 10.18178/ijmerr.7.1.83-92.
[18] Noviello M. C., Dimino I., Concilio A., Amoroso F., Pecora R., “Aeroelastic Assessments and Functional Hazard
Analysis of a Regional Aircraft Equipped with Morphing Winglets”, Aerospace, Volume 6, Issue 10, 2019, pp.19,
Publisher: Mdpi, DOI:10.3390/aerospace6100104.
[19] Concilio A., Dimino I., Pecora R., Arena M., “Effect of Hinge Elasticity on Morphing Winglet Mechanical
Systems”, SPIE Smart Structures and NDE Conf. 2019, Denver (CO-USA), 3-7 March 2019, Proc. Vol. 10967,
Active and Passive Smart Structures and Integrated Systems XIII; DOI: 10.1117/12.2514356.
[20] Dimino I., Concilio A., Arena M., Noviello M.C., Pecora R., Mechanical systems for morphing wing structures,
AIDAA 2019 XXV International Congress, 9-12 September, Rome, Italy.
[21] Amendola G, Dimino I, Concilio A, Magnifico M, Pecora R (2016). Numerical design of an adaptive aileron. In:
Proceedings of SPIE – The International Society for Optical Engineering (2016). vol. 9803, 98032A, SPIE, ISBN:
9781510600447, Las Vegas (NV), USA, March 20-24, 2016, doi: 10.1117/12.2219167.
[22] Della Vecchia P, Corcione S, Pecora R, Nicolosi F, Dimino I, Concilio A (2017). Design and integration
sensitivity of a morphing trailing edge on a reference airfoil: The effect on high-altitude long-endurance aircraft
performance. Journal of Intelligent Material Systems and Structures, vol. 28, p. 2933-2946, ISSN: 1045-389X,
doi: 10.1177/1045389X17704521.
[23] Amendola G, Dimino I, Amoroso F, Pecora R (2016). Experimental characterization of an adaptive aileron: Lab
tests and FE correlation. In: Proceedings of SPIE - The International Society for Optical Engineering (2016). vol.
9803, 98034P, ISBN: 9781510600447, Las Vegas (NV), USA, March 20-24, 2016, doi: 10.1117/12.2219187.
Proc. of SPIE Vol. 11376 113760M-12
Downloaded From: https://www.spiedigitallibrary.org/conference-proceedings-of-spie on 04 Jun 2020
Terms of Use:View
https://www.spiedigitallibrary.org/terms-of-use
publication stats