strain actuated aeroelastic control

173 Pages·2009·7.51 MB·English

STRAIN ACTUATED AEROELASTIC
CONTROL
Charrissa Y. Lin
B.S., Aeronautics and Astronautics
Massachusetts Institute of Technology, 1990
Submitted to the Department of Aeronautics and Astronautics
in Partial Fulfillment of the Requirements for the Degree of
MASTER OF SCIENCE in AERONAUTICS AND ASTRONAUTICS
at the
MASSACHUSETTS INSTITUTE OF TECHNOLOGY
February 1993
© Massachusetts Institute of Technology, 1993.
All rights reserved
Signature of Author ..~.Y -' '~
I" . . . .. "rl ir I I I -
Department of Aero /htic and Astronautics
Janu ary 15, 1993
-.
Certified by I - -'
Professor Edward F. Crtley
Department of Aeronautics and Astronaitics
Mac Vicar Faculty Fellow
Thesis Advisor
Accepted by
Sofessor Harold Y. Wachman
Chairman, Department Gradiate Cormittee
MASSACHUSETTS INSTITUTE
OF TFCi~hi"' nny 0
FEB 17 1993 1
UBRARIES

STRAIN ACTUATED AEROELASTIC CONTROL
by
CHARRISSA Y. LIN
Submitted to the Department of Aeronautics and Astronautics
on January 15, 1993 in partial fulfillment of the requirements
for the Degree of Master of Science in Aeronautics and
Astronautics
ABSTRACT
The preliminary design of a wing with strain actuation and conventional
flap actuation for vibration and flutter suppression experiments is
completed. A two degree of freedom typical section model with steady
aerodynamics is used to gain an understanding of the fundamentals of the
strain actuated aeroelastic control problem. Actuation issues and the
effects of fiber and geometric sweep are examined using the typical section.
Controllers are designed using the Linear Quadratic Regulator (LQR)
method and observers are designed using the Kalman filter. The results
are verified through a series of parameter variations and the incorporation
of unsteady aerodynamics. With the typical section analyses as a
foundation, the actual design is begun. The functional requirements and
the design parameters are explicitly outlined. Non-parametric studies are
used to determine several of the geometric design parameters. Specifically,
a scaling analysis is used to determine the piezoelectric thickness and the
spar thickness. Three parametric trade studies are used to determine the
remainder of the design parameters. A five mode Rayleigh-Ritz analysis
with two dimensional unsteady strip theory aerodynamics is used for all of
the parametric trade studies. The first trade study examines the
interaction of the fiber and the geometric sweep. The effect of fiber and
geometric sweep on the stability characteristics, the piezoelectric actuation,
and the relative authority of LQR controllers using piezoelectric actuation
or conventional flap actuation is observed. The second trade study consists
of the design of a tip mass flutter stopper. The final trade study investigates
the influence of taper on the dynamics of the wing.
Thesis Supervisor: Dr. Edward F. Crawley
Title: Professor of Aeronautics and Astronautics
MacVicar Faculty Fellow

Acknowledgements
Although there is only one author's name on the title page of this
thesis, there are many people who have contributed greatly to its
completion.
First I would like to thank my advisor, Professor Ed Crawley, for the
countless discussions and meetings that have peppered the last two and a
half years and that have aided my intellectual growth (or at least we hope
so). In addition, I would like to thank Professor John Dugundji who has
served as an unofficial co-advisor for the past half year for all of the time he
has been willing to spend.
I also have to thank the National Science Foundation for their
generous fellowship during my years of being a Master's student.
Next I would like to say thanks to all of the people of SERC - past and
present (although I guess there aren't too many in the past category).
Thanks for the technical discussions and the social ones, too. I'd especially
like to mention my officemates who have had to put up with my
idiosyncrasies, even if they haven't always turned up the heat.
To my parents who have always taught me that education is very
important and to my sister - for always trying to understand me.
To Alissa Fitzgerald - whom I will always admire for her strength.
To "the gang" - for friendship and fun times.
To Mark Campbell - thank you for listening to me and keeping your
cool when I was losing mine. Without you around, grad school would have
been much less enjoyable. Go Penguins!
And finally, to Terry. I hope you will always know how much I
appreciate your unflagging support. Thank you for always being there to
listen to me vent my frustrations, for helping me find my strength when it
didn't seem like I had any left, and for providing a safe harbor. I can't say
enough about your role in my thesis, my sanity, and my life.

Table of Contents
Introduction ......................................................................... 15
Chapter 1......................................................................... 15
Foundation for Design ....................................................................... 23
Chapter 2: Typical Section Analyses .......................................... 23
2.1 Introduction ........................................ 23
2.2 Description of model .................................................. 24
2.3 Control analysis for the reference case.........................28
2.4 Fiber vs. Geometric Sweep..........................................49
2.5 Robustness of Qualitative Results: Parameter
Variation ......................................................... 58
2.6 Incorporation of unsteady aerodynamics...................64
2.7 Sum m ary ................................................................. 71
Building the Design ........................................................................ 73
Chapter 3: Functional Requirements and Design Parameters ..... 73
3.1 Introduction ............................................................. 73
3.2 Functional Requirements ................. 74
3.3 Design Parameters .................................................. 78
Chapter 4: Non-Parametric Studies...........................................81
4.1 Introduction ............................................................. 81
4.2 Survey of commercial aircraft.......................................82
4.3 Scaling analysis ....................................... ....... 83
Chapter 5: Design Trade 1: Geometric vs. Fiber Sweep...........93
5.1 Introduction ........................................................... 93
5.2 Model Development....................................................94
5.3 Application to simple rectangular plates ................... 103
5.4 Application to Wing Model: Aeroelastic Behavior ...... 107
5.5 Application to Wing Model: Actuation Issues ............ 112
5.6 Summary ....................................... ......... 128
Chapter 6: Design Trade 2: Tip Mass Flutter Stopper ................ 131
6.1 Introduction ................................... .......... 131
6.2 Variation in hinge position....................................133
6.3 Variation in mass ......................................... .......... 137
6.4 Variation in length... .............................. ................ 139
6.5 Final design............................................................141
Chapter 7: Design Trade 3: Taper Ratio............................. 143
7.1 Introduction ........................................................... 143
7.2 Structural and aerodynamic models........................ 143
7.3 Flutter analysis................................. ......... 145
7.4 Effect on actuation .............................................147
Conclusion ........................................................................................ 151
Chapter 8................................................................. ............... 151
8.1 Summary of final design ........................................ 151
8.2 Summary of Scientific Issues.......................153
Appendix A........ ....................................... 157
Appendix B .................................................................................. 161
Appendix C ...................................................................................... 163
Appendix D ............................................. 169
Bibliography.................................................................................... 171
List of Figures
Figure 2.1 Typical section geometry...............................24
Figure 2.2 Transformation from Leading edge-Wing-Trailing
Edge to Wing-Aileron-Tab.................................................25
Figure 2.3 Pole movement for nominal typical section as airspeed
changes ..................................................................... 30
Figure 2.4 Pole and individual SISO transfer function zero
frequencies versus non-dimensionalized airspeed.
Nominal param eters.....................................................33
Figure 2.5 Pole and zero locations for the individual SISO transfer
functions at design point 1 ....................................... 34
Figure 2.6 Pole and zero locations for the individual SISO transfer
functions at design point 2 ........................................... 35
Figure 2.7 Loci of the LQR closed loop poles for the four actuators
acting individually ..................................... 39
Figure 2.8 Cost curves for single actuator systems at design point
1. ................................................................................ 40
Figure 2.9 Loci of LQR closed loop poles for systems using
m ultiple actuators ...................................................... 42
Figure 2.10 Cost curves for systems with multiple actuators ............ 43
Figure 2.11 Loci of LQR closed loop poles for design point 2, all
actuator combinations ................................................. 44
Figure 2.12 Cost curves for all actuator combinations for design
point 2 ............ ...................................................... 45
Figure 2.13 Cost curve comparison of different measurement
schemes at 1% noise.............. ...................................48
Figure 2.14 Sign convention for Rayleigh-Ritz modeshapes.............50
Figure 2.15 Location of elastic axis for varying fiber sweep angle.........53
Figure 2.16 Transformation of coordinates for addition of
geometric sweep........................................................ 54
Figure 2.17 Typical section stability characteristics for varying
geometric and fiber sweep angles ................................. 57
Figure 2.18 Parameter variation on the spacing between elastic
axis and center of gravity...........................................59
Figure 2.19 Pole/zero movement with respect to the non-
dimensional airspeed for the variation of the spacing
between the elastic axis and the center of gravity .......... 61
Figure 2.20 Parameter variation on location of elastic axis / center
of gravity pair............................................................. 62
Figure 2.21 Pole/zero movement with respect to non-dimensional
airspeed for variation of location of elastic axis/center
of gravity pair......................................... .......... ....... 63
Figure 2.22 Comparison of one-pole approximations to the
tabulated values of Theodorsen's function.....................65
Figure 2.23 Pole movement with change in airspeed for nominal
typical section, unsteady aerodynamics ........................... 66
Figure 2.24 Pole/zero movement with respect to non-dimensional
airspeed for nominal typical section with unsteady
aerodynamics .................... . ............ .................6.8.
Figure 2.25 Loci of LQR closed loop poles for all combinations of
actuators at design point 1, unsteady aerodynamics .......... 69
Figure 2.26 State cost vs. control cost for nominal plant with
unsteady aerodynamics at design point 1.......................70
Figure 5.1 Sign convention for Rayleigh-Ritz and aerodynamic
analysis ................................... ....................................9 4
Figure 5.2 Calculated flutter and divergence speeds for the ply
fiber angle vs. structural sweep angle trade . 3" by 12"
plates...................................................................... 105
Figure 5.3 Pole locus for a ply fiber angle of -15 degrees and a
structural sweep angle of 30 degrees ............................ 107
Figure 5.4 Schematic of wing model used in analysis .................... 108
Figure 5.5 Flutter and divergence speeds for the ply fiber angle vs.
structural sweep angle trade. Wing model ...................... 110
Figure 5.6 Pole locus for a ply fiber angle of -45 degrees and a
structural sweep angle of 30 degrees.............................111
Figure 5.7 Pole locus for a ply fiber angle of -15 degrees and
structural sweep angle of 30 degrees.........................112
Figure 5.8 Inclusion of flap in wing model ..................................... 115
Figure 5.9 Deflection and curvature contours for the two primary
modes of wing model with a [0/0/90]s laminate ................ 119
Figure 5.10 Deflection and curvature contours for the two primary
modes of wing model with a [-15/-15/0]s laminate............120
Figure 5.11 Deflection and curvature contours for the two primary
modes of wing model with a [-30/-30/0]s laminate..........121
Figure 5.12 Cost curves for the wing model at a geometric sweep
angle of 30 degrees for varying ply fiber angles .............. 125
Figure 5.13 Cost curves for the wing model with a [-15/-15/0]s
laminate for varying geometric sweep angles................ 127
Figure 6.1 Schematics of nominal wing model and wing model
with typical flutter stopper deployed positions................ 134
Figure 6.2 Fixed and deployed flutter speeds for hinge position
trade ............................................................... 135
Figure 6.3 Deployed/undeployed flutter speed and dynamic
pressure ratios for hinge position trade ......................... 135
Figure 6.4 Pole loci for the undeployed flutter stopper and the
deployed flutter stopper at the leading edge hinge
position ........................................................ ............... 136
Figure 6.5 Undeployed and deployed flutter speeds for mass
trade .............................................................. 138
Figure 6.6 Deployed/undeployed flutter speed and dynamic
pressure ratios for mass trade........................................138
Figure 6.7 Undeployed and deployed flutter speeds for length
trade . ................................................................... 140
Figure 6.8 Deployed/undeployed flutter speed and dynamic
pressure ratios for length trade ................................... 140