Elements of Aeroelastic Design: Xie Changchuan

Elements of
Aeroelastic Design
Week 1~35~9
Xie Changchuan
16 hours
Sept.~Nov. 2014
Department of Aircraft
School of Aerospace Science and Engineering
Self introduction
Xie Changchuan
Aeroelastic Laboratory
New Main Building D516
xiechangc@163.com xiechangc@buaa.edu.cn
13691215604
82338723
Department of Aircraft
School of Aerospace Science and Engineering
Research Area: Nonlinear aeroelasticity;
Aerodynamics;
Structural dynamics; Air vehicle design

2
Course Introduction
Course codeF05D413I
Chinese course name
English course nameAeroelastic Design
Course semesterAutumn
Credit score/Teaching hours1/16
Pre-courses(not requisite)Structure mechanics,
VibrationAerodynamics
Suitable major/GradeAircraft design/4th
Aims of Course
Realize the basic phenomena and concepts

Staticdivergencyload redistributioncontrol reverse
Dynamicfluttergust responseaeroservoelasticity
Learn the basic theory and engineering approach

Mechanism from simple models: 2 freedom airfoil, fixed wing
Engineering approach: structural FEM, panel method of aerodynamics
Establish the idea of aeroelastic design

Avoid the design failure, reduce the design cost,
decrease the design compensation
Break the traditional restriction,
utilize the structural deformation
4
Referrence Textbooks
D.H. Hodges, G.A. Pierce, Introduction to Structural

Dynamics and Aeroelasticity(2rd Edition), Cambridge
University Press, New York, 2011
J R WrightJ E Cooper, Introduction to Aircraft
Aeroelasticity and Loads, Wiley, Hoboken, NJ, 2007
W P Rodden, Theoretical and Computational Aeroelasticity,
2011
Chen GB, Yang Chao, Zou CQ, Elements of Aeroelastic
Design(In Chinese), Beihang University Press, Beijing, 2010
[
(2004)(2010)]
5
Assessment Means
Check on attendance
Homework
Some words on the Elective
Elective Course: active, interesting,

study with research
Teaching & learning: opening, interactive,
independent
Videos on Aeroelasticity
1st Introduction
Aeroelasticity
aerodynamics + elastic structure

A applied mechanics to study the elastic structure moving
in the air flow.
Generally the Aeroelasticity is a sub-discipline
of fluid-solid coupling mechanics
wind reduced vibration hydroelasticity
Coupling disciplines: aerodynamics
structural mechanics
with control system
aeroservoelasticity
thermodynamics
aerothermoelasticity
electromagnetics
A: Aerodynamic forces
E: Elastic forces
I: Inertia forces
Relative discipline
V: Vibration
DS: Flight dynamics
Aeroelastic phenomena
F: Flutter
B: Buffeting
Z: Dynamic response
L: Load redistribution
D: Divergence
C: Control efficiency
R: Reversal of control
DSA: aeroelastic effects on dynamic stability of flight
SSA: aeroelastic effects on static stability of flight
Extended Collars Triangle
New suport points in aeroelasticity
Control theory
aeroservoelasticity
1960s, Autopilot and stablize system
1990s, Fly by wire flight control system
Phenomena of aeroservoelasticity came out
Thermodynamics
aerothermoelasticity
Ma>3 aerodynamic heating effects
Youngs Module of material decrease,
thermo-stress change the structural stiffness
Electromagnetics
piezoelectric material,
electromagnetic environment
9
Math background of aeroelasticity
normal differential equation, partial differential equation

matrix theory, linear algebra, functional analysis
functional transform, complex function, numerical analysis
differential manifold, operator theory
Structure theory
matured at some extent
many comercial software, NASTRAN, ANSYS, ABAQUS
structural dynamics, structural mechanics,
theory of elasticity, mechanics of continuum
new material, new structure, micro-meso-macroscopic
Aerodynamics continuum, non-continuum
Steady: stripe, lifting line, vortex lattice method, CFD
Unsteady: Theodorsen, DLM, VLM, CFD
Control theory
classic control theory, modern control theory
10
Brief history of aeroelasticity

The history of aeroelastic theory is mainly
that of the aerodynamic theory of lifting surface.
---- Garrick1962
19031910s
Langley
&
Wright brothers
monoplane
PK biplane
dedign focuslift & strength
initial experience of aeroelastic practice
11
Success of Wrights &

Failure of Langley
Wright brothers
Elder: Wilbur Wright
1867.4.161912.5.12
YoungerOrville Wright
1871.8.191948.1.30
1901, invent the wind tunnel for test

1903.12.17, Flyer I
encountered gust after successful flight
and broke on the ground
1906 got the patent of USA
1908 after the praise by French media, was accepted by
the US government and public
12
Langley, Samuel Pierpont
Astronomer, physical Scientist, fly pioneer

1896, constructed a powered airplane model
Flight height: 150m, flight endurance: 3h
The first powered air vehicle heavy than air
in mankind history
Sustained stable flight was realized
Tandem monoplane, power of

internal combustion engine,
catapult-assisted take-off.
1903.10.7, failure of first test.
1903.12.8, 2nd test, the wing is
broken when launch, then the
plane is plunged into the
Potomac river.
13
Success or Failure
Experience and Rethinking
Langley: tandem monoplane
without wing box, low torsion stiffness
destroyed by static aeroelasticity
Wrights: biplane, 2 wings connected by
strut-wire braced structure
high torsion stiffness
Rethinking:
Strength/Stiffness design
Success of Wrights developing biplane???

material & structure restriction, before WW II
Failure of Langley merit & shortage of monoplane??
material & structure developing,
Aeroelastic
mainstream till now
design ahead of
his time in Wrights airplane
14
Brief history of aeroelasticity

The history of aeroelastic theory is mainly that of the aerodynamic theory of
lifting surface.
---- Garrick1962
1920s1930s
Fokker D8 the wing is broken when diving
the first documented static aeroelastic
wing failure (Fokker, WW I)
Changing the design idea:

strength+stiffness design
static aeroelastic analysis

method is established
Handley Page 0/400 biplane bomber
flutter on horizontal tail
The first known case of flutter
was investigated by Lanchester,
Bairstow, and Fage(1916)
15
1930s1940s
Theodorsen theory, excact solution of 2D unsteady aerodynamics
Wagner function, aerodynamics of airfoil with step AOA/down wash

Kussner function, aerodynamics of airfoil goes into sharp edge gust
dedign focusincrease power

1936, the Theodorsens report claimed the establishment of
the theory of aeroelasticity
1950s1980s
Panel method for steady aerodynamics of subsonic and
supersonic flow
Doublet Lattice Method(DLM) for unsteady aerodynamics
aeroelastic analysis for generic configuration entered its
engineering application stage
16
1980s
CFD(Computed Fliud Dynamics) come into use
Mature of panel method for steady/unsteady aerodynamics
The age of computational aeroelasticity:
subsonic
transonic
supersonic
17
Relative developing
1) Aeroservoelasticity
AFW(Active Flexible Wing) plan, USA
AAW(Active Aeroelastic Wing) plan, USA
2) Aeroelastic tailoring
X-29 Mig29
2000
UVLM(Unsteady Vortex Lattice Method)
Geometrical nonlinear aeroelasticity
Development in China and some accident
18
Other aeroelastic problems

propeller, rotor blade,
cable suspended bridge, very tall building
cable of transmission line, transport pipe
wind turbine blade, vertical transported rocket
flying of insect & bird
19
Engineering problems in aeroelasticity of fixed wing

plane
Statics(ignoring inertia forces)
Stability: divergence
Response: flight loads, control efficiency,
reversal of control
jig-shape design
Dynamics
Stability: Flutter, instability of ASE(ASE flutter)
Response (loads/motion):
gust response, buffeting,
maneuver response,
toss and emission response .
20
Changing the idea of aircraft aeroelastic design
Verify Design
(Avoid Utilize)
AAW plan of USA: synthesis of aeroelasticity,
control and optimal tailoring
Morphing wing/air plane: smart material & structure
21

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Elements of

Structural dynamics; Air vehicle design

Realize the basic phenomena and concepts

Learn the basic theory and engineering approach

Establish the idea of aeroelastic design

D.H. Hodges, G.A. Pierce, Introduction to Structural

Some words on the Elective

Elective Course: active, interesting,

aerodynamics + elastic structure

Extended Collars Triangle

New suport points in aeroelasticity

Math background of aeroelasticity

normal differential equation, partial differential equation

Brief history of aeroelasticity

Success of Wrights &

1901, invent the wind tunnel for test

Langley, Samuel Pierpont

Astronomer, physical Scientist, fly pioneer

Tandem monoplane, power of

Success of Wrights developing biplane???

Brief history of aeroelasticity

Changing the design idea:

static aeroelastic analysis

Wagner function, aerodynamics of airfoil with step AOA/down wash

dedign focusincrease power

Other aeroelastic problems

Engineering problems in aeroelasticity of fixed wing

Statics(ignoring inertia forces)

Changing the idea of aircraft aeroelastic design

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