AAE556 lecture 01 introduction Aeroelasticity (made simple)

Aeroelasticity
(made simple)
Terry A. Weisshaar
Purdue University

Armstrong Hall 3329
765-494-5975
Purdue


Details
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Class in ARMS 1021

Purdue


Grading - Tests and
Homework
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Homework is assigned on Fridays and is
handed in at the beginning of each class the
following Friday.
Homework counts 30% of final grade score
Two tests (two hours long) – each 35% of
final grade score

– One test the week before Spring Break – covers
static aeroelasticity
– Second exam during Finals Week – covers
dynamic aeroelasticity


Course materials
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Text distributed free
– Reading assignments for each lecture
– Help me edit

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Notes, homework and supplemental
material available on the AAE website
– Look under AAE556 Restricted folder

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Reading for Wednesday
– Chapter 1
– Chapter 2, sections 2.1-2.5
Purdue
Aeroelasticity

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What’s it all about?
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What is
aeroelasticity?
Why is it
important?
When is it
important?
Key features of
aeroelastic
response

UAV flutter.mp4

Purdue


Aeroelasticity definition &
effects
A eroelasticity is a design activity
concerned with interactions between
aerodynamic forces and structural
deformation, both static and dynamic,
and the influence of these interactions
on aircraft performance.

• Aerodynamic load and structural deflection interaction
• Static stability
• Control surface effectiveness
• Flutter and dynamic response
Purdue


Classical aeroelastic
problems
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Static aeroelasticity
– wing divergence , aero/structure stiffness
– load redistribution - drag, stresses change
– aileron reversal, lack of control
– lift ineffectiveness, vertical tail yaw control

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Flutter and dynamic response
– self-excited wing vibration/destruction
– self-excited panel vibration, LCO
Purdue


Venn diagram showing
interactions
Aerodynamic
forces
L=qSCL

Dynamic
Static
stability
aeroelasticity
Flutter

Elastic
Forces
F=kx

Purdue

Vibrations

Inertial
Forces
F=ma


Flutter at a glance

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Early history- static
aeroelasticity

Elastic
Forces
F=kx

Purdue

Aerodynamic
forces
L=qSCL
Static
aeroelasticity


Aeroelasticity changes history
and puts the hex on monoplanes
Langley
Wright
Bleriot

Purdue


Samuel Langley
well financed, doomed to failure

Excessive wing twist
caused by too much wing
camber

After

Before

“almost everything unexpected during the
development process is bad”

Purdue


The Wright Stuff
innovation in action
Wing morphing
(warping) in action

Wing warping
Purdue


Griffith Brewer weighs in on
aeroelasticity – sort of …

Purdue Aeroelasticity


Bleriot XI - monoplane wing warping
England here we come!

Purdue


John B. Moissant
1868-1910

Moissant in Bleriot airplane airplane
Cross-Channel flight 1910
Moissant all-aluminum airplane 1910

The end of the trail-Dec. 31, 1910 1910

Purdue


Control effectiveness
Reduced ability, or loss of ability, to roll or turn quickly

aileron reversal
Purdue


Swept wing load
redistribution

1.0

Total lift is the
same
spanwise center of
pressure moves
inboard to reduce
root bending
moment

Elastic

Forces
F=kx

Purdue

Aerodynamic
forces
L=qSCL
Static
aeroelasticity


Forward swept wings
X-29 began as a
Ph.D. dissertation
topic in 1972

Purdue


Aeroelastic tailoring
Intentional use of directional
stiffness and load interaction to
create beneficial performance

Purdue


Flutter and dynamic
response

Aerodynamic
forces
L=qSCL
Dynamic
Static
stability
aeroelasticity
Flutter
Inertial
Elastic
Forces
Forces
Vibrations
F=ma
F=kx

Purdue


Heinkel flutter

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Flutter in practice

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Classical Flutter

aileron frequency & motion

Purdue

wing bending and torsion


Glider flutter

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