aeroelasticity in femap and nx nastran
TRANSCRIPT
5/22/2012Page 1
Introduction to Aeroelastic Analysis UsingNX NASTRAN with FEMAP
Ben Names
Email:
Website:
Phone:
http://structures.aero/
Phone: (703) 935-2827
Today’s topics:• Static Aeroelasticity• Aeroelastic Tailoring• Flutter
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Presentation Summary
• SDA Overview
• Aeroelasticity Overview
• Static Aeroelastic Example
• Aeroelastic Tailoring
• Flutter Example
• Conclusions
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NASTRAN Capabilities
• SOL 144 – Static Aeroelastic Response• SOL 145 – Aerodynamic Flutter• SOL 146 – Dynamic Aeroelastic Response• SOL 200 – Sensitivity and Optimization
• Aerodynamic Theories– Doublet Lattice Method (subsonic compressible)– ZONA51 (supersonic)– Mach Box (Supersonic)– Strip Theory (Any)– Piston Theory (Hypersonic)
• Most aerodynamic theories are based in potential flow – No viscous terms = NO DRAG!
• For more info on the Doublet Lattice Method, check out the NASTRAN documentation or my thesis:– http://www.slideshare.net/BenNames/namesbjt2016-65943918?ref=https://www.linkedin.com/
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Aeroelasticity
• Coupling between aerodynamic forces, inertial forces, and elastic forces:
Dynamics(Inertial Forces)
DynamicAeroelasticity
(Flutter and more)
StaticAeroelasticity
FlightMechanics
Fluid Mechanics(Aerodynamic Forces)
Structural Mechanics(Elastic Forces)
StructuralDynamics
SCACL
U
U SCACL
U SCAC
L
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Static Aeroelastic Demo!
• Problem: You are a part of a team that is testing a wing in a wind tunnel and your job is to predict whether it will break!
• Cantilevered, composite wing in a wind tunnel (x-z aero symmetry)
• Span of 160 in• Chord of 17 in
• U = 74 mph (1300 in/s)• Sea level density = 0.0023769
slug/ft^3 (1.146e-7 slinch/in^3)• q = 0.968 psi
• 1 degree AoAView the Demonstration
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Aeroelastic Tailoring
• Use anisotropic material behavior to manipulate wing loading
• Add stiffness couplings to the wing• bending-torsion• shear-torsion
• This tailoring can result in various behaviors, including reducing the root bending moment of a wing
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Aeroelastic Tailoring in Action!
• Blue laminate will be soft, fiberglass skin
• By choosing specific layup schedules in laminates 1, 2, 3, and 4, we can achieve bending-torsion coupling in our new composite wing box
• values of -20, -10, 0, 10, and 20 will be sampled.
1
3
2 4
Laminate Number Layup Schedule
1
2
3
4
Design
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Spanwise Loading of the Wing
Rigid
Increasing theta, the angle of spar cap plies
Min, θ=-10°
Max, θ=20°
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Internal Shear Force
Increasing theta, the angle of spar cap plies
Min, θ=-10°
Max, θ=20°
Rigid
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Internal Bending Moment
Increasing theta, the angle of spar cap plies
Min, θ=-10°
Max, θ=20°
Rigid
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Flutter
• Flutter is a coupling between the inertial, aerodynamic, and elastic forces
• Much harder to predict than the quasi-static behavior since it is a coupling between 3 sets of forces, not two
• Can predict both dynamic as well as static instability (i.e., flutter and divergence)
View the Demonstration
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V-ω Plot
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V-g Plot
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V-g Detailed View
Flutter Speed 1: V=123 mph
Flutter Speed 2: V=228 mph
With a small amount of structural damping (1-5%), it is likely that mode 4 would go unstable before mode 2
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About SDA (aka “Structures.Aero”)
• SDA was founded in 1997 and provides expert aerospace structural analysis
• We serve a variety of industries• We specialize in composites, and developing strong,
lightweight structures that are readily manufacturable• Low level support up through developing test plans
and advanced stress analysis• Typical support programs include small to large UAVs,
manned and unmanned spacecraft, naval structures• Our team consists of over a dozen B.S., M.S., and PhD
level engineers• SDA is located in Sterling, VA, just north of Dulles Airport
near Washington DC
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Typical Projects we support
• Some of our previous projects include:– Aircraft
• Aurora Excalibur• MHADD ARES• Vanilla VA1• Lockheed Constellation restoration for Lufthansa
– Spacecraft• NASA NESC Composite Crew Module (CCM)• NASA NESC Max Launch Abort System (MLAS)• NASA James Webb Space Telescope/IEC• NASA Orion Heatshield mass reduction for NESC• NASA Orion Crew Module (with Lockheed)• NASA WFIRST Telescope for Goddard
Aerosonde
Heatshield
Shadow M2
CCM
Orion Crew Module
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Partnerships
Siemens Value Added Reseller Collier Research Corporation Reseller
FEMAP NX Nastran
Fibersim Solid Edge
HyperSizer Pro
HyperSizer Express
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Additional Resource
What The only Siemens-approved third part resource book for new users of Femap. Published Fall 2014
WhyLearning with the help documentation can be like drinking from a fire hose. Learning Femap succinctly covers the bases on using Femap without being a “bible”.
Covers Introduction Femap Application Interface Modeling/ Pre-Processing Analysis Post-Processing Programming Femap
How Explanation of features Numerous illustrations Annotated examples Guided tutorials
Learning FemapISBN 978-1-4951-2963-6By Eric Gustafson ([email protected]), Senior Aerospace Stress Analyst, SDA
$49.99*B&W, color
available
Available online at www.learningfea.com
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Contact Us:
Contact:
Marty Sivic
Email:[email protected]
Website:http://structures.aero/
Phone: (724) 382-5290
Try FEMAP For Free!Download a free 45-day trial of FEMAP with NX Nastran
• Full FEMAP capabilities• All Nastran solution sequences included• (http://structures.aero/femap-trial/)
Contact:
Ben Names
Email:[email protected]
Website:http://structures.aero/
Phone: (703) 935-2827