Transcript What is MDO? Some popular definitions for

Multidisciplinary Design Optimization
Activities at CASDE, I I T, Bombay
K Sudhakar &
PM Mujumdar
Centre for Aerospace Systems Design & Engineering
Department of Aerospace Engineering, IIT Bombay
Presentation at
Aero-India 2003, International Seminar
February 7, 2003
February 7, 2002
Aero India 2003, Bangalore
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Has MDO Been Around?
M (L/D)
Progress in aerodynamic design ?
• B-707
• DC-8
• B-747
• L-1011
• B-767
• A-300
20
15
10
5
0
1960
1970
1980
1990
Year
AIAA-97-1408
Series1
Improvement in Aerodynamics siphoned off for
other system level benefits – MDO in action
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Multi-disciplinary Design Optimization

Low fidelity models
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Tightly coupled inter-disciplinary codes
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All or most of the following,
- High fidelity models
-
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Formal Optimization
Disciplinary authority
Interdisciplinary couplings formally modeled/retained
Design freedom to significantly affect system
performance in multiple disciplines simultaneously
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MDO Growth Over the Years
1982 : Holt Ashley AIAA lecture "Making Things Best ..."
"There are over 8073 papers in Optimal Control,
Aerodynamic
Optimisation
& Structural Optimisation.
Not one paper on Optimization in Aircraft Design”
1991 : AIAA White Paper on MDO; &
Special issue of Journal of Aircraft
1996 : Over 200 papers on MDO application to
A/C Design, including from Industry
1998 : AIAA White Paper on MDO.
“Summary of Industry MDO Applications & Needs”,
Geising & Barthelemy
1999 : Second Special Issue of Journal of Aircraft
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Industry Application of MDO
Source: AIAA MDO White Paper, 1998
Reproduced with permission
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MDO@CASDE Over the Years
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Aug 1999
- CASDE initiates MDO activities
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Aug 2000
- First meeting of SIG-MDO
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Jan 2001
- Professional Development Course on MDO
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Jun 2002
- Second meeting of SIG-MDO, Workshop
on MDO
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Feb 2003
- Third Meeting of SIG-MDO
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Sep 2003
- International Conference on MDO
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Design / MDO Studies @CASDE
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AEW System Level Optimization
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Aero-elastic Design of Transport A/C wings
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Aircraft Intake (3D-Duct) design
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Low Fidelity Analysis
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High Fidelity Analysis (CFD)
For more information
http://www.casde.iitb.ac.in/MDO/
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Design Optimization of AEW
User requirements
E
Mission
AEW System
P, H, V, CL
D1
D2
P
D4
D3
DC
H, V, CL
H, V
Radar
Rotodome
Heat exchanger
Platform
WAnt
WR
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LAnt
BAnt
Qr
WRot
Wds
CD,R
WHX
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CD,H
D, T
L, W
E
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MDO of Transport Aircraft Wing
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Stage I : Analysis based on empirical formulae
Stage II : semi-empirical analysis
 realistic aerodynamic loading - VLM
 simplified structural analysis - EPM
Stage III : Hi-fidelity analysis with aeroelasticity
 VLM
 FEM - NASTRAN
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Design Problem
3
Cruise for 3000 Km at
best range M ≥ 0.74
4
Descend to
1500 m
1
2
Climb to 11000 m
at best
ROC ≥ 11 m/s
Loiter 45 min
(Reserve)
Takeoff at sea level
d ≤ 2150 m
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5
6
7
8
Land at sea level
d ≤ 1220 m
~150 seater aircraft
Mission profile shown
B 737-200 candidate for numerical study
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MDO of Transport Aircraft Wing
MDO Problem

Simultaneous aerodynamic and structural optimization
 variables - wing aerodynamic shape + wing structural sizing
 constraints - mission, aerodynamics, structural, aeroelastic
Analysis tools
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Optimizers : FFSQP / NPSOL (SQP)
Aerodynamic analysis : Vortex Lattice Method (VLM)
Structural analysis :
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Medium fidelity – Equivalent Plate Method (EPM)
 High fidelity – Finite Element Method (MSC NASTRAN)
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MDO of Transport Aircraft Wing
Aerodynamic Geometry
• Planform
• Geometric Pre-twist
• Camber
• Wing t/c
• single sweep, tapered wing
• divided into stations
• S, AR, , 
y

croot
citp
b/2
x
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AR = b2/S
 = citp/croot
Wing stations
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MDO of Transport Aircraft Wing
Structural Geometry
• Cross-section
• Box height
• Skin thickness
• Spar/ribs
A
• symmetric
• front, mid & rear boxes
• r1, r2
y
A
A
r1 = l1/c
r2 = l2/c
A
l1
l2
c
x
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MDO of Transport Aircraft Wing
Function Evaluations
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Structural
 Stresses (x ,  y , xy )
 Structural Weight (Wt)
 Deformation Function (W(x,y)) / Nodal displacements
Aerodynamic & Mission
 CL ,sectional Cl , CDi (VLM)
 Mdiv (semi-empirical) & CDo (empirical)
 Vstall, , Takeoff & Landing Distance
 Ceiling, ROC, Cruise Mach No.
Geometric
 Fuel volume (Vf)
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MDO of Transport Aircraft Wing
Loads
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Load case - quasi-static pull-up maneuver
Aerodynamic pressure loads
Engine loads
Inertia Relief
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Fuel Weight Inertia Relief
Wing Mass Inertia Relief
Both are distributed as equivalent uniform pressures over
wing stations
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MDO of Transport Aircraft Wing
Aerodynamic
W/S
AR

i

Structural
h/c
d/c
r1
r2
hroot
h’1
h’ 2
ts
Ars
System
Analysis
Cl
CL
R
dto
Mdd
Cdo
Wt
Vf
Structural
Aerodynamic
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MDO of Transport Aircraft Wing
Aerodynamic
W/S
AR

i

Structural
h/c
d/c
r1
r2
hroot
h’1
h’ 2
ts
Ars
VLM
FEM
Cl
CL
R
dto
Mdd
Cdo
Wt
Vf
Structural
Aerodynamic
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MDO of Transport Aircraft Wing
Aerodynamic
W/S
AR

i

Structural
h/c
d/c
r1
r2
hroot
h’1
h’ 2
ts
Ars
VLM
FEM
Cl
CL
R
dto
Mdd
Cdo
Wt
Vf
Structural
Aerodynamic
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MDO of Transport Aircraft Wing
Aerodynamic
W/S
AR

i

Structural
h/c
d/c
r1
r2
hroot
h’1
h’ 2
ts
Ars
VLM
Fidelity level for
Mdd and Cdo ?
FEM
Cl
CL
R
dto
Mdd
Cdo
Wt
Vf
Structural
Aerodynamic
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MDO of Transport Aircraft of Wing
Optimization Framework Architecture
History
Block
Optimizer
FSQP
I
N
T
E
R
F
A
C
E
Aerodynamics
(VLM)
Input
Processor
Aeroelasticity
Iterator
NASTRAN
Interface
Output
Processor
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Structures
MSC/
NASTRAN
Analysis Block
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MDO of Transport Aircraft Wing
•
For more information
http://www.casde.iitb.ac.in/MDO/
• Contact : [email protected]
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3D-Duct Design
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Composite team
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ADA, Bangalore
ARDB Associate Node for CFD, IIT Bombay
ARDB CASDE, IIT Bombay
Bring in CFD into Optimization loop
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Commercial codes?
In-house codes?
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3-D Duct Design
Design Problem in Brief
• Pressure Recovery?
• Distortion?
• Swirl?
Entry
Exit
Location and shape known
Geometry of duct from Entry to Exit ?
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Parametrization
Y
Z
X
Duct Centerline
X
Control / Design Variables
A
• Ym, Zm
• AL/3, A2L/3
Cross Sectional Area
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X
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Parametrization
Y
Z
X
Duct Centerline
X
Control / Design Variables
A
• Ym, Zm
• AL/3, A2L/3
Cross Sectional Area
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X
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Typical 3D-Ducts
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3D-Duct Design Using
Low Fidelity Analysis
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Low Fidelity Design Criteria (Constraints)
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Wall angle < 6°
Diffusion angle < 3°
6 * Equivalent Radius < ROC of Centerline
Low fidelity analysis for pressure recovery
(Objective function)
No low fidelity analysis for distortion or swirl
For results & discussion
http://www.casde.iitb.ac.in/MDO/3d-duct/
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3D-Duct Design Using
High Fidelity Analysis
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Low Fidelity Design Criteria (Constraints)
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Wall angle < 6°
Diffusion angle < 3°
6 * Equivalent Radius < ROC of Centreline
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CFD (Fluent) for pressure recovery & distortion
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Doyle Knight’s Group @Rutger’s University
Optimization of width-depth of bump for
minimising distortion.
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Grid quality required to capture distortion?
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3D-Duct Design Using
High Fidelity Analysis
X2-MAX
?
X2-MIN
X1-MIN
X1-MAX
Domain for search using high fidelity code is large
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3D-Duct Design Using
High Fidelity Analysis
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X2-MAX
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X2-MIN
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X1-MIN
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X1-MAX
Low Fidelity Design Criteria
 Wall angle < 6°
 Diffusion angle < 3°
 6 * REQ < ROC
Fluent for CFD
RSM / DOE
DACE
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3D-Duct Design Using
High Fidelity Analysis
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X2-MAX
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X2-MIN
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X1-MIN
X1-MAX
Low Fidelity Design Criteria
 Wall angle < 6°
 Diffusion angle < 3°
 6 * REQ < ROC
Fluent for CFD
RSM / DOE
DACE
http://www.casde.iitb.ac.in/MDO/3d-duct/
[email protected]
[email protected]
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MDO Framework
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Easy integration of analysis modules
Support for distributed analysis
Optimization environment
...
Salas & Townsend AIAA-98-4740
Commercial Frameworks are available
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MDO Framework Issues
I cannot find the correct
tuning parameters!
Why do you want
my program?
System Designer’s
Nightmare!
I have a new version
of analysis software
You have to know my code
to be able to execute it!
(it’s all in Russian)
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MDO Framework Issues
Analysis codes should
reside with experts.
System analysis should
execute analysis codes on
experts’ computers.
Structures Expert
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Aerodynamics
Expert
System Analysis
Aero India 2003, Bangalore
Controls Expert
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Framework Development @CASDE
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Distributed computing (CORBA based)
Database driven
Tools to integrate analysis modules
using wrappers
Automatic data exchange between
analysis modules
[email protected]
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Framework Architecture
GUI
Configuration
Manager
Optimizer
Manager
OPT1 OPT2 OPT3
MDO
Controller
Data
Server
Database
Sequence
Logic
Name
Server
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Execution
Manager
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AM1
AM2
AM3
Analysis
Manager
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Optimization Issues
• Gradient based optimization
• Evaluation of gradients? Finite Difference.
Requirements on convergence more severe
than that required for engineering analysis.
• Noisy functions?
f
X
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User Supplied Gradients
Manually extract
sequence of
mathematical
operations
Complex Analysis
Code in Fortran
Manually differentiate
mathematical
functions - chain rule
FORTRAN
source code
that can evaluate
gradients
February 7, 2002
Code the complex
derivative evaluator
in Fortran
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User Supplied Gradients
Manually extract
sequence of
mathematical
operations
Complex Analysis
Code in FORTARN
Use symbolic math
packages to automate
derivative evaluation
FORTRAN
source code
that can evaluate
gradients
February 7, 2002
Code the complex
derivative evaluator
in Fortran
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User Supplied Gradients
Parse and
extract the sequence
of mathematical
operations
Complex Analysis
Code in FORTARN
Use symbolic math
packages to automate
derivative evaluation
FORTRAN
source code
that can evaluate
gradients
February 7, 2002
Code the complex
derivative evaluator
in Fortran
Aero India 2003, Bangalore
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Gradients by ADIFOR
Complex Analysis
Code in FORTARN
Automated
Differentiation
Package
Euler
FORTRAN
source code
that can evaluate
gradients
February 7, 2002
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Design / MDO Studies @CASDE
MDO Studies in formative stages
 Hypersonic Vehicles - Integrated System
Optimization (J Umakant)
 Launch Vehicles - Reliability Based Design
(Shyam Mohan)
 Launch Vehicle – Simultaneous optimization of
trajectory & system (Geethaikrishnan)
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Presentation made on behalf of
CASDE
PM Mujumdar, K Sudhakar
Amitay Isaacs, SK Sane, AG Marathe
VISIT
http://www.casde.iitb.ac.in/
for information on MDO & Other activities
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