Harald Hasselblad, Volvo PV Optimeringsdriven design vid Volvo PV

ProOpt Workshop
on Optimization Driven Design
Structural Optimization in Early Design Phase
@ Volvo Cars
Harald Hasselblad
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Issue date: 10/14/2010
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Background
Background
• Industrial research 1999-2005
• PhD dissertation by Harald Hasselblad
• PhD dissertation by Nicklas Bylund
2005 -Today
• Applied optimization at body engineering
Optimization has been identified as a key to
meet future demands.
Future strategy
• Continue optimization work within projects.
• Simplified load cases and models to support
analysis driven engineering.
• PhD student focused on robust analysis and
optimization. Finansed by FFI. Part of the
research group ProOpt.
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Issue date: 10/14/2010
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• FrameOpt by Hasselblad
• Optistruct by Altair
• Optistruct by Altair
• modeFRONTIER
• SFE-Concept
• …
• modeFRONTIER
• NASTRAN
• CATIA V5
• …
Global Req.
and ideas
Earlier cars
Work Flow
Architecture
Studies
Advanced
Engeineering.
Robust and
Optimized
Approximative
Body Structure
Detailed
Models
Detailed models of
Complete Vehicle
Structure
Pre-Concept
Analysis model
Concept
FE-model
System
FE-model
Pre-Concept
analysis and
Optimization
Concept
analysis and
Optimization
Complete
Vehicle Analysis
and Optimization
Studies
• Architecture studies
• Load path analysis
• Advanced engineering
• Core and System dev.
• Load path analysis
• Late concept work
and projects
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Issue date: 10/14/2010
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Structural Optimization @ Advanced Engineering
Frame Topology
Thickness Optimization
Thickness Optimization
Thickness Optimization
modeFRONTIER
modeFRONTIER
Nastran
FrameOpt
Shape Optimization
Topology Optimization
Optistruct
modeFRONTIER
Frame Topology
Frame Topology
Optistruct
Topography Optimization
Optistruct
FrameOpt
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Issue date: 10/14/2010
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Convertible Architecture Study
Closing the tunnel
Mazda MX-5 MIATA
Big sill section
Diagonal beams
Nissan 350Z
Nissan 350Z
Strong tunnel
Mazda MX-5 MIATA
Diagonal rods
Connection to sill
KARMANN Concept
Diagonal rods
Ver 008 with closed tunnel
Rigid subframe
SAAB 9 3
Volvo C70
Rigid subframe
VW EOS
Diagonal rods
Opel Tigra
MB SLK
Mini Cabrio
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Issue date: 10/14/2010
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Convertible Architecture Study
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Issue date: 10/14/2010
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Architecture Study using Topology Optimization
Using Optistruct by Altair Engineering
Styling model Sketch Interior volume identification
Shell model
Load cases:
• Front crash*
• Rear crash*
• Side crash* (x2)
• Torsion Stiffness (x2)
*Stiffness representation
Topology optimization result
Optimization:
Min Weighted Compliance
s.t. Volume fraction < 0.0125% 327 kg
# Load Cases: 6
# Constraints: 1
# DV: 922 893 thetra elements
Analysis model in Optistruct
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Issue date: 10/14/2010
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Benchmarking
Vanderplaats R&D
Mercedes-Benz bionic car
Chrysler
BMW
Source
Chrysler & Daimler
Source
VW Eco-Racer Concept
Source
Porsche
University of Missouri
Source
Source
Magna
Source
Alcoa Auto
Source
Source
Source
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Issue date: 10/14/2010
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Robustness Analysis of Body Side Concept
using modeFRONTIER
DOE Study Based on ~200 Simulations.
• 23 Design Variables
Thicknesses (+/- 0.1 mm)
• 13 Responser
B-plr Velocity (6)
B-plr Deformation (6)
Total Mass
• 1 Load Case
IIHS
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Multi-Criteria Decisions Making
Objective Weights
“Optimal Design”
Small deformation
Low velocity
Heigh weight
∑=1
Deformation
Weight
Velocity
Ranking
Diameter = Velocity
Large deformation
High velocity
Low weight
Verification Run
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Issue date: 10/14/2010
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Verification of “Optimal Design”
Node Diff [%] Diff [%]
Def. rsm/FE ref/FE
720 8,70 -7,27
721 0,09 0,45
722 1,96 0,96
723 2,56 1,71
724 3,57 1,83
725 6,22 1,89
Vel.
720 1,26 -0,13
721 3,45 0,60
722 0,00 3,65
723 0,00 -0,97
724 1,79 1,10
725 1,64 0,38
Weight [kg] [kg]
-1,30 -1,80
Bifurcation!
RSM optimal design
1.3kg
3.6%
FE verification run
-1.8kg
1.8%
Reference
724
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Issue date: 10/14/2010
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Rear Floor Optimization
modeFRONTIER project
Intrusion
Z-lift
Door defirmation
Rear Floor Design Variables
9 PID´s: 13 variables
FMVSS 301
ODB 55 mph 70% Offset
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Convergence and Results
Result:
-5 kg
More stable deformation mode
However:
No improvement in robustness
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Multi Objective Optimization
• # Design Variables: 17
Thicknesses (+/- 0.2 mm) in
0.1 mm steps
• # Load Case: 4
IIHS
ODB
Roof Drop
Global Stiffness
Uniform Distribution
Latin Hypercube (LH)
gives negligible interactions
between factors.

Single Load Case Analysis Based on DOE
mF project Correlation Effect analysis Single Objective Effect Analysis
IIHS
250 sim á 11h
ODB
Roof Drop
250 sim á 21h
250 sim á 8h
Response Distr.
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Issue date: 10/14/2010
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Multidisciplinary Optimization
MDO based on KPI can be performed using the
RSM based modeFrontier model.
Example:
Min: Mass, KPI Front , KPI Side , KPI Roof
s.t: Performance constraints.
RSM based Pareto optimization using a genetic
algorithm
5000 sim ~3.5h
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Issue date: 10/14/2010
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Spape Optimization of Beam Triggers
Using SFE-Concept and modeFRONTIER
Define geometrical triggers and use design variable on trigger location (3,4)
and shape (1,2) to find an optimum triggering setup to minimize stopping
distance and deflection.
Depth
Position
V 0
Min Deflection
Bad design
Min Stopp-dist
M
Min Deflection
“Optimum”
t=1.2mm
Mat: 1464
Min Stopp-dist
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Issue date: 10/14/2010
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Optimization of Beam Triggers
Design variables: Shape and location of triggers
15 design variables: Trigger shape and location.
Optimization
Objective:
• Minimize deflection in y- and z-direction.
s.t.
• Deformation constraints
SFEC model
Final FE-model
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Issue date: 10/14/2010
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Topography Optimization Example
Using Optistruct by Altair
Rigid Boundary Cond.
Optimization:
Max 1st dyn. mode
s.t. Bead fraction < 10%
1st dynamic mode
37.5 Hz
Constraint on beeds:
• Max Hight=10 mm
• Min Width=10 mm
• Max Angle=60 deg
Final freq 187.7 Hz
1st dynamic mode
187.7 Hz
Optimized Topography
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Issue date: 10/14/2010
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Optimization Challenges
• CPU time
• Design Changes
• Parameterization
• Objective, Constraints & Design Variables
• Multi Disciplinary/Objective Environment
Cite:
“The MDO is normally started with an initial model already well developed….”
“The problem is already pre-optimized…”
“In this case the model pushed near to highly non-linear regions…”
“ …depend on a robustness analysis of the optimum…”
Fabian Duddeck**; Str.Multidisc. Optim. (2008)
* *Queen Mary university of London. Former BMW employee
• PhD in Robust Optimization @ Volvo Cars
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Issue date: 10/14/2010
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Back Up Slides
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Issue date: 10/14/2010
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Thinking Optimization Helps Defining the Task
Component analysis:
System analysis:
Responses:
Parameter:
Varables:
Constraint:
Objective:
Robustness ??
Rigid Wall
0-20 deg. angle on wall around z-axis
Rigid wall with x deg. angle on wall around z-axis
Energy: Box
Deformation. Stopping dist.
Force in box. Max and mean.
Barrier force
Mass
Wall angle around z
Box thickenss
Cell thickness
mass