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Vehicle Body
Sandeep Sovani,
ANSYS, Detroit, USAAugust 26, 2011
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Outline
Vehicle Design & Development Process
Driven by CAE Simulation
Automotive Industry Challenges
ANSYS for Automotive Body Simulation Case Studies
Upfront Aerodynamics Optimization
Simulating Body-In-White
Reducing Vehicle Noise
Summary
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Product Knowledge
0%
50%
100%
Product Design & Development Production
Degree of Freedom for
Decisions
CONCEPT DESIGN PERFECTION PREP.
Cost Responsibility
Vehicle Design & Development
Process
[1]
[1] Ref. NAFEMS Autosim White Paper 2008
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CONCEPT
Specifications
DESIGN PERFECTION
Styling
Design
Parameters
Packaging
PRODUCTION
CAE
UseC
AE
to
decidedesign
specs
ReducedN
o.ofPrototypes
Physical Testing
CAE Simulations
Vehicle Design & Development
Process Driven by CAE Simulations
Product Design & Development Production
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Product Knowledge
0%
50%
100%
Product Design & Development Production
Product Knowledge
Degree of Freedom for
Decisions
CONCEPT DESIGN PERFECTION PREP.
Cost Responsibility
Vehicle Design & Development
Process Driven by CAE Simulations
[1] Ref. NAFEMS Autosim White Paper 2008
[1]
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Environmental Protection Reducing CO2 Emission
Improving Fuel Economy
Efficient Thermal Systems
Occupant/Pedestrian Safety Fuel Leaks
Crashworthiness
Comfort, Handling &Aesthetics Noise & Vibration comfort
Vehicle Dynamics
Vehicle Styling
Alternative Propulsion Hybrid Electric Vehicles /
Alternative Fuel Vehicles
Fuel Cell Vehicles / ElectricVehicles
Automotive Industry Challenges :Regulations, Customer/Market Demands
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Market Demands
Fuel Economy
Aerodynamic shape
Weight Reduction
Safety
Rollover/ Impact
Crash worthiness
Comfort, Handling &
Aesthetics
Noise & Vibration Comfort
Vehicle Styling
Manufacturability
ANSYS Solutions
External Aerodynamics
BIW Structural Modeling Virtual Rollover/ Impact /
Crash Modeling
Aero/ Vibro Acoustics
Vehicle Soiling Modeling
Vehicle Painting Process
Simulations
Vehicle Body
.
.
.
ANSYS for Automotive Body
Simulation
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External Aerodynamics
1. Drag, Lift & Side
Forces
2. Front End Flow
3. Dirt accumulation /
water splashing Body-In-White
1. Static/Dynamic Analysis
2. Component Mode
Synthesis (Sub-structuring)
3. Spot Weld, Riveting etc
4. Fatigue & Design Life
Vehicle NVH
1. Wind Noise
2. Structural Vibrations
3. Road Noise
4. Noise Propagation
5. Modal Analysis / FRF
ANSYS for Automotive Body
Simulation
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Upfront Aerodynamics
More Degrees of Freedom to Vehicle Shape
Exploration During Early Stages of Design Process
Key Requirements of Upfront VehicleAerodynamics
Fast, Automated & Reliable Pre-processing
Fast & Accurate Solver
Mesh Morphing Technology Inbuilt in Solver
Design Exploration & Optimization Tools
Automated Work Flow Management
Case Study #1
Upfront Aerodynamics Optimization
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Fast, Automated & Reliable
Preprocessing
SAE Paper 2009-01-0335
Fast, Automated &Reliable Preprocessing ANSYS Meshing
TGrid 13.0
ICEM 13.0
Cleaned CAD to Solution
Time Statistics(1) Ford Taurus (26 M)
Total Time for CleanedCAD to Solution = 7.5 Hours(2) Second Vehicle (31 M)
Total Time for CleanedCAD to Solution = 8.5 Hours
(3) Third Vehicle (36 M)
Total Time for CleanedCAD to Solution = 9.0 Hours
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Fast & Accurate Solver
Model Exp. DDES DES LES
Drag (SCx) 0.70 0.71 0.75 0.69
Courtesy
DDESDES
Near-Linear
Speedup
Till 1000
Cores
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Upfront Aerodynamics Example
(SAE Paper 2011-01-0170)
Study effect of various vehicle shapeparameters on drag force
Shape parameters are defined using
mesh morphing technology in ANSYS
Fluent
ANSYS WB & DX are used to drive the
shape parameters, create DOE &
perform goal driven optimization
ANSYS WB makes the process
automatic
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Define shape parameters UsingMesh Morpher in FLUENT Solver
Setup Baseline CFD model inFLUENT solver
Access Shape Parameters in WB
Generate & Solve DOE
Generate Response Surface &Perform Goal Driven Optimization
2
3
4
5
6
1
ANSYS Work Bench Automated
Work Flow Management Framework
ANSYS D i X l
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ANSYS Design Xplorer :Generate DOE, Study Design Space &
Perform Optimization
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Design Space Point:-- Baseline Design
(Velocity Contours on x=0)
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Design Space Point:-- Worst Design
(Velocity Contours on x=0)
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Design Space Point:-- Optimized Design
(Velocity Contours on x=0)
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Rain Water Management, Soiling & Water
Wading
Contours of volume fraction of liquid forBMW air-scoop
Rainwater management
Driving through water puddle
Water ingestion
Water films on body
Soil Deposition
Water wading
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Fast & Reliable Structural
Preprocessing
Efficient Mid surfacing, Automatic Contact Detection
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Automated Spot Welds & Contact
Modeling
Nonlinear Analysis of Door Frame
using Spot Welds
Mesh Independent Spot Welds
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Hood Model
Node Number : 16048
Element Number : 16611
Door Model
Node Number : 11419
Element Number : 10990
Component Mode Synthesis
Efficient Simulation of Substructures
Car Body ModelNode Number : 87680
Element Number : 94760
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Component Mode Synthesis
Efficient Simulation of Substructures
0 500 1000 1500 2000 2500 3000
CMS- FULL
FEM- FULL
FEM- FULL
CMS- FULL
(S)
1. Huge Speed up using
CMS for BIW withoutloss of accuracy
2. Full FEM & CMS Results
match within 1 %
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Design Life & Fatigue Analysis of
Body In White
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Case Study #3 Reducing Vehicle
Noise
[2]
[2] J. Plunt , Finding and fixing NVH problems with transfer path analysis, Sound and Vibrations, 2005
Vehicle NVH Sound Sources Vehicle NVH : Sound Transfer Paths
Frequency
RangeDominant Sound Source
Low Frequency
(0- 100 Hz)
Mostly structure-borne noise
(Exception Buffeting)
Mid Frequency
(100 250 Hz)
Structure and Air borne noise
High Frequency
(> 250 Hz)
Airborne
Key Requirements for Vehicle Noise Modeling
Accurate modeling of air borne noise source
Accurate modeling of propagation of noise source from source location to receiver
Propagation of noise within fluid or solid medium
Structural and Acoustics Coupling (FSI)
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Side View Mirror
Door Gaps
Rain Gutter
Wipers
Sunroof
Courtesy: Opel
Accurate Modeling of Air borne
Noise Sources
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Accurate Noise Propagation
Modeling
Far Field Noise Propagation Ffowcs Williams Hawkings (FWH)
Model
Validated & First in Commercial
CFD Solver
ANSYS CFD & FFT Actran coupling
AIAA 2008-2906
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ANSYS Acoustics Structures
From Harmonic Vibrations to Noise Estimates
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Summary
Industry leading solutions from ANSYS
Automated Work-Flow Management
Advanced & Easy to Use Modeling Techniques
Fast Solver Algorithms (CFD & Mechanical Solvers)
Efficient High Performance Computing
Simulation Best Practices for Automotive Industry
ANSYS Provides Comprehensive Solutions forVehicle Body Simulation
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Thank You !