1

Virtual Vehicle DevelopmentRequirements for Safety CAE

Michael BuckleySafety CAE Technical SpecialistPaul WoodWarwick Manufacturing Group

Autosim, Birmingham April 2008

Agenda

• JLR Body & Trim CAE Group Background

• CAE Challenges for Virtual Vehicle Delivery

• Case Study: Modelling of Self Piercing Rivets

• Summary

JLR Body & Trim CAE

• Team of around 80 engineers in Body & Trim Engineering.

• Attributes Supported

> BIW & Component NVH (BIW, Seating, Interior Trim, IP etc.)

> BIW & Component Durability

> BIW, Component & Full Vehicle Safety

> Closures

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Challenges of Delivering Robust Data

CAE Challenges

• Full Virtual Test Programs

• No Surprises at Test!

> CAE is reliably capable of predicting error states

• More Demanding Targets

> (e.g. EuroNCAP, IIHS) requiring increased CAE fidelity &

capability.

• Compressed Program Timelines

> Speed/ accuracy balance

Increase Predictive Capability with Limited Resource

Mesh to CAD Variation

Shape

Heat Treatment

Gauge Variation

Residual Stress Pre Strain Damage

Part Production

Manufacturing Artifacts

Supplier Specific

Average of all Suppliers

Base

Mechanical Properties

Material

Body PanelExtrusionCasting

Adhesive

SPR

Bolts

RSW

Joints

BIW

Incr

easi

ng C

AE

Mod

el C

ompl

exity

& P

redi

ctiv

e C

apab

ility

Where do we get best S/N

improvements?

How accurate do we need to

be?

Example: SPR Joint Modelling

• Around 4000 mechanical joints on a vehicle (spotwelds, self piercing

rivets, bolts, etc.).

• All joints cost time & money, some cost weight.

• Unpredicted panel failure can lead to reduced vehicle performance.

• In order to optimise joints we need to be able to predict their behaviours

in terms of stiffness & failure (load, toughness etc.) characteristics.

• Challenges

> Acquisition of appropriate test data

> Implementation in CAE.

5mm

Physical Entities

SPR

CAE Entities

Beam or Spring

Solid Element

5mm

RSW

Joints Background & CAEImplementation Issues

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Lap Shear U tension Peel tension

Explore Test Systems Using CAE

• Protocol Design

• Test & Measeurement System Design

• System Prove Out

High Speed Test Facility

• 1mm/s -> 1m/s (closed loop)

• 1m/s -> 20m/s (open loop)

• Rated at 100kN

• Bi-directional

• Gauge Lengths:

• 50mm (Quasi)

• 25mm (High Speed)

Typical Test Results: SPR in ‘U’ Tension

Effect of Speed

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�Initial model stiffness too low�Probable causes? – diameter of SPR and effect of bolt constraint on side of specimen in model.

Initial CAE Model

0.3

mm

1.5

mm

0.3

mm

Rivet Side Clamp Side

Bulge on top face 9 mm dia

1.3 mm9 mm dia

5.9

mm

dia

3.7

mm

2.1

mm

4.8 mm dia

Investigate Test Results & Samples

Part Number and Definition1) Rivet Side: Moving Rigid given Constant Velocity BC in X (~ Grip Movement) 2) Clamp Side: Deformable Central Body3) Clamp Side: Deformable Corner of body4) Clamp Side: Rigid Sides Fully Constrained5) Rivet Side: Rigid SPR Constrained to Part 16) Clamp Side: Deformable Sleeve7) Clamp Side: Deformable Button

Contact Definition Between Parts 1, 5 (Slave Side) and Parts 2, 6 (Master Slide) using Contact Automatic Surface to Surface with part definition and friction initially set to 0.3

1

2

3 4

�Solid element size in deformable parts ~ 0.5mm fully integrated (type 3)�Shell element size in rigid SPR ~ 0.25 mm

5

6

7Rivet side

Clamp side

Detail Model to Understand Mechanisms

Deformed shape corresponds to test specimen geometry

Section View

End View Side View

Section ViewSection View

End View Side View

Section View

Moving Rigid ~ Grip

Deformable

Detailed CAE vs Test

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End of test specimen displacement (K1)

End of rivet pull out (K2)

Improved CAE Correlation in Detailed Model

Force Output from Physics Model

Detailed Model 8 mm Spring PCDk2 Scaled

Sub-model1 x 6dof beamk2 scaled

Industrial Level CAE Model

Summary

• The competative automotive environment will continue to challenge CAE, asking new questions & wanting the answers faster

• New predictive capabilities require significant investment• CAE must be used at all stages of new virtual technology delivery• At JLR, CAE is enabling the goal of the fully virtual program.

CAE, a Key Contributer to , ‘Better Cars, Faster’

Acknowledgements

The authors wish to acknowledge the financial contribution of

Advantage West Midlands to this project.

Questions?