Advanced Compliant Variation Analysis

FEA Compliant Modeler for 3DCS Variation Analyst Suite

Clamp/Weld Clamp/Weld

                                  

Agenda

• Rigid Body Modeling• Compliant Modeling• 3 Compliant Cases

–Aircraft Wing–Car Hood–Rail Assembly

• FEA Interfaces• Q & A

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2008

Rigid Body Tolerance Analysis

Inputs• Assembly Strategy• Part Tolerances (GD&T)• Desired Measurements

Outputs• Datum Locating Scheme• Tolerance Sensitivity• 6sigma Variation

*Assumption: Parts do not bend or morph to meet over-constraining targets

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2008

Compliant (Flexible) Parts

What Parts are Compliant?• Structures • Interiors• Power Train• Suspension

Why?• Size & Thickness• Gravity• Heat• Force

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Compliant Tolerance Analysis

Uses Finite Element Methods to simulate variation with deformable parts

Additional Model Inputs• FEA Data

o Mesho Material Propertieso Stiffnesso Masso Thermal

• Compliant Processeso Clampingo Weldingo Bendingo Springbacko Etc.

Compliant

FEA Data

Compliant Processes

Analysis Results3DCS Model

Rigid Body

Assembly Method

Part GD&T

Measurements

Compliant

FEA Data

Compliant Processes

Compliant Tolerance Analysis

Uses Finite Element Methods to simulate variation with deformable parts

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2008

Methods for Modeling Compliant Parts

User Experience Difficulty Level Relative # of Moves

Locating Points in Example

Relative Timing / Part Software

Rigid-Body 3DCS® training Beginner 1 5 1.0 3DCS® Analyst

Bend Routine 3DCS® Advanced 1 17 2.0 3DCS® Analyst + User DLLs

Compliant Modeler 3DCS®, FEA Intermediate 3 18 1.5 3DCS® Analyst + 3DCS® FEA CM AddIn +FEA Software

Accuracy

1.Rigid-Body Traditional Moves - part does not deform2.Bend Routines User DLLs - part deforms about defined bend lines 3.Compliant Modeler using Finite Element Analysis (FEA) - part

deforms to target points

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Compliant Modeling Benefits

• More Accurate Analysis• Faster to build Model• Limited FEA interaction • Analyze Assembly Sequence• Optimize Clamp, Fasten, Weld,… Sequence• Analyze Gravity and Thermal effects

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2008

Use Cases Overview

AIRCRAFT: Ground Clearance

AUTOMOBILE: Hood to Fender Flushness

Rail Model

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2008

Aircraft Engine Ground Clearance

Examples of Very Low Ground Clearance

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DCS Model

Gravity acting on Wing and Engine

Effect of Gravity On Distance (mm)

Wing Tip 29.17

Ground Clearance 5.97

1. Gravity

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*min & max position measurements are relative to nominal position

nominal

minmax

Effect of Engine Position On Min Position (mm) Max Position (mm)

Tip Displacement - 0.30 + 0.36

Ground Clearance - 70.17 + 68.76

2. Engine PositioningEngine moved from min to max position

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Tolerances were added to simulate imperfect parts

3. Dimensional Variation

Measurement Nominal Range with Variation

Wing Tip 29.18 264.48

Ground Clearance 5.97 57.62

Results: Engine Placement1st Tolerance Scenario:• Engine at nominal• Fuselage Tol- 5mm

5 mm

2nd Tolerance Scenario:• Engine at nominal• Fuselage Tol- 3mm

Measurement 1st Scenario 2nd Scenario % Change

Tip Displacement 264.48 158.71 40

Ground Clearance 57.62 35.12 39

Results: Fuselage Tolerance Scenarios

3 mm

Automobile Bumper Placement

Problem

Hood Fender

Hood is under-flush to Fender with high variation

Add a pair of bumpers to contour the Hood to the Fender and reduce flush variation…

Suggested Solution

but where?

1. Front 2. Mid 3. Mid2 4. Upper

Determine the location of lowest flush variation between Hood and Fender.

Simulate the placement of Bumpers at (4) locations:

Bumper Positions

5000 Simulated Builds in 3DCS

Flush variation measured at these locations

1 2 3 4 5 6 7 81.2

1.4

1.6

1.8

2

2.2

2.4

2.6

2.8

3

3.2

NoFrontMidMid2UpperAvg

Rear - Mid - Front

Est.

Rang

e Va

riatio

n (m

m)

Mid2 and Upper Bumper placement result in least f lush variat ion

Hood to Fender Flush

1 2 32.7

2.8

2.9

3

3.1

3.2

3.3

3.4

3.5

3.6

3.7

NoFrontMidMid2Upper

Front - Mid - Rear

Est.

Rang

e Va

riatio

n (m

m)

Hood to Fender Gap

Hood to Fender Gap is Independent of Bumper Location

1. Front

2. Mid

3. Mid2

4. Upper 2.173 mm

2.172 mm

2.305 mm

2.328 mm

2.483 mm0. None

Conclusions

Mid2 bumper location is best for Hood to Fender flushness.

Avg. Est. Range at Bumper Locations

Pushing the Envelope…• Real Time Diagnosis of Manufacturing issues• Mechanical System Analysis

– Analysis through a range of motion– Effects of Rubber Bushings on Variation

• Fuel Efficiency Impacts– Tolerances on Mass– Number of Shims on Mass– Surface Quality on Wind Drag

• Plant Layout \ Cycle Times– Clamps and welds required per station– Machining stations required

• Design & Manufacturing Optimization– Fit and Finish based on Perceived Quality– Design Interfaces, Cut Lines & Locators– Tolerances– Number of parts and Sequence of Assembly and Fastening

• Non Linear Sensitivity Analysis

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Thank you, Questions?

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How is the model Created?

2. Using the 3DCS FEA CM Modeler create clamp, weld, unclamp operations.

1. Create Model utilizing the standard DCS Moves, Measures, and DCS Tolerances and/or FTA

3. Generate FEA Input Deck and Stiffness Matrix using your FEA Pre & Processor and Solver.

4. Link 3DCS FEA CM to Input Deck and Stiffness Matrix and run Visual and Statistical Study.

© Dimensional Control Systems Inc. 2008

How does it work?The 3DCS FEA Compliant Modeler deforms the parts during simulation based on the part stiffness matrix for each compliant part that has been imported into the 3DCS model.

The FEA Mesh and stiffness matrix is acquired from software like Abaqus, Hypermesh and NASTRAN. The part stiffness matrix defines how a deformation at one point will affect other areas of the part – where, and how severely.

Clamp/Weld Clamp/Weld

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Causes

Moves method

Sequence

Rigid moves

Compliant moves

Clamping method

Joining type

N° clamping points

FEA files

Input data

Type and size elements

Pre-processor and solver

SOFT 1DOF vs HARD 3DOF

CM Model Influences

Product Mesh File Extension Stiffness Matrix Extension

Abaqus .inp .mtx

Nastran .bdf, .blk, .dat, .nas .bdf

Optistruct .fem, .parm .dmig

MSC Nastran .dat .pch

Supported FEA Solvers*DCS is constantly adding new features and functions, making this list subject to change

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What Process are Supported?• Clamping• Spot Welding• Unclamping • Spring Back• Bolting• Riveting• Joining• Clipping• Heat Staking• Compliant to Rigid• Compliant to Compliant

• Single Stage Assemblies• Multi Stage Assemblies• Force Application • Gravity• Thermal Expansion \

Shrinkage• Distortion • Load Sequence • Clamp, Weld and Un-Clamp

Sequence• 3+ thickness welding• Nearly anything supported by

the state of the art FEA tools.