The document discusses advanced compliant variation analysis using finite element analysis (FEA) compliant modeling. It describes how compliant modeling uses FEA to simulate variation in assemblies with deformable parts. Key benefits of compliant modeling include more accurate analysis, faster model building, and the ability to analyze effects like gravity, thermal impacts, and assembly sequences. Examples shown include analyzing ground clearance of an aircraft wing and hood-to-fender flushness variation in a car. The document also outlines the compliant modeling process and interfaces with FEA software.

1. Advanced Compliant Variation
Analysis
FEA Compliant Modeler for 3DCS Variation Analyst Suite

2. 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

3. 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

4. Compliant (Flexible) Parts
What Parts are Compliant?
• Structures
• Interiors
• Power Train
• Suspension
Why?
• Size & Thickness
• Gravity
• Heat
• Force
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2008

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Compliant Tolerance Analysis
Uses Finite Element Methods to simulate variation with
deformable parts
Additional Model Inputs
• FEA Data
o Mesh
o Material Properties
o Stiffness
o Mass
o Thermal
• Compliant Processes
o Clamping
o Welding
o Bending
o Springback
o Etc.
Compliant
FEA Data
Compliant
Processes

6. 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

7. 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 deform
2.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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2008

8. 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

9. AIRCRAFT: Ground Clearance
AUTOMOBILE: Hood to Fender Flushness
Rail Model
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2008

10. Examples of Very Low Ground Clearance
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12. Gravity acting on Wing and Engine
Effect of Gravity On Distance (mm)
Wing Tip 29.17
Ground Clearance 5.97
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2008

13. *min & max position measurements are relative to nominal position
Effect of Engine Position On Min Position (mm) Max Position (mm)
Tip Displacement - 0.30 + 0.36
Ground Clearance - 70.17 + 68.76
Engine moved from min to max position
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2008

14. Tolerances were added to simulate imperfect parts

15. Measurement Nominal Range with Variation
Wing Tip 29.18 264.48
Ground Clearance 5.97 57.62
1st Tolerance Scenario:
• Engine at nominal
• Fuselage Tol- 5mm
5 mm

16. 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
3 mm

18. Hood Fender
Hood is under-flush to Fender
with high variation

19. Add a pair of bumpers to contour the Hood to the Fender
and reduce flush variation…
but where?

20. 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:

21. Flush variation measured at these locations

22. 1.2
1.4
1.6
1.8
2
2.2
2.4
2.6
2.8
3
3.2
1 2 3 4 5 6 7 8
Est.RangeVariation(mm)
Rear - Mid - Front
No
Front
Mid
Mid2
Upper
Avg
Hood to Fender Flush

23. 2.7
2.8
2.9
3
3.1
3.2
3.3
3.4
3.5
3.6
3.7
1 2 3
Est.RangeVariation(mm)
Front - Mid - Rear
No
Front
Mid
Mid2
Upper
Hood to Fender Gap
Hood to Fender Gap is Independent of Bumper Location

24. 1. Front
2. Mid
3. Mid2
4. Upper 2.173 mm
2.172 mm
2.305 mm
2.328 mm
2.483 mm0. None
Mid2 bumper location is best for Hood to Fender flushness.
Avg. Est. Range at Bumper Locations

25. 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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2008

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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.

28. © 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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29. 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

30. Product Mesh File Extension Stiffness Matrix Extension
Abaqus .inp .mtx
Nastran .bdf, .blk, .dat, .nas .bdf
Optistruct .fem, .parm .dmig
MSC Nastran .dat .pch
*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.