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Using FE to simulate the effect Using FE to simulate the effect of tolerance on part of tolerance on part

deformation deformation By

I A Manarvi & N P Juster

University of Strathclyde

Department of Design Manufacture and Engineering Management

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Outline Outline • Introduction• Methodology • Experimental phase• Procedure • Tolerance Vs. deformation experimental results• FE simulations • Tolerance Vs. deformation FE results• FE deformation pattern at tolerance values • Comparison of Experimental and FE results• Conclusions

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IntroductionTolerance Allocation in Product Design: a) Vital activity for mass production and interchange-

ability of parts

b) Required during design, Manufacturing, Assembly, Quality and performance evaluation phases.

Major influences on function, cost, customer requirements and aesthetics.

Scope :

Investigating use of FE simulations as a tool to verify influence of tolerance on part deformation at initial design stages

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MethodologyExperimental phase: a) Selection of specific type of tolerance , a simplified

geometry and commonly used materialb) Design and manufacturing of a test rig for

experiments simulating tolerance conditions. Execution of experiments and collection of data

FE simulation phase:a) FE modelling and simulation with ABAQUS

software with similar boundary conditions as experiments.

b) Collection of FE results at same Axis location as of experimental data

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Known Parameters: a) Selection of tolerance: Location of two hole centresb) Simplified geometry: Rectangular strip 200 x 40 x 1 mmc) Material : ABS plastics ( Astyrn BR 712 A)

Test rig designed and manufactured:

Base Platform

Parallel Precision slides

Side supports

Sliding platform

Rotary Knob

Dial Indicator 1

Dial Indicator 2

Dial Indicator 3

Experimental Phase

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Procedure

Specimen Rotary knob

Pin B (0.2, 0.4, 0.6, 0.8, 1.0, 1.2mm)

Pin A (Fixed)

Z

Y

X

Y

Z

Dial Indicator 1 for tolerance measurement

Dial Indicator 2,3 for side deflection measurement

Out of plane deformation Z axis

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Tolerance vs. Deformation Experimental Results

-10

-8

-6

-4

-2

0

1 3 5 7 9 11 13 15 17

Length x 10mm

Def

orm

atio

n (

mm

)

0.2mm 0.4mm 0.6mm

0.8mm 1.0mm 1.2mm

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FE simulations

Material properties: ABS plastics ( Astyrn BR 712 A)

• Material type = Elastic

• Young’s Modulus = 106 e 3 MPa

• Poison’s ratio = 0.39

Analysis steps : Initial & Step 1 with assumptions as:

• Non linear geometries ON

• Buckling criteria = Static Riks

Model creation: Rectangular strip 200 x 40 x 1 mm

40200

1

180

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FE SimulationsBoundary conditions:

YX

ZPin B Pin A

Ux = 0.0Uy = 0.0Uz = 0.0Rx = 0.0Ry = 0.0Rz = 0.0

Ux =FreeUy =FreeUz =FreeRx =FreeRy =FreeRz =Free

Pin B would move in steps to 0.2, 0.4, 0.6, 0.8, 1.0, 1.2 mm in X-axis

Meshing conditions:

Mesh seeds = 2mmElements = Hexagon

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Tolerance vs. Deformation FE Results

-10.0

-8.0

-6.0

-4.0

-2.0

0.0

1 3 5 7 9 11 13 15 17 19

Length x 10 (mm)

Def

orm

atio

n (

mm

)

0.2mm 0.4mm 0.6mm

0.8mm 1.0mm 1.2mm

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FE Deformation Pattern of Model at Different Tolerance values

0.2 mm

0.4 mm

0.6 mm

0.8 mm

1.0 mm

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Comparison of Experimental and FE Deformation at 0.2, 0.4 & 0.6mm

0.0

1.0

2.0

3.0

4.0

1 2 3 4 5 6

Length X 10 (mm)

Defo

rmat

ion

(mm

)

FE 0.2mm Exp 0.2mm

0.0

1.0

2.0

3.0

4.0

5.0

6.0

1 2 3 4 5 6Length x 10 (mm)

Defo

rmati

on (m

m)

FE 0.4mm Exp 0.4mm

0.0

2.0

4.0

6.0

8.0

1 2 3 4 5 6

Length x 10 (mm)

Defo

rmati

on (m

m)

FE 0.6mm Exp 0.6mm

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0.0

2.0

4.0

6.0

8.0

1 2 3 4 5 6Length x 10 (mm)

Def

orm

ation

(mm

)

FE 0.8mm Exp 0.8mm

0.0

2.0

4.0

6.0

8.0

10.0

1 2 3 4 5 6Length x 10 (mm)

Def

orm

ation

(mm

)

FE 1.0mm Exp 1.0mm

0.0

2.0

4.0

6.0

8.0

10.0

1 2 3 4 5 6

Length x 10 (mm)

Def

orm

atio

n (m

m)

FE 1.2mm Exp 1.2mm

Comparison of Experimental and FE Deformation at 0.8, 1.0 & 1.2mm

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FE Analysis of complex geometry

2.07 1.97

1.87

1.66

0.00

0.42

1.04

1.35

1.56

1.76

0.62

0.73

0.83

0.93

IDEAS VISUALISERFEM 1 B.C. 1, DISPLACEMENT_1, RESTRAINT SET 1 DISPLACEMENT Magnitude Un averaged Top Shell Min: 0.00 mm Max: 2.07 mm

X

Y

Z

Y= 1.0mm Rest all DOF set free

All DOF constrained

All DOF free

All DOF free

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FE Analysis of complex geometry

Hole C Y= 1.0mmRest all DOF set free

All DOF constrained in Hole A

All DOF constrained in Hole B

IDEAS FEM 1 B.C. 1, DISPLACEMENT_1RESTRAINT SET 1 ELEMENT SIZE = 0.2mmType: Thin shell 2.5mm thicknessNo. of Elements = Over 400,000

Hole D No constrain applied

XZ

Y

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FE Analysis of complex geometry

0.00

2.72

2.44

2.172.04

1.491.36

1.22

0.68

0.540.410.27

0.14

0.820.951.09

1.631.771.90

2.31

2.58

mmUn deformed modelDeformed model

No deformation Zone

Maximum deformation Zone due to 1.0mm tolerance

Deformed modelUn deformed model

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FE Analysis of complex geometryIDEAS FEM 1 B.C. 1, DISPLACEMENT_1RESTRAINT SET 1 ELEMENT SIZE = 2.5mmType: Thin shell 2.5mm thickness No. of Elements = Over 400,000

Y= 1.0mm

Rest all DOF set free

All DOF constrained

All DOF constrained

No constrain applied

Y

Z

Y

SIDE VIEWFRONT VIEW

X

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FE of Automotive Glove boxIDEAS VISUALISER FEM 1 FRONT VIEW B.C. 1, DISPLACEMENT_1, RESTRAINT SET 1 DISPLACEMENT Magnitude un averaged Top Shell Min: 0.00 mm Max: 3.86 mm

0.00

3.86

3.48

2.70

1.931.74

1.55

0.77

0.58

0.39

0.19

0.14

0.97

1.16

1.35

2.12

2.32

3.28

mm

2.51

2.90

3.67

Max. deformation

No deformation

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Conclusions Peak deformation at center of specimen reducing

towards edges. FE and experimental results showed tolerance

leading to deformation subsequently influencing part assembly

Existence of a linear relationship between tolerance and deformation of parts confirmed by FE and experiments

Similarity of experimental and FE results signified the possibility of using FE as a tool for tolerance allocation.

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Thank You for attentionThank You for attention

Questions ?