MSC Software Confidential MSC Software Confidential

The Affect of Temperature Dependent

Materials in an Explicit Nastran Analysis

on a Plastic Container

Travis Hunter

Lead Analyst

Graham Packaging Company

May 7, 2013

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• Review of Graham Packaging Company

• Describe the Stretch Blow-Molding Process

• Define the Hot-Fill Process

• Compare the Old versus New Method

• Review the New Results

• Summary

Outline

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Graham Packaging Company

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– Empty and Vented Top Load

– Filled and Capped Top Load

– After Vacuum Top Load Analysis

– Pressure

– Vacuum

– Retort

– Hydrostatic Bulge

– Hot Fill Bulge

– Grip and Side Load

– Drop (Filled & Unfilled)

– Conveyance

– Shrink-wrap

– Thermal Mold Analysis

– Flash Pocket Thermal Analysis

– Stretch Rod Flow Analysis

– Thermal/Flow combined with Structural

– PET Blow Simulation

– Poly Blow Simulation

– Polymer Flow Simulation

– Machine Component / Motion

– Part Fatigue

– Plant / Line Simulation

Simulations at Graham Packaging

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Stretch Blow-Molding Process

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• Typical Fill Temperature

– 185ºF

• Bottle is filled to required volume

• Bottle then is cooled to room temperature

• The geometry of the bottle needs to withstand the

vacuum

Hot-Fill Process and Boundary Conditions

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Hot-Fill Process Probe Data

60

80

100

120

140

160

180

0:00 0:04 0:08 0:12 0:17 0:21 0:25

Tem

per

atu

re (

ºF)

Time (minutes)

14

14.2

14.4

14.6

14.8

15

15.2

15.4

15.6

6080100120140160180

Pre

ssu

re (

psi

)

Temperature (ºF)

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Thermal effects on the Structural Properties

of PET

0

20

40

60

80

100

120

140

160

0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6

Str

ess

(MP

a)

Strain (mm/mm)

72ºF

100ºF

128ºF

156ºF

185ºF

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• Only using 1 stress-strain curve

• Model is too stiff

• Model does not deform when the

material is the weakest

Disadvantages of Old Method

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• MATD106

New Material Card

Table of Tables

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• Table references temperature and the corresponding

Stress-Strain Curve

Table of Tables

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Deformation After Hot Fill

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Thermally Induced Stress Plot

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Deformation after cooling

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• Need to take vacuum results on the next

analysis

• Files required:

– The original run file

– .nastin file

• Setup next analysis

Recombining the Results for Final Analysis

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Top Load Results

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• Approximately $1.5 million in total savings

• 15% improvement in accuracy of the

simulation

• Faster speed to market

• Material savings

• Results closely match lab data

Conclusions

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• Add different filling processes

• Continue to improve material models

• Unable to recombine the material card

Future Work

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• Any questions

Thank You for your attention