FEA Internship

Matthew SchomischSummer 2015

Overview

1. About Me

2. Lid Application

3. Drop Testing

4. Practical Experience

5. Conclusion

6. Pizza

Home Sweet Home

•Born and Raised in Kalamazoo

•Kalamazoo Central 2013 Grad

•Full Kalamazoo Promise Recipient

Michigan State University

•Junior at Michigan State

•Studying Mechanical Engineering with a Minor in Spanish

Michigan State University

•Director of MSU’s Improvisational Comedy Team

How I Found Fabri-Kal

Monroe Brown Foundation

9th year of organizing internship opportunities for students in Southwest Michigan.

Getting Started With Solidworks

•Worked through Basic, Professional, and Premium Manuals

What Is FEA?

FEA (Finite Element Analysis) • An algorithm based technique for analyzing designs.

• How it works:• Applies nodes or common points• Applies manifold line to create elements• Elements can be arranged as a curvature based mesh or a

standard based mesh• Each node is given a number from the analysis • Each node is also given 3 Degrees of Freedom (DOF) and 3

Degrees of Rotation (DOR).

Solidworks Simulations

1. Build a model2. Build a prototype of the design3. Test the prototype in the field4. Evaluate the results of the testing5. Modify the design based on the results

Simulation is good way for companies to take their products to see how forces, displacement, and more will react on them.

11

Lid Application

Goal: 1. Use FEA simulation to replicate collected data from new

lid application method. 2. Come up with a strategy to test how design changes will

affect the force required to apply a domed lid to a cup.

Domed Lid Application

DLGC 12/20GC12S

•PLA•In Production/Readily Available•Product Realization Process

Lid Application Fixture

Benefits of Hinged Fixture

•Old method used top loading to apply the lid and did not capture the rolling motion used by customers to apply the lid.

•Very tight lids were not being applied completely.

•With the old method, the sides of the cup needed to be constrained, essentially pre-loading the container.

•Operator to operator inconsistencies in how the lid was half seated before application.

•Force testing results are more accurate for the hinged press plate.

Physical Lid App Results

Force Increases Until Snapping Motion Occurs

Average Force Required: 5.8614 lbf

Sample Ultimate Force (lbf) Ultimate Displacement (in)1 6.051 0.1642 7.291 0.1583 6.717 0.1554 5.476 0.1535 5.789 0.1566 5.766 0.1417 6.403 0.1578 5.361 0.1529 5.219 0.161

10 5.993 0.1611 5.63 0.15912 6.132 0.14713 5.467 0.1414 4.765 0.153

0 0.03 0.05 0.08 0.10 0.13 0.15 0.18 0.20 0.23 0.25Displacement (in)

Forc

e (lb

f)

This graph is what we want to replicate through simulation.

Initial Simulations

•Slow starting out, many consecutive steps.•Needed to half seat the lid then lower the fixture onto the lid, then complete the application of the lid.

17

Using Symmetry

Symmetry- The fixture only allowed for the use of ½ symmetry while simulating. While this reduces the runtime from the fully modeled fixture, more simplification (¼, ⅛) is ideal.

Reoccurring Issues

•The physical lid application starts out with the lid half seated on the cup. Solidworks will not begin simulating if there is initial interference between parts.

•This caused us to have to use multiple step in the simulation, to first half seat the lid, then to complete the application of the lid onto the cup.

•More steps meant longer runtimes, less opportunities to test different settings, and more chances for errors to occur during simulation.

Using An Alternate Pusher

•Could not fully capture the real motion of applying the lid.

•Resultant force was unable to be extracted due to the pusher hitting the lid at different locations as the simulation ran.

Outside Suggestions

•We sought the help of Shaun Bentley from Dasi Solutions for lid app and drop testing.

•He suggested working around the interference problem with the use of shrink fit contacts.

•He also offered the idea of using shell elements for the domed part of the lid in order to save time during simulation.

Shrink Fit Modifications

•Using this type of contact set, we were able to get a working model.

Resultant Force

•The resultant force was 8.15 lbf using the symmetry model, because of this the real simulated force is double that (16.30 lbf)

Response GraphSimulation

Actual

0 0.03 0.05 0.08 0.10 0.13 0.15 0.18 0.20 0.23 0.25Displacement (in)

Forc

e (lb

f)

0.00 0.20 0.40 0.59 0.79 0.99 1.19Time (sec)

Requ

ired

forc

e (lb

f)

At this point we should see a drop off in force caused by the snapping motion of the lid into the cup which corresponds to the drop off in the actual testing

Vertical force

Moving Forward

Draft Quality Mesh• Specifies 4 corner nodes for each

solid element• Draft quality mesh is

recommended for quick evaluations and the default high quality option for final results.

• Makes models more stiff.

Moving Forward

Normal Quality Mesh• Smooth• More adaptive to

curves• Takes longer time to

compute.• i.e. draft quality

took ~1 hour. and normal quality took 12 hours+ before giving errors

• More accurate Results

Moving Forward

•Shell elements simplify the mesh on dome while leaving the nibs more defined.

27

Drop Testing

Goal: Use Solidworks Simulation to develop a method to test design changes and how they compare during drop studies.

NC9OF: Getting Our Feet Wet

•This type of simulation had not yet been attempted at Fabri-Kal.

•We chose the NC90F because it was already modeled and its simple shape would allow us to get a feel for how changes made to design features would affect simulated results.

Drop Study vs. Nonlinear Dynamic

Drop Study Nonlinear Dynamic Study

Pros:•Easy to set up

Cons:•Very long runtimes

Pros:•Short runtimes•More loading optionsCons:•More complicated to use

Temperature Based Modulus

•Solidworks gives the option to input a temperature based elastic modulus that adjusts during the simulation to represent the change in tensile properties as the temperature of the part changes.

Easier Said Than Done •Unfortunately, this type of information is not readily

available from suppliers and we were not able to explore this option.

31

RD16WF 35, 48, 58, 70 Gage

Sidewall Top

Sidewall Mid

Sidewall Bottom

Bottom Corner

Bottom Mid

Bottom Center

00.0050.01

0.0150.02

0.0250.03

0.0350.04

0.045

Wall Thickness

35485870

Location

Thic

knes

s (in

ches

)

•What we were missing was the ability to come up with a certain stress that if exceeded by a part with the same material properties, would result in failure.•With this in mind we moved on to the RD16WF.

•Metallocene PP (Same as SCJ bowls). •Drop parts of different thicknesses at different heights to isolate material property we needed (stress of failure).

35, 48, 70 were the most linearly related

GageGageGageGage

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RD16WF Trial 1 Results

•Samples were all refrigerated overnight.•Attempted to hone in on a single height that would cause part failure.•70 Gage failed at a lower height than the 48.•Not a clear enough results to move forward with simulations.

35 GageSample Drop Height Result

1 18.00 Broken 2 17.00 3 17.00 4 17.50 5 18.00 6 18.00 7 17.50 8 17.50 9 17.25

10 17.25 11 17.25 12 17.25 13 17.25 14 17.00 15 17.00

48 GageSample Drop Height Result

1 24.0 2 21.0 3 18.0 4 18.5 5 18.5 6 18.5 7 18.5 8 19.5 9 19.5

10 19.5 11 20.5 12 20.5 13 21.0 14 22.0 15 23.0

70 GageSample Drop Height Result

1 48 2 42 3 36 4 30 5 24 6 18 7 17 8 17 9 17

Pass

Fail

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Changes Made

•Better Seal: Some lids were popping on impact making it difficult to compare results to those that did not break.

•Room Temperature Samples: Did not refrigerate the samples because of inconsistencies in cooling depending on where in the refrigerator they were kept.

•More Samples: In order to get more precise data we needed more data points which meant more samples formed, sealed, and dropped.

34

Set Up

•Formed, trimmed, punched, filled, sealed, and dropped 50 parts each for the 35, 48, and 70 Gage PP.

35

RD16WF Trial 2 Results70 mil 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 nx no % pass

Total Drop/row

82 x 1 0 0% 8278 o x x x 3 1 25% 312

76.5 o 0 1 100% 76.575 o 0 1 100% 7572 x x o o o 2 3 60% 36066 o x o o 1 3 75% 26465 o 0 1 100% 6561 o 0 1 100% 6160 o x o 1 2 67% 18054 x x o 2 1 33% 16248 o x o 1 2 67% 14442 x o 1 1 50% 8436 o 0 1 100% 36

12 18Total Drop 1901.550% Fail 63.4

48 mil 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 nx no % passTotal Drop/row

82 x o x x o o o o x x 5 5 50% 820

78 x x o o o o o 2 5 71% 546

72 o o o 0 3 100% 216

66 x o 1 1 50% 132

60 o o 0 2 100% 120

8 16Total Drop 1834

50% Fail 76.4

70 Gage Recommended Height: 78in

48 Gage Recommended Height: 76.4in

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RD16WF Trial 2 Results35 mil 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 nx no % pass

Total Drop/row

60 x 1 0 0% 6054 x x x x 4 0 0% 21651 x 1 0 0% 5150 x x 2 0 0% 100

49.5 o 0 1 100% 49.548.75 o 0 1 100% 48.75

48 x o o o 1 3 75% 19242 o 0 1 100% 4236 0 0 #DIV/0! 0

9 6Total Drop 759.2550% Fail 50.635 Gage Recommended Height: 50.6in

•With the different drop heights from the physical trial we were able to simulate the stress at impact for each gage and its respective height.

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RD16WF Simulation Results

Max Stress (lbf)

35 Gage, 50.6in 1.13E+04

48 Gage, 76.4in 1.13E+04

70 Gage, 78in 1.13E+04

The maximum stress for the recommended drop heights are the same (1.13E+04 lbf) for the PP Homopolymer we used, thus giving us the material property we were looking for.

0 0.0002 0.0004 0.0006 0.0008 0.001 0.00120.00

2000.00

4000.00

6000.00

8000.00

10000.00

12000.00

Drop Test Simulation Results

35 Gage 50.6in Half Sim48 Gage 76.4in Half Sim70 Gage 78in Half Sim

Pseudo-Time (unit-less)

Max

imum

Str

ess

(psi

)

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RD16WF Simulation Results

0 0.0002 0.0004 0.0006 0.0008 0.001 0.00120.00

2000.00

4000.00

6000.00

8000.00

10000.00

12000.00

Drop Test Simulation Results

70 Gage 78in Half Sim70 Gage 63.4in Half Sim

Pseudo-Time (unit-less)

Max

imum

Str

ess

(psi

)

39

RD16WF Simulation Results

PassFail

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What’s Next?

•The next step will be to drop a cup of the same material but different dimensions to test the maximum stress we found.

•From there process can be repeated for more materials used at Fabri-Kal.

•In the end we would like to be able to receive a survivable maximum height requirement and fill amount from the customer and use simulation to test if the part and subsequent design modifications will be able to survive the fall.

41

Practical Experience

Learning More About Materials

Materials• Solidworks generally

has the data for injection molding plastics which is totally different than thin extrusion.• Modulus of elasticity• Poisson's ratio• Material density

•I was able to apply what I learned in my materials science courses to real world applications.

Modeling Lab Tooling

•Created 3D models from existing 2D drawings in order to help operators in referencing and installing and equipment.

Learning About Thermoforming

45

Conclusion

How do FEA studies help Fabri-Kal?

• Allows for designers to test out ideas without constructing physical models.

• Reduced the amount of modeling errors.• Easy to edit different thicknesses and different materials

before going into production.• Saves in both tooling, prototyping and material costs.

47

Recommendations

Lid Application• Continue with trying to get successful

simulations using normal quality mesh.• Explore more simplifications and using

shell elements to save on runtimes.Drop Testing• Test a different cup with the same

material to prove out the method we came up with.

• Try to get temperature dependent modulus data for future simulations that might involve a refrigerated container.

My Big Takeaways From This Summer

1. Never be afraid to answer questions.

2. Seek help when you need it.

3. Don’t accidentally drink water from the quality lab.

Questions?

Any Questions?

50

Thank You Everyone At Fabri-Kal

And a special thanks to Jason Trahan and Adam Powers

The Monroe Brown Foundation