Statistical Analysis of the Tensile Properties of Various Polymers Processed through

3D Printing

Introduction• Additive Manufacturing is a new processing method

developed for creating a 3-Dimensional object by adding layer upon layer of material whether it is a polymer, metal, concrete or even human tissue.

• The main techniques used in Additive Manufacturing are:• SLA (Stereolithography)• FDM (Fused deposition modeling)• MJM (Multi-jet modeling)• 3DP (Three dimensional printing) • SLS (Selective laser sintering)

• The polymers studied in this project are:• PLA (Polylactic acid)• ABS (Acrylonitrile butadiene styrene)• Bio-ABS

• They are processed using the FDM technique on a Lulzbot Mini following the ASTM (American Society for Testing and Materials) standards.

Methodology1. Designing the Test Specimen in CAD• In order to test the polymers for the tensile properties, the

test specimen was designed in Solidworks following the ASTM standards for tensile testing polymers.

• The CAD file was then converted into STL and sliced to create G-code so that the printer could print the mechanical testing specimens

Conclusions• Using 3-D printing, three different polymers were successfully

processed and tested for mechanical properties.• The PLA exhibits highest strengths among three polymers under

the given processing and test conditions.• ABS and Bio-ABS show very comparable mechanical properties.• The effect of fill density on mechanical properties is clearly

shown in that both modulus and strength increased linearly with density.

Results

2. Printing & Testing the Tensile Specimens• After the CAD file is converted from STL to G-Code the

specimens are printed out of each material using the Lulzbot Mini using the same conditions for each print job

• After all of the specimens were printed they were tested on the Instron APEX 60UD and pulled until fracture

Figure 7: Stress-Strain Curves of ABSFigure 8: Effect of Fill Density on Strength Figure 9: Effect of Fill Density on Modulus

Figure 1: The ASTM Standard and A 3-D render of the test specimen

Figure 2: The specimens being 3-D printed

Acknowledgements:This work was supported primarily by the Engineering Research Center Program of the National Science Foundation and the Department of Energy under NSF Award Number EEC-1041877 and the CURENT Industry Partnership Program.

1. Mechanical Properties of Different Polymers• Tensile testing was performed on the Instron APEX

60UD with a strain rate of 5.6x10-4/sec. The data was analyzed using Microsoft Excel and Origin programs.

2. Effect of Fill Density on Mechanical Properties• ABS test specimens were made with varying fill

densities of 25, 60, and 100% and then tested to investigate the effect of fill density on Elastic Modulus and Ultimate Strength for ABS.

Luke Buckner, Oak Ridge High School[Mentors: Peijun Hou, Yuan Li , Zane Palmer, Hahn Choo, University of Tennessee]

Figure 3: The specimen tested on the Instron

Figure 5: Modulus of Elasticity for the 3 Polymers

Figure 4: Stress-Strain Curves for the 3 Polymers

Figure 6: Ultimate Strength and Maximum Elongation for the 3 Polymers

0.00 0.02 0.04 0.06 0.08 0.10 0.120

5

10

15

20

25

30

35

Eng

inee

ring

Str

ess

(MP

a)

Engineering Strain

100% 60% 25%

ABS

PLA ABS Bio-ABS0

5

10

15

20

25

30

35

31.5

18.0 18.7

2.4 4.4 1.8

Ultimate Strength & Maximum Elongation of Various Polymers

Ultimate Strength (Mpa)Max Elongation (mm)

0.00 0.02 0.04 0.06 0.08 0.10 0.12 0.140

5

10

15

20

25

30

35

Eng

inee

ring

Str

ess

(MP

a)

Engineering Strain

PLA ABS Bio-ABS

Comparison of the Three Polymers

0.009 0.010 0.011 0.012 0.013 0.014 0.015 0.0163

4

5

6

7

8

9

Modulus: 595.58 MPa

Modulus: 488.5 MPa

Eng

inee

ring

Str

ess

(MP

a)

Engineering Strain

PLA Fit ABS Fit Bio-ABS Fit

Modulus: 495.46 MPa

Modulus of Elasticity of 3-D Printed Polymers with 25% Fill Density

R2

= 0.9983

20 30 40 50 60 70 80 90 100

18

20

22

24

26

28

30

Ulti

mat

e S

tren

gth

(MP

a)

Fill Density (%)

Strength (MPa) Linear Fit

20 30 40 50 60 70 80 90 100

500

550

600

650

Ela

stic

Mod

ulus

(M

Pa)

Fill Density (%)

Modulus Linear Fit

Objectives• To study each polymer for their mechanical (tensile) properties • To study the effect of fill density on elastic modulus and

ultimate strength

Figure 7 Figure 8

Figure 9