1. Statistical Analysis of the Tensile Properties and Effect of Fill Density in Various Polymers Processed through 3D Printing
Luke Buckner
YSP Student
CURENT Young Scholars Midterm
13 July 2015
Min Kao Building, University of Tennessee

2. Introduction Additive Manufacturing (i.e. 3D Printing)
Using various materials such as metals, polymers, concrete and even human tissue
Multiple Techniques
SLA (Stereolithography)
FDM (Fused deposition modeling)
MJM (Multi-jet modeling)
3DP (Three dimensional printing)
SLS (Selective laser sintering)
AM is being used to fabricate end-use products in aircraft, dental restorations, medical implants, automobiles, and even fashion products.
Aerospace, Automotive, electronics,
Boeing Phantom Ray
SLA: Very high end technology utilizing laser technology to cure layer-upon-layer of photopolymer resin (polymer that changes properties when exposed to light).
FDM: Process oriented involving use of thermoplastic (polymer that changes to a liquid upon the application of heat and solidifies to a solid when cooled) materials injected through indexing nozzles onto a platform.
MJM: incorporates hundreds of small jets to apply a layer of thermopolymer material, layer-by-layer Much like an inkjet printer
3DP: This involves building a model in a container filled with powder of either starch or plaster based material. An inkjet printer head shuttles applies a small amount of binder to form a layer
SLS: utilizes a high powered laser to fuse small particles of plastic, metal, ceramic or glass.

3. Background/Objectives
To study PLA, ABS, and Bio-ABS using the FDM techniques for their mechanical (tensile) properties
To study the effect fill density on elastic modulus and ultimate strength
Following ASTM (American Society for Testing and Materials) standards

4. Designing the test specimen in CAD
Methodology
Designing the test specimen in CAD
Designed in Solidworks following ASTM standards
CAD → STL→ G-Code
Left: A rendering of the specimen in CAD
Right: ASTM Standards dimensions for polymer testing

5. Printing and Testing the Specimens
Methodology
Printing and Testing the Specimens
Printer: Lulzbot Mini
Tester: Instron APEX 60UD
Left: The specimens being printed
Above: An ABS specimen fractured on the tensile tester

6. Results Stress-Strain Curves for PLA, ABS, Bio-ABS
Elastic Modulus (Young’s Modulus) for PLA, ABS, Bio-ABS

7. Results cont.

8. Analysis of Results
Stress-strain curves of ABS at varying fill densities

9. 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.

10. Acknowledgements
This work was supported primarily by the ERC Program of the National Science Foundation and DOE under NSF Award Number EEC
Other US government and industrial sponsors of CURENT research are also gratefully acknowledged.

11. Questions and Answers

12. ABS

13. ABS 60% & 100%

14. Bio-ABS

15. PLA