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3D Print Strength Analysis

Statistically determine the ultimate strength of different printable materials.

* This page is a summary of work done in a group. A lot of credit is given to my group members - my involvement is noted below.


 

Involvement 

  • Research
  • 3D Printing
  • Experiment
  • Statistical Analysis
 

Abstract

 

This experiment was created in order to find the strongest common 3D printable material. While materials such as nylon and PETG are known for being stronger and tougher than more traditional printing materials such as PLA, most low end printers are not easily capable of printing these materials. The ultimate strength of 3 commonly printed materials, PLA, ABS, and a wood-PLA hybrid were tested. Hooks were designed to be printed and forced until fracture.

 

Methodology

 

In order to test the strength of each material, a test matrix of 3 materials and 3 infill percentages was created. Each instance in the test matrix was randomly tested 5 times for a total of 3*3*9 = 45 runs. The apparatus consisted of a frame holding a bucket of water via the 3d printed hook. Water was added to the test bucket until the printed hook broke. Measuring the water placed in the bucket until fracture, force on the hook was able to be calculated from the gravitational force on the measured volumer.

A pilot study was conducted in order to determine the feasibility of the experiment as well as conduct a power analysis for complete experiment repetitions. After a successful pilot study, the full experiment continued.

 

Infill: The 'fullness' or 'hollowness' of a 3D print.

Material: 3D printers are cabable of printing various materials

Apparatus: The apparatus is capable of testing ultimate strength

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Results

 
 

Discussion

 

For both the material and infill factors, the P-Values from the general linear model are very low (<0.000). With high confidence, PLA can withstand the largest static load, followed by ABS and Wood. One major aspect of this experiment is the strength test, that is, the experiment only tested ultimate strength, not toughness of material. While conducting the experiment, PLA was noted to be much more brittle than ABS and wood. Though PLA is much stronger than ABS and wood, ABS is likely the toughest material of the 3. Since PLA is brittle, it has a small area under the stress strain curve; it will bend very little before fracture unlike ABS where fracture is easily predictable due to warping under stress.

 

See https://www.rtejournal.de/ausgabe11/3872 for a deeper analysis of ABS and PLA properties

 

Conclusion

 

  • PLA is the strongest material, followed by ABS, and WOOD, the weakest.
  • 60% infill is the strongest density, followed by 40%, and finally 20% (no surprise there)
  • The effect that infill had on strength is not reliant on type of material used and vice versa.
 

Material:

PLA holds on average
10.2 - 15.1 more lbs than ABS, and
22.5 - 27.3 more lbs than WOOD.

ABS holds on average
9.8 - 14.7 more lbs than WOOD.

Infill: 

60% holds on average
1.9 - 6.7 more lbs than 40%, and
6.3 - 11.1 more lbs than 20%. 

40% holds on average
2 - 6.9 more lbs than 20%.

Appendix

 
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