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Tensile stress test (ASTMD-IV)

by moonj, published

Tensile stress test (ASTMD-IV) by moonj Nov 26, 2009

Description

A strip of material for use in a tensile testing machine. The dimensions of the test strip(i don't have the exact ASTM D reference number in front of me) are standardised so the tensile properties can be compared with other materials. The machine grips either end of the strip and pulls the grippers apart at constant speed, whilst measuring the force required, this is usually done until the strip is destroyed (unless you want to look at elastic properties etc).

We are currently printing these in HDPE, and comparing the results with stamped out HDPE sheet. We have plans to move onto other materials also. The aim is to print with various patterns of infill, in order to see how the properties change, and eventually use this data to come up with build rules. The build rules will tell you how much material to print in an area, in order to withstand the forces you expect to apply (and help to design stronger parts with less plastic). There is obviously alot of knowledge about this for injection moulding etc, but very little on fused deposition modelling/fused filament modelling.

Not the most fun part to print, but if you have some spare printer time and want to help us out we would appreciate it if you sent us some copies of it, from any material. There is an address on my profile, feel free to contact me for any info. Thanks!

Recent Comments

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OK. I have made some white PLA test pieces and tested them on a Mecmesin Tensometer at work. The typical strength at 95% fill and at about 13 degrees C room temperature is between 54 and 58 N/mm2. (ie 54-58MPa).

The 'book' value for tensile strength is in the region of 57.8 MPa so a really well made PLA part seems to achieve close to its nominal tensile strength at least in my tests. I haven't tested other colours or done enough samples to determine any statistical parameters such as spread or effects of temperature.

Hope this helps

Chris

Me Too, Can we see any results yet. Even inconclusive or raw results would be useful! I'll volunteer to do any statistical calculations if needed. Thanks. (24-2-2014)

What ever happened with this? I'd love to know the results.

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Instructions

To be printed with various infill patterns (hexagonal, rectangular, line).
I'm not sure on the scaling at the moment, will update with the expected dimensions asap.
I think it should be about 70mm long, please let me know if I haven't exported the .stl correctly, or any other problems with it.

Comments

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EngineerChris on Feb 25, 2014 said:

OK. I have made some white PLA test pieces and tested them on a Mecmesin Tensometer at work. The typical strength at 95% fill and at about 13 degrees C room temperature is between 54 and 58 N/mm2. (ie 54-58MPa).

The 'book' value for tensile strength is in the region of 57.8 MPa so a really well made PLA part seems to achieve close to its nominal tensile strength at least in my tests. I haven't tested other colours or done enough samples to determine any statistical parameters such as spread or effects of temperature.

Hope this helps

Chris

EngineerChris on Feb 24, 2014 said:

Me Too, Can we see any results yet. Even inconclusive or raw results would be useful! I'll volunteer to do any statistical calculations if needed. Thanks. (24-2-2014)

heytiger on Jan 20, 2014 said:

What ever happened with this? I'd love to know the results.

booktinker on May 28, 2011 said:

I am wondering where you are with this project. I have been very curious to know about extruded abs tensile properties and how the direction of the infill affected it's strength. Any update would be appreciated. :)

ferret7 on Nov 28, 2009 said:

OK - I'll help - I can do FMD ABS - how many and where do you want then sent ?
Just post the data where we can access it please.

I also used Magics 14 to sanitized the original .STLs

moonj on Nov 28, 2009 said:

Excellent, we'll take as many as your willing to make, as I plan to spend winter in the lab pulling them apart (and making new ones).
If you could note the skeinforge settings (well the equivalent version for your equipment), and any other information you think is important, and do a few repeats with the same settings that would be great.

Will definitely post the data, not sure where yet, but if we get enough data to write a paper, it'll be on the arxiv.org so you wont have to pay to access it. I'll make sure to put all the raw data up somewhere to, for those interested.

Please post them to;
John Mooney and Ben Varcoe
Quantum Information Group
School of Physics and Astronomy
University of Leeds
Leeds
LS2 9JT

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