tl8

Lego Technic Strength

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Hi all

Over the pass few months I have been compiling a report on the strength of various beams and pin connections.

With the help of USQ, I was able to run a number of tests that produced some very interesting results and a lot of broken and crushed beams.

I hope you find the report interesting and I look forward to hearing your feedback and own commentary.

Report 2011 (PDF 1.2 MB)

Report 2012 (PDF 1.9 MB)

Cite Report 2012

Edited by tl8

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Thanks for the report. It matches the intuition I have of the beams. Sorry about the pieces.

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Hi all

Over the pass few months I have been compiling a report on the strength of various beams and pin connections.

With the help of USQ, I was able to run a number of tests that produced some very interesting results and a lot of broken and crushed beams.

I hope you find the report interesting and I look forward to hearing your feedback and own commentary.

Interesting tests but you need to refine your test technique and use more samples to get some statistically valid results.

I think you need to test the beams with lego connectors through the pinholes or even steel bars of the correct diameter, crushing the beams in the tensile rig jaws makes the whole test invalid.

What fulcrum contact shape did you use for the three point bending test?

DrRod

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From the report #1:

 Studless beams are better in tension than studded

 Studded beams are better in transverse than studless

 Studless beams are stronger in transverse with the pins on the side

-> Prior to this topic I was reading through the studded vs. studless discussion, perhaps these results can once and for all show that both have their use.

From the report #2:

 Lego is quite strong for its weight

-> Indeed, given the constructions I've come across e.g. Liebherr cranes and such.

Thx for sharing and now a minute of silence for the beams that were sacrificed...

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@ tl8/ Tristan Lostroh: Your analysis is very good! I have not seen a similar report, and I've been looking for something like this for years. As a professional Civil Engineer myself in the USA, I recognize the standard "Strength of Materials" machinery and methodology. Did you get any Mechanical Engineering course credit for this work?

I'm sure The Lego Group has conducted similar experiments, and that the "failure mode" is the CONNECTIONS (as it is for most beam assemblies). One wants the Lego friction pins to pop out of the Technic Liftarms and Technic Beams, and not have the beams crack under load.

Since you said "There are many alterations to the tests and testing procedure that could be changed. I would certainly be willing to do more tests if I was given assistance with resources....outside assistance will be accepted to further the data and conclusions", I would be willing to donate any additional Lego Technic pieces you need. I realize that Lego parts are VERY EXPENSIVE in Australia. Please e-mail me at LudersDG@MSN.com to tell me what you need, and where to send it. I have sent Lego parts to an AFOL in Australia several times, and the transit time is about 2-1/2 weeks. :classic:

Edited by DLuders

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Wow, you have done a good work ! I am a student un mechanical engineering and it is always interesting to know more about our lego parts, especialy the mechanical field. Therefore, many thanks to you, you acheived an usefull and interesting work !

At Setechnic.com, we have many crane-builders who migh be interested in your study (regarding the design of boom and jib).

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Your report contains very interesting and useful facts that are now available to anyone. Thank you for sharing your magnificent work.

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Did you get any Mechanical Engineering course credit for this work?

None at all, I am a student Computer Systems Engineer :P.

Interesting tests but you need to refine your test technique and use more samples to get some statistically valid results.

I was aware of this but has issues of time and cost against me. I didn't know what to expect so decided to go for a number of tests and see what happened.

I think you need to test the beams with lego connectors through the pinholes or even steel bars of the correct diameter, crushing the beams in the tensile rig jaws makes the whole test invalid.

While it wasn't the ideal solution, I don't think it invalidates the whole test. The numbers presented may not be exactly right but they present a minimum standard to be expected in extreme conditions. It wouldn't surprise me if I get the same number using a steel rig as the stress points would still be very similar.

What fulcrum contact shape did you use for the three point bending test?

It was a ~1cm dia cylinder.

Thanks for everyone's kind words. It really helps!

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Very interesting work, but as said, you need multiple samples to get more valid results. Beams can be easily ordered in lots from bricklink.

- Sok.

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@tl8

Thanks for all the hard work and tests! The data is very interesting, although not surprising.

tim

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Thanks for the report, but... I'm sorry, I couldn't really read it. The moment I saw the first couple of damaged pieces, butterflies went flying in my stomach. :sad:

Although important and informative, the report is not for the faint of Lego heart...

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Tl8's 29-page "Investigation Into the Strength of Lego Technic Liftarms and Brick Beams, and of Liftarm Pin Connections" is very thorough. The conclusions and graphs come from SACRIFICING *oh2* (in the name of science) ~70 ea. 1x15 Technic Liftarms, ~14 ea. 1x16 Technic Bricks, and ~250 Technic Pins. Great research! :thumbup:

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This is interesting. It reminds me to the test processes of trussing, which we use in my job.

That the forces are going up to 0,5 KN is really impressive for a piece of plastic.

Head on with this kind of testing.

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I have updated the links in the first post with the new report.

I have also linked to the archive that contains the information required to cite it. This also makes it visible to the wider academic community.

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Wait, so a single beam could carry my weight (68kg) without breaking?! wow! *oh2*

also, if I have 10 beams placed sideways, it should easily carry my weight. LEGO is actually pretty strong!

I think it would actually be possible to build a (small) bridge out of technic that a person could walk across.

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