Sooo, im just interested in 1 thing.
How strong is this plastic printing?
Is it as strong as a piece that is say cast or extruded in normal manufacturing?
Ohh - finally something I can kind of answer.
I’ve had some professors at uni who were researching 3D printing concrete, and other materials for construction and basically the big problem is that with printed materials, they tend to be anisotropic, whereas traditionally cast materials are isotropic. Basically, the printed stuff is as strong in one or more directions/planes, but not all directions.
So something printed might be strong in general compression or tension load cases, but might fail in shear, or certain bending cases. It would be like building with wood, where the grain direction really matters.
Wow. I was watching something on modelling stress points last night.
@Tempestman interesting, does it assume a 1:1 sort of ratio of material? For example, I am going to print X cc’s of concrete vs pour X cc’s of concrete? And if it’s about efficiency, then wouldn’t expanding material to selectively reenforce high stress points (which I assume is doable with printing?) to save time be a better option than expanding time?
I know in my slicer tool I can add more support and material in some points than others, wouldn’t in fact make the deliverable stronger?
N.B.
I have no idea what I am talking about, so thinking out loud here.
interesting, does it assume a 1:1 sort of ratio of material? For example, I am going to print X cc’s of concrete vs pour X cc’s of concrete?
Yep, these kind of things really care about the volume of the material used, as the end volume affects the cost and the self weight, but also how much space you need to build into. It’s an endless debate between architects and structural engineers on whether the columns should be thinner for aesthetics, or larger for efficiency.
And if it’s about efficiency, then wouldn’t expanding material to selectively reenforce high stress points (which I assume is doable with printing?) to save time be a better option than expanding time?
Not quite sure what you mean on the time part, but expanding out the material is definitely done in the name of efficiency. Designing structures has both a material, as well as a geometric component. It’s why you never see solid steel columns or beams, as it’s so much cheaper and more efficient to make it hollow as a square section, or as an I-beam. The only solid columns you would find would be concreted ones, as they generally come to the build site as quite fluid. It’s actually another bit of research one of my lecturers is working on, is making porous concrete, similar to loads of bubbles made of concrete, allowing it to keep more of it’s strength, but be significantly lighter.
Selectively reinforcing points is also done for failure planning. When building structures, certain failure modes are planned to occur before others, so that you have more warning on when the overall structure goes. Such as how with rebarred concrete, it’s planned for the concrete to failure first, so you can observe cracking, which lets you know that the structure needs to be examined.
I know in my slicer tool I can add more support and material in some points than others, wouldn’t in fact make the deliverable stronger?
I think you definitely could, and you could probably counter most of the problems with the anisotropic behaviour by selectively organising the way it’s layered on, so you take advantage of what anisotropic behaviour you want and where.
Ha! Concise and answers everything.
I meant using more material at faster build time, than less material with longer manufacturing time, but you answered all that.
I just finished reading all that and now I have a headache.
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I found a decent paper comparing the isotropic and anisotropic properties if you want a bigger headache.
@juststarting
Also helps that build time isn’t as big of a concern in industry, seeing that concrete needs to cure for at least 28 days if it’s going to be used for structural purposes.
Is strength a big concern for your printing though? Are you using this stuff in a structural application?
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@Tempestman, thanks for the offer but I am way too old to be reading those sort of papers. I will leave that to you and juststarting
Not yet. But eventually I’d like to play with polycarbonate and whatever else that has strength and durability.
The paper I was reading pretty much states that ABS only has a 3-5% strength loss for isotropic v. anisotropic (which I’m really surprised by), so you can just equate them from approximations, unless you need precision.
I love pictures and small words.
And videos!
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That thing went off quicker than a 16 year old virgin.
I think he was game even standing behind the timber.
Its ok, coz “Merica”
Im glad he was standing behind a thin bit of bullet proof plywood and plastic table for safety. @Oldbloke can you have a look at this and comment on his OHS procedures and measures.
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Not much to say, stupid.
In the real world that type of test is done remotley behind a steel screen. “windows” are usually some form of polycarbonate. Same stuff face shields and safety glasses are made of. But much thicker.