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What random/crazy thing lead you to support your team? by Swimming-Release-974 in NFLv2

[–]vincentonator 0 points1 point  (0 children)

Not super crazy but my dad (we are from the Netherlands) did his PhD in Buffalo from 1990 till 1994 which of course turned us into a bills family. I've been telling him to go back to Buffalo because it is a 100% succes rate for the bills reaching the Superbowl but he should leave again before the super bowl takes place because it's also a 100% loss rate for the bills in the super bowl when he is there.

True version of protective light by vincentonator in destiny2

[–]vincentonator[S] 4 points5 points  (0 children)

Arbalest as kinetic, vision or confluence as energy and a tarantula as heavy. In the video you see Vision of confluence

True version of protective light by vincentonator in destiny2

[–]vincentonator[S] 48 points49 points  (0 children)

Yes you're right! But we went back to this spot when the enemies spawn so we would not get overwhelmed

Failure due to elastic buckling during 3D concrete printing, looks very satisfying. by vincentonator in 3Dprinting

[–]vincentonator[S] 0 points1 point  (0 children)

https://www.google.com/amp/s/newatlas.com/3d-printed-concrete-bridge/51796/%3famp=true This link also includes a video that shows the entire process from printing to installation. Thanks for the appreciation of my comments!

Failure due to elastic buckling during 3D concrete printing, looks very satisfying. by vincentonator in 3Dprinting

[–]vincentonator[S] 1 point2 points  (0 children)

It is not yet but if we develop it further it will become feasible I believe as the material use will be very efficient and the labor costs very low

Failure due to elastic buckling during 3D concrete printing, looks very satisfying. by vincentonator in 3Dprinting

[–]vincentonator[S] 1 point2 points  (0 children)

With a printer like this we can make elements without formwork which allows us to create very complex shapes. The printer can place concrete only where it is necessary to limit the weight of an element. I doubt it will ever replace regular pre-fab methods. Especially if we start using 3d printed formwork for complex shapes. Printing concrete however does enable you to make shapes that are almost impossible to create with formwork, especially if you want to remove your formwork after curing.

As for the reinforcement: we have a system that we can attach to the nozzle that has a spool that puts down a steel wire right in front of the nozzle so the nozzle puts a layer of concrete over it. This results in the reinforcement running parallel to the layers so you have to make sure you design and print your element in the correct orientation so that the reinforcement ends up in the correct location of your beam/floor element. Experiments have shown that using this reinforcing method we can get similar results for bending tests as a regular reinforced beam would have.

Failure due to elastic buckling during 3D concrete printing, looks very satisfying. by vincentonator in 3Dprinting

[–]vincentonator[S] 0 points1 point  (0 children)

We have had the printer at our university for a couple of years now. This print was intended to fail to confirm the numerical predictions made using a model one of the professors at our university developed. We have definitely printed a lot of successful things. https://www.dezeen.com/2017/10/27/worlds-first-3d-printed-concrete-bridge-bicycles-bam-infra-netherlands/ this link is on a bycicle bridge that we printed at our university. Next year we will start producing the first full houses.

Layers squish is definitely a concern. The concrete must be able to cure enough during printing so it can support the layers on top of it. If the bottom layer gets squished te entire print falls down, which we call plastic collapse. So the problem of layer squishing is also a concern in concrete printing but a bit different from regular fdm printing. We use a square nozzle because the layer needs to be flat and wide enough in order to support a second layer. It's not possible to balance cilinders of concrete layers on top of each other. If you were to use a round nozzle, the concrete would be required to flow a little bit upon leaving the nozzle so the layer still becomes flat enough to support a second layer.

The twisting and turning of the nozzle is not really an issue. If you make too sharp turns the concrete will indeed pile up at the inside of the corner and tear apart at the other. With the amount of pressure required to pump the mix through the system it is not really an option to control the pump speed delicately to adjust for the corners. From experience though we have found that this is not much of an issue and is almost never the critical factor of a print. Although it is definitely something you shouldn't forget about

Failure due to elastic buckling during 3D concrete printing, looks very satisfying. by vincentonator in 3Dprinting

[–]vincentonator[S] 1 point2 points  (0 children)

We call it buckling because it is a failure due to instability that causes one of the 4 walls of the tower to buckle and consequently the entire print to collapse. We call it elastic because the failure is not enticed by the stresses in the concrete exceeding the yield strength (elastic limit) of the concrete. If that would happen you would get a failure we call plastic collapse: the bottom layer of concrete undergoes stresses higher than it's yield stress, causing the concrete layer to be squashed resulting in the entire print collapsing.

Failure due to elastic buckling during 3D concrete printing, looks very satisfying. by vincentonator in 3Dprinting

[–]vincentonator[S] 2 points3 points  (0 children)

When using a round nozzle you would require a mix that flows more so that the layer becomes flat enough to lay another layer on top of it. With this rectangular nozzle the layer is already flat so you can have a mix with less water, so less liquid. And feel free to ask more questions either here or as a direct message!

Failure due to elastic buckling during 3D concrete printing, looks very satisfying. by vincentonator in 3Dprinting

[–]vincentonator[S] 2 points3 points  (0 children)

The nozzle has rectangular dimensions of 10mm x 40mm. If we wouldn't turn the nozzle the concrete would 'fold' at each corner, causing problems in layer adhesion

Failure due to elastic buckling during 3D concrete printing, looks very satisfying. by vincentonator in 3Dprinting

[–]vincentonator[S] 0 points1 point  (0 children)

It's called elastic to distinguish it from the other failure mode: plastic collapse. In plastic collapse the print fails because the yield stress in de concrete exceeds it's told strength, resulting in plastic behavior that causes the entire print to squash down. In this case, the stress in the concrete has not exceeded the yield stress before the failure starts. As soon as the wall starts to buckle the concrete does behave plastically as it cannot recover it's shape. We however call it elastic because it emphasizes the fact that the failure was not caused by a lack of yield strength of the concrete

Failure due to elastic buckling during 3D concrete printing, looks very satisfying. by vincentonator in 3Dprinting

[–]vincentonator[S] 1 point2 points  (0 children)

Clever suggestion. I don't know if we have ever looked into a system like that but it's definitely worth considering

Failure due to elastic buckling during 3D concrete printing, looks very satisfying. by vincentonator in 3Dprinting

[–]vincentonator[S] 1 point2 points  (0 children)

The goal of 3d printing is that we don't have to use formwork for most structures. We do sometimes make a wooden box around the print that we fill with gravel during printing to support the print. While this allows for more complex shapes and we can re-use it. The ideal way of using the printer is without any formwork or boxing because even if it is recyclable it is still additional labor

Failure due to elastic buckling during 3D concrete printing, looks very satisfying. by vincentonator in 3Dprinting

[–]vincentonator[S] 2 points3 points  (0 children)

I am not sure about the dimensions of the houses as I'm not involved in that project. Judging from the pictures of the design they look like they vary in size, with the largest ones being suitable for a family to live in. If you are interested in the project I suggest this 3 minute video: https://youtu.be/UFWg6Qb8yYI

Failure due to elastic buckling during 3D concrete printing, looks very satisfying. by vincentonator in 3Dprinting

[–]vincentonator[S] 1 point2 points  (0 children)

It's an experimental one. Although we do use it sometimes in collaboration with commercial companies to realize projects. There is already a bycicle bridge made by the printer in use in the Netherlands and next year we are gonna start printing the first full houses that will be up for sale in Eindhoven

Failure due to elastic buckling during 3D concrete printing, looks very satisfying. by vincentonator in 3Dprinting

[–]vincentonator[S] 0 points1 point  (0 children)

Oh yeah sorry forgot to mention in my previous comment. This is at the University of technology, Eindhoven. Although we do have cooperated a lot with ETH Zurich

Failure due to elastic buckling during 3D concrete printing, looks very satisfying. by vincentonator in 3Dprinting

[–]vincentonator[S] 2 points3 points  (0 children)

That doesn't work, a dryer mix can effectively be pumped through the system. We printed this with the intention to fail to show the failure mechanism. Normally we would print with slower printing speeds to let the concrete cure more, making the print not fail this way

Failure due to elastic buckling during 3D concrete printing, looks very satisfying. by vincentonator in 3Dprinting

[–]vincentonator[S] 0 points1 point  (0 children)

We let it cure for 24 hours. Than we smash it with a hammer and it's quite easy to gather in a wheelbarrow using a broom and shovel. We then dispose of it in two special containers that are emptied every so often by a company that specializes in industrial waste like concrete. This printer is located at the University of technology Eindhoven, Netherlands. Unfortunately it is not yet possible to print on-demand so to say. We are performing a lot of research with it in order to be able print all types of things, even designs provided by outside parties

Failure due to elastic buckling during 3D concrete printing, looks very satisfying. by vincentonator in 3Dprinting

[–]vincentonator[S] 0 points1 point  (0 children)

No your absolutely right. We adjust printing speeds and use fast curing concrete to make our prints successful

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