Reinforcement strategies for additive maufacturing in construction based on Dynamic Fibre Winding: Concepts and initial case studies
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| Anzahl der Teile | 12 | |
| Autor | 0000-0001-6756-8942 (ORCID) | |
| Lizenz | CC-Namensnennung 3.0 Deutschland: Sie dürfen das Werk bzw. den Inhalt zu jedem legalen Zweck nutzen, verändern und in unveränderter oder veränderter Form vervielfältigen, verbreiten und öffentlich zugänglich machen, sofern Sie den Namen des Autors/Rechteinhabers in der von ihm festgelegten Weise nennen. | |
| Identifikatoren | 10.5446/56109 (DOI) | |
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00:00
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Transkript: Englisch(automatisch erzeugt)
00:00
And especially I will present concepts and initial case studies. But before I want to give a quick overview, I want to present to you the research context in which the work is performed. Then I will show you our basic fabrication setup and methodology that we developed and
00:22
that finally led to the decision for three case studies. And this will give you a good insight into our research and when I say our research, it refers to the people involved in a research project and there I am guided by my supervisor
00:42
Norman Hack, but also I am supported by my project partner Tom Rote and his supervisor Christian Hühne, we are all from the University of Braunschweig, from two different institutes. The project, shortly termed A05, is pretty much about the integration of fiber reinforcement
01:06
and it is placed within a bigger collaborative research center, namely 277, Additive Manufacturing in Construction. And this research center deals about or performs research on different 3D printing
01:26
techniques, some of them are shown here and we are collaborating with different techniques. And so the basic question of our project is how we can implement non-metallic fiber
01:41
material into those printing techniques as reinforcement. The advantages of textile reinforcement were already named by the speakers before me, the most important advantage is the corrosion resistance. And I do not want to go too deep into the state of the art, but just name works
02:08
that are influencing the project. Of course the work of Theo Dresden and Erwitt Herr Aachen with all their collaborative research centers on textile concrete are very important for us and I am glad they
02:25
already investigated so much about this material. However for us it is also interesting to look at the work of University of Stuttgart, they are, with a technique called Corliss fiber winding, they developed a method to
02:44
process fibers robotically and by that produce purely fiber structures. But also the work of, a certain work from ETH Zurich which we have already seen more
03:03
than once today, the mesh mold is very important for the project as this project showed that a reinforcement cage can be produced automatically and that it can also serve
03:20
as a form work for concreting. In our project it is important to have a basic set up that gives us or that provides us with reinforcement so we can work with that and this is the machinery we work with
03:42
now, until now, on the left side we feed in raw material, glass fiber, it could be also carbon fiber, then this fiber gets impregnated with Resign and the purpose of that is to
04:06
later activate all the fibers within the fiber roving and then we wind a secondary yarn of glass fiber around it to give the fiber strand profile similar to steel reinforcement
04:25
bars to improve the compound and at the end we have a tension control unit with active extrusion so that we always can pull out fibers of this machine with a constant
04:41
force and then this fiber coming out of this pretreated fiber strand coming out on the right side can be fed into a robot arm and then deposited on certain structures and this deposition process I will focus on more in detail.
05:03
Here just three basic ideas are sketched out roughly and now what is their meaning with respect to reinforcement strategies for additive manufacturing and construction. In order to answer this question we developed a certain framework, a schematic, I won't
05:26
go too much into detail about all the aspects of this methodology but I will show you three passes through this diagram to give you an understanding of how we use this diagram
05:42
as a tool for designing our processes. So the first approach we call it the frame winding approach where we start with a frame on the edges of part where we can wind fibers robotically on this mesh so it's a
06:06
bit similar to the work of University of Stuttgart, a bit similar to the Corliss winding approach and in this case the reinforcement structure would act as support for the concrete.
06:25
This technique to us seems most suitable in combination with shotcrete 3D printing and it would fit very well to produce slender wall like elements that exhibit a single curvature or certain ruled curvatures for example like hyperbolic surfaces and the fiber mesh
06:51
should be rather dense in resolution in order to really serve as a support for the concreting.
07:00
The second approach we call pin grid winding where we would have flat tooling with a regular distribution of pins so we can wind arbitrary contour lines in 2D and that would serve very
07:23
well as base for particle bed printing technologies because those inlays we would produce on a pin grid we can then integrate into particle bed printing.
07:41
So this process combination would fit very well for other small elements of high complexity and a fine resolution or something like that is not really needed. Finally I want to show you the path of the combination of core binding approach
08:03
and shotcrete 3D printing. Here core binding is meant in a way that first structure is printed normally with a shotcrete 3D printing or extrusion and this structure then serves as a form work to wind
08:22
on it so this is how we understand core winding. So the accessible geometries depend only on the 3D printing concrete process and not on the winding process at all and also there's no restriction in mesh resolution for example.
08:44
In the remaining time I want to present three case studies that refer to the presented examples. First of all we tested the pin grid approach first time in a simplified manner
09:03
when we fabricated a demonstrator for the novel technology of large particle bed 3D concrete printing. In this technology in contrast to other particle bed printing technologies very large aggregates of a size of up to three centimeters are used
09:24
and then selectively glued together by means of shotcrete 3D printing. We have chosen two most relevant layers of this design to insert reinforcement layers.
09:41
We designed the reinforcement layout heuristically and then in a digital way of course and then used this digital layout to drill holes in a wooden carrier plate so it's kind of a simplified version of a pin grid which would have all a distribution of
10:04
pins over the whole plate but for this case we just used it like this by drilling those holes robotically we made sure that they would fit with the printing and then we inserted this so after curing we inserted this inlay manually into the printing process and the
10:27
insertion was in this case very easy as the layer height is pretty high but the thickness of the inlay is comparably low maybe we chose a too low or too thin diameter for the
10:44
fibers here but even if the fibers would be thicker it would be still easy to integrate it into the process. As a second example I want to show a scheme at first about the approach of
11:02
frame winding in combination with shotcrete printing here you can see we are really aiming for curved slender elements and this is of course very similar to what the speakers before me have shown already we want to generate a mesh and then spray on it but I think our technique
11:25
also has its uniqueness but for our first tests the uniqueness that is not apparent yet because we used flat frames just to prove or just to see how well this technique works
11:42
and also we winded the mesh we generated a reinforcement fiber mesh with robotic winding but this mesh is still regular so we could have used a mesh like shown by got some little before but by doing the whole workflow digitally and we can in future vary
12:08
this and adopt the mesh distribution or for example to the force flow or to the work to the load on the element and this first experiments it turned out when we shotcrete on this mesh
12:26
we have some issues still so for me it was totally clear that the uncovered rear side of the fibers are definitely a problem but now when I hear the
12:43
work of Igor maybe we could discuss this later and maybe it turns out it's not really a problem that there is no cover on the back side but what is definitely a problem is that we have a lot of excess resign when we spray upon the mesh but we think that in future we can
13:02
solve this issue by guiding a shield similar to the way got some little presented maybe the difference in our case would be that we use a rotating shield and also that we want to adopt two curved shapes okay finally I want to present the most recently developed fiber
13:26
reinforcement strategy I'm happy to present this year it's the first time that I can present this method unlike the formally presented methods here the shot creating or 3d printing process
13:41
is taking place normally at first place and then in subsequent steps a reinforcement can be applied to the faces of the element finally a cover layer should be applied so to have a full
14:03
or a proper compound between fibers and concrete to understand how we can fix the fibers to a face I want to introduce this end factor we developed it's pretty much a fiber deposition tool where
14:22
a staple device is implemented and with this process sketch you can see how this tool can fix fibers on a concrete core by shooting staples around the fibers and like this fixing it on the
14:41
surface the great thing about is that here we are not restricted to the built-up logic of 3d printing so we can also guide the fibers in whatever direction we want along the surface we took this wall geometry of 120 centimeters height for a first proof of concept and for that we
15:12
calculated the principal stress directories and used that as a reinforcement layout or to derive our reinforcement layout so the whole fabrication process is shown here first we
15:27
printed the wall by shotcrete 3d printing and then in a certain time window when the concrete is still in green state we can apply those fibers in in fact we were a little bit too
15:43
late and some of the staples got deformed a bit when applying but as you can see the whole process still worked out fine as a third step we once again use shotcrete 3d printing to apply a cover layer and then we use the stone mill of our digital building fabrication laboratory
16:08
with a disc on it to make a surface finish and a disc like that could also be used as a shield for the formally presented method of frame winding so to come to the conclusion
16:25
as you have seen in the three case studies we have pretty much a focus on manufacturing in this project we are trying to find answers to the question how we can get continuous fiber reinforcement into different differently printed parts no matter if simultaneously or retrospectively
16:49
but during all this practical work we should still be aware of the overall context and that's where the methodology or this scheme is very important as it helps us to
17:01
keep this kind of an holistic overview and always find best process combinations and reasonable fields of application okay i think i do not need to go into the outlook as i'm already a bit over the time maybe so maybe it's better to leave time for
17:24
questions or discussion