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hello and welcome to technically speaking where scientists and Engineers come together to chat about a common interests share knowledge and satisfy some curiosity I'm Laura and I'm joined by Rwayda to talk about 3D printed materials that could be using construction projects to make better buildings but were originally developed for a very specific different application so I found this really cool piece of research about meta materials it's a mesh of tiny 3D printed gears where you
can change the stiffness of the meta material by rotating the gears through a particular angle so it was designed with robotics in mind as the robot can be soft while it's moving around but strong while it has to carry something heavy and this is what got me thinking about other applications so rude I thought you might be interested in this yes it's really interesting for um civil engineers to know what's happening in the printing world because we need to build the bridges and
other form of construction so such material could have a good application and the bridges in the future because it if it changes stiffness and if we think of um London Bridge um when it's open and closed that that could be really helpful to have such a material yeah and I remember in the episode we did about bridges you mentioned Dynamic load where the bridge has to put up with a whole variety of different forces going through like when it's really windy or when a lot of
people are walking across it it has to be able to withstand effectively different conditions but using just one material so you I got the impression you're a bit limited by your materials properties does that sound right yes the material properties would be limited on where you put the the bridge really so if you have um strong wind that would cause the bread to to shake on the other direction and would cause wave in the bridge also as you mentioned human walking on the bridge will cause
um like a dynamic load coming from the movement um and as these Lord comes in Cycles so it's good to have a material that could adjust to different type of loading yeah so I'm imagining like when it's really windy you know sometimes Bridges get close to certain Vehicles like you just make your Bridge go really floppy so it can wave around in the wind all at once well as long as it's safe to keep the car on it yeah you still might have to close it in that case to be fair
I'll explain more about this meta material because it sounds like a bit of a weird Niche term so basically the research paper that I was reading uh the the scientists are designed these 3D printed gears they're made of plastic and they print them directly into a grid layout so they're not assembling the grid layout after printing the gears they're doing the whole thing sort of in position and I said the gears are really tiny they're like no more than four mil
in diameter and they've got tiny tiny teeth they're a few 100 microns wide and the research paper gave loads of stats about the mechanical properties about strain and stress and all that sort of thing and I'm I'm not too familiar with what that means necessarily to a civil engineer so can you sort of help explain some of that to me okay so we can start with the tensile stress of the material if you think of having a cable and you pull it to stretch it in both Direction
the load you're applying is in Newton and it affects the cross-sectional area of that cable so the tensile strength is load over area for this cable being pulled in both Direction and that would apply to the material that we're talking about so it's basically how much load it would stand Until It Breaks being pulled in two sides in the paper seem the strength depend on the Gear's angle yeah yes the idea is that if you rotate the case they all line up in one particular direction then
they'd have like a really high tensile stress or something like that and then if you rotate them through another angle they're sort of rotate it a different way they'd have a very different tensile stress so they could be like really strong or not I feel like I'm not um getting that quite right you're the expert here on materials properties it seems from them they start with an angle of a 12 degrees and they increase their angle to 78 degrees and the strength was
for the 12 is it about one Mega Pascal and mega Pascal mean is Newton per millimeter square so if you go back to what I was saying in my example of having the force which is how much you pull and the cross-sectional area of the section how did they estimate their cross-sectional area because they could do net or gross so basically there is it the area of each gear and each layout or is it the gross area of the cube they use to find the tensile strength they did not mention that in the paper uh I
would assume it would be because I talk about the matching material so the gay mesh as a whole right so I think it'll be the cubes that they measured rather than just the area of the gears yeah I think that would be the case but did not they did not say anything so I can't comment on that fair enough and it's basically how much force um they were required to break it taking that into consideration how this material would change because it's tiny at this point
so if we want to use it for Bridges we want to make it bigger is this number will increase in a linear way or will they not be linear and the other question is how dependent is the the properties on the mother input material because in this case they have plastic or something in to print these gears okay so there's like there's three different questions going on here so I'm going to take it back to what you were saying at the beginning about the megapascals that's Force per unit area
and you said that was up to two and a half megapascals of tensile stress yes this test between one to two and a half that's what they got okay so how does that compare to traditional construction materials like concrete and steel so concrete tensile strength measured to be 10 percent of its compressive strength and the normal concrete grid is 30 megapascal and 10 percent of that is three Mega Pascal okay so compressive strength is if if you're trying to squash it it's how much load it can take
before it shatters yes and then the tensile strength is a fraction of that and if you're trying to stretch it yes okay and it's difficult to measure it in concrete that's why they have this estimate of it's being 10 of the compressive strength of concrete so it seemed to be very comparable in terms of strength for concrete but concrete is not really good in tension so it seemed to be at this point as the lower end of the construction material so the one that is the construction material like
it's really good in tension is the steel and this steel will have a much higher 100 something tensiles trying that with carry that same load and the whole idea of reinforced concrete came from merging so concrete is really good in compression and it's cheap steel is good intention but it's expensive so that's why they have the bars when the member is in tension so this material seemed to be similar to Concrete but we don't know because it's still kind of tiny on that measure if
that makes sense yeah this is what you were saying about does this graph of the properties that you're looking at is it linear does it scale up so if you made your material your meta material bigger could you just multiply the tensile strength or tensile stress by the size that you so if you make it 10 times bigger is the 10 cell stress like 10 times better or the same yeah it could be much better and it could be behaving like reinforced concrete which is it
makes concrete steel but it it could not be as long as we don't have a bigger scale test and I really am really very curious on how dependent this material is on the properties of the mother material I'm calling it The Mother material I'm not I'm not sure what the right terminology of the word is because you would input some material in that already have some properties right yeah yeah the shape is not the only kind of factor that determine the properties of the material is the strength of the
original material so let's say we put the concrete casted into a mold somehow with 3D printing that look like these gears so we know the original strength of concrete so how much that would be impacted by making it to a gear but I don't think that's suggesting that you would use something like concrete to make these gears necessarily yes I guess they were using and the plastic in this case because that's what 3D printers tend to work with I know you can also 3D
print in metal yes but that sounds like it would be much more expensive than the experiment they were doing to be honest but I really liked this idea that you've got this material that you can just change these gears somehow and it completely changes what your material can do well I can just imagine say we're doing it for robots right you can imagine this robot walking around like being really floppy to get through a gap and then suddenly stiffening up when it
has to like drag something out of its way you can just imagine it like an animal crawling around being able to adapt to its environment sounds like you wouldn't do the same for something like a bridge necessarily you wouldn't have it crawling around for a start well maybe we'll have this like Flying Bridge I need a bridge here and comes and fly and do itself to a bridge like the the robot like a robot Bridge yeah or some sort of a house that just like I can't be bothered to go home I'll get my
house to come to me and then it just lives there and it's 3D printed out with these gears and it's brilliant so it looks after you she follows you around yeah like um a shell to make my house like a snail yeah you were saying that the tents I'll stress or the tensile strength of the 3D printed material is nowhere close to the steel so I don't know maybe we're not going to use it in several engineering projects just yet yeah maybe with me dolls because they printed them now is out of some
plasticky looking material maybe when they printed the same gear they have they have in their meta material in a form of a metal maybe the behavior will change we don't know yet yeah I mean this was the research paper that I saw it was very much sort of lab based like almost like a proof of concept like the printed gears in different ways to improve the material properties even further as well so there was a lot of mechanical engineering you could do with this material to give it particular
tunable properties to make it like really stiff and really floppy in the same instance which I thought was great so I can definitely see there's like more work that could be done to improve this even further and turn it into a real world application yeah I I totally agree on that yeah but I get the impression that there is something else going on in civil engineering that uses 3D printing in a slightly more practical way have you come across anything like this yes so
now they're using 3D printing um for new housing um there is that they use their big printers to print the housing concrete and add some material to it the houses look really cool in Germany the one of the companies won The Innovation award for the year in 2021 for building one of these 3D printed housing and it's these houses are are quite cool okay what specifically did It win that award for so there are lots of control that you would have on the final product when you
build with this so it's more consistent it eliminates um human error a save labor um and it's cost effective is more sustainable because it's a quality assurance on the site because you have the machine doing your concrete casting so it have lots of advantages that they seem to think it would be the new building in the future okay so 3D printing is doing people how jobs because you don't need people like laying bricks instead pretty much that's one of the the thing that
does and once you invest in the set right when you have the equipment once you invest in that set first time it's gonna be much cheaper for you to build more and more houses and because it's like you would input the map and the design into this machine you can pretty much be flexible on what you want like the layout of the house I mean yeah and you've mentioned before that concrete is quite formable so you can make some really interesting shapes with it yes so that's what they're doing so
you can see like if you Google these houses they're very curvy and kind of like you they look like future houses like more I don't want to say it's more modern it's not about modern they look like something that you've seen in a movie with all the curvature because they get to do it easily in these 3D printing kind of like big concrete thingies that they're using to build them cool I'm going to keep bringing robots into this now I can imagine you've got these robots sort of crawling
around printing these walls for you other people just just kind of sit there chilling out letting it do its thing yeah and it seemed to be very cost effective because the same the labor cost is one of the huge costs that they're reducing um in this project and since the quality assurance is quite high so even they would be able to control more the environmental impact how would they do that because I know concrete is necessarily an environmentally friendly material because it's got quite High
greenhouse gas emissions well there are a few few things happening with the concrete now so they're trying to reduce the cement content and add other additives to make it more um kind of like environmental friendly so there's a lot of way that trying to do that but it's because the machinery and the traditional machinery and moving the materials um to distances to come here to where you build having the 3D printer do that because people need to commute to come labor
need to commute to come and all of that is costed as an impact on the environment right yeah so by having machines and you move them on one go they will have less of impact and it seems the machine itself the huge 3D product that they use to build the houses does not mean they have a big carbon footprint so that's the the other thing that they're saying the the quality of the building itself seem to be much better because it's higher quality assurance will make it more
sustainable in the future yeah so something that should last longer be more affordable and be built to a higher standard with fewer carbon emissions or like when it during the construction process that's like the definition of sustainability different sustainability pillars yeah that's why this house won this Innovation award in in Germany and it seemed there's somewhere here in the UK south of England forgot the area location uh have started investing on building the 3D houses in the UK okay so
it's spreading yeah but seemed to be quite big in Germany at this point cool I mean we're talking at the top about the mechanical properties of this 3D printed metal material that's made out of tiny gears so I'm assuming concrete being a more traditional material it's it's only got one set of mechanical properties you mentioned concrete it's great under compression and that's one of the reason now most of these buildings uh because they using most likely reinforced concrete is focused on houses
because like it's it's two-story house it's does not have that high load in it I still have a long way to do Bridges skyscrapers and other forms of building that they still can't fully use 3D printing into them okay so that meta material could be something that do that in the future so it's not because I think in the skyscrapers episode again you mentioned like the the winds that are swirling around these really tall skyscrapers again they create these Dynamic loads that you have to account
for somehow yes you have the dynamic lot because they're like like if you think of it is kind of shaking but you want it to be flexible enough to shake because if it's rigid it will just snap so you wanted to have a bit of movement but not too much movement and such a material could be the way to do that a 3D printed concrete structure wouldn't have that flexibility to build something that high that would last so not yet I feel like I'm learning so much about how
to build everything yeah because like these buildings usually are framed off steel but maybe the metal 3D printing is better for the environment because the Steelers are quite harsh because the steel is the way you produce the steel is a quite intensive on carbon emission it's not as high as concrete but it's also like you need to molt it use furnaces and all of that then move it to the face I'm not sure what B tells this 3D printing can do but I'm sure they will
get a way to do some metal thing that would replace the steel frame oh that's interesting so I know a very little amount about 3D printing using metals and you pretty much you start off with a powder and you melt it with a laser so you can sort of move your laser through the powder and where the Laser's being the powder melts into a solid object so you can see that you could form all these different shapes out of this powder but how you translate that into construction I have no idea
so that sounds like quite time intensive time intensive now right if you think of the how the the way that computer changed over the future and if you even if you think of their smartphones like in the early 2000s they were kind of like something you would see in a science fiction movie so you don't know how fast this technology develop and now we have the AI working with us in so many ways so maybe they will find a better way to utilize this if they found a really good
application for it and then in civil engineering which make it build more efficient and they can save money on labor and they can save money on the emissions and it would be more sustainable so maybe maybe it's gonna be something that the future building would look like one thing you'd want to do is reduce how much steel or metal you use in your construction project right so you kind of 3D print all these sort of almost like lacy structures so you've got little holes in
there and it would be just as strong because your AI is kind of like figured out how to put these holes in certain places without affecting the material properties and you just have this really beautiful printed wild looking structure that you can never really think of yourself yeah and also it could have like how light this structure will be because it would kind of like would be able to remove or not redundancy material here and there and would save you cost and the overall project because
it have less material on it yeah exactly so you're saving emissions you're saving time you're saving materials that is the future and one of the things that I forgot to mention before and the advantages of 3D printing is you save waste material so it's not as wasteful as normal construction building because is utilize the whole mix and everything because it's kind of like I don't want to say perfect but they're aiming for Perfection with because it's a machine
right and it just use every little bit of the material it have in it so they would eliminate waste as well yeah so rather than sort of making a block that you then sort of shape down so you sort of reducing stuff from the surface of it you're just putting in place exactly what you need yes yeah cool see this is the future we need we need some engineers and scientists to get together and collaborate on that putting this idea into action I think I feel like I'm coming at this from a
really weird way because I'm a scientist right who's just interested in like really fundamental stuff and then you've sort of pass that fundamental understanding on the engineers to find applications that's what we're doing right exactly that's why like with kind of like using this initial material that they have to see what potential it could do for the future because like it can do so many things but we don't know yet it's like we have a limited sciencey research to give us
um enough background to kind of like have a more firm conclusions yes there's more research to do to figure out what 3D printing can do for us it sounds like there's a role for slightly crazy ideas like some of mine to do something that no one's thought of doing yet it's actually it's really good when you talk to someone from outside of the field because they would look at things differently so some of these wild ideas could be very applicable I love it thank you because I feel like
I'm just spouting utter random things and loads of people be listening to this going that woman's crazy [Laughter] Sciences scientists will be crazy but we would all have some kind of like other layer that we have this wild ideas and it could work and could not work but that's how science works right like that's how science move because again like if you look at the science fiction movies from the 70s like Star Wars and and things everything there seems like this that can't happen
and now we have space travel this is a slightly different thing yeah I'm sure people have looked at those films and said oh well that can't happen because this fundamental law of physics I see your point and it allows people to dream right and think of new stuff yeah like even the the robot guy in in the Star Wars forgot what's name the C3PO yeah and now we have this circular um vacuum thingy that goes around her the house and vacuum if you want them to do that they still are not as fancy as
him I think C3PO would be offended if you just told him he's essentially a fancy vacuum cleaner yeah it's still it's like we still developing until we get there but like the idea of having such a thing was very far in the 70s yeah and progress is happening at an ever increasing rate more scientists looking into new things so yeah we need wild ideas yeah I think that is an excellent line to end this episode on do you agree yeah brilliant so I hope you've enjoyed
listening to this and we have lots more wild ideas coming up in the future so stay tuned and we'll see you next time the views expressed in this podcast belong entirely to the person that said them they do not represent any industry or organization if you enjoyed listening to these views it would really help us out if you could rate US leave a review and tell a friend this podcast was sponsored by no one but if you're interested in funding us to continue to
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