[HN Gopher] Lobster shell patterns make concrete stronger
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Lobster shell patterns make concrete stronger
Author : quotha
Score : 65 points
Date : 2021-01-26 16:01 UTC (6 hours ago)
(HTM) web link (www.reuters.com)
(TXT) w3m dump (www.reuters.com)
| andrewl wrote:
| Biomimicry is fascinating. There's some good info at the
| Biomimicry Institute:
|
| https://biomimicry.org
| PEJOE wrote:
| Negative post here - interesting research but shame on reuters /
| researcher for pretending this is biomimicry. The article does
| not say at all how the concrete has anything to do with lobster
| shells.
|
| Further, rotating layers to change the bulk performance of
| materials composed of anisotropic plies is very old technology
| developed originally for aerospace / racing applications.
|
| Ansys has an entire package devoted to the analysis of structures
| made from anisotropic materials in this way.
| ericol wrote:
| Did you actually read the article?
|
| > Their bio-mimicking spiral patterns improved the overall
| durability of the 3D printed concrete...
|
| That's like, the 4th paragraph in the article published by the
| university.
| ghostbrainalpha wrote:
| I'm confused. They printed a helicoidal pattern, which is
| basically a flattened spiral which was absolutely inspired by
| the Lobster shell.
|
| Why doesn't that qualify as biomimicry?
| ChuckMcM wrote:
| So it is a bit click baity, sure. But how many people really
| think about anisotropic plies? (cool word, anisotropic, by the
| way)
|
| Folks who have done 3D printing figure out pretty quickly that
| the orientation of the print can have a large effect on the
| various structural properties of the thing printed. I basically
| spent the first couple of months printing various test objects
| in different orientations to get a better understanding of
| this.
|
| For that reason, the paper gives a reasonable way to approach
| the question of "how can I make this stronger?".
| rwcarlsen wrote:
| I feel like plywood is a really common thing that a lot of
| people know to have alternating/anisotropic layers of wood
| grain
| ChuckMcM wrote:
| Agreed, that is a great example. That an oriented strand
| board or OSB.
| tantalor wrote:
| > very old
|
| > originally for aerospace / racing applications
|
| That's a wild take on "very old"!
|
| I bet you can find even older examples, e.g., textiles
| ajuc wrote:
| Composite bows were made thousands of years ago using this
| principle. Tendons glued in alternating layers.
| analog31 wrote:
| >>> ...rotating layers to change the bulk performance of
| materials composed of anisotropic plies is very old technology
| developed originally for aerospace / racing applications.
|
| Indeed the original engineered composite material: Plywood.
| ozborn wrote:
| I believe plywood has piles/fibers orthogonal to each other,
| in this video they were laid over diagonal to the underlying
| concrete.
| TT3351 wrote:
| Isn't concrete an engineered composite material to begin
| with? It's ancient. AFAIK plywood is an 19th century
| invention.
| BariumBlue wrote:
| Plywood was used for shields by the Romans, I'm fairly
| certain the Vikings, and wikipedia mentions the Greeks and
| Egyptians used it as well. From what I can tell from a
| quick google, it does seem to be a casualty of the Dark
| ages though.
| PoachedSausage wrote:
| Maybe not. The Dutch police appear to be using wicker
| riot shields in 2021. Good for the environment.
|
| https://www.bostonglobe.com/2021/01/25/nation/weekend-
| riotin...
| TT3351 wrote:
| I believe the implication was it was lost in the Dark
| Ages and re-discovered in 19thc. No reason to suggest
| plywood is not in use today
| engineer_22 wrote:
| In engineering parlance composites are materials with high
| tensile strength bonded to materials with high compressive
| strength.
|
| Concrete is compressive strength materials (rock, sand)
| bonded with cement. OTOH - We could say reinforced
| concrete, (steel, fiberglass, etc reinforcement) is a
| composite.
| sradman wrote:
| See _FIG. 1. Hierarchical microstructure of the cuticle of the
| lobster (Homarus americanus; based on existing studies)_ from
| the paper:
|
| https://www.liebertpub.com/doi/10.1089/3dp.2020.0172
| PEJOE wrote:
| > Further, rotating layers to change the bulk performance of
| materials composed of anisotropic plies is very old
| technology developed originally for aerospace / racing
| applications.
|
| > Ansys has an entire package devoted to the analysis of
| structures made from anisotropic materials in this way.
|
| Also, if you read your link paper, they are not doing
| anything different that what has been known for a long time
| in long-fiber composites - see: https://www.liebertpub.com/cm
| s/10.1089/3dp.2020.0172/asset/i...
| sradman wrote:
| > they are not doing anything different that what has been
| known for a long time in long-fiber composites
|
| They are using a new material (concrete) and in-situ
| fabrication technique (extrusion/printing) that is at an
| early stage of development and doesn't seem to be
| performing well. I'm assuming that the type of empirical
| data produced by these experiments is a prerequisite to
| developing a finite element model for these
| materials/techniques.
|
| The worst case here is that civil engineers have to
| reinvent the knowledge that you believe other engineering
| disciplines have mastered using different materials.
| Computer guided in-situ reinforced concrete seems quite
| novel to me; perhaps that is a reflection of my own
| knowledge gap.
| dr_orpheus wrote:
| Links to the press release from the university [1] and the
| published study [2] have more information than this. The study is
| more specifically how different patterns of 3D printing concrete
| can increase strength over the conventional unidirectional
| printing in parallel lines.
|
| [1] https://www.rmit.edu.au/news/all-news/2021/jan/lobster-
| concr...
|
| [2] https://www.liebertpub.com/doi/10.1089/3dp.2020.0172
| Blikkentrekker wrote:
| It would be nice if there were a picture of this pattern
| included.
| beeforpork wrote:
| A criss-cross pattern is now called biomimicry?
|
| The following article has pictures and a video:
| https://www.theconstructionindex.co.uk/news/view/lobster-shells-
| inspire-stronger-3d-printed-concrete
|
| This is the normal top/bot pattern for 3D printing, right? I
| don't think it was copied from lobsters.
|
| Or am I missing something? Or is this totally misrepresented?
| maxerickson wrote:
| The press release:
|
| https://www.rmit.edu.au/news/all-news/2021/jan/lobster-concr...
|
| Links the paper:
|
| https://www.liebertpub.com/doi/10.1089/3dp.2020.0172
|
| Figure 2 shows it is more than just criss-cross, the layout
| rotates for each layer following a pattern.
| slingnow wrote:
| This is a common technique when laying up carbon fiber /
| fiberglass parts. For each layer you put down, you vary the
| orientation of the fibers such that you don't end up with them
| all pointing in the same direction. This makes the material
| behave more like something homogeneous, like steel or aluminum,
| for example.
|
| I don't see what this has to do with lobster shells.
| xrd wrote:
| This reminds me of tabby, concrete mixed with oyster shells. You
| can still find all these old buildings made of it from the
| Colonial days in Georgia and South Carolina.
|
| https://en.wikipedia.org/wiki/Tabby_concrete
|
| The "tech" you find in the oceans is truly amazing.
| bumbada wrote:
| Mmmm, Reading the title I was expecting they were developing some
| system that made a super strong exo skeleton with a porous
| interior just like lobsters, or bones.
|
| They have done nothing like that. Criss cross printed lines?
| Adding reinforcement fibers?
|
| That is as old as 3D printing.
| tutfbhuf wrote:
| Completely unrelated, but I somehow thought https://lobste.rs had
| invented a new shell (script) pattern at first.
| lailalessdad wrote:
| https://nplink.net/eck6p3am
| sradman wrote:
| The news release _Bio-inspired: How lobsters can help make
| stronger 3D printed concrete_ [1] from RMIT University (with 1
| minute video) and the paper _Influences of Printing Pattern on
| Mechanical Performance of Three-Dimensional-Printed Fiber-
| Reinforced Concrete_ [2]:
|
| > Underperformed interfacial bond and anisotropic properties are
| often observed in three-dimensional-printed concrete, where the
| printing pattern is unidirectional. Such issues could be
| potentially alleviated by replicating microstructures of natural
| materials or applying different architectures, where printed
| layers are arranged into unique and unconventional patterns.
|
| > The addition of steel fibers leads to noticeable improvement on
| both compressive and flexural strengths of samples in any pattern
| compared with their counterparts without fibers. Besides, the
| inclusion of steel fibers into unconventional layups (cross-ply,
| quasi-isotropic, and helicoidal patterns) leads to the
| alleviation of directional dependence of mechanical properties,
| which is a limitation of the unidirectional samples with fibers.
|
| [1] https://www.rmit.edu.au/news/all-news/2021/jan/lobster-
| concr...
|
| [2] https://www.liebertpub.com/doi/10.1089/3dp.2020.0172
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