Posted on 07/12/2018 4:23:05 PM PDT by Diana in Wisconsin
A new theory could help engineers to create materials for use as smart textiles, artificial tissue and even the aerodynamic contours in jet turbines – by knitting them.
The oldest known example of knitting is from Egypt over a thousand years ago, yet until now scientists did not fully understand how a non-stretchy yarn could be entangled into such a stretchy fabric.
The new study, published in the journal Physical Review X, boils knitwear properties down to three parameters – yarn bendiness, the length of yarn, and the number of crossing points in each stitch.
The simplicity of the model will enable scientists to begin designing knitted materials with custom shapes and properties, says lead author of the paper, Samuel Poincloux from the Ecole Normale Superiore in Paris, France.
“If you understand it well, you can tune your structure to have the properties that you want,” he says.
Poincloux’s analysis found that the primary source of a knitted fabric’s stretchiness came from the loop created as the yarn in one row of stitches weaves through the row above and the row below. When the fabric is pulled, it is able to stretch because the loops become distorted. The energy to do so comes from bending the yarn.
The way the loop can stretch is also limited by the number of times the yarn crosses with neighbouring stitches, and the total length of the yarn in the fabric.
The analysis found yarn bendiness, crossing points and total yarn length were enough parameters to accurately deduce the properties of the material. Poincloux says this should provide a theoretical basis for material designers looking a much more efficient way to create new materials, compared to the current trial and error methods used in industry.
“When I discussed with industry they said they do not have a good fundamental bottom-up design model,” Poincloux explains.
The work originated when Pouncloux’s PhD supervisor, Frédérick Lechenault, watched his wife knit clothes for their unborn child. Lechenault marvelled at the way she could create three-dimensional shapes, such as booties, that would return to their shape even after being stretched significantly.
Lechenault was at the time studying origami, investigating how structure created by folds could alter the properties of a paper object. The one-dimensional nature of yarn suggested the challenge would not be too complex, so he set Poincloux to work analysing knitting stitches.
To get his head around the task Poincloux visited the knitting workshop at the École Nationale Supérieure des Arts Décoratifs across the road from his lab, and learned some stitches.
“Discussing with artists and designers is very interesting, they have a different point of view and a very deep knowledge of what you can do, which can inspire you to design new stuff,” Poincloux says.
“Knits have interesting three-dimensional shapes that appear naturally by changing the stitch pattern. The composite industry can use knitting because it’s quite stretchable and they can fit it to a complex shape, for example in an aeroplane engine turbine.”
Save Us, Sully! ;)
Interesting that knit material has not been studied in this fashion before.
Kool!
Thanks for posting.
But just pull one little string and it all unravels.
My mom could knit like a mofo she could knit smoke and drink and watch Red Skelton and still catch me teasing my twin sister
Scientists thoroughly understand Global Warming, and know exactly how much the seas will rise in 100 years.
And, oh yeah, we’re also beginning to understand that “knitting” stuff too ...
During the industrial revolution, different types of complex knitting machines were invented for socks, underwear, just about everything. Then they came up with a home knitting machine, but I didn’t persist to get the hang of it. I prefer to knit by hand but need instructions or diagrams. Some people can just cast on some stitches and make about anything on the fly.
Haha.. God bless her! They don’t make moms like they used to!
Thanks for reminding me to start my Christmas gifts! Heh.
Bendiness? Is that the new scientific term for flexibility?
Don’t cast your pearls before the turbine.
Last week: why do water drops make a sound when they land?
This week: why is fabric knitted from stiff fibers stretchy?
Next week? The suspense is killing me.
Somebody smart once said, "Does the ornithologist teach the bird to sing?"
Because the real, underlying kick to knitting or sewing is that you get to stab things with sharp needles over and over and over! and no one gets hurt! Great stress reliever at the end of the day.
Very clever! But it should be ‘purls.’ ;)
I was doing some Thrift-Store shopping today - there is SO MUCH Christmas cr@p out there, that our local shop has started to have ‘Christmas in July.’ Saints Preserve Us! ;)
But I know what you mean - if I don’t have my Christmas Gifts bought or made by October, I’m being a slacker! :)
Heh. It starts earlier each year.
My family has gone two ways - once the Grandkids were all surly teens, we adults decided that we would NOT give gifts among extended family members. I mean, there were 13 Grandkids, and then 2 (or more with Steps and Ex’s) adults per kid, so it was just ridiculous.
Anyhow, each family threw $50 in the kitty and then those of us that wanted to would give a little talk about which Charity our cash would go to that year. (Between us, we had $1K to donate!)
We donated to Juvenile Diabetes the year one of the Grandkids was diagnosed. We built a well in Africa. We gave to The Wounded Warriors and one year to the very rural Nursing Home where one of the SILs worked and they needed basic supplies - like TP and tissues!
My immediate family has gone ALL consumables (food, candles, personal care items) or Gift Cards. No one needs more, ‘stuff’ in our family.
Besides, when one of us dies, we get back all the previous JUNK we’ve given one another through the years, LOL!
God Bless Us, Every One! :)
Mr. RightField tells people that I knit so I don’t kill people.
Thanks i miss her
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