fabric tension, PES material
fabric tension, PES material
(OP)
Greetings,
I want to measure fabric tension in a material. I have a cylindrical bag made from PES (polyether sulphone), PVC coated. (Mehler Texnologies, POLYMAR 8556)
The bag is partially filled with water and air. The bag is in flowing water. I am trying to find out a way to measure the tension in the fabric as it collides with various objects. Anyone know of proven methods for this type of measurement? Most of my work has been done with metals, and strain gages would be my first inclination. I am finding out that this may not be the best way to go for an anisotropic material. thanks.
I want to measure fabric tension in a material. I have a cylindrical bag made from PES (polyether sulphone), PVC coated. (Mehler Texnologies, POLYMAR 8556)
The bag is partially filled with water and air. The bag is in flowing water. I am trying to find out a way to measure the tension in the fabric as it collides with various objects. Anyone know of proven methods for this type of measurement? Most of my work has been done with metals, and strain gages would be my first inclination. I am finding out that this may not be the best way to go for an anisotropic material. thanks.





RE: fabric tension, PES material
Fabric tension will cause much higher strains than typical strain gages are designed for. You should probablly be looking at extensometers or force measuring devices.
RE: fabric tension, PES material
Thanks for the advice.
RE: fabric tension, PES material
These colors can be correlated to the strain if you calibrate them versus known strains. In this way you can quantify the strain without using for example a strain gauge, which would alter the system.
I used this method many years ago to detect stresses in tableware glaze (ceramics).
Chris DeArmitt
"Knowledge has no value except that which can be gained from its application toward some worthwhile end."
Think and Grow Rich - Napoleon Hill
RE: fabric tension, PES material
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Somewhere else, years back, I read a paper or two that described putting very fine wires into the fabric, and measuring resistance across the wire, essentially a strain gage but at much larger scales than the preprinted gages we all know.
The other main diagnostic I know of from airbag systems is to use high-speed cameras, and measure the actual deflections of the bag surface (accounting for parallax and other errors while doing so), translating those measurements to a dynamic model, and backing out the membrane stresses from said model. Painful, but it can be done if the numbers are worth enough to you.
RE: fabric tension, PES material
RE: fabric tension, PES material
Chris DeArmitt
"Knowledge has no value except that which can be gained from its application toward some worthwhile end."
Think and Grow Rich - Napoleon Hill
RE: fabric tension, PES material
RE: fabric tension, PES material
Chris DeArmitt
"Knowledge has no value except that which can be gained from its application toward some worthwhile end."
Think and Grow Rich - Napoleon Hill
RE: fabric tension, PES material
RE: fabric tension, PES material
Chris DeArmitt
"Knowledge has no value except that which can be gained from its application toward some worthwhile end."
Think and Grow Rich - Napoleon Hill
RE: fabric tension, PES material
I also was envisioning a bag made from coated fibers (the word fabric was my cue). Not sure how you could see fringe patterns in multiple fibers, unless I am missing something. I say this with all due respect to Chris, he's a damn sharp guy, and if there is a do-able method for fibers i'd like to know...
RE: fabric tension, PES material
The pressure in the bag must tell you the stress on the fabric. Afterall, no matter which direction the stress is applied from, it will be exerted equally across the total surface area of the fabric. So, all you need to know is the internal water pressure (from a tite gauge or other simple pressure meter) and the surface area of fabric.
As this is not my strongest area, would someone more mechanical please correct me if I'm wrong.
Chris DeArmitt
"Knowledge has no value except that which can be gained from its application toward some worthwhile end."
Think and Grow Rich - Napoleon Hill
RE: fabric tension, PES material
We also increased load on test samples until they failed then studied the failure.
This looks more like a trial and error and experience type scenario rather than a scientific lab test to me as the conditions under use will be very variable under very poor conditions and at times desperate with an element of panic by the operators. Not a situation for consistent and predictable correct use.
A high efficiency nylon yarn will be better overall than polyester due to it's higher elongation and the retention of properties after weaving and coating.
Software for analysis of car tyre impact performance might help. I only mention this because I guess it is likely to already exist and there are some similarities in how it might be broken in some cases.
If you post in the automotive wheels and tyre section asking f software exists, a guy called capriracer might help.
DO NOT DOUBLE POST THE OP FROM HERE. Ask a specific new question on software and impact testing of coated fabrics. Include your photo as it is big help in understanding our question.
Regards
Pat
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RE: fabric tension, PES material
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It captures tire footprint pressure patterns. It looks like an off the shelf product that cold be adapter for other uses.
I agree that what I am looking at is more of a science project/research. The folks handing out the money seem to disagree! Good ideas and suggestions from everyone. thanks.
RE: fabric tension, PES material
No expert here neither, but I know that curvature of the membrane also plays a role (in addition to the pressure) in the derivation of stress in diaphragms. I'm still thinking about your idea, but extending it - perhaps a pressure-sensitive coating? Could an aluminum or similar reflective layer be applied, then a clear coat of something that provides birefringence/photoelasticity? Hm, like mtnman says, it sounds like a science project...
RE: fabric tension, PES material
Regards
Pat
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