kevlar and compression
kevlar and compression
(OP)
hello gentlemen,
knowing that kevlar has similar charecteristics to metal(i assume someone may know the answer to my question) can anyone answer why kevlar has a high impact resistance but low compression.
let me rephrase that. first briefly: i'm considering using kevlar for a safety measure to rest the butt of a tool on in order to leverage off an automobile side window while pedrforming my craft. i'm not sure of the psi i put on the window while working my craft, but it has to be substantial considering at times i use every ounce of energy my 180 lb body can muster.
so understanding that in body armor a bullets impact is stopped by kevlar, i'm wondering if by compression they(dupont) means steady pressure in one area when they are talking about compression. as in continuing increased pressure by me and my tool in this instance.
knowing that kevlar has similar charecteristics to metal(i assume someone may know the answer to my question) can anyone answer why kevlar has a high impact resistance but low compression.
let me rephrase that. first briefly: i'm considering using kevlar for a safety measure to rest the butt of a tool on in order to leverage off an automobile side window while pedrforming my craft. i'm not sure of the psi i put on the window while working my craft, but it has to be substantial considering at times i use every ounce of energy my 180 lb body can muster.
so understanding that in body armor a bullets impact is stopped by kevlar, i'm wondering if by compression they(dupont) means steady pressure in one area when they are talking about compression. as in continuing increased pressure by me and my tool in this instance.





RE: kevlar and compression
RE: kevlar and compression
The fibers are surprisingly brittle. The butt of your tool will chew through a Kevlar pad and scratch the glass while you're not paying attention.
A sheet of nylon would probably be a lot more satisfactory.
Mike Halloran
Pembroke Pines, FL, USA
RE: kevlar and compression
RE: kevlar and compression
RE: kevlar and compression
You really need to try and match the stiffness (flexural modulus) of the glass. Your Lexan (polycarbonate) if too flexible. What about an steel plate with plastic coating on it? Cut a plate the right size, (thickness will dictate stiffness), and have someone in your area that does spray-on pickup truck bed liners coat it for you.
= = = = = = = = = = = = = = = = = = = =
Corrosion, every where, all the time.
Manage it or it will manage you.
http://www.trent-tube.com/contact/Tech_Assist.cfm
RE: kevlar and compression
Also, Kevlar is not brittle. Rather, it has good ductility, in contrast to other fibers (like glass or high modulus carbon).
Regards,
Cory
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.
RE: kevlar and compression
Two problems:
- The ferrules couldn't maintain a grip on the cable. _I_ didn't engineer the connection; this was all commercial stuff, alleged to work together, etc. Think of the cable stays on a power pole, except the cable is 1/32" diameter. Damn stuff just oozed through the ferrules. Even multiple ferrules. Even every damn ferrule in the bag. Even crimped extra hard.
- Despite being very careful about bend radii, the fibers fractured when the cable was bent, even just once, even over a controlled radius mandrel, at room temperature.
The broken fibers leave a fairly nasty puncture wound. They are stiff, and the broken ends are sharp.
Nylon dial cord worked much better.
Mike Halloran
Pembroke Pines, FL, USA