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Help with Kevlar

  1. Jan 5, 2008 #1
    I am doing a materials presentation on Kevlar and I decided to test the material with mallets, hammers and baseball bats. For some reason when I felt the material afterwards it felt crumpled, and when I held it to the light it revealed large cracks. Why is this?
     
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  3. Jan 7, 2008 #2

    Danger

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    Hi, Tommy. I can't speak for tires and the like, but bullet-proof vests are a one-time deal. Because of the way the fibres 'crystalize' under impact, they become damaged while doing the job. My '2nd Chance' armour came with a stern warning to discard it or at least have it professionally attended to if I were ever to intercept a bullet.
     
  4. Jan 7, 2008 #3

    turbo

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    You did not specify what type of Kevlar material you were beating on. If it was a resin reinforced with Kevlar, you got exactly what you should have expected. It can be made lighter and stronger than resins reinforced with glass fiber, but it is not indestructible. Once you have shattered the resin, The Kevlar may hold the fragments together, but there will be cracks loose fragments, etc.
     
  5. Jan 7, 2008 #4

    Danger

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    You know, Turbo, I never even considered that aspect of it. I always think of Kevlar as a cloth.
     
  6. Jan 7, 2008 #5

    turbo

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    I wouldn't have tipped to it, either, except that I have a little experience with resins reinforced with graphite and carbon fiber as well as Kevlar. My experience with Kevlar is mostly as woven products, too, such as cut-resistant gloves. They are incredibly durable, but like any materials, heavy use can degrade them.
     
  7. Jan 7, 2008 #6

    Danger

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    Strange thing about that is that while my body armour is rated up to .44 Mag handgun (and the test patch stopped a 7mm Remington deer cartridge point blank), it makes no guarantees against knives. Apparently, that particular weave is susceptible to penetration by a wiggling blade that can work its way through.
     
  8. Jan 7, 2008 #7

    turbo

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    Penetration through weaves is dependent on the coarseness of the weave, the cross-sectional area of the penetrating body, and the force with which the penetrating body is projected. I'll bet that Second Chance would give you NO guarantee against an attack with an ice-pick.
     
  9. Jan 7, 2008 #8

    Danger

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    5-by, pal. They don't like pointy things. (Reminds me of the Monty Python sketch: "What if he has a pointed stick?" :biggrin:)

    There's also the little matter of the impact trauma stopping your heart even if the bullet doesn't get through. Not to mention that the coverage is torso and abdomen only. I read an article once in one of my gun magazines that stated (I don't know if accurately) that if I were to shoot someone in the upper arm with my .44, it could force the blood back into the body with enough hydraulic pressure to rupture the heart.
    When I first got into the game, the rule was 2 to the chest and 1 to the head. I firmly believe that my own approach is superior... 3 to the crotch. If you're high, it's a gut-shot. High to either side takes out a hip. Low to either side takes out a leg (and, with luck, a femoral artery). And if you hit where you're aiming, he'll wish that he was dead.
    Not that I engage in any such activities... :uhh:
     
    Last edited: Jan 8, 2008
  10. Jan 7, 2008 #9

    turbo

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    My home-defense weapon is a Glock 20 in 10mm Auto. I don't care if the intruder is wearing Kevlar or not. He's going to be on his back in seconds after the home-invasion, and it'll get ugly from there. I'm not paranoid about this type of thing, but my wife and I live on a back-road that is probably at least 20 minutes from a 911 response, and there is a growing culture of oxycontin burglars that break in to steal pain-killers or break in to steal money and goods to buy the pain-killers. It's pretty sick. When I was a kid, we never locked our doors. I learned to do that (the hard way) when I went to college in 1970 and things have gone downhill ever since.
     
  11. Jan 7, 2008 #10

    Danger

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    Good choice. I prefer to stick with the Colt-Browning action myself, because it's so natural and comfortable. Now that I'm eligible to possess firearms again (if that confuses you, check back into GD), my next one will be a Para-Ordnance P10 in .45 ACP. I love that calibre. Unfortunately, we can't buy Glazer Safety Slugs up here. They're legal to possess, but not on the market. I have my own device along that line, but haven't yet had a chance to test it. I'm thinking of a hollow copper jacket with a bath-tub cork type bead chain coiled up in it, filled with lithium grease and capped with a nylon nosecone.
     
  12. Jan 7, 2008 #11

    turbo

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    My wife and my friends' wives are a little on the small side, and though they love blazing through my 9mm ammo with handguns, they tend to shy away from the 10mm Auto. My wife liked to shift back an forth from .38 to .357 with my Python to challenge herself and learn to handle the heavy rounds, but she is a bit intimidated by the 10mm Autos, still. My Chicago friend's wife (with a daughter in law enforcement) is shy of the 10mm, too. I think it's a matter of hand strength, and probably a lack of confidence which leads to and overly-rigid grip and shooting stance.
     
  13. Jan 7, 2008 #12

    Danger

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    Yeah, I always wonder about that fear factor. I remember reading one article in 'Shooting Times' or a similar magazine about the terrors of the .44 Magnum. One story regarded a 'Revenuer' who decided to dismantle a hillbilly still with one. Layed off one shot that destroyed the equipment and blew his hat off, and he was deaf for a day or two. What really bugged me (and contributed to my opinion that most Yanks talk bigger than they walk) was that the author was a Grizzly Adams clone. The guy had to have been over 6'2", at least a couple of hundred pounds, supposedly an experienced firearms expert... and he was moaning and whining about how badly a Super Blackhawk hurt him when he fired it.
    A couple of weeks after that, I bought a Super Blackhawk. (Beautiful item.) My best friend was with me when I got it, so we stopped at his place on the way back. I immediately put a set of hearing protectors on his 15-year-old sister (who had never seen a handgun before), passed the gun to her, and she proceded to blow the living **** out of the target one-handed without even flinching. So much for tough guys... :rolleyes:
     
    Last edited: Jan 7, 2008
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