Kevlar strong?General


  1. jmj3783

    jmj3783 Well-Known Member

    So I love this phone, but noticed today if I squeeze the phone from the sides, the thin layer of kevlar flexes up like a pc of rubber...kind of disappointing.

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  2. BeastMD

    BeastMD Well-Known Member

    Kevlar is very flexible.
  3. jmj3783

    jmj3783 Well-Known Member


    Well carbon fiber is too until it meets resin. I work in the body armor business and see kevlar that is flexible (vest) and kevlar that is hard and stiff (riot shield) just figured stiff would be a better option since having flexible kevlar on a phone does absolutely nothing for strength.because its not bullet proof, so the kevlar in reality does nothing to help the phones overall strength.
  4. Powersurge

    Powersurge Well-Known Member

    Then what does it actually do to protect/strengthen the phone?
  5. jmj3783

    jmj3783 Well-Known Member

    Nothing. Which is fine but was hoping it was added for strength, but looks cool at least.
  6. BeastMD

    BeastMD Well-Known Member

    It has to do something to help the phone, or why would they bother and not just make the back plain plastic.
  7. jmj3783

    jmj3783 Well-Known Member


    Same reason car companies make the dash look like carbon fiber. It looks cool. Actually, when engineers want something strong and light, they use carbon fiber. Kevlar is never used to build something for strength. For example the Corvette Z06 is made with lots of carbon fiber, not kevlar.
  8. jmj3783

    jmj3783 Well-Known Member

    Ps. Kevlar can be very strong. My point is I find it hard to believe its real kevlar. Because if they used resin the kevlar back would be hard as glass. It seems as its just something glued to plastic. I love this phone but just found this to be misleading because the way they put it on the phone, made Nothing kevlar strong.
  9. pm1066

    pm1066 Well-Known Member

    Looking at the overall construction of the phone, the Kevlar does add to the stability. The phone's stiffness doesn't just come from the kevlar, but the combinations of the shell, the battery, and the internal structure.

    The Kevlar may be a bit gimmicky (carbon fiber would have worked as well), but in a monocoque shell structure it does indeed provide a one piece shear web.
  10. Powersurge

    Powersurge Well-Known Member

  11. Martimus

    Martimus One bite at a time... Moderator

    I would be skeptical to believe that Motorola used something other than Kevlar fibers for the back of the phone. Doing so would potentially place them in legal hot water since the Kevlar back is a feature of the phone.

    If I recall correctly (I worked for many years for a manufacturing company that built crash-worthy seats for military helicopters) the resin that they use when layering Kevlar fibers is an epoxy of some sort. I would guess Kevlar could be baked into other resins and have unique characteristics. My guess is that they had a supplier use only a few layers of Kevlar suspended in a different resin. The Kevlar panels we used to build were nearly an inch thick in places. As such I'd imagine that they'd have much different ballistic properties and amounts of flexibility than a Kevlar sheet that's maybe 1/16-inch thick.
  12. pm1066

    pm1066 Well-Known Member

    The exact same way the tin foil thick skin of an aircraft holds it together at 700 knots. Obviously the thin sheet of kevlar isn't doing everything all by itself. Think of it this way: have you ever questioned the thin plastic skin on the back of your phone before? Because there is no cut out for a battery door the kevlar panel can provide a tremendous amount of shear strength. And it can do so while being thinner, lighter and stronger than comeparable materials.
  13. jmj3783

    jmj3783 Well-Known Member

    All I know is mine, its peeling off like rubber. And i'm not trying to talk bad about the phone because this is a great phone in every aspect. And i'm not returning it even if the glue I used doesn't hold. Just saying I see kevlar every day used for different applications, and gluing a flimsy piece of rubbery kevlar has no purpose. And they say built kevlar strong....sure it is unless it peels off like mine!
  14. Powersurge

    Powersurge Well-Known Member

    My point is not the thickness but the fact that it looks like the sheet is flexible. From my understanding then it could at most provide strengthening against forces strictly within the same plane, couldn't it? Wouldn't that refute the intended general perception that the added strength would help negate a robustness deficit caused by the thinness? I'm confused.

    (btw. I'm not trying to argue here; I know little about physics and want to understand why this would make the phone stronger)
  15. jmj3783

    jmj3783 Well-Known Member

    It is a gimmick. I love the phone but the kevlar does nothing for the phone. Trust me, when I show the phone off I say "look kevlar, that's strong as shit". And hope they don't see the picture of it being bent like a strip of rubber in the tear down pictures.
    stpbby likes this.
  16. pm1066

    pm1066 Well-Known Member

    Not trying to be a smartass here, but you did remove the clear plastic sheet it was shipped with, right?

    If the kevlar is indeed peeling off and delaminating, you are the first. I'd take that puppy back immediately.
  17. jmj3783

    jmj3783 Well-Known Member

    Lol yes plastic is off. I'm not taking it back just used contact cement. That should last me.
  18. dantheman4162

    dantheman4162 Member

    One of the reviews i read said that the reason its strong isn't the kevlar but that there is some type of metal frame built in to re-enforce the thinness. The kevlar is there because its badass.
  19. rushmore

    rushmore Well-Known Member

    Structurally on the Razr, it is a gimmick. Kevlar is as good as the composite layers and frame design is. The metal unibody frame is the key on Razr and the Kevlar as far as the Razr is concerned, means diddly.
    jmj3783 likes this.
  20. mdecipher

    mdecipher New Member

    After 5 days of use the "kevlar" back started to bubble and loosen around the edges. The distinctive pattern now has the unappealing appearance of a blistering skin condition. I am still within the 30 day exchange period; maybe I'll try the Samsung Nexus which is being released tomorrow.
  21. Szadzik

    Szadzik Well-Known Member

    Take it back for sure. Not saying xchange it for a Nexus, but definitely exchange it.
  22. rushmore

    rushmore Well-Known Member


    The Kevlar should be glued and pressed to the back, so return for sure. Once that stuff is set as a composite layer, the Kevlar should go nowhere. Seems a production goof that has nowhere to go but worse.

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