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  1. Kung-Fu Joe is offline
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    Posted On:
    11/14/2007 12:30pm


     Style: Brazilian Jiu-Jitsu

    --
    Hell yeah! Hell no!

    An analysis of Breaking from a non-Martial-Artist

    I know that the topic of Breaking is not a new one for Bullshido, but I thought people might find this interesting. I somehow managed to bring up the subject in casual conversation with a buddy of mine. This friend is not a martial artist, but he is a structural engineer, by trade. His entire profession revolves around understanding how materials can support different forces, and what causes failure in such systems.

    Here are his hand-written notes on the subject (in Adobe Acrobat format):
    http://crimsonsundown.com/Breaking%20Stuff%20Notes.pdf

    It doesn't really contain any new information, honestly-- just a quick, scientific analysis of the basic points we already knew about Breaking. It briefly explains exactly why the peculiar cut of boards for Karate make the board easier to break, and why it isn't surprising that concrete can be shattered by human strikes.

    --Joe
  2. MaverickZ is offline

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    Posted On:
    11/14/2007 12:38pm

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     Style: white boy jiujitsu

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    Hell yeah! Hell no!
    Can you ask your friend why he believes the typical cinder blocks used in karate breaking are anisotropic?
  3. FickleFingerOfFate is offline
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    Posted On:
    11/14/2007 1:16pm

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    Comparative to wood and cinderblocks at 1" and 2" respectively,

    How much sheer strength and tensile strength does the human bone have?


    specificly the flat bones of , let's say, ones face?

    :XXbirdman
    If you can't laugh at yourself,
    Others will be happy to do it for you. :evil6:

    The 2 most abundant elements in the universe are hydrogen and stupidity.


  4. JohnnyFive is offline

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    Posted On:
    11/14/2007 1:23pm


     Style: Judo/BJJ

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    Hell yeah! Hell no!
    Human bone tends to have similar mechanical properties to wood -- this is why orthopedic surgeons tend to use similar looking instruments, like saws, etc. The difference between breaking and hitting a human being, however, lies in other things like fixturing and padding.
  5. FickleFingerOfFate is offline
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    Posted On:
    11/14/2007 1:25pm

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     Style: Karate/ Arnis

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    Quote Originally Posted by JohnnyFive
    Human bone tends to have similar mechanical properties to wood -- this is why orthopedic surgeons tend to use similar looking instruments, like saws, etc. The difference between breaking and hitting a human being, however, lies in other things like fixturing and padding.
    How much padding do you have around the Orbit, Temple, or Mandible?


    I would bet a wet towel placed on the boards would adequately simulate this.



    Qualitative analysis Plz.

    Kthx.

    :needpics:
    Last edited by FickleFingerOfFate; 11/14/2007 1:29pm at .
    If you can't laugh at yourself,
    Others will be happy to do it for you. :evil6:

    The 2 most abundant elements in the universe are hydrogen and stupidity.


  6. Kung-Fu Joe is offline
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    Posted On:
    11/14/2007 1:33pm


     Style: Brazilian Jiu-Jitsu

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    Quote Originally Posted by MaverickZ
    Can you ask your friend why he believes the typical cinder blocks used in karate breaking are anisotropic?
    Can and will. So far, he's just sent me these few notes. I'll try to have a more in-depth discussion with him as soon as I can (most likely, this weekend).

    --Joe
  7. MaverickZ is offline

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    Posted On:
    11/14/2007 2:11pm

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    Quote Originally Posted by Kung-Fu Joe
    Can and will. So far, he's just sent me these few notes. I'll try to have a more in-depth discussion with him as soon as I can (most likely, this weekend).

    --Joe
    What he's saying about wood, mainly the cut of wood used in most martial arts breaking, is correct. It's fairly basic structures stuff. It's his statement about isotropism being a function of the direction of applied force that I find a bit contrary to what I've learned.
  8. Kung-Fu Joe is offline
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    Posted On:
    11/14/2007 2:35pm


     Style: Brazilian Jiu-Jitsu

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    Quote Originally Posted by MaverickZ
    What he's saying about wood, mainly the cut of wood used in most martial arts breaking, is correct. It's fairly basic structures stuff. It's his statement about isotropism being a function of the direction of applied force that I find a bit contrary to what I've learned.
    I'll ask him to clarify that, but I was under the impression that he was implying the formative structure of the cinder block is what causes the anisotropic properties. Perhaps some sort of latticework that occurs as the concrete solidifies, or some function of the concrete's composite nature?

    --Joe
  9. attakmint is offline

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    Posted On:
    11/14/2007 7:59pm


     Style: mozambique drill

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    Hell yeah! Hell no!
    The very definition of an isotropic material is that the material has no directional bias with regards to applied force - if you pull it apart or squish it together, the amount of deformation wrt applied force is the same, the failure mode is the same, etc.. Concrete has horrible tension properties. Kungfujoe's friend is correct.

    And yeah, it probably has something to do with the microstructure of concrete.
  10. MaverickZ is offline

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    Posted On:
    11/14/2007 8:43pm

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    Quote Originally Posted by attakmint
    The very definition of an isotropic material is that the material has no directional bias with regards to applied force - if you pull it apart or squish it together, the amount of deformation wrt applied force is the same, the failure mode is the same, etc.. Concrete has horrible tension properties. Kungfujoe's friend is correct.

    And yeah, it probably has something to do with the microstructure of concrete.
    That is partially incorrect. Isotropism means that the material behaves the same in whichever direction you apply the force. It does NOT mean that it behaves the same whether you apply tension or compression in any one direction. Concrete will behave the same no matter which direction you PULL it. Concrete will behave the same no matter which direction you PUSH it. Concrete will NOT behave the same if you pull it or push it in the same direction. Tensile strength and compressive strength are two different things.

    So his friend stating that this property of concrete is the same as for wood is incorrect. Wood is anisotropic, concrete is isotropic.
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