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Thermal Stresses in the barrel of a tank

  1. Dec 24, 2014 #1
    I want to calculate the thermal stresses in the barrel of a tank. The barrel is smooth bore, auto-frettaged and chrome-platted. I want to know if the thermal stresses are small enough to be neglected and if not, then how can I find them?
    Relevant Equation:
    Thermal Stress= modulus * coefficient of expansion * change in temperature
     
  2. jcsd
  3. Dec 24, 2014 #2

    Doug Huffman

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    Empirically the thermal stresses cannot be neglected. The Muzzle Reference System provides thermal strain input to the fire control computer.
     
  4. Dec 24, 2014 #3
    I would like to hear a little more information. Is the barrel constrained in any way? Is it composed of layers of materials with different thermal expansion coefficients?

    Chet
     
  5. Dec 24, 2014 #4

    Doug Huffman

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    The publicly accessible information on the M256 Rheinmetall 120 mm smoothbore gun, the M1 Abrams MBT armament, would suggest not, and it does use a Muzzle Reference System to the FC computer. Remember that the device must be as economical as possible and this one's life span is roughly one ammunition load ~50 rounds.

    ETA: Fact checking myself, I noticed that barrel heating by sunlight is specifically mentioned.
    ETA II: Over wine at supper I realized that layering might increase hoop strength but not longitudinal strength/stiffness, that would come from an increase in overall diameter/thickness or fluting.
     
    Last edited: Dec 24, 2014
  6. Dec 24, 2014 #5

    berkeman

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    Wow, just 50 shots?
     
  7. Dec 24, 2014 #6

    Doug Huffman

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    Yes, with the highest velocity ammo.

    Burton, Larry; Robert Carter; Victor Champagne; et al. (1 January 2004). "Army Targets Age Old Problems with New Gun Barrel Technologies". AMPTIAC Quarterly (Rome, New York: Advanced Materials and Processes Technology Information Analysis Center) 8 (4)
     
  8. Dec 24, 2014 #7

    berkeman

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    Interesting. So in Desert Shield, they were replacing gun barrels like crazy, or did they settle for less accuracy over the few-day campaign?
     
  9. Dec 24, 2014 #8
    Even if the barrel is unconstrained and is not layered, thermal stresses can still develop within the barrel as a result of temperature non-uniformities that occur as a result of firing.

    Chet
     
  10. Dec 24, 2014 #9

    Doug Huffman

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    How many rounds were fired and how many on average?
     
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