Thermal Stresses in the barrel of a tank

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Discussion Overview

The discussion focuses on calculating thermal stresses in the barrel of a tank, specifically a smooth bore, auto-frettaged, and chrome-platted barrel. Participants explore whether these thermal stresses can be neglected and how to quantify them if they cannot. The conversation touches on empirical observations, material properties, and operational contexts.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant suggests that thermal stresses cannot be neglected, citing the Muzzle Reference System's role in providing thermal strain input to the fire control computer.
  • Another participant inquires about the constraints on the barrel and whether it consists of layers of materials with different thermal expansion coefficients.
  • A participant references the M256 Rheinmetall 120 mm smoothbore gun, noting that it does not appear to be layered and mentioning the economic considerations of the barrel's lifespan.
  • It is noted that barrel heating from sunlight is a factor to consider.
  • One participant asserts that even unconstrained barrels can develop thermal stresses due to temperature non-uniformities from firing.

Areas of Agreement / Disagreement

Participants express differing views on the significance of thermal stresses, with some asserting they cannot be neglected while others seek clarification on the barrel's construction and constraints. The discussion remains unresolved regarding the extent and implications of thermal stresses.

Contextual Notes

Participants have not reached a consensus on the conditions under which thermal stresses can be considered negligible, and there are unresolved questions regarding the barrel's material composition and constraints.

UsamaHameed
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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
 
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Empirically the thermal stresses cannot be neglected. The Muzzle Reference System provides thermal strain input to the fire control computer.
 
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
 
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:
Wow, just 50 shots?
 
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)
 
Interesting. So in Desert Shield, they were replacing gun barrels like crazy, or did they settle for less accuracy over the few-day campaign?
 
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
 
How many rounds were fired and how many on average?
 

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