Accession Number:

ADA265564

Title:

Thermal Expansion, Modulus, and Muzzle Drift

Descriptive Note:

Final rept.,

Corporate Author:

ARMY ARMAMENT RESEARCH DEVELOPMENT AND ENGINEERING CENTER WATERVLIET NY BENET LABS

Personal Author(s):

Report Date:

1993-03-01

Pagination or Media Count:

18.0

Abstract:

Drifts in gun muzzle orientation are commonly observed during firing and are generally attributed to thermal stresses generated by temperature differences in different parts of the tube. Thermal shrouds are used to reduce the amplitude of such drifts. The present report addresses drifts that may originate from overall tube temperature rather than temperature differences. In these cases, the original muzzle orientation is recovered only when the tube returns to its original temperature. One familiar effect is the deflection from tube weight, known as muzzle droop, which increases in magnitude with firing. Another possible source for effects of this type is asymmetry in properties that may originate from plastic bending during tube straightening. The physical properties that govern such effects are the thermal expansion coefficient and the temperature dependence of the modulus, One of the main objectives of this report is to clarify some of the formalism related to muzzle drift from uniform heating. The question of how to treat the effect of stress on the thermal expansion coefficient is addressed in detail, since this is a quantity that is rarely measured. It is shown that the effect of stress on thermal expansion can be formulated in the more familiar terms of the temperature dependence of the elastic modulus. The concepts are illustrated with applications to tensile testing and muzzle droop.

Subject Categories:

  • Guns
  • Thermodynamics

Distribution Statement:

APPROVED FOR PUBLIC RELEASE