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Statics of circular-ring stiffeners for monocoque fuselages

Description: For circular-ring stiffeners in monocoque fuselages the bending moments, axial forces, and shear forces under the action of applied external forces or a moment are accurately computed by known methods. Circular-ring stiffeners with variable moments of inertia are likewise considered. In comparison with the step-by-step and partially graphical procedure, the one here described is a more accurate and at the same time a simpler method.
Date: February 1, 1942
Creator: Stieda, W

Stemming in Metal Mines. Progress Report 3: Relative Advantages and Disadvantages of Different Types of Stemming and No Stemming When Used with 60 Percent Ammonia Gelatin Dynamite at the Mount Weather Testing Adit

Description: Report issued by the U.S. Bureau of Mines on the progress made in metal-mine stemming. Previous reports have been presented impartially, or under different procedures. This report contains updated progress results from current procedures and mine conditions. The report includes tables, and illustrations.
Date: February 1942
Creator: Johnson, John A.; Agnew, Wing G. & Mosier, McHenry

The stresses in stiffener openings

Description: The present study treats as a typical example a ring the center line of which is produced by the intersection of two circular cylinders of different diameter. Three load cases are analyzed: (1) Axial and circumferential stresses in both cylinders, the cylinder stresses themselves to be in the ratio conformal to the cylinders loaded under internal pressure. (2) Pure longitudinal tension in the large cylinder. (3) Pure shear (torsion) in the large cylinder. To simplify the calculation, it is assumed that the ring, compared to the shell, is very strong, so that its deformations have no perceptible effect on the stress condition in the shell. This provides an upper limit for the ring stresses actually produced in a shell design, for, according to the theory of stressed skin statics the shells, by elastic flexibility of the ring, regroup the forces deposited on it in such a manner that the ring is relieved.
Date: February 1, 1942
Creator: Marguerre, K

Tensile and pack compressive tests of some sheets of aluminum alloy, 1025 carbon steel, and chromium-nickel steel

Description: Tensile and compressive stress-strain curves, stress-deviation curves, and secant modulus-stress curves are given for longitudinal and transverse specimens of 17S-T, 24S-T, and 24S-RT aluminum-alloy sheet in thicknesses from 0.032 to 0.081 inch, 1025 carbon steel sheet in thicknesses of 0.054 and 0.120 inch, and chromium-nickel steel sheet in thicknesses form 0.020 to 0.0275 inch. Significant differences were found between the tensile and the compressive stress-strain curves, and also the corresponding corollary curves; similarly, differences were found between the curves for the longitudinal and transverse directions. These differences are of particular importance in considering the compressive strength of aircraft structures made of thin sheet. They are explored further for the case of compression by giving tangent modulus-stress curves in longitudinal and transverse compression and dimensionless curves of the ratio of tangent modulus to Young's modulus and of the ratio of reduced modulus for a rectangular section to Young's modulus, both plotted against the ratio of stress to secant yield strength.
Date: February 1, 1942
Creator: Atchison, C S & Miller, James A

Tidewater and weather-exposure tests on metals used in aircraft II.

Description: This report is an addendum to NACA Technical Note No. 736, which dealt with tidewater and weather-exposure tests being conducted by the National Bureau of Standards on various aluminum alloys, magnesium alloys, and stainless steels used in aircraft. The exposures were begun in June 1938 and were terminated, for this particular series, in June 1941. The methods of exposure and the materials being investigated are described, and the more important results obtained up to the conclusion of the second year's exposure are reported.
Date: February 1, 1942
Creator: Mutchler, Willard & Galvin, W G