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Nondestructive Test Methods for Spot Welds in Aluminum Alloys

Description: Note presenting the results of a study and research investigation of nondestructive test methods for spot welds in aluminum-alloy sheets. The purpose of the research was to investigate proposed nondestructive test methods for spot welds in aluminum alloys, to determine the feasibility of the tests, and to recommend the research methods found suitable for development and reduction to practical application.
Date: November 1944
Creator: McMaster, R. C.; Manildi, J. F. & Woolsey, C. C.
Partner: UNT Libraries Government Documents Department

Analysis of Square Shear Web Above Buckling Load

Description: "A solution of Von Karman's fundamental equations for plates with large deflections is presented for the case of a shear web divided into square panels by reinforcing struts. Numerical solutions are given for struts of infinite rigidity and for struts the weight of which is one-fourth the weight of the sheet. The results are compared with Wagner's diagonal tension theory as extended by Kuhn and by Langhaar. It is found that the diagonal tension theory as developed by Kuhn agrees best with the present paper in the practical range when r=1/4. Kuhn's theory is in especially good agreement for the force in the strut when r=1/4" (p. 1).
Date: July 1944
Creator: Levy, Samuel; Fienup, Kenneth L. & Woolley, Ruth M.
Partner: UNT Libraries Government Documents Department

Simplified Truss Stability Criteria

Description: Report presenting a note in two parts regarding simplified truss stability criteria. The first part covers the development of simplified criteria for the stability of planar pin-jointed trusses against buckling in the plane of the truss. The second part constitutes a report on tests carried out to verify the validity of the criteria developed in part one.
Date: July 1944
Creator: Ballhaus, W. F. & Niles, A. S.
Partner: UNT Libraries Government Documents Department

Simply Supported Long Rectangular Plate Under Combined Axial Load and Normal Pressure

Description: Note presenting a solution for the load-strain curve of a simply supported rectangular plate with a width-length ratio of 1:4 under combined normal pressure and axial load. The results indicate it to be conservative design in the elastic range to neglect the effect of lateral pressure on the sheet buckling load and on the load carried by the sheet after buckling.
Date: October 1944
Creator: Levy, Samuel; Goldenberg, Daniel & Zibritosky, George
Partner: UNT Libraries Government Documents Department

Torsion Test to Failure of a Monocoque Box

Description: Note presenting a torsion test to failure for a monocoque box of 24S-T aluminum alloy. The box had a rectangular section and was reinforced by Z-stringers, antirolls, bulkheads, and corner posts.
Date: October 1944
Creator: McPherson, A. E.; Goldenberg, D. & Zibritosky, G.
Partner: UNT Libraries Government Documents Department

Normal Pressure Tests on Unstiffened Flat Plates

Description: "Flat sheet panels of aluminum alloy (all 17S-T except for two specimens of 24S-T) were tested under normal pressures with clamped edge supports in the structures laboratory of the Guggenheim Aeronautical Laboratory, California Institute of Technology. The thicknesses used ranged from 0.010 to 0.080 inch; the panel sizes ranged from 10 by 10 inches to 10 by 40 inches; and the pressure range was from 0 to 60-pounds-per-square-inch gage. Deflection patterns were measured and maximum tensile strains in the center of the panel were determined by electric strain gages" (p. 1).
Date: September 1944
Creator: Head, Richard M. & Sechler, Ernest J.
Partner: UNT Libraries Government Documents Department

On the General Theory of Thin Airfoils for Nonuniform Motion

Description: "General thin-airfoil theory for a compressible fluid is formulated as boundary problem for the velocity potential, without recourse to the theory of vortex motion. On the basis of this formulation the integral equation of lifting-surface theory for an incompressible fluid is derived with the chordwise component of the fluid velocity at the airfoil as the function to be determined. It is shown how by integration by parts this integral equation can be transformed into the Biot-Savart theorem" (p. 1).
Date: August 1944
Creator: Reissner, Eric
Partner: UNT Libraries Government Documents Department

The Shear of Aluminum Alloy Driven Rivets as Affected by Increasing D/T Ratios

Description: "A decrease in shear strengths for increasing D/t ratios was shown in a previous investigation of protruding-head aluminum alloy rivets in double shear conducted at Aluminum Research Laboratories in 1942. Since single shear joints are more common than double shear joints, it was desirable to extend the investigation to single shear joints. This reports describes the results of this investigation of single shear joints and also includes the results of the previous investigation on double shear joints" (p. 1).
Date: July 1944
Creator: Hartman, E. C. & Wescoat, C.
Partner: UNT Libraries Government Documents Department

Artificial Aging of Riveted Joints Made in Alclad 24S-T Sheet Using A17S-T, 17S-T, and 24S-T Rivets

Description: Note presenting an investigation of the effect of artificial aging on the strengths of driven rivets of the alloys used commercially for rivets: specifically, A17S-T, 17S-T, and 24S-T. The change in shear strength for each type of rivet after being exposed to artificial aging treatment of 10 hours at 375 degrees Fahrenheit applied to the driven rivets is described.
Date: September 1944
Creator: Zamboky, A. N.
Partner: UNT Libraries Government Documents Department

Tests of Airfoils Designed to Delay the Compressibility Burble

Description: Note presenting a method of deriving certain airfoil shapes that delay certain compressibility phenomena, and the aerodynamic data for a wide range of Mach numbers obtained from tests of the airfoils in the 24-inch high-speed tunnel. The airfoils, which are designated the NACA 16-series, have increased critical Mach number. Results regarding the airfoil comparison, critical speed, minimum drag, and use of the data are provided.
Date: December 1944
Creator: Stack, John
Partner: UNT Libraries Government Documents Department

The "Limiting Line" in Mixed Subsonic and Supersonic Flow of Compressible Fluids

Description: "It is well known that the vorticity for any fluid element is constant if the fluid is non-viscous and the change of state of the fluid is isentropic. When a solid body is placed in a uniform stream, the flow far ahead of the body is irrotational. Then if the flow is further assumed to be isentropic, the vorticity will be zero over the whole filed of flow. In other words, the flow is irrotational. For such flow over a solid body, it is shown by Theodorsen that the solid body experiences no resistance" (p. 1).
Date: November 1944
Creator: Tsien, Hsue-Shen
Partner: UNT Libraries Government Documents Department

Dynamics of the Inlet System of a Four-Stroke Engine

Description: "Tests were run on a single-cylinder and a multicylinder four-stroke engine in order to determine the effect of the dynamics of the inlet system upon indicated mean effective pressure. Tests on the single-cylinder engine were made at various speeds, inlet valve timings, and inlet pipe lengths. These tests indicated that the indicated mean effective pressure could be raised considerably at any one speed by the use of a suitably long inlet pipe" (p. 1).
Date: 1944
Creator: Boden, R. H. & Schecter, Harry
Partner: UNT Libraries Government Documents Department

Effect of Curvature on Strength of Axially Loaded Sheet-Stringer Panels

Description: Note presenting compressive testing made on twenty-one 24S-T aluminum-alloy sheet-stringer panels 12 inches in length and 16 inches in developed width, reinforced by four Z stringers spaced 4 inches apart. Results regarding strains, buckling, and failure are provided.
Date: August 1944
Creator: Ramberg, Walter; Levy, Samuel & Fienup, Kenneth L.
Partner: UNT Libraries Government Documents Department

The Effect of Temperature on Sheet Metals for Airplane Firewalls

Description: Note presenting tests conducted on 5 uncoated steels and 20 steels with various coatings to determine the effect of temperature on the tensile properties and surface characteristics of the metals. The metals were subjected to furnace-heating tests over a range of temperatures for various times and to flame-impingement and airplane-fire tests. Results regarding metals without surface coatings, low carbon steels with surface coatings, and discussion of comparative behaviors regarding the different surface coatings are provided.
Date: December 1944
Creator: Mutchler, Willard
Partner: UNT Libraries Government Documents Department

The Influence of the Aerodynamic Span Effect on the Magnitude of the Torsional-Divergence Velocity and on the Shape of the Corresponding Deflection Mode

Description: "A procedure which takes into account the aerodynamic span effect is given for the determination of the torsional-divergence velocities of monoplanes. The explicit solutions obtained in several cases indicate that the aerodynamic span effect may increase the divergence velocities found by means of the section-force theory by as much as 17 to 40 percent. It is found that the magnitude of the effect increases with increasing degree of stiffness taper and decreases with increasing degree of chord taper" (p. 1).
Date: February 1944
Creator: Hildebrand, Francis B. & Reissner, Eric
Partner: UNT Libraries Government Documents Department

Numerical procedures for the calculation of the stresses in monocoques 1: diffusion of tensile stringer loads in reinforced panels

Description: Report presenting experiments with both curved and flat reinforced sheet models, the longitudinals of which were loaded axially. The stress distribution in longitudinals and sheet was measured with electric strain gages.
Date: June 1944
Creator: Hoff, N. J.; Levy, Robert S. & Kempner, Joseph
Partner: UNT Libraries Government Documents Department

Numerical procedures for the calculation of the stresses in monocoques 2: diffusion of tensiles stringer loads in reinforced flat panels with cut-outs

Description: Report presenting experiments with a flat reinforced sheet model, the longitudinals of which were loaded axially. Two groups of sheets, one with one panel and one with two panels, were cut out and the stress distributions in stringers and sheet was measured with electric strain gages.
Date: November 1944
Creator: Hoff, N. J. & Kempner, Joseph
Partner: UNT Libraries Government Documents Department

The inward bulge type buckling of monocoque cylinders 1: calculation of the effect upon the buckling stress of a compressive force, a nonlinear direct stress distribution, and a shear force

Description: "In the present part I of a series of reports on the inward bulge type buckling of monocoque cylinders the buckling load in combined bending and compression is first derived. Next the reduction in the buckling load because of a nonlinear direct stress distribution is determined. In experiments nonlinearity may result from an inadequate stiffness of the end attachments in actual airplanes from the existence of concentrated loads or cut-outs" (p. 1).
Date: October 1944
Creator: Hoff, N. J. & Klein, Bertram
Partner: UNT Libraries Government Documents Department

Determination of stress-strain relations from "offset" yield strength values

Description: Report presenting an investigation of the shape of stress-strain curve for a material, especially when the material is subjected to compression, which may cause materials to become unstable at stresses beyond the elastic range. The ratio of stresses to effective modulus is explored in equation form.
Date: February 1944
Creator: Hill, H. N.
Partner: UNT Libraries Government Documents Department

Elastic properties of channels with unflanged lightening holes

Description: Report presenting testing of fifty-eight lightened and five unlightened aluminum-alloy channels as simply supported beams in pure or simple bending produced by loads parallel to the plane of symmetry, and fifty-three lightened and four unlightened aluminum-alloy channels with loads parallel to the back. Four types of testing occurred with various types of support and loading.
Date: March 1944
Creator: Niles, Alfred S.
Partner: UNT Libraries Government Documents Department

A unit laboratory engine oil system providing for a remote indication of oil flow and oil consumption together with blow-by measurement

Description: From Summary: "A unit oil system and oil-weighing device designed for laboratory engine tests to permit the remote measurement of oil-flow rate and oil consumption is described. The system regulates the oil pressure and temperature and is closed to make possible the accurate measurement of blow-by gas. The oil is weighed by a self-contained diaphragm and pilot-valve assembly, which uses compressed air as the transmitting medium. Several of those unit systems have given satisfactory service for more than a year."
Date: September 1944
Creator: Koffel, William K. & Biermann, Arnold E.
Partner: UNT Libraries Government Documents Department

The numerical solution of compressible fluid flow problems

Description: Numerical methods have been developed for obtaining the steady, adiabatic flow field of a frictionless, perfect gas about arbitrary two-dimensional bodies. The solutions include the subsonic velocity regions, the supersonic velocity regions, and the transition compression shocks, if required. Furthermore, the rotational motion and entropy changes following shocks are taken into account. Extensive use is made of the relaxation method. In this report the details of the methods of solution are emphasized so as to permit others to solve similar problems. Solutions already obtained are mentioned only by way of illustrating the possibilities of the methods described. The methods can be applied directly to wind tunnel and free air tests of arbitrary airfoil shapes at subsonic, sonic, and supersonic speeds.
Date: May 1944
Creator: Emmons, Howard W.
Partner: UNT Libraries Government Documents Department