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Torsion of flanged members with cross sections restrained against warping

Description: "The longitudinal stresses and the stiffness of flange members - I-beams, channels, and Z-bars - were investigated when these members were subjected to torque with constraint against cross-sectional warping. Measured angles of rotation agreed with corresponding calculated values in which the torsion bending factor of the cross section was involved; the agreement was better for the I-beam and the Z-bar than for the channel. Longitudinal stresses measured at the mid-span were found to agree with the calculated values that involved unit warping as well as the torsion-bending factors: the channel showed the greatest discrepancy between measured and calculated values" (p. 1).
Date: March 1943
Creator: Hill, H. N.
Partner: UNT Libraries Government Documents Department

Plastic buckling of a long flat plate under combined shear and longitudinal compression

Description: Report presenting the condition for plastic buckling of a long flat plate under combined shear and longitudinal compression is obtained by using the theory of plastic buckling developed for simple loading, provided the ratio of shear to longitudinal compression is assumed constant during the loading process. A detailed calculation for a number of simply supported plates made of a typical aluminum alloy shows that an approximate algebraic relationship provided in the paper will suffice for determination of buckling stress.
Date: December 1949
Creator: Stowell, Elbridge Z.
Partner: UNT Libraries Government Documents Department

Tension fields in originally curved, thin sheets during shearing stresses

Description: The analysis of the stresses in the sheet and stiffeners is predicated upon the direction of the wrinkles, particularly the tensile stresses (principal stresses). This analysis and the calculation of stresses after buckling form the subject of the present article. It includes: 1) metal cylinders with closely spaced longitudinal stiffeners; 2) metal cylinders with closely spaced transverse rings.
Date: August 1935
Creator: Wagner, H. & Ballerstedt, W.
Partner: UNT Libraries Government Documents Department

The combinations of thermal and load stresses for the onset of permanent buckling in plates

Description: A simple and practical method for evaluating the onset of permanent buckling in plates in the presence of combined thermal and compressive load stresses is outlined. A particular application of the method shows reasonable agreement with tests of 17-7 PH stainless-steel square tubes. The results indicate that the compressive load stress which the plate can support at the onset of permanent buckling is substantially reduced as the temperature difference of the plate and adjoining members increases.
Date: June 1957
Creator: Zender, George W. & Pride, Richard A.
Partner: UNT Libraries Government Documents Department

Critical Combinations of Shear and Direct Stress for Simply Supported Rectangular Flat Plates

Description: Note presenting an investigation of the buckling of a simply supported rectangular flat plate under combinations of shear and direct stress by means of an energy method. The critical combinations of stress for several length-width ratios were determined to an accuracy of about 1 percent in conjunction with a modified matrix iteration method. Results regarding the shear and longitudinal stress and shear and transverse stress are provided.
Date: March 1947
Creator: Batdorf, S. B. & Stein, Manuel
Partner: UNT Libraries Government Documents Department

Critical Combinations of Shear and Direct Axial Stress for Curved Rectangular Panels

Description: "A solution is presented for the problem of the buckling of curved rectangular panels subjected to combined shear and direct axial stress. Charts giving theoretical critical combinations of shear and direct axial stress are presented for panels having five different length-width ratios. Because the actual critical compressive stress of rectangular panels having substantial curvature is known to be much lower than the theoretical value, a semiempirical method of analysis of curved panels subjected to combined shear and direct axial stress is presented for use in design" (p. 1).
Date: August 1949
Creator: Schildcrout, Murry & Stein, Manuel
Partner: UNT Libraries Government Documents Department

Analysis of elastic thermal stresses in thin plate with spanwise and chordwise variations of temperature and thickness

Description: From Introduction: "The object of the present paper is to present an approximate method for calculating accurately the thermal stresses in a thin plate with both chordwise and spanwise variations in temperature and chordwise but restricted spanwise variations in thickness."
Date: November 1956
Creator: Mendelson, Alexander & Hirschberg, Marvin
Partner: UNT Libraries Government Documents Department

Behavior of materials under conditions of thermal stress

Description: A review is presented of available information on the behavior of brittle and ductile materials under conditions of thermal stress and thermal shock. For brittle materials, a simple formula relating physical properties to thermal-shock resistance is derived and used to determine the relative significance of two indices currently in use for rating materials. For ductile materials, thermal-shock resistance depends upon the complex interrelation among several metallurgical variables which seriously affect strength and ductility. These variables are briefly discussed and illustrated from literature sources. The importance of simulating operating conditions in tests for rating materials is especially to be emphasized because of the importance of testing conditions in metallurgy. A number of practical methods that have been used to minimize the deleterious effects of thermal stress and thermal shock are outlined.
Date: 1954
Creator: Manson, S. S.
Partner: UNT Libraries Government Documents Department

Determination of stresses in gas-turbine disks subjected to plastic flow and creep

Description: Report presenting an extension of a finite-difference method to include the computation of disk stresses when plastic flow and creep are considered. The results of numerical examples indicate qualitatively that plastic flow markedly alters the elastic-stress distribution and that, if the amount of creep is small, the effect on stress distribution is also small.
Date: June 1948
Creator: Millenson, M. B. & Manson, S. S.
Partner: UNT Libraries Government Documents Department

Propeller blade stresses caused by periodic displacement of the propeller shaft

Description: The present report deals with different vibration stresses of the propeller and their removal by an elastic coupling of propeller and engine. A method is described for protecting the propeller from unstable oscillations and herewith from the thus excited alternating gyroscopic moments. The respective vibration equations are set down and the amount of elasticity required is deduced.
Date: June 1942
Creator: Meyer, J.
Partner: UNT Libraries Government Documents Department

A study of elastic and plastic stress concentration factors due to notches and fillets in flat plates

Description: Report presenting testing on six large 24S-T3 aluminum alloy sheet specimens containing various notches and fillets to determine their stress concentration factors in the elastic and plastic ranges. Results regarding elastic stress concentration factors, plastic stress concentration factors, a suggested formula, and stress and strain distributions are provided.
Date: December 1951
Creator: Hardrath, Herbert F. & Ohman, Lachlan
Partner: UNT Libraries Government Documents Department

A semi-graphical method for analyzing strains measured on three or four gage lines intersecting at 45 degrees

Description: Report presenting a method for analyzing strains measured on three or four gage lines intersecting at 45 degrees, which helps determine the state of stress at a point on a plane. An equation for adjustment factor and a master curve is provided, which can be memorized and easily used in the future.
Date: May 1939
Creator: Hill, H. N.
Partner: UNT Libraries Government Documents Department

A numerical approach to the instability problem of monocoque cylinders

Description: Report presenting two closely related methods which employ operations tables that have been developed and used in the calculation of buckling load of a monocoque cylinder subjected to pure bending. The buckling loads of three cylinders with very different characteristics were calculated using the methods.
Date: April 1951
Creator: Boley, Bruno A.; Kempner, Joseph & Mayers, J.
Partner: UNT Libraries Government Documents Department

Relative loading on biplane wings

Description: Recent improvements in stress analysis methods have made it necessary to revise and to extend the loading curves to cover all conditions of flight. This report is concerned with a study of existing biplane data by combining the experimental and theoretical data to derive a series of curves from which the lift curves of the individual wings of a biplane may be obtained.
Date: February 15, 1933
Creator: Diehl, Walter S.
Partner: UNT Libraries Government Documents Department

An evaluation of some approximate methods of computing landing stresses in aircraft

Description: Report presenting an investigation to obtain some information concerning the nature and magnitude of the errors involved in computing the landing stresses for large and relatively flexible aircraft when several simplifying assumptions are made. Results regarding the exact solution and approximate solutions are provided. The results suggest that a satisfactory treatment of the landing problem may possibly be obtained from an analysis which assumes that, in landing, the aircraft is an elastic structure subject to the forces or accelerations found in a drop test in which a rigid mass is used.
Date: May 1948
Creator: Stowell, Elbridge Z.; Houbolt, John C. & Batdorf, S. B.
Partner: UNT Libraries Government Documents Department

A unified theory of plastic buckling of columns and plates

Description: On the basis of modern plasticity considerations, a unified theory of plastic buckling applicable to both columns and plates has been developed. For uniform compression, the theory shows that long columns which bend without appreciable twisting require the tangent modulus and that long flanges which twist without appreciable bending require the secant modulus. Structures that both bend and twist when they buckle require a modulus which is a combination of the secant modulus and the tangent modulus.
Date: July 29, 1947
Creator: Stowell, Elbridge Z.
Partner: UNT Libraries Government Documents Department

Compressive strength of flanges

Description: The maximum compressive stress carried by a hinged flange is computed from a deformation theory of plasticity combined with the theory for finite deflections for this structure. The computed stresses agree well with those found experimentally. Empirical observation indicates that the results will also apply fairly well to the more commonly used flanges which are not hinged.
Date: 1951
Creator: Stowell, Elbridge Z.
Partner: UNT Libraries Government Documents Department

Local instability of columns with I-, Z-, channel, and rectangular-tube sections

Description: From Summary: "Charts are presented for the coefficients in the formulas for the critical compressive stress at which cross-sectional distortion begins in thin-wall columns of I-, Z-, channel, and rectangular-tube sections. The energy method of Timoshenko was used in the theoretical calculations required for the construction of the charts. The deflection equations were carefully selected to give good accuracy. The calculation of the critical compressive stress at stresses above the elastic range is briefly discussed in order to demonstrate the use of the formulas and the charts in engineering calculations. Two illustrative problems are included."
Date: December 1939
Creator: Stowell, Elbridge Z. & Lundquist, Eugene E.
Partner: UNT Libraries Government Documents Department

Critical stress of plate columns

Description: Report presenting solutions for the elastic buckling stress of flat rectangular plates with simply supported or fixed ends when loaded as columns. The procedure for determining the critical stress of plate columns with intermediate end fixities is also given.
Date: August 1950
Creator: Houbolt, John C. & Stowell, Elbridge Z.
Partner: UNT Libraries Government Documents Department

Comparison of the structural efficiency of panels having straight-web and curved-web Y-section stiffeners

Description: Report presenting comparisons of the structural efficiency of panels with straight-web and curved-web Y-section stiffeners. In the high-stress region in which failure is at least in part associated with local buckling, panels with curved-web Y-section stiffeners have higher structural efficiencies than panels with straight-web Y-section stiffeners, which is evidenced by higher average stresses at failure, smaller stiffener heights, or wider average spacing of rivet lines.
Date: January 1949
Creator: Dow, Norris F. & Hickman, William A.
Partner: UNT Libraries Government Documents Department

Numerical procedures for the calculation of the stresses in monocoques 4: influence coefficients of curved bars for distortions in their own plane

Description: "Formulas for the calculation of influence coefficients of curved beams of constant radius of curvature are presented corresponding to displacements in the plane of curvature. Moreover, numerical values are given in tabular and graphic form for a limited number of values of the parameter involved" (p. 1).
Date: April 1946
Creator: Hoff, N. J.; Klein, Bertram & Libby, Paul A.
Partner: UNT Libraries Government Documents Department

Stresses in and general instability of monocoque cylinders with cutouts 2: calculation of the stresses in a cylinder with a symmetric cutout

Description: A numerical procedure is presented for the calculation of the stresses in a monocoque cylinder with a cutout. In the procedure the structure is broken up into a great many units; the forces in these units corresponding to specified distortions of the units are calculated; a set of linear equations is established expressing the equilibrium conditions of the units in the distorted state; and the simultaneous linear equations are solved. A fully worked out numerical example, corresponding to the application of a pure bending moment, gave results in good agreement with experiments carried out earlier at the Polytechnic Institute of Brooklyn.
Date: June 1946
Creator: Hoff, N. J.; Boley, Bruno A. & Klein, Bertram
Partner: UNT Libraries Government Documents Department

Critical stress for an infinitely long flat plate with elastically restrained edges under combined shear and direct stress

Description: "A simple interaction curve is presented for evaluating the conditions of combined shear and direct stress under which an infinitely long, flat plate with equal elastic restraints against rotation along the edges will become unstable. The theoretical work that led to the interaction curve is presented in the form of appendixes" (p. 1).
Date: November 1943
Creator: Stowell, Elbridge Z. & Schwartz, Edward B.
Partner: UNT Libraries Government Documents Department

Application of obliquely mounted strain gage to measurement of residual stresses in disks

Description: Report presenting a method by which the residual stress distribution in a disk can be determined with the aid of the obliquely mounted strain gage when the directions of the principal stresses are radial and tangential. The strain gages are mounted in such a way as to make them sensitive only to the tangential stresses in the disk. Results regarding cutting procedure, accuracy of the method, and an independent check of the method are required.
Date: September 1957
Creator: Hirschberg, M. H.; Kemp, R. H. & Manson, S. S.
Partner: UNT Libraries Government Documents Department