12,184 Matching Results

Search Results

Advanced search parameters have been applied.

Secondary Stresses in Thin-Walled Beams With Closed Cross Sections

Description: Note presenting an accurate method of determining secondary stresses in thin-walled, uniform beams of closed cross section. In the first part of the report, the integrodifferential equation governing axial displacements is formulated and solved for a beam without longitudinal stiffeners. In the second part, the corresponding summation-difference equation is developed and solved for a beam with stiffeners.
Date: October 1951
Creator: Benscoter, Stanley Urner
Partner: UNT Libraries Government Documents Department

Production of Large Energetic Neutral Deuteron Beams

Description: Introduction: A proposal for using an energetic neutral deuteron beam for injection into a mirror machine has been made by Eugene Lauer. This report describes an experimental attempt to produce a large neutral deuteron beam. The beam from the NTA ion source was passed through a target of hydrogen gas where the charge exchange mechanics produced a beam of energetic neutral deuterium atoms.
Date: January 24, 1956
Creator: Hester, R. E.
Partner: UNT Libraries Government Documents Department

Elastic Scattering of Atoms and Molecules in the Thermal Energy Range

Description: Abstract: the goal of research on elastic scattering of atomic (or molecular) beams is the elucidation of the interaction potential V(r). the present discussion is confined to thermal energy collisions ([less than]1 ev), sensitive primarily to the attractive part of the potential. Studies of the velocity dependence of the differential and total elastic scattering cross sections have yielded information as follows: (1) The functional form of the long-range attraction : V[tilde]-C/r6, from differential cross sections I(0), at low angles: I(0) oc 0-7/3. (2) The attractive potential constant C, from total cross sections: Q oc (C/v)2/5, (3) The depth of the potential well [epsilon], from the rainbow effect in I(0): 0r=f(1/2mv2/[epsilon). (4) The equilibrium separation rm, from de Broglie interference producing undulations in (I0). (5) the product [epsilon]rm, from extrema in Q(v), and thus rm (from absolute Q's). (6) Observations of m maxima in plots of vQ5/2 vx. v-1 (termed elastic impact spectra) implied the existence of at least m bound states (discrete vibrational levels of zero angular momentum for the composite system).
Date: 1963
Creator: Bernstein, Richard B. (Richard Barry), 1923-1990.
Partner: UNT Libraries Government Documents Department

Simplified Procedures and Charts for the Rapid Estimation of Bending Frequencies of Rotating Beams

Description: Note presenting a Rayleigh energy approach utilizing the bending mode of the nonrotating beam in the determination of the bending frequency of the rotating beam, which is evaluated and is found to give good practical results for helicopter blades. Charts are presented for the rapid estimation of the first three bending frequencies for rotating and nonrotating cantilever and hinged beams.
Date: June 1955
Creator: Yntema, Robert T.
Partner: UNT Libraries Government Documents Department

The Torsion of Box Beams With One Side Lacking

Description: "The torsion of box beams of rectangular section, the edges of which are strengthened by flanges, and of which one side is lacking, is analyzed by the energy method. The torsional stresses are generally taken up by the bending of the two parallel walls, the rigidity of which is augmented by the third wall. The result was checked experimentally on duralumin and plywood boxes. The torsion recorded was 10 to 30 percent less than that given by the calculation, owing to self-stiffening" (p. 1).
Date: April 1940
Creator: Cambilargiu, E.
Partner: UNT Libraries Government Documents Department

Shear Lag in Corrugated Sheets Used for the Chord Member of a Box Beam

Description: "The problem of the distribution of normal stress across a wide corrugated sheet used as the chord of a box-beam-like structure is investigated theoretically and experimentally. Expressions are developed giving the stress distribution in beams, symmetrical or unsymmetrical, about a plane passed spanwise through the center of the sheet. The experiments were arranged to insure bending without torsion and surveys of the normal stresses were made by means of mechanical and electrical strain gages" (p. 1).
Date: January 1941
Creator: Newell, Joseph S. & Reissner, Eric
Partner: UNT Libraries Government Documents Department

Derivation of Stability Criterions for Box Beams With Longitudinally Stiffened Covers Connected by Posts

Description: "An investigation has been made of the elastic stability of an idealized box beam with longitudinally stiffened covers connected by posts and subjected to end moments and axial loads. Stability criterions which give the axial stiffness of the posts required to achieve desired stress values in the box-beam covers are derived" (p. 1).
Date: August 1952
Creator: Seide, Paul
Partner: UNT Libraries Government Documents Department

Fatigue Testing of Wing Beam by the Resonance Method

Description: "Preliminary fatigue tests on two aluminum-alloy wing-beam specimens subjected to reversed axial loading are described. The motion used consists in incorporating one or two reciprocating motors in a resonance system of which the specimen is the spring element. A description is given of the reciprocating motors, and of the method of assembling and adjusting the vibrating system" (p. 1).
Date: August 1938
Creator: Bleakney, William M.
Partner: UNT Libraries Government Documents Department

Rapid Estimation of Bending Frequencies of Rotating Beams

Description: Memorandum presenting a procedure in the form of charts which permits the rapid estimation of the natural bending frequencies of helicopter rotor blades, both rotating and nonrotating. An evaluation of the method with regard to such things as higher modes, blade offset, and variable mass and stiffness distributions is also given. The valuation shows that, when nonrotating beam bending modes are used, Southwell's equation yields reasonably accurate bending frequencies for rotating helicopter blades.
Date: August 18, 1954
Creator: Yntema, Robert T.
Partner: UNT Libraries Government Documents Department

Approximate Stress Analysis of Multistringer Beams With Shear Deformation of the Flanges

Description: "The problem of the skin-stringer combinations used as axially loaded panels or as covers for box beams is considered from the point of view of the practical stress analyst. By a simple substitution the problem is reduced to the problem of the single-stringer structure, which has been treated in NACA Report no. 608. The method of making this substitution is essentially empirical; in order to justify it, comparisons are shown between calculations and strain-gage tests of three beams tested by the author and of one compression panel and three beams tested and reported elsewhere" (p. 469).
Date: April 20, 1938
Creator: Kuhn, Paul
Partner: UNT Libraries Government Documents Department

The lateral instability of deep rectangular beams

Description: "Experimental and analytical studies were made of solid and hollow deep rectangular beams to study their lateral instability under various conditions of loading and restraint. The tests were made on bars and tubes of 17ST aluminum alloy. Failure by lateral buckling occurred only in tests on the solid beams. It was found that, within the elastic range, the test results were in agreement with the classical theory for the lateral buckling of deep beams as given by Prandtl, Mitchell, and Timoshenko" (p. 1).
Date: May 1937
Creator: Dumont, C. & Hill, H. N.
Partner: UNT Libraries Government Documents Department

Effects of panel flexibility on natural vibration frequencies of box beams

Description: From Summary: "Effects of local panel oscillations on bending and torsional vibrations of box beams with flexible covers and webs are investigated. Theoretical analyses of simplified models are made in order to shed light on the mechanism of coupling between local and overall vibrations and to derive results than can be used to estimate the coupling effects in box beams."
Date: March 1954
Creator: Budiansky, Bernard & Fralich, Robert W.
Partner: UNT Libraries Government Documents Department

Determination of flame temperatures from 2000 to 3000 K by microwave absorption

Description: Report presenting equations derived for the measurement of flame temperatures from the attenuation of a microwave beam by temperature-induced free electrons from chemical elements introduced in the flame. The free electron collision frequency and an effective ionization potential for four alkali elements were determined experimentally. Results regarding the blast burner, liquid propellant burner, and effects of addition of salt solutions on flames are provided.
Date: August 1954
Creator: Kuhns, Perry W.
Partner: UNT Libraries Government Documents Department

Stress and distortion measurements in a 45 degree swept box beam subjected to antisymmetrical bending and torsion

Description: Report presenting an untapered aluminum-alloy box beam representing the main structural component of a full-span, two-spar, 45 degree swept wing with a carry-through section subjected to antisymmetrical tip bending and twisting loads such that stresses were kept below the proportional limit. Results regarding stresses due to antisymmetrical bending, stresses due to antisymmetrical torsion, distortions due to antisymmetrical bending, and distortions due to antisymmetrical torsion are provided.
Date: April 1950
Creator: Zender, George W. & Heldenfels, Richard R.
Partner: UNT Libraries Government Documents Department

Stress and distortion analysis of a swept box beam having bulkheads perpendicular to the spars

Description: Report presenting a method for the approximate calculation of the stresses and distortions in a box beam representing the main structural component of a swept wing with a carry-through section and with bulkheads perpendicular to the spars. Results regarding determination of shear-leg effects, effect of bulkhead flexibility, and extension of the method are provided.
Date: November 1950
Creator: Heldenfels, Richard R.; Zender, George W. & Libove, Charles
Partner: UNT Libraries Government Documents Department

An analysis of the stability and ultimate bending strength of multiweb beams with formed-channel webs

Description: From Introduction: "The purpose of the present paper is to develop a simple method of calculating both the stress at which initial wrinkling occurs in muti-web beams and the ultimate bending strength of beams which are susceptible to this mode of instability."
Date: August 1954
Creator: Semonian, Joseph W. & Anderson, Roger A.
Partner: UNT Libraries Government Documents Department

Analytical determination of coupled bending-torsion vibrations of cantilever beams by means of station functions

Description: From Summary: "A method based on the concept of Station Functions is presented for calculating the modes and the frequencies of nonuniform cantilever beams vibrating in torsion, bending, and coupled bending-torsion motion. The method combines some of the advantages of the Rayleigh-Ritz and Stodola methods, in that a continuous loading function for the beam is used, with the advantages of the influence-coefficient method, in that the continuous loading function is obtained in terms of the displacements of a finite number of stations along the beam."
Date: 1951
Creator: Mendelson, Alexander & Gendler, Selwyn
Partner: UNT Libraries Government Documents Department

Differential equations of motion for combined flapwise bending, chordwise bending, and torsion of twisted nonuniform rotor blades

Description: The differential equations of motion for the lateral and torsional deformations of twisted rotating beams are developed for application to helicopter rotor and propeller blades. No assumption is made regarding the coincidence of the neutral, elastic, and mass axes, and the generality is such that previous theories involving various simplifications are contained as subcases to the theory presented in this paper. Special attention is given the terms which are not included in previous theories. These terms are largely coupling-type terms associated with the centrifugal forces. Methods of solution of the equations of motion are indicated by selected examples.
Date: February 1957
Creator: Houbolt, John C. & Brooks, George W.
Partner: UNT Libraries Government Documents Department

Investigation of the Vibrations of a Hollow Thin-Walled Rectangular Beam

Description: "Experimental modes and frequencies of an unstiffened hollow beam of rectangular cross section are presented, and comparisons are made between experimental and theoretical frequencies. Theories based on rigid cross sections were found to be sufficiently accurate to predict the frequencies of only the lowest three bending modes. For the higher bending modes and all the torsional modes it was necessary to include the effects of cross-sectional distortions in the calculations" (p .1).
Date: October 1955
Creator: Kordes, Eldon E. & Kruszewski, Edwin T.
Partner: UNT Libraries Government Documents Department