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Blasting Vibrations and Their Effects on Structures

Description: Report issued by the Bureau of Mines over the effects of air blast vibrations. As stated in the abstract, "this report presents the results of the Bureau of Mines 10-year program to study the problem of air blast and ground vibrations generated by blasting" (p. 1). This report includes tables, and illustrations.
Date: 1971
Creator: Nicholls, Harry R.; Johnson, Charles F. & Duvall, Wilbur I.
Partner: UNT Libraries Government Documents Department

The Influence of Acoustical Vibrations on Convective Heat Transfer to Liquids

Description: From Introduction: "The research work described in this report consisted of two phases: analytical and experimental. Because of the complexity of the problem of the interaction between acoustical vibrations and heat transfer, the effort to analyze this problem theoretically began with a search for simplified "mathematical models" of the actual physical processes involved."
Date: March 1964
Creator: Fand, R. M.
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.
Date: October 1955
Creator: Kordes, Eldon E. & Kruszewski, Edwin T.
Partner: UNT Libraries Government Documents Department

Flight Measurements of the Vibration Experienced by a Tandem Helicopter in Transition, Vortex-Ring State, Landing, Approach, and Yawed Flight

Description: Note presenting an investigation involving several flight maneuvers that are critical with respect to vibration. The maneuvers include transition near the ground, landing approaches, vortex-ring state, and yawed forward flight. Some methods of reducing vibration during these maneuvers are described.
Date: September 1958
Creator: Yeates, John E.
Partner: UNT Libraries Government Documents Department

Resonance Vibrations in Intake and Exhaust Pipes of in-Line Engines 3: The Inlet Process of a Four-Stroke-Cycle Engine

Description: Using a previously developed method, the boundary process of four-stroke-cycle engines are set up. The results deviate considerably from those obtained under the assumption that the velocity fluctuation is proportional to the cylinder piston motion. The deviation is less at the position of resonance frequencies. By the method developed, the effect of the resonance vibrations on the volumetric efficiency can be demonstrated.
Date: October 1940
Creator: Lutz, O.
Partner: UNT Libraries Government Documents Department

Resonance Vibrations of Aircraft Propellers

Description: On the basis of the consideration of various possible kinds of propeller vibrations, the resonance vibrations caused by unequal impacts of the propeller blades appear to be the most important. Their theoretical investigation is made by separate analysis of torsional and bending vibrations. This method is justified by the very great difference in the two natural frequencies of aircraft propeller blades. The calculated data are illustrated by practical examples.
Date: February 1932
Creator: Liebers, Fritz
Partner: UNT Libraries Government Documents Department

Heat Capacity Lag in Gases

Description: Note presenting a review of the literature on the sonic studies of the problem of the excitation of molecular vibrations by collision. The theory on which the interpretation of almost all the sonic work has been based is discussed rather qualitatively in some detail. Results concerning techniques, principal experimental programs, and an interpretation of the results are provided.
Date: November 1951
Creator: Walker, Richard
Partner: UNT Libraries Government Documents Department

Contribution to the Theory of Propeller Vibrations

Description: This report presents a calculation of the torsional frequencies of revolving bars with allowance for the air forces. Calculation of the flexural or bonding frequencies of revolving straight or tapered bars in terms of the angular velocity of revolution. Calculation on the basis of Rayleigh's principle of variation. There is also a discussion of error estimation and the accuracy of results. The author then provides an application of the theory to screw propellers for airplanes and the discusses the liability of propellers to damage through vibrations due to lack of uniform loading.
Date: June 1930
Creator: Liebers, F.
Partner: UNT Libraries Government Documents Department

The Role of Triple Collisions in Excitation of Molecular Vibrations in Nitrous Oxide

Description: Note presenting an investigation of the importance of triple collisions in the thermal relaxation process of gaseous mixtures. Results of the experiments have shown that the thermal relaxation times of the gas mixtures studied can be very well explained on the basis of binary collisions alone and that triple collisions do not play a discernible part in the excitation of molecular vibrations.
Date: May 1954
Creator: Walker, Richard A.; Rossing, Thomas D. & Legvold, Sam
Partner: UNT Libraries Government Documents Department

Preliminary Investigation of the Effects of Cascading on the Oscillating Lift Force of an Airfoil Vibrated in Bending

Description: Memorandum presenting measurements of the oscillatory lift force acting on an airfoil vibrated in bending. Results were obtained for an isolated airfoil and for the same airfoil oscillated in a cascade, at low and high angles of attack.
Date: September 9, 1953
Creator: Johnson, Donald F. & Mendelson, Alexander
Partner: UNT Libraries Government Documents Department

Control of Torsional Vibrations by Pendulum Masses

Description: "Various versions of pendulum masses have been developed abroad within the past few years by means of which resonant vibrations of rotating shafts can be eliminated at a given tuning. They are already successfully employed on radial engines in the form of pendulous counterweights. Compared with the commonly known torsional vibration dampers, the pendulum masses have the advantage of being structurally very simple, requiring no internal damping and being capable of completely eliminating certain vibrations" (p. 1).
Date: November 1942
Creator: Stieglitz, Albert
Partner: UNT Libraries Government Documents Department

Vibration survey of blades in 19XB axial-flow compressor: 3 - preliminary engine investigation

Description: Strain gages were used to measure blade vibrations possibly causing failure in the 10-stage compressor of the 19XB jet-propulsion engine. The seventh and tenth stages were of great concern as a result of failures experienced by the manufacturer. Strain-gage records were obtained from all stages during acceleration, deceleration, and constant speed runs. Curves are presented herein showing the maximum allowable vibratory stress for a given speed, the change of the damping coefficient with the mounting of a strain gage at the base of the blade, the effect of rotor speed, on blade natural frequency, and the effect of the order of first bending-mode vibration on stress. It was found that for all stages the lower the order of vibration the higher the stress but no destructive vibrations were detected.
Date: January 28, 1948
Creator: Meyer, André J., Jr. & Calvert, Howard F.
Partner: UNT Libraries Government Documents Department

Theoretical and Experimental Investigations of Delta-Wing Vibrations

Description: Note presenting the results of some theoretical and experimental investigations of delta-wing vibrations. Experimental nodal-line patterns and frequencies for a 60 degree thick-skin delta wing are shown. Comparisons of the different investigations have shown that the idealized-strucutre type of method as proposed by Levy gives excellent results for thin-skin wings provided that corrections are made for the effects of transverse shear.
Date: June 1957
Creator: Kruszewski, Edwin T.; Kordes, Eldon E. & Weidman, Deene J.
Partner: UNT Libraries Government Documents Department

Measuring Vibration and Torque With the Oscillograph

Description: "The recent development of technical science demands maximum reliability of functioning, together with maximum utilization of construction materials. For this purpose we must know what stresses are produced during functioning. One cause of great stresses are mechanical vibrations and this report describes a method of using an oscilloscope to measure the stresses of rapidly changing phenomena" (p. 1).
Date: December 1924
Creator: Elsässer, R.
Partner: UNT Libraries Government Documents Department

Transverse Vibrations of Hollow Thin-Walled Cylindrical Beams

Description: "The variational principle, differential equations, and boundary conditions considered appropriate to the analysis of transverse vibrations of hollow thin-walled cylindrical beams are shown. General solutions for the modes and frequencies of cantilever and free-free cylindrical beams of arbitrary cross section but of uniform thickness are given. The combined influence of the secondary effects of transverse shear deformation, shear lag, and secondary effects of transverse shear deformation, shear lag, and longitudinal inertia is shown in the form of curves for cylinders of rectangular cross section and uniform thickness" (p. 1).
Date: 1953
Creator: Budiansky, Bernard & Kruszewski, Edwin T.
Partner: UNT Libraries Government Documents Department

Effect of Angle of Incidence of Second-Stage Vane Assembly on Third-Stage Compressor-Blade Vibration and Engine Performance

Description: "Strain-gages were used to measure blade vibrations causing failures in the third stage of a production 11-stage axial-flow compressor. After the serious third-stage vibration was detected, a series of investigations were conducted with second-stage vane assemblies of varying angles of incidence. Curves presented herein show the effect of varying the angle of incidence of second-stage vane assembly on third-stage rotor-blade vibration amplitude and engine performance" (p. 1).
Date: June 12, 1951
Creator: Meyer, André J., Jr. & Calvert, Howard F.
Partner: UNT Libraries Government Documents Department

NONLINEAR VIBRATION

Description: Nonlinear vibration is discussed and compared with linear vibration. Nonlinear vibration phenomena are described, and methods for testing a nonlinear system, collecting and analyzing the data, and interpreting the results are suggested. (D.L.C.)
Date: November 1, 1963
Creator: Otts, J.V.
Partner: UNT Libraries Government Documents Department

Vibration modeling and supression in tennis racquets.

Description: The size of the 'sweet spot' is one measure of tennis racquet performance. In terms of vibration, the sweet spot is determined by the placement of nodal lines across the racquet head. In this studx the vibrational characteristics of a tennis racquet are explorod to discover the size and location of the sweet spot. A numerical model of the racquet is developed using finite element analysis and the model is verified using the results from an experimental modal analysis. The affects of string tension on the racquet's sweet spot and mode shapes are then quantified. An investigation is also carried out to determine how add-on vibrational datnpers affect the sweet spot.
Date: January 1, 2003
Creator: Farrar, C. R. (Charles R.); Buechler, M. A. (Miles A.); Espino, Luis & Thompson, G. A. (Gordon A.)
Partner: UNT Libraries Government Documents Department

Nonlinearity in modal and vibration testing.

Description: This set of slides describes some aspects of nonlinear Vibration analysis thru use of analytical fromulas and Examples from real or simulated test systems . The Systems are drawn from a set of examples based on Years of vibration testing experience . Both traditional and new methods are used to describe nonlinear vibration.
Date: January 1, 2003
Creator: Hunter, N. F. (Norman F.)
Partner: UNT Libraries Government Documents Department

Vibration survey of NACA 24-inch supersonic axial-flow compressor

Description: From Summary: "Vibration investigations were made of two blade cascades in wind tunnels and of blades operated in the NACA 24-inch supersonic compressor. The results showed that the blade vibrations were present at all tunnel and compressor air velocities and were influenced primarily by tunnel design, simulated centrifugal loading, surging, angle of attack, and possible critical Mach numbers. "
Date: July 30, 1948
Creator: Meyer, André J., Jr. & Hanson, Morgan P.
Partner: UNT Libraries Government Documents Department