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1960-01-01
Technical Paper
600361
F. J. HOOVEN
1960-01-01
Technical Paper
600360
JOSEPH R. FARNHAM
1960-01-01
Technical Paper
600287
I. L. RYHMENG, Y. A. YOLER, Y. AOKI
1960-01-01
Technical Paper
600301
E. STRINGAS
Synopsis Presented in this paper is a brief review of momentum exchange theory for Jet Noise Suppression. “Experimental Results from Scale Model Tests” are included. These data exhibit peak to peak attenuation of 20 db along maximum exhaust noise azimuths at a nozzle pressure ratio of 3.1.
1960-01-01
Technical Paper
600295
R. N. BINGMAN
1960-01-01
Technical Paper
600294
E. W. THRALL
SUMMARY Since acoustically induced fatigue has become such a widespread problem, all information that assists in the overall solution of the problem is desirable. This paper presents the fatigue problem that developed in the empennage area of the Navy A3D aircraft, presents the details of ground and flight test programs that were undertaken, and presents the test results. One effective solution to the cracking problem was found. It was the addition of an elastomer at the point where cracks occurred. Specimen tests plus flight test data prove that an increased life was obtained. Also the need of silencers for ground run up was established. Finally there is presented a procedure whereby test results may be incorporated with analytical analysis to produce a set of design curves that can be used for design analysis. The design curves do not cover all possible configurations or materials but are intended to serve as a guide for such curves.
1960-01-01
Technical Paper
600418
M. D. LAMOREE
1960-01-01
Technical Paper
600417
J. N. CHRISTIANSEN
1960-01-01
Technical Paper
600149
William D. Route
1960-01-01
Technical Paper
600166
WILLIAM C. SPERRY
1960-01-01
Technical Paper
600383
W. R. Walley, R. N. Gardner
1960-01-01
Technical Paper
600037
Sheldon Rubin
PAPER DESCRIBES a procedure for the dynamical design of linear vibration isolators to protect a rigid equipment from the sinusoidal motions of a nonrigid supporting structure. A single degree of translational freedom of the equipment is assumed. Three types of data are required: (1) The equipment mass and its so-called fragility curve, (2) the mechanical admittance of the supporting structure and its amplitude of vibration when it supports no load, and (3) information to establish a minimum stiffness of the isolators. The procedure yields a region of permissible natural frequency and fraction of critical damping combinations for the isolator-mass system. The specification for the isolator dynamical requirements, including allowable tolerances, is derived from this region.*
1960-01-01
Technical Paper
600025
R. F. Stebar, W. M. Wiese, R. L. Everett
A NEW BARRIER to higher compression ratios has recently become apparent — engine rumble! This phenomenon will prevent further increases in compression ratio unless corrective measures are taken. This paper describes the phenomena of engine rumble not only in terms of the noise and vibrations that emanate from the engine but also in terms of the pressure development inside the cylinder. Rumble is the result of abnormally rapid pressure buildup in the combustion chamber due to multiple ignition of the fuel-air mixture by glowing deposits. Since deposits are responsible for the occurrence of engine rumble, studies have been made to determine the contribution of various gasolines and oils to the rumble tendency of the deposits formed. Results from dynamometer and road tests show that combustion-chamber deposits formed by the use of some oils and fuels are considerably less likely to cause rumble than deposits from others.
1960-01-01
Technical Paper
600055
B. J. Lazan
THE INCREASING importance of near-resonant vibrations and the role of system damping in their control is discussed. The various component parts of system damping are classified and analyzed within the framework of: 1. Hysteretic damping within the structural materials. 2. Structural damping associated with (a) interface slip or Coulomb friction, and (b) shear strain in an adhesive layer at an interface. Each of these mechanisms is analyzed to emphasize the factors important in the utilization of damping as an engineering property. Particular attention is paid to analytical concepts for maximizing the shear damping in an interface adhesive by design optimization procedures.*
1960-01-01
Technical Paper
600015
E. S. Starkman, W. E. Sytz
SIMULTANEOUS RECORDINGS of cylinder pressure, audible sound, and crankshaft motion have shown that rumble is a noise associated with bending vibrations of the crankshaft. The vibrations are caused by abnormally high rates of pressure rise near the top dead center piston position. In this study the high rates of pressure rise were obtained by inducting deposits into the the engine. Thud is a torsional vibration of the crankshaft, similar in sound to rumble but resulting from much earlier occurrence of the maximum rates of pressure rise. Rumble vibrations consisted of a fundamental frequency of 600 cps and higher harmonics in the 11/1 compression ratio V-8 laboratory engine used in the investigation. The audible noise of rumble was predominantly composed of the second harmonic or about 1200 cps.
1959-10-01
Magazine
1959-08-01
Magazine
1959-07-01
Magazine
1959-01-01
Technical Paper
590296
THOMAS M. SULLIVAN
1959-01-01
Technical Paper
590345
THOMAS P. RONA
1959-01-01
Technical Paper
590346
C. T. MOLLOY
1959-01-01
Technical Paper
590365
R. C. TUPA
In laboratory engines instrumented to measure surface ignition, vibration and noise; various types of surface ignition, even non-knocking, caused obvious roughness. Additives effective in controlling surface ignition were helpful in reducing vibration and noise. However, in clean engines, pure hydrocarbons with normally high combustion rates resulted in obvious harshness and roughness. These effects, comparable to surface ignition, indicated the margin between normal and abnormal manifestations may be quite narrow. A severe and increasingly common occurrence with test engines has been shorting of spark plug gaps by grossly migrating light duty deposits under moderate to heavy stress.
1959-01-01
Technical Paper
590359
IRWIN VIGNESS
Abstract Shock and vibration tests are usually established on the basis of the maximum intensities of shock and vibration that occur in the field and for locations at which an equipment to be tested may probably be used. It is shown that for equipment, that is not negligibly light compared with the foundation on which it is mounted, that such a procedure leads to overconservative and difficult-to-perform tests. This is caused by consistent less-than-maximum intensity of excitation which occurs at frequencies for which the equipment has large values of mechanical impedance. It is at these frequencies that damage to the equipment is most likely to occur. If tests were performed on machines such that the impedence of the mounting platform were as great as the field mounting foundation, then a more realistic and easier-to-perform test would result if no compensation were made in order to eliminate dips in the excitation spectra caused at frequencies of large equipment impedence.
1959-01-01
Technical Paper
590398
JOHN O. ANDERSON, C. HAROLD EK, CHARLES W. GADD
1959-01-01
Technical Paper
590007
K. P. Pettibone
1959-01-01
Technical Paper
590019
R. H. Perry, H. V. Lowther
ENGINE noise has become an increasing problem with the higher and higher compression ratios of present-day automotive engines. Because fuel octane number cannot be raised indefinitely, the problem is one of engine design and selection of crankcase lubricating oils and gasoline formulations, the authors think. This paper describes investigations into the cause of spark knock, wild ping, rumble, and the added problem of hot-spot surface ignition (which also intensifies as compression ratios increase). The authors have found gasolines with phosphorous additives, used with properly formulated multiviscosity lubricating oils, provide a partial answer to the problem of engine rumble. The authors conclude that very exact tailoring of fuels, lubricants, additives, and engines will be necessary to prevent engine noise if compression ratios continue to rise.
1959-01-01
Technical Paper
590006
Guy J. Sanders
WITH the advent of low-pressure tires and the success of car noise reduction efforts by automotive engineers, tire thump has become a more noticeable problem. This paper discusses some recent research in this area.* A tire's susceptibility to thump can be predicted from the difference frequency between diametrical and circular modes of vibration. The author describes the testing and procedure uses to find the source of thump. The way to minimize thump is to shape and construct the tire so that it does not permit coincidence of two natural frequencies with two revolution rate harmonics in the 20–35 mph speed range.

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