bluuebunny/crossref_metadata_2025_split huggingface dataset:
Stresses in a Metal Tube Under Both High Radial Temperature Variation and Internal Pressure
Authors: Chang Chieh-Chien , Chu Wen-Hwa 
Published: June 2021

Abstract
The paper treats the stress distribution in a metal tube which is subject to a very high radial temperature variation and pressure. The radial temperature distribution across the tube wall and the variations of the modulus of elasticity and the coefficient of thermal expansion are obtained from experimental data, and all these effects of temperature are taken into account in the calculations. The fundamental equations in the case of plane strain and plane stress can be formulated as the nonhomogeneous Whittaker differential equations. The corresponding solutions are obtained by the method of variation of parameters and in terms of Kummer series. An example is shown, and the stress distribution across the wall is given. For comparison, the stress distribution of the case of constant modulus of elasticity and coefficient of expansion is included.
Bending of Isotropic Thin Plates by Concentrated Edge Couples and Forces
Authors: Yu Yi-Yuan 
Published: June 2021

Abstract
In this paper the complex variable method of Muschelišvili for solving the biharmonic equation is applied to problems of bending of isotropic thin plates by concentrated edge couples and forces. The results of the method as applied to plate problems by previous authors are presented first. Methods of handling concentrated edge couples and forces are developed. These are then applied to the circular plate as an example, for which exact solutions in closed forms are obtained. Worked out in detail are three particular problems; namely, those of circular plates subjected, respectively, to two bending couples, to two twisting couples, both applied at the ends of a diameter, and to four forces applied at the ends of two diameters perpendicular to each other. Numerical results are presented in the form of graphs.
Torsional Vibrations of Beams of Thin-Walled Open Section
Authors: Gere J. M. 
Published: June 2021

Abstract
This analysis deals with the free torsional vibrations of bars of thin-walled open cross section for which the shear center and centroid coincide. Such sections include I-beams and Z-sections. The differential equation for torsional vibrations is derived and includes the effect of warping of the cross section. The effect of warping on the frequency of vibration and the shapes of the normal modes of vibration are determined for bars of single span with various end conditions. For a simply supported bar, a formula for the principal torsional frequencies and an expression for mode shape are derived. For other conditions of support, the frequency equations are derived and their solutions presented in graphical form. From these graphs the frequencies of vibration and the mode shapes may be obtained directly. The case of a cross section which does not warp is a limiting case of the general problem. For such shapes (for example, a cross-shaped or cruciform section) the formulas for torsional frequencies and modes of vibration are quite simple. These formulas also are valid for a circular shaft and may be used approximately for other solid sections.
Propagation of Elastic Impact in Beams in Bending
Authors: Goland Martin , Wickersham P. D. , Dengler M. A. 
Published: June 2021

Abstract
A theoretical and experimental comparison is made of the strain propagation in steel beams impacted by a sharp, transverse blow. The theoretical analysis is based on an earlier paper by Dengler and Goland, in which a solution based on the Timoshenko bending mechanism is deduced. (An analytical error in this paper is corrected here.) The experimental work was performed on a square beam, impacted by a steel sphere. Measurements are reported both for the strain propagation in the beam and also for the history of forces acting between the ball and beam. The results of the comparison show excellent agreement between the observed and predicted strain propagation, so long as the beam behaves essentially in bending. It is pointed out in the discussion, however, that many impacted beams do not perform essentially in bending, so that the present work does not apply. A small-amplitude high-frequency strain component, not properly predicted by the theory, is also encountered in the experimental data.
Experimental and Theoretical Study of Transverse Vibration of a Tube Containing Flowing Fluid
Authors: Long R. H. 
Published: June 2021

Abstract
The free transverse vibrations for the fundamental mode of a single-span tube containing a flowing fluid are investigated analytically and experimentally. An approximate solution of the differential equation of motion is made with an infinite power series. Care must be taken in evaluating the large-order determinant that appears so that erroneous results may be prevented. The solution indicates a slight decrease in frequency and no decaying vibration with an increase in flow rate that can be attributed to the flowing fluid for simply supported, fixed, and fixed-simple ends. For fixed-free ends a decaying vibration due to the flowing fluid is indicated and a slight frequency decrease. The experimental results agree reasonably well with these solutions, although the frequency decrease is within the experimental error. The theory neglects internal damping of the tube and “support” damping. The latter appears significant in magnitude and is evaluated for the constructions used. This paper shows the reason for the incorrect conclusions of previous paper and gives experimental results that tend to verify the analytical results presented here and those in another previous paper by a different procedure.
A Refinement of the Theory of Buckling of Rings Under Uniform Pressure
Authors: Boresi A. P. 
Published: June 2021

Abstract
A general variational theory of elastic stability that was originated by E. Trefftz (1) is applied to the problem of buckling of rings of rectangular cross section subjected to uniform external pressure. The theory is believed to be more rigorous than previous treatments of the problem, since it avoids conventional assumptions of curved-beam theory, such as the assumptions that plane sections remain plane and that radial stresses vanish. The classical result of Levy (2) is confirmed for a ring of infinitesimal thickness. New results are obtained which show the effect of the finite thickness of a ring on the coefficients in the buckling formula.
Cylindrical Shells: Energy, Equilibrium, Addenda, and Erratum
Authors: Kennard E. H. 
Published: June 2021

Abstract
The strain energy in a homogeneous cylindrical shell of uniform thickness is calculated from equations obtained by Epstein’s method. The indeterminateness of the equations of equilibrium is further discussed and simplified forms of these equations and of the expressions for the stress resultants are given. Addenda and an erratum to a prior paper are included.
Momentum and Mass Transfer in a Submerged Water Jet
Authors: Forstall Walton , Gaylord E. W. 
Published: June 2021

Abstract
For a round water jet issuing into stationary water, momentum and material diffusion were measured, the latter by means of a sodium chloride tracer technique. It was found that (a) the behavior of the water jet was the same as that found by others for an air jet issuing into air, and hence constants obtained from measurements in air can be applied to water; (b) the turbulent Schmidt number for water is approximately the same as the turbulent Schmidt number for air and about equal to the turbulent Prandtl number for air jets; and (c) the error curve serves as a useful and satisfactory representation of diffusion profiles for water just as it does for air.
Application of Saint Venant’s Principle in Dynamical Problems
Authors: Boley B. A. 
Published: June 2021

Abstract
The propagation of stresses in bars under time-dependent self-equilibrating end loads is discussed by means of a simple model. It is found that high stresses are restricted to a short region near the end of the bar if the loads are applied comparatively slowly, but extend to longer portions if the loads are rapidly applied.
A Kinematic Notation for Lower-Pair Mechanisms Based on Matrices
Authors: Denavit J. , Hartenberg R. S. 
Published: June 2021

Abstract
A symbolic notation devised by Reuleaux to describe mechanisms did not recognize the necessary number of variables needed for complete description. A reconsideration of the problem leads to a symbolic notation which permits the complete description of the kinematic properties of all lower-pair mechanisms by means of equations. The symbolic notation also yields a method for studying lower-pair mechanisms by means of matrix algebra; two examples of application to space mechanisms are given.
On the Nonlinear Differential Equation for Beam Deflection:
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dx
2
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2
Authors: Scott E. J. , Carver D. R. 
Published: June 2021

Abstract
A general solution of the nonlinear beam equation is given for all problems in which the moment can be expressed as a function of the independent variable alone.
Inertia Forces in Lubricating Films
Authors: Brand R. S. 
Published: June 2021

Abstract
The usual theory of hydrodynamic lubrication is based on the assumption that the inertia forces in the equations of motion are negligible compared to the viscous forces. This paper shows that if the Reynolds number ρRω/μ is of the same order as R/h, then the inertia forces will be of the same order as the viscous forces.
The Analysis of Dynamic Stresses in Aircraft Structures During Landing as Nonstationary Random Processes
Authors: Fung Y. C. 
Published: June 2021

Abstract
The basic fact is recognized that throughout the service life of an airplane there occurs a variety of landing conditions and, consequently, it is subjected to transient dynamic loads of varied time histories. Accordingly, a statistical analysis is proposed. The landing-gear impact load is regarded as a nonstationary random process. In this paper the ensemble means and the correlation functions of landing impacts are defined and their experimental determination from flight or drop tests is illustrated. From these the mean response (displacement, bending moment, shear, or stress), the root mean square deviation from the mean, and higher statistical moments are computed. The results are used to find the most probable maximum stress (at any point in the structure) attained in a given number of landings, or the most probable total number of landings a given aircraft can withstand. A stress envelope can be derived which represents the distribution of the severest stress in the structure for a large number of landings. A design based on such an envelope, statistically, will have a uniform factor of safety over the entire aircraft with respect to landings.
Steady-State Behavior of Systems Provided With Nonlinear Dynamic Vibration Absorbers
Authors: Arnold F. R. 
Published: June 2021

Abstract
The response of vibrating systems subjected to sinusoidal excitations and to the action of nonlinear dynamic vibration absorbers is determined by means of a simple procedure. Extensive information including that from more complicated methods of analysis is obtainable. System behavior is described by means of “response diagrams,” and certain peculiarities are discussed.
A Study of the Stability of Plane Fluid Sheets
Authors: Hagerty W. W. , Shea J. F. 
Published: June 2021

Abstract
In studying the performance of a system for producing sprays of any kind it would be desirable to arrive at an expression which would relate the drop-size distribution and the spatial distribution of the drops in terms of the variables of the system including pressure, density, surface tension, and geometry. In an earlier study of the performance of hollow-cone swirl-type nozzles, photographs were taken of the region where the fluid sheet breaks up into drops. These photographs showed that before the break-up occurred, waves or ripples appeared on the surface of the liquid sheet. It was believed that the waves were responsible for the break-up and that frequency and wave length of the ripples might be related to the size range of drops produced. Difficulties were encountered in an analytical treatment of the stability of the surface produced by a swirl-type nozzle, the surface being a hyperboloid of revolution. Therefore a system was selected for study in which a flat sheet of fluid is produced by a slender orifice, and which may be subjected to waves of any desired frequency. This plane sheet, exposed on both sides, appears to have the essential characteristics of the sheet produced by a conventional nozzle.
Nonlinear Dynamic Coupling in a Beam Vibration
Authors: McDonald P. H. 
Published: June 2021

Abstract
This investigation treats the vibration of a uniform beam with hinged ends which are restrained, and which has arbitrary initial conditions of motion. A representative example is discussed in which the beam is subjected to a concentrated lateral force at the mid-point of its span and released from rest at the deflected position. The equations of motion are found to be inherently nonlinear, even for small vibrations, and there is dynamic coupling of the modes. It is found that the frequencies of the various modes are functionally related to the initial conditions, particularly the amplitudes of all the modes.
A Matrix Solution for the Vibration Modes of Nonuniform Disks
Authors: Ehrich F. F. 
Published: June 2021

Abstract
An arbitrary disk is represented by a simulated disk composed of circumferential strips. Alternate strips are considered to be massless, constant-thickness elements with the average local elastic properties of the actual disk. Intermediate strips are considered to have the properties of local mass and polar moment of inertia, but to have no physical dimensions or elasticity. A matrix vector, formed of the local antinodal value of deflection, slope, moment, and transverse force, may be operated on by matrices representative of the elastic strips and by matrices representative of the vibratory inertia loading, centrifugal inertia loading, internal stress, and external supports at the mass strips. Thus the influence of boundary conditions at the outer edge on conditions at the inner edge may be calculated in a simple efficient manner. Successive guesses of vibration frequency lead to final satisfaction of all boundary conditions. Concise treatment of all types of boundary conditions and numerical values of required matrices are given in tables. The results of a sample calculation are compared with exact analytic results.
Studies in Dynamic Photoelasticity
Authors: Frocht M. M. , Flynn P. D. 
Published: June 2021

Abstract
Equipment and techniques are described for obtaining dynamic photoelastic stress patterns from arbitrary lines in plane-stress systems by means of streak photography. Streak-type stress patterns of such lines were obtained which provide continuous records throughout the entire period of impact (of the order of milliseconds) at times of exposure of 2/3 microsec. This is thirty times faster than the time of exposure (20 microseconds) obtained by Tuzi and Nisida in 1935. Dynamic photoelastic stress patterns showing stress-wave propagation are given for a bar struck axially by a rigid mass, and these patterns show that a uniform state of stress was obtained. Theoretical stress patterns based on the Boussinesq solution are in essential agreement with the experimental results.
Pretwisted Beams and Columns
Authors: Zickel John 
Published: June 2021

Abstract
A theory is developed for the behavior of pretwisted structural members of thin-walled section with slight initial bending. The stresses are at first determined along and perpendicular to the fibers and are then transformed to stresses in the cross section and along the axis. Although the development is perfectly general the integrations are only indicated for doubly symmetric sections. The buckling of doubly symmetric columns which are initially straight but are pretwisted at a constant rate is treated in detail. The results show that columns of decidedly unequal principal moments of inertia can be strengthened up to 90 per cent, but columns of equal moments of inertia are weakened by initial twist. In analogy to the Euler load of the buckling theory for straight, untwisted columns, a reduced Euler load is defined. The buckling load is the product of this reduced Euler load and a stiffening factor.
A Study of Axisymmetric Vibrations of Cylindrical Shells as Affected by Rotatory Inertia and Transverse Shear
Authors: Lin T. C. , Morgan G. W. 
Published: June 2021

Abstract
An analysis is presented of the problem of the propagation of axisymmetric waves in an elastic circular tube. The theory includes the effects of rotatory inertia and transverse shear in the same manner as does Timoshenko’s theory of the vibrations of bars. These effects are of importance for waves at high frequencies; they tend to decrease the velocity of propagation and introduce an additional mode due to shear.
A Suction Device Using Air Under Pressure
Authors: Welanetz L. F. 
Published: June 2021

Abstract
An analysis is made of the suction holding power of a device in which a fluid flows radially outward from a central hole between two parallel circular plates. The holding power and the fluid flow rate are determined as functions of the plate separation. The effect of changing the proportions of the device is investigated. Experiments were made to check the analysis.
Some Dynamic Properties of Oil-Film Journal Bearings With Reference to the Unbalance Vibration of Rotors
Authors: Hagg A. C. , Sankey G. O. 
Published: June 2021

Abstract
Some dynamic properties of oil films have been determined experimentally and their significance in the problem of unbalance vibration and critical speeds of rotor systems is illustrated by an example. It is shown that oil films have an important role in the imbalance-vibration behavior of rotor systems, particularly the vibration magnification at resonance.
A Study of Orthogonally Stiffened Plates
Authors: Hoppmann W. H. , Huffington N. J. , Magness L. S. 
Published: June 2021

Abstract
A previous theory and method for the analysis of orthogonally stiffened plates (1) has been extended to include additional study of theoretical and experimentally determined frequencies of vibration and strain distributions. Some details of calculations based on the theory as well as experimental results are provided in curves and tables. Sufficient verification of the theory is obtained to warrant serious consideration of possible use of the method for design purposes.
Effects of Boundary Conditions and Initial Out-of-Roundness on the Strength of Thin-Walled Cylinders Subject to External Hydrostatic Pressure
Authors: Galletly G. D. , Bart R. 
Published: June 2021

Abstract
Using classical small-deflection theory, an investigation was made of the effects of boundary conditions and initial out-of-roundness on the strength of cylinders subject to external hydrostatic pressure. The equations developed in this paper for initially out-of-round cylinders with clamped ends, and a slightly modified form of the equations previously derived by Bodner and Berks for simply supported ends, were applied to some actual test results obtained from nine steel cylinders which had been subjected to external hydrostatic pressure. Three semiempirical methods for determining the initial out-of-roundness of the cylinders also were investigated and these are described in the paper. The investigation indicates that if the initial out-of-roundness is determined in a manner similar to that suggested by Holt then the correlation between the experimental and theoretical results is quite good. The investigation also indicates that while the difference in collapse pressures for clamped-end and simply supported perfect cylinders may be quite considerable, this does not appear to be the case when initial out-of-roundnesses of a practical magnitude are considered.
On the Determination of a Viscoelastic Model for Stress Analysis of Plastics
Authors: Bland D. R. , Lee E. H. 
Published: June 2021

Abstract
A method of assessing whether or not the measured variation of complex compliance with frequency for a viscoelastic material is consistent with a four-element model is presented. The four-element model was chosen since it is relatively simple to analyze, and exhibits the three main types of viscoelastic response; namely, instantaneous elasticity, viscous flow, and delayed elasticity. If the compliance measurements are found to conform with the behavior of a four-element model over the whole or part of the frequency range studied, a graphical method of determining the model constants is presented. The significance of the application of such a model to stress analysis under transient loading is discussed.
Deflection of a Beam Referred to Any Set of Rectangular Centroidal Axes
Authors: Levy J. C. 
Published: June 2021

Abstract
An expression is developed for the deflection of a straight beam subjected to unsymmetrical bending which eliminates the necessity of first finding the principal axes and principal moments of inertia of the section. Since it is already possible to calculate the position of the neutral axis and also the stress distribution without referring to principal axes, the present work offers one method of completing such a solution for the class of problems where deflections besides stresses are required.
Effect of Imperfections on Buckling of Thin Cylinders Under External Pressure
Authors: Donnell L. H. 
Published: June 2021

Abstract
The buckling of thin cylinders under external pressure is studied by finite-deflection theory, assuming the same type of imperfections as had been assumed in a previous study of buckling under axial compression (3). Unlike the axial compression case only a small elastic postbuckling reduction in resistance is found, and this only for long cylinders. However, if reasonable imperfections are assumed, failure loads initiated by yielding are found to be of the same order as those indicated by experiments.
A Calculation Method of Surface Wear of Plastic Line Gear Pair Under Dry Friction Conditions
Authors: Lin Yifan , Chen Yangzhi , Ye Changkun , Lyu Yueling 
Published: June 2021

Abstract
Parallel line gear pair (PLGP) can achieve pure rolling meshing along its theoretical contact curves under the ideal condition. However, the actual meshing positions may deviate from the theoretical ones under the actual operating conditions, which may result in the alternation of contact pressure distribution and cause relative sliding of the meshing surfaces. Contact pressure and relative sliding are two main factors causing surface wear. A calculation method of surface wear of plastic line gear (LG) pair under dry friction conditions was studied theoretically and experimentally, taking a polyoxymethylene (POM) PLGP as an example. Based on the geometric model of PLGP considering the misalignments under the actual operating conditions, this method employs the three-element model and influence coefficient method to compute the contact pressure with the consideration of the viscoelasticity of the gear material. Archard’s wear equation is applied to calculate the surface wear depth. Results of the wear experiment of the POM PLGP specimens validated the feasibility of the calculation method. This study provides a necessary basis for the engineering application of plastic LG pairs.