bluuebunny/crossref_metadata_2025_split huggingface dataset:
Anisotropy and the Bauschinger Effect in Cold Rolled Aluminium
Authors: Svensson N. L. 
Published: February 2007

The paper deals with a study of the development of anisotropy and the Bauschinger effect in cold rolled aluminium. In the first instance, the development of a yield criterion considering both of these phenomena is discussed. By following a recent development by Yoshimura, a criterion involving only two parameters, one for anisotropy and the other for the Bauschinger effect, is developed. Considering the simple homogeneous rolling deformation model of Orowan, the yield criterion is applied to the case where cold rolled metal is subsequently tested in tension and compression at various orientations. Experimental procedures are described and the method of correlating the experimental results with the yield criterion is discussed. As a result of the analysis of the experimental results, it may be concluded that the yield criterion provides satisfactory correlation with experiment. The anisotropy parameter and a Bauschinger modulus are then specified in terms of rolling strain and the order of their magnitude considered. The last part of the paper is concerned with a discussion of additional factors which have a bearing on the results obtained. In the first place, the question of inhomogeneous deformation is considered. One of the consequences, the development of residual stresses, is shown to have little effect. However, additional evidence shows that the mode of deformation exerts a considerable influence on the Bauschinger modulus. It is concluded that anisotropy is probably not greatly influenced by the details of deformation, but the manifestation of the Bauschinger effect certainly is.
Effect of Sudden Changes in Flow Area on Pressure Waves of Finite Amplitude
Authors: Trengrouse G. H. , Soliman M. M. 
Published: February 2007

Previous investigations of the flow of gases through sudden area changes in pipes are briefly reviewed, both unsteady and steady flow conditions being considered. The present paper concerns the effects of such area changes on single pressure waves of finite amplitude, and covers incident wave amplitudes greatly in excess of those previously investigated. Theoretically, the flow at the area change is assumed to be quasi-steady and one-dimensional, and two alternative treatments are presented. These are based respectively on reversible adiabatic (isentropic) and, more accurately, irreversible adiabatic conditions. Experiments using a simple shock tube confirm the validity of the more accurate theoretical treatment over the range of area and incident pressure ratios considered, namely, 8.1 and 2.4 respectively. The theoretical treatment based on the assumption of isentropic flow at the section change, however, is inadequate in some respects. Discrepancies between theory and experiment are observed when considering, firstly, the reflected wave at an enlargement and, secondly, the transmitted wave at a contraction. Steady flow experiments in which the discharge coefficient for flow through a sudden contraction is measured are also described, this coefficient being required in the theoretical analysis.
Isoviscous Lubrication of Rigid Cylinders: A Modification to Classical Theory
Authors: Boness R. J. 
Published: February 2007

Measurements of oil film thickness between lightly loaded lubricated discs show that the original theory of Martin over-estimates the film thickness by between 100 and 800 per cent, depending on the ratio of the difference of the surface velocities and their sum. Theoretical results indicate that the upstream boundary condition could account for the discrepancy between the experimental results and the Martin theory. A procedure for the calculation of load-carrying capacity of lightly loaded cylinders based upon new upstream velocity and velocity gradient boundary conditions suggested by Lauder is presented.
Expanding of Boiler Tubes into a Tube Nest
Authors: Culver L. E. 
Published: February 2007

This paper describes a series of tests in which tubes have been rolled into tube nests under carefully controlled conditions using the test rig previously developed for a general investigation of the tube expanding process. The tube spacing used corresponds closely to the minimum reported in industry. It is shown that considerable interference of the plastic zones associated with the joints can occur in the ligaments between the tube holes and the strains developed in the plate are larger than for a single-tube expanding. Nevertheless, the expanding of subsequent tubes tended to relax the strain around previously rolled joints and these joints had a low strength. The strengths of all the joints in a nest were lower than that of a tube rolled, to the same degree of expanding, into a single-hole plate owing to the interaction of the plastic zones or to the greater flexibility of the tube nest plate. There appears to be an optimum degree of expanding in a tube nest which corresponds closely to that obtained for single-tube expandings. The results found from these tests depend upon the geometry of the tube nest and the manner in which the joints are rolled.
The Oscillogyro
Authors: Whalley R. , Holgate M. J. , Maunder L. 
Published: February 2007

Part I of this paper describes, in a non-mathematical way, a new type of gyroscope suitable for stabilizing an inertial navigation platform. The instrument is shown to belong to a general family of free rotor gyroscopes and the advantages of this configuration are discussed. The construction of a practical instrument is briefly described. Part II of this paper contains a brief analysis of the oscillogyro. Its general equation of motion is derived and from it particular solutions are obtained which describe the response to steady rates of turn and to certain applied torques. It is shown that the instrument can be used to measure either the rate of turn or the total angular displacement, depending on the tuning and damping conditions. In either mode of operation the oscillogyro responds to angular inputs about any axis in a plane perpendicular to its drive-axis and may thus be classed as a two-axis instrument. The response to control torques may take a variety of forms, depending on the nature of the torque as well as on the damping and tuning conditions. It is shown that the motion can be deduced from the known results for angular inputs if the torque is harmonic and is applied about the spring-axis of the oscillobar.
Contact Fatigue in Hard Steel Specimens with Point and line Contacts
Authors: Dawson P. H. 
Published: February 2007

Kennedy and others have repeatedly loaded steel spheres together and produced ring cracks due to the radial tensile stress that exists at the edge of the contact zone. Merritt has pointed out that no such tensile stress exists in line contact. Tests similar to those of Kennedy have now been carried out both in line and point contacts. Both produced cracks. The cracks in line contact have been explained by residual tensile strains which develop near the edges of the contact zone when the elastic limit has been exceeded. A number of interesting features which appeared in the tests both with line and point contacts are noted.
Creep Deformation of a Composite Beam Subjected to Combined Axial and Bending Loads
Authors: Ellison E. G. , Webster G. A. 
Published: February 2007

The theoretical analysis presented here considers the general case of the creep deformation of a composite beam subjected to combined axial and bending loads. The beam may be considered to consist of two components bonded together or of numerous continuous fibres discretely dispersed in a matrix. The equations may also be reduced to the particular case of a beam composed of just one material so that present day problems involving combined loads may be analysed. Though elastic analyses have shown the advantages of a composite beam, it was noted that improvements in strength are further accentuated under creep loading conditions since the deformation is then generally more stress sensitive. For a composite member, it was found that even small percentages of reinforcing material substantially reduced the axial strain, curvature and stresses. Under the action of a bending moment, the composite was even more efficient when the reinforcement was incorporated in the outermost fibres of the beam. The effects of thermal strains were noted especially in the primary creep stages and their importance under possible load and/or temperature cycling conditions discussed. Although an iterative procedure, involving the use of a computer, is required to solve the analytical equations, it is shown that values for the strain and curvature may be approximately determined by use of the rule of mixtures approach.
Iterative Procedures for Elastic, Plastic and Creep Deformation of Beams
Authors: Webster G. A. , Ellison E. G. 
Published: February 2007

Since an analytical solution is not often possible, the determination of deformations in parts subjected to elastic, plastic, thermal and creep strains generally must be obtained by an iterative procedure which requires the aid of a computer. A number of iterative procedures can be used. In view of the fact that the particular procedure adopted may determine whether or not an answer is obtained, some practical methods of solution and their limitations are discussed in detail. The example chosen as a basis for comparison of the various methods is a composite beam subjected to combined bending and axial loads, since this case is reasonably general in that all the strains mentioned above must be considered. Essentially the problem is one of preventing divergence during the solution procedure while at the same time achieving convergence in a reasonable number of iterations. No one method was found that would achieve convergence in all instances. However, a systematic procedure, involving three main methods, termed the strain-bound, Taylor expansion, and averaging methods, is described which enhances the chances of attaining convergence.
Study of the Effects of Rotor Bearing Clearance on the Whirling of a Gimbal-Mounted Gyroscope
Authors: Fawcett J. N. , McCallion H. 
Published: February 2007

It has been observed that under certain conditions a gimbal-mounted gyroscope will assume a whirl of increasing amplitude upon the application of an impulsive force, the rate of increase of amplitude depending upon the gimbal inertia and the type and condition of the rotor bearings. This paper describes experimental and theoretical work carried out to investigate the effects of varying the gimbal inertia and bearing clearance upon the motion of the rotor shaft within its bearings during whirling, and upon the stability of the system. The investigation has been limited to systems in which the rotor shaft runs in ball races as most gimbal-mounted gyroscopes are of this type. The design of a suitable experimental rig to represent the simplest possible system is discussed and a description of the rig used is given. Theory, based on the experimentally observed behaviour of the rotor shaft within the bearing is given. The effects of varying the bearing clearance thus predicted are shown to have similar trends to the experimentally observed behaviour for the cases considered.
Measurement of Turbulent Skin Friction by a Preston Tube in the Presence of heat Transfer
Authors: Holmes W. E. , Luxton R. E. 
Published: February 2007

Experiments have indicated that Preston's surface pitot tube method for the measurement of turbulent skin friction in incompressible flows can be extended to cover flows with heat transfer. By evaluating the fluid properties at Eckert's intermediate temperature the resulting calibration formula corresponds with that obtained by Preston for the zero heat transfer case. It is shown that the calibration formula for the Preston tube is relatively insensitive to the temperature at which fluid properties are evaluated. Because of this the choice of a reference temperature is not critical and for flows involving moderate heat transfer the isothermal calibration of the Preston tube may be used if fluid properties are evaluated at wall temperature.
Effect of Static Deflection on the Natural Frequency of a System with a Hardening Non-Linear Spring
Authors: Reif Z. F. 
Published: February 2007

The effect of the static deflection on the natural frequency response is investigated for a single-degree-of-freedom system with a positive cubic non-linearity in the restoring force. The Ritz averaging method is used for the theoretical analysis, and by comparison with analogue computer solutions the first approximation, consisting of two terms, is shown to be satisfactory for most applications. Results indicate that in systems with a non-linear restoring force the existence of a static deflection produces significant effects and cannot be neglected in a theorectical analysis.
Some Calculations to Assess the Effect of the Stress-Strain rate Relationship on Creep in the Neighbourhood of An Opening in a Pressurized thin Spherical Shell
Authors: Calladine C. R. 
Published: February 2007

Calculations were performed on a pressurized thin spherical shell with a sealed opening for material obeying a simple r-power steady creep law; they were done by an iterative procedure on an IBM 7090 computer. The results, in terms of stress resultant distributions and deformation patterns in the neighbourhood of the opening for different edge load boundary conditions, were examined critically with a view to detecting simple overall patterns of behaviour which are a function of the creep index r. Examination of the results from two different points of view leads to the conclusions that stress concentration factors vary smoothly and almost linearly with 1/ r and that deformation patterns are practically independent of r, for the same edge load boundary conditions. The strain rate concentration factors may be very high. The consequences of these conclusions are examined in the context of the design process.
Method of force Defect Coefficients Applied to An Asymmetric Two-Dimensional Orifice
Authors: Begg R. D. 
Published: February 2007

The method of force defect coefficients was developed by Jobson and improved by Bragg to calculate compressible discharge coefficients for axisymmetric orifices from the more easily computed or measured incompressible values. This method has been adapted to deal with two-dimensional flow, and the analysis for a particular case, that of compressible jet flow emerging from an asymmetric straight-sided orifice, has been completed. Predictions of jet angle and thickness have been calculated for a range of orifices, and these are shown to compare well with experimental measurements.
Testing of Materials at Medium rates of Strain
Authors: Cooper R. H. , Campbell J. D. 
Published: February 2007

The problems involved in the measurement of the mechanical properties of rate-dependent materials are discussed, with special reference to the role of the elastic stiffness of the testing machine and specimen. A description is given of a newly developed universal testing machine, operated by hydraulic pressure and capable of testing at crosshead velocities up to about 40 in/s. The machine has been used in two ways: for tensile tests at approximately constant strain rates in the range 10-1 to 10-2 s-1; and for compression tests in which a load is applied in a few milliseconds and maintained at a nearly constant value while the specimen is plastically deformed. The machine is instrumented so that the applied load and cross-head velocity are recorded throughout the test. The testing technique and the accuracy of measurement are discussed with reference to experimental results obtained in tests on annealed copper, mild steel, silicon-iron, and a high-strength aluminium alloy.
Natural Frequencies of Plate Systems using the Edge Effect Method
Authors: Dickinson S. M. , Warburton G. B. 
Published: February 2007

In this paper the Bolotin edge effect method is used to consider the free flexural vibrations of systems built up from rectangular plates. The constituent plates of the systems are considered either to lie in the same plane and form part of a plate continuous over line supports or to lie in planes at right angles to each other, as in box constructions. The application of the edge effect method to single-and multi-plate systems is described and the approximate frequency equations for two two-plate systems are given. The first 10 natural frequency parameters for these two systems for particular side ratios are compared with those obtained using a series solution and agreement is shown to be good. A few frequency parameters for a closed box computed using the edge effect method and the series solution are also compared. The range of plate systems to which the edge effect method may be applied with complete success and the range to which it may be applied with only partial success are indicated. The sources of errors in the edge effect solutions are indicated.
Lateral Vibration of a Pipe Conveying a Fluid
Authors: Naguleswaran S. , Williams C. J. H. 
Published: February 2007

The lateral vibration of a pipe conveying a fluid is investigated theoretically and experimentally. An exact solution for the natural frequency, axial distribution of phase and modal envelope is computed for a pinned-pinned, fixed-fixed and pinned-fixed span. Approximate one and two term Galerkin, Rayleigh-Ritz and Fourier series solutions are obtained and compared with the exact solution. It is found that a two term Galerkin or Rayleigh-Ritz solution is simple to evaluate and provides a good estimate of frequency and phase. The influence of axial tension and internal pressure is included. The experimental results are in agreement with theory at low flow speeds but show the difficulty of accurate buckling flow speed prediction.
Two-Phase Critical Flow through Suction Slots in Low Pressure Steam Turbine Blades
Authors: Ryley D. J , Parker G. J. 
Published: February 2007

As part of an investigation to study the removal of water from the trailing edge of a low pressure steam turbine fixed blade by suction slots, experiments were made on a perspex test section in which a 1-in wide section of the suction slot was simulated. The flow characteristics are considered of the passage in the choked condition and a comparison is made with some two-phase critical flow theories. The theories are briefly presented and discussed, and the relevant formulae given. It is found that the homogeneous-equilibrium model grossly underestimates the discharge rates whilst all of the other flow models overestimate by at least 30 per cent.
Coupled Bending-Bending Vibrations of Pre-Twisted Cantilever Blading Treated by the Rayleigh-Ritz Energy Method
Authors: Dawson B. 
Published: February 2007

The Rayleigh-Ritz method is used to determine the natural frequencies and mode shapes of vibration of pre-twisted rectangular cross-section beams. The method is dependent upon a good choice of approximating functions for the dynamic deflection curves. In the present analysis, series of the characteristic functions representing the normal modes of vibration are taken as the approximating functions for the bending displacements in the directions of the co-ordinate axes. The choice of this particular series leads to a considerable reduction in the number of elements in the final matrix equation and also considerably reduces the computing time. The natural frequencies of vibration are obtained for various width-to-thickness ratio beams with pre-twist angle in the range 0-90°, and the mode shapes of vibration are presented for one particular width to thickness ratio beam. The results are compared to results obtained by other methods and to experimental results, and good agreement is shown to exist.
Film Cooling Slots: The Importance of Lip Thickness and Injection Angle
Authors: Sivasegaram S. , Whitelaw J. H. 
Published: February 2007

Measurements of adiabatic-wall effectiveness in a two-dimensional, constant-property flow are reported for a slot of fixed height but with two different slot-lip thicknesses. The results confirm the trends exhibited by earlier measurements of the impervious-wall effectiveness which showed that the ratio of slot-lip thickness to slot height, t/yc, is an important parameter in determining the effectiveness of film cooling. The effectiveness is shown to decrease significantly as t/yc is increased beyond a value of 0·25; for lower values, the influence is dependent upon the ratio of slot to free-stream velocities. The influence of the injection angle has also been investigated and measurements of the adiabatic-wall effectiveness are reported for angles of 30, 60 and 90 to the direction of the free-stream. These measurements agree qualitatively with the measurements of Papell but show quantitative differences.
Flow Disturbances Due to Blade Thickness in Turbomachines
Authors: Lewis R. I. , Horlock J. H. 
Published: February 2007

Variations of blade thickness from hub to casing of a turbomachine, which impose a non-uniform blockage upon the meridional flow, often give rise to significant perturbations. In the first part of this paper this effect is simulated by considering the circumferential average of the source distributions required to represent the blade profiles. In the second part the equations of fluid motion are first averaged across the blade passage and the resulting equations solved for the averaged properties. Similarity between the differential equations obtained in these two ways is noted. A number of analytical examples are discussed and a simple experimental result is reported.
Presentation of Elastohydrodynamic Film-Thickness Results
Authors: Greenwood J. A. 
Published: February 2007

Yet another set of dimensionless variables is offered. These have the advantage of the Blok groups, that all results can be plotted on a single graph, but in addition one group is of secondary importance, so that all results lie in a narrow band. Thus, film thickness is shown to depend primarily on a single parameter. It is deduced that the extrapolated rigid cylinder theories give a very good estimate of the film thickness under elastohydrodynamic conditions.
Noise and Flow Characteristics of Coaxial Jets
Authors: Williams T. J. , Ali M. R. M. H. , Anderson J. S. 
Published: February 2007

The noise from cold subsonic coaxial jets issuing from concentric nozzles with external mixing has been examined and an attempt made to relate the results to the flow patterns of the jets. As the velocity of the annular jet was increased in relation to a given central jet velocity, an initial attenuation of the jet noise was observed. On further increasing the annular jet velocity until the velocities of the two streams were nearly equal, the noise was in excess of that of the central jet alone. An attempt has been made to predict the curve relating the attenuation attained to the coaxial jet velocity. In comparing the attenuation produced by a coaxial jet combination with that of a single jet, it could be argued that the total thrust in each case should be the same and experimental results are presented on this basis. Results are also available for a nozzle configuration in which the jets are mixed internally in a tube before discharge, and the paper is completed with the results obtained from an annular nozzle acting alone.
Detailed Analysis of a Two-Stage Four-Way Electrohydraulic Flow-Control Valve
Authors: Nikiforuk P. N. , Ukrainetz P. R. , Tsai S. C. 
Published: February 2007

A detailed analysis is given of a flow-compensated, two-stage, four-way, closed-ports electrohydraulic flow-control valve. Factors considered in the analysis of the first stage include: the electromagnetic forces generated by the torque motor, impedance of the motor coil, inertia of the flapper, viscous damping forces, spring forces, pressure feedback forces, and leakage flow. Factors considered in the analysis of the second stage include the acceleration force on the spool, viscous friction forces, restraining spring forces, flow reaction forces, leakage flow, and the compressibility of the oil. Experimental verification of the analytical work is included.