bluuebunny/crossref_metadata_2025 huggingface dataset:
Creep of Metallic Thick-Walled Cylindrical Vessels Subject to Internal and External Pressure and Torque at Elevated Temperatures
Authors: Johnson A. E. , Khan B.
Published: February 2007

A theoretical analysis has been made of the distribution of stress and strain in metallic thick-walled cylindrical pressure vessels, subject to internal and external pressure., and also to a torque, at elevated temperatures.

The analysis deals with the general case where creep strains and elastic strains occurring as a result of the applied pressure and torque are both of significant order. Some practical figures are given.
Shear Plane Theories of Hot and Cold Flat Rolling
Authors: Green J. W. , Sparling L. G. M. , Wallace J. F.
Published: February 2007

The shear plane theory of hot rolling of thick stock, due to Green and Wallace, is extended to hot and cold flat rolling. Values calculated from the hot rolling theory compared satisfactorily with the theory of Sims and the experimental results of Wallquist. The cold rolling theory is similarly satisfactory in comparison with the experimental results of Ford and it is anticipated that the theory will be more accurate than that of Bland and Ford for small R/h ratios and large reductions.

Examples of calculation of load and torque for rolling are given in Appendixes for both Coulomb friction and sticking and shearing at the metal surface and it is shown that both conditions may occur and be taken into account concurrently. A method of determining the total torque is given which is derived from an upper bound to the work done on shear planes which are shown to have the same configuration as that chosen in the analysis of forces.
Use of Upper Bound Solutions for Predicting the Pressure for the Plane Strain Extrusion of Materials
Authors: Halling J. , Mitchell L. A.
Published: February 2007

An upper bound solution, based on a kinematically admissible velocity field, is proposed for plane-strain symmetrical extrusion through wedge-shaped dies. The pattern chosen consists of a double-triangle arrangement of velocity discontinuities and the solution was optimized using a digital computer programme. Analysis of the results for a full range of die angles, reductions and frictional conditions provides useful predictions relating to the formation of dead zones. Such an analysis is given in detail for a 90° die. The results obtained compare favourably with the predictions of analytical slip-line field solutions in the regions where such solutions are available.

The solution is also extended to accommodate the strain-hardening characteristics of the material. These results show that the alternative mean strain hypothesis is prone to errors in the presence of friction. This solution also yields an indication of the nature of the hardness distribution across the extruded product with particular reference to the effects of die geometry and reduction in area.
Effects of Temperature Rise on the Flow of a Viscous Liquid through a Concentric Annulus with an Inner Cylinder Rotating
Authors: Newbery L. A.
Published: February 2007

An exact solution is presented for the forced flow of a viscous liquid through a concentric annulus in which the fluid temperature is increased and the viscosity decreased by rotation of the inner boundary. Such a solution has not previously appeared in the published literature.

Some practical applications are mentioned.
Heat Transfer in a Supersonic Parallel Diffuser
Authors: Baker P. J.
Published: February 2007

This paper presents the results of heat transfer measurements taken on a two-dimensional supersonic parallel diffuser. The wall static pressure distributions and the corresponding heat transfer coefficients and fluxes have been measured for a range of initial total pressures. The effects of varying the area of the diffuser cross-section for the same upstream generating nozzle have also been studied. Mach number profiles measured at sections along the diffuser show that in the presence of shock waves and a positive pressure gradient the flow is very much underdeveloped. In general, the mean level of heat transfer is found to be much greater than that predicted by conventional empirical equations for subsonic pipe flows with zero pressure gradient. Further, on comparison between normal and oblique shock diffusion the former is found to give the higher level of heat transfer.
Some Operating Characteristics of the Supersonic Axi-Symmetric Parallel Diffuser
Authors: Baker P. J. , Martin B. W.
Published: February 2007

This paper extends the investigation of the supersonic parallel diffuser previously reported by Martin and Baker (I)‡ and Baker (2) to cover the case of the axi-symmetric cross-section. The flow patterns and the wall static pressure distributions appear broadly to correspond to those which occur in the parallel diffuser of rectangular cross-section. But the axi-symmetric diffuser is found to have a wider operating range (in terms of overall blowing pressure ratio) before the single shock gives way to an oblique shock system, and this permits higher optimum recovery of static pressure. In the axi-symmetric configuration, only very short lengths of duct are necessary to achieve full static pressure recovery in both the single shock and the oblique shock regimes. The use of short diffusers would lessen the cooling problems of large-scale jet engine test facilities, in which exhaust jets must be recompressed at elevated temperatures.
A Finite Element Approach to Plate Vibration Problems
Authors: Dawe D. J.
Published: February 2007

A method of computing the natural frequencies of vibration of flat plates of arbitrary shape is outlined in which the plate is considered as an assemblage of elements.

Both stiffness and inertia matrices are derived for a rectangular isotropic plate element of uniform thickness, and these matrices are used to find the natural frequencies of square plates subject to various boundary conditions. Comparison of finite element frequencies with known exact, experimental and energy solutions shows the method to give good results even for relatively few elements.
Wave Theory of Free Torsional Vibration of Composite Systems of Shafts
Authors: Beddoe B.
Published: February 2007

This paper gives a general theory of free torsional vibration of systems in which allowance is made for both elasticity and inertia of each component shaft. The governing equation of motion is the elementary wave equation in one dimension and the problem is solved by wave methods that use the concepts of reflection and transmission. Both the frequency equation and the equations of modal shape are derived in terms of defined reflection and transmission coefficients.

The theory is illustrated by two examples that include stepped shafts, rigid discs, a light elastic coupling and shafts connected by rigid gears.
Lubricating Action of Cutting Fluids
Authors: Cassin C. , Boothroyd G.
Published: February 2007

An experimental investigation into the lubricating action of carbon tetrachloride when cutting copper for a carefully selected range of controlled conditions has enabled the formulation of a fundamental specification for a cutting lubricant. In this specification, a new proposal has been made concerning the penetration of the fluid to the contact regions of the cutting tool. The penetration rate of a neat chemical compound chosen on the basis of this fundamental specification appears to behave as predicted when applied during the machining of copper.
Vibration of a Spring-Supported Body
Authors: Grootenhuis P. , Ewins D. J.
Published: February 2007

The equations of motion for a rigid body supported on four springs are derived for the general case of the centre-of-gravity being anywhere within the body and allowing for the sideways as well as the longitudinal stiffnesses of the springs. This constitutes a six-degrees-of-freedom case with three degrees of asymmetry. Coupling between motions in all directions occurs even when the centre-of-gravity is at the geometric centre with the exception then of vertical oscillations and rotation about the vertical axis. Any number of additional springs can be allowed for by adding terms to the expression for the potential energy stored in the springs. Allowance is made in the expression for kinetic energy for the products of inertia which arise with an offset centre-of-gravity.

The real case is simulated for purposes of analysis by replacing the rigid body by a rectangular box with a light framework and all the mass concentrated at the eight corners. The matrix solution is changed into dimensionless parameters and the effect of an offset centre-of-gravity upon the eigenvalues and eigenvectors studied. Only the proportions of the box and the stiffness ratio between sideways to longitudinal stiffness of the springs remain as factors. The numerical example given is for proportions of height to width to length of 3/4/5 and for a stiffness ratio of 5. Small amounts of offset of the centre-of-gravity from the geometric centre do not alter the dynamic behaviour of the system much but displacing the total mass towards either a lower or an upper corner has marked effects. Some of the natural frequencies associated with motion in rotation when the system is symmetric become less than the frequencies connected with motion in translation for the centre-of-gravity being close to a corner connected to a spring. A large region free from any natural frequency arises when the centre-of-gravity is moved towards a corner furthest removed from the plane containing the springs. The asymptotic conditions for the position of the centre-of-gravity are also considered.
Creep Rupture of Ductile Materials under Variable Load
Authors: Singer J.
Published: February 2007

Hoff derived expressions for the creep rupture time when the creep deformations are governed by the Norton-Bailey law, which yielded results in agreement with experiments for pure aluminium and some aluminium alloys. He later extended the analysis for other creep laws.

The author has extended Hoff's analysis for a constant load to a load which varies with time, the material being considered incompressible.

Several suitable examples have been considered.
Discharge Coefficients for Incompressible Non-Cavitating Flow through Long Orifices
Authors: Lichtarowicz A. , Duggins R. K. , Markland E.
Published: February 2007

The results of a number of previous investigations of the discharge characteristics of parallel-bore orifices with length/diameter ratios up to 10 and Reynolds numbers up to about 105are collected and discussed, together with new data which extend to Reynolds number as low as unity.

Simple empirical expressions, which fit the data well, are suggested for design purposes.
Thermodynamic Testing of Turbines and Pumps
Authors: Thom A. S.
Published: February 2007

Hydraulic losses experienced by fluids in passing through machines effectively raise the temperature. The thermodynamic method of testing is basically a way of determining these losses by measuring temperature rise. When pressure change through a machine is measured along with temperature, the enthalpy change is known and the hydraulic efficiency can be evaluated. Knowledge is necessary of certain thermodynamic properties of the liquid which change with pressure and temperature. Heat transfer between the machine and its surroundiings is assumed to be negligible.

Apparatus is described for use in several different applications of the method, but principally in the thermometric and null methods. Temperature change has usually been measured by resistance thermometers in various bridge networks. Three types of bridge are discussed, the direct current, the transformer ratio and the hydraulic bridge. Methods of sampling small quantities of the main flow are described for the null method; when the two thermometer pockets are in streams having different velocities, a differential recovery factor has to be applied. Calorimeter design details are given, with a brief review of tests in the U.K. and abroad.
Effect of a Change in Position of a Support on the Natural Frequencies and Modes of Vibration of a System
Authors: Mahalingam S.
Published: February 2007

The effect of a small change in position of one of the supports on the natural frequencies and modes of a structure, which is ‘continuous’ over a number of supports, is examined in this paper. Using energy and receptance methods a simple formula is obtained for the change in natural frequency of a beam when the support displacement is infinitesimal. The corresponding displacements of other nodal points are also obtained. When the support displacement is finite, but not large, changes in mode and frequency are determined by iteration. The method of solution is extended to the coupled flexural and torsional vibration of a non-symmetrical beam. In the case of a rectangular plate with stiffeners parallel to an edge, frequency changes due to the change in position of a stiffener may be determined by the same method. Alternative approximate formulae, based on the static deflection curve, are derived for the change of fundamental frequency.
A Method for Investigating the Coefficient of Friction in Tube Sinking through Conical Dies
Authors: Moore G. G. , Wallace J. F.
Published: February 2007

A theory, apparatus and experimental technique for the continuous determination of the coefficient of friction, μ, in tube sinking are briefly discussed and illustrated by some experimental results. The values of μ which have been obtained are lower than those usually accepted for evaluation of tube sinking theories. Suggestions are made for the further development of the technique.
Behaviour of a Cylindrical Shell Subject to Sinusoidal and Shock Couples
Authors: Hedges J. L. , Mills B.
Published: February 2007

The response of a thin cylindrical shell subject to sinusoidal and shock excitation is predicted using the Rayleigh theory of inextensibility. In the theoretical analysitwo separate cases are considered; in the first the loads are applied at each end of the shell while in the second the loads are applied at one end only. In each case the position of the loads is perfectly general. Experimental verification is provided for the special case of the load and support points being in the horizontal plane through a shell diameter; one end of the shell being supported while the other end is subjected to sinusoidal and shock excitation.

The correlation between the experimental and theoretical results indicated that the response of the shell could be predicted from the theory of inextensibility.
Experimental Measurement of the Effect of Heat Flux on Local Heat Transfer Coefficient and Friction Coefficient in an Annulus
Authors: Larkin B. S.
Published: February 2007

This paper describes a closed-circuit apparatus for the measurement of local heat transfer coefficients from the inner surface and overall friction coefficients for air flowing through an annulus (radius ratio 1.7). Results were obtained for Reynolds numbers from 35 000 to 170 000 for temperature ratios Ti/Tb up to 1.74. A novel type of heater bar was used in order to avoid some of the disadvantages of the more usual designs. The results were very consistent.

It was found that the effect of heat flux on the heat transfer coefficient could be eliminated either by the film temperature method using a film temperature coefficient of 0.25 or by including a temperature ratio term ( TiTb)-0.2 in the Nu-Re relationship. Over most of the Reynolds number range the overall friction coefficient did not vary with heat flux.
Strain Distributions around Cracks in Ductile Sheets during Loading and Unloading
Authors: Dixon J. R. , Strannigan J. S.
Published: February 2007

Strain distributions around fatigue cracks in different sheet metals have been obtained by using a photoelastic surface coating with a reflection polariscope. It is shown that an estimate of the distribution of the maximum shear strain, y, near the crack tip, during both loading and unloading of the sheet, requires a knowledge of only the stress-strain curve of the material and the theoretical elastic plane-stress solution.
On the Method of Displaced Frequencies in Vibration Analysis
Authors: Mahalingam S.
Published: February 2007

An analysis is made of the experimental method of displaced frequencies for the determination of the generalized masses of a freely vibrating structure. Energy and receptance methods are combined to determine the changes in frequency, mode and equivalent mass caused by the addition of one or more small masses. Special attention is given to the behaviour of a system with close or equal natural frequencies and some of the properties of a system with two equal frequencies are examined in detail.
Calculation of Velocity Distributions in Rod Clusters
Authors: Rapier A. C. , Redman J. D.
Published: February 2007

A method of calculating velocity distributions in rod cluster flow passages is described and shown to be in good agreement with experiment in two particular cases. The method is compatible with that of Deissler and Taylor and, because of its greater simplicity, is to be preferred.
On the Design of Reinforcement for Openings and Nozzles in thin Spherical Pressure Vessels
Authors: Calladine C. R.
Published: February 2007

A simple plastic design approach is made to the problem of design of reinforcement for openings in thin spherical pressure vessels. The essence of the approach is to adjust the thickness and shape of the vessel in the vicinity of the opening so that the full limit pressure of the vessel may be carried with relatively little bending action. A novel constant-thickness shallow conical reinforcing pad emerges as a design which satisfies these requirements. The design, which is easily adapted to the reinforcement of nozzles, appears to have several important advantages over conventional designs not only in the plastic range but also in the elastic range, in which stress concentration factors are low.

When the internal pressure is steadily increased, the resulting deformation does not effectively alter the ‘conical-spherical’ profile of the vessel, and the action is predominantly ‘membrane’ throughout the elastic, elastic-plastic and plastic ranges. It follows that simple plastic theory gives a good description of the plastic behaviour. This is in sharp contrast with the case of unreinforced nozzles, where plastic bending effects are superseded, as deflections become ‘large’ by membrane effects. Detail of welds, etc., must be designed by conventional procedures.
Effect of Mistuning on the Vibration of Turbo-Machine Blades Induced by Wakes
Authors: Whitehead D. S.
Published: February 2007

The report gives a theoretical investigation of the effect of blade mistuning on the vibration of the blades induced by wakes in the incident gas flow which rotate relative to the blades in question. An upper limit to the effect of mistuning is found, which shows that the amplitude on one blade may increase by a factor of roughly ½(1 + √ N), where N is the number of blades in the row.

This limit is only approached in special and unusual circumstances. In normal circumstances the amplitude will not increase by more than about 20 per cent. It is concluded that blades expected to work under forced vibration conditions should be made as nearly identical as possible. This is in contrast to the situation when flutter may occur, where the effect of mistuning is always favourable.
Response of a Cylindrical Shell to Internal Blast Loading
Authors: de Malherbe M. C. , Wing R. D. , Laderman A. J. , Oppenheim A. K.
Published: February 2007

The paper is concerned with stresses induced in a thin-walled cylinder that is exposed to internal blast loading originating from a detonation wave. The mathematical form of the pressure-time profile of the blast wave was formulated on the basis of experimental data. The stress response of the cylindrical shell to this loading was then predicted using a simplified dynamic model for the vibrating system. The theory was checked experimentally by means of surface strain measurements made on a 2-ft diameter, 20-ft long stainless steel vessel that was subjected to the impact loading of a detonation wave propagating in a hydrogen-oxygen mixture which filled the vessel initially at pressures of 100 to 200 mmHg.
Thermal Model for the Fluidity of Metals in Casting
Authors: Hillier M. J.
Published: February 2007

The fluidity of a cooling liquid metal is calculated using a slug flow model in which metal in the freezing range flows as a mixture of liquid and solid, and freezing is assumed to occur first at the face of the slug. Comparison is made with an alternative model in which solid metal is assumed to be deposited continuously on the mould wall. Application of the theory to the solidification of an iron-carbon alloy indicates results at variance with experiments on sand casting. It is concluded that mathematical analysis of the fluidity of binary alloys which incorporates heat transfer effects alone is inadequate to describe solidification during flow. This conclusion is not necessarily true for pure metals and eutectic alloys, nor for the solidification of binary alloys under pressure die casting conditions.
Design of Turbine Blades Suitable for Supersonic Relative Inlet Velocities and the Investigation of Their Performance in Cascades: Part I-Theory and Design
Authors: Colclough C. D.
Published: February 2007

Certain applications for turbines require units with a large work output per stage. The whole of the expansion takes place across the nozzles and at inlet to the turbine blades the gas velocity is supersonic. Impulse blading is usually employed with flow turning angles ranging from 90° to 160°. However, advancing steam conditions suggest that the first stages of turbines presently designed with subsonic blading may have to accept increasing heat drops to reduce the steam temperature to the first moving row and to reduce gland losses. Under these conditions blading designed to accept supersonic velocities could be employed.

This paper, which deals with blading designed specifically for supersonic flow, is divided into two parts, the first of which outlines the theory and design of the blading. The second part describes tests run on cascades of these blades and discusses the results. In Part I a design method based on inviscid isentropic supersonic vortex flow theory is evolved in which the uniform flow ahead of the blade is transformed into a vortex flow, turned through the required angle and then converted back to uniform flow again at the exit. The blades thus obtained are cusped and a design method has been developed to produce blades with finite leading and trailing edges. Blades designed on this basis were tested in cascade and the results were used to modify the design procedure.

The revised design method for non-isentropic conditions incorporating the measured losses and allowable contraction ratio was programmed for a Ferranti Pegasus digital computer and this was used to produce an impulse blade section with a flow turning angle of approximately 137° and capable of accepting an upstream Mach number of 1.285 and a blade inlet Mach number of 1.514.
Pressure Pulsations in Reciprocating Compressor Delivery Systems
Authors: Wallace F. J.
Published: February 2007

In an earlier paper (1)†, the author discussed the nature of pressure pulsations in suction systems of free-piston gas generators, and in particular various forms of pulsation damping devices.

A theoretical approach was based on a simple linear treatment of the system, i.e. (1) regarding all pressure pulsations as small in relation to the mean pressure on which they are superimposed, (2) treating dissipative elements (pipe friction or concentrated restrictions) as having linear pressure drop-velocity relationships about the mean flow condition, and (3) treating all distributed elements as having wave motion in accordance with small wave (2) or acoustic theory (rather than the non-linear finite wave theory (3) (4)).

Although the physical conditions in compressor delivery systems are very different from those in gas generator suction systems, a similar theoretical approach, verified by acoustic model tests, has been found both to provide a good insight into the problem, and to give an acceptably accurate quantitative indication of pressure pulsation amplitudes.

For this purpose systems have been divided into: (1) lumped impedance systems, (2) distributed impedance systems.
Master and Slave Hydrostatic Bearing Systems for Machine Tools
Authors: Kearney G. P.
Published: February 2007

Master and slave systems utilize two types of hydrostatic bearing in order to provide high load capacity in conjunction with non-redundant location by rigid-film hydrostatic bearings. Master bearings are controlled both by applied thrust and by their clearance, and they also control the thrust in the slave bearings which act independently of their own clearances. A journal bearing is used to illustrate analysis of bearing systems, redundant locations, and master and slave systems. A general analysis of master and slave systems is given and a design procedure, advantages, fields of application, and design calculations for individual bearings are outlined in the text and appendixes.
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.
Flow and Load Parameters of Hydrostatic Oil Bearings for Several Port Shapes
Authors: Lewis G. K.
Published: February 2007

Flow parameters are presented for journal and circular pad hydrostatic bearings supplied with oil through a central port shaped as a regular polygon with rounded corners. Load parameters are evaluated for the circular pad bearing. The analysis, by the method of conformal mapping, is extended to the rectangular port and also yields solutions for narrow oilways radiating from a central point in the bearing.
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.
Secondary Creep of a Cylindrical thin Shell Subject to Axisymmetric Loading
Authors: Byrne T. P. , Mackenzie A. C.
Published: February 2007

A method is presented for the solution of boundary value problems in the secondary creep of circular cylindrical thin shells subject to axisymmetric loading. Approximate stress resultant-middle surface deformation relations based on an n-power creep law are used. Solutions are given for deformation rates and stress resultants in a long cylinder with fixed ends under uniform radial loading and uniform internal pressure. Quantities important for design purposes are found to be reasonably well predicted from the linear elastic solution for a useful range of n values.
Effects of Symmetrical Nonlinear Bearing Flexibility on Shaft Whirl
Authors: Billett R. A.
Published: February 2007

A shaft-rotor system which has a symmetrical nonlinear restoring force exerted on the rotor when it is radially displaced is analysed. Solutions which predict harmonic whirl are obtained and their stability is investigated. The effect of viscous friction in the rotating members is considered and, as a result of the nonlinearity, a whirl is shown to occur at frequencies which correspond to the free undamped vibrations of the system rather than at the synchronous speed.
Forced Oscillations of Non-Linear Two-Degree-of-Freedom Systems
Authors: Bycroft G. N.
Published: February 2007

This paper shows how the Lighthill-Poincaré perturbation technique may be used to determine the transient response of ‘lightly coupled’ non-linear multi-degree-of-freedom oscillatory systems subject to arbitrary forcing functions. The results in general are complex but simplify in many important cases. A comparison is made between the analytical results and results obtained by a numerical integration of the equations on a computer. Good agreement is noted. The method fails under conditions of ‘internal resonance’ of the system.
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.
Effect of Vessel Diameter/Thickness Ratio on the Behaviour beyond the Elastic Limit of Flush Nozzles in Cylindrical Pressure Vessels: Experimental Investigation
Authors: Clare K. D. , Gill S. S.
Published: February 2007

Three tests have been carried out on mild steel cylindrical pressure vessels with flush nozzles. The cylindrical vessels were nominally 18-in outside diameter and 3/16-in thick. The branches were nominally 3 1/2-in diameter x1/8-in and 3/16-in thick and 2 1/2-in diameter x 1/8-in thick. The results are discussed and compared with a similar series of tests for which the main vessel was 18-in outside diameter and 3/8-in thick.
Inversion of the Eccentricity Effect in Stiffened Cylindrical Shells Buckling under External Pressure
Authors: Singer J. , Baruch M. , Harari O.
Published: February 2007

The analysis of the general instability of stiffened cylindrical shells under hydrostatic pressure carried out earlier is continued in order to study the inversion of the eccentricity effect: 500 typical shells of varying geometries are considered. The results show that for lateral pressure loading the inversion of the eccentricity effect is practically independent of the geometry of the rings but depends very strongly on the shell geometry parameter Z, whereas for hydrostatic pressure the inversion is also influenced by the bending stiffness of the rings. A range of inversion is found for both loadings. A detailed physical explanation of the cause of the eccentricity effect and its inversion is proposed.
Instability Phenomena due to Circular Bearing Oil Films
Authors: Holmes R.
Published: February 2007

In this paper is presented a range of instability phenomena arising from the elastic and damping properties of circular bearing oil films. In particular the effects of bearing length to diameter ratio and inequality of bearing loading are discussed.
Plastic Deformation when Cutting into an Inclined Plane
Authors: Palmer W. B.
Published: February 2007

Plastic flow and tool forces were observed as an orthogonal tool cut slowly into an inclined plane of En 9 steel. A slip-line field is constructed which represents the observed flow, and on the basis of the theory of plasticity for work-hardening material estimates of stress are consistent with observed tool forces.
Pressure loss Associated with Compressible flow through Square-Mesh wire Gauzes
Authors: Pinker R. A. , Herbert M. V.
Published: February 2007

The body of previous literature relating to the pressure loss characteristics of woven wire gauzes fails to provide adequate information on the separate effects of Reynolds number and Mach number in the range of usual interest for duct flow experiments. For this reason, tests have been carried out on a selection of eight single gauzes placed normal to the axis of a duct, of sizes (wire diameter and mesh) such as might be commonly used to give values of porosity between 0·3 and 0·7. Pressure loss measurements were carefully made, and covered independently duct Mach numbers up to choking and a 50-fold range of Reynolds number. The test data are presented so as to provide a single relation between the incompressible loss factor and a form of Reynolds number, plus a compressibility correction which depends on gauze porosity.
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.
Elastic-Plastic Behaviour of Flush Nozzles in Spherical Pressure Vessels
Authors: Marcal P. V. , Turner C. E.
Published: February 2007

A computer program for the elasto-plastic analysis of axially symmetrical shells of revolution has been modified to allow interaction loads at nozzle junctions to be distributed over bands of finite width, rather than the conventional concentrated lines of loading at the intersection of the shell centre-lines. Comparison with previously published test results for displacements, yield and collapse loads of flush nozzles shows that this modification greatly improves the predictions from those of conventional shell theory so that realistic behaviour of nozzle junctions can be forecast.
D-partition Stability Analysis of a Two-Degree-of-Freedom System with Delayed Restoring Force
Authors: Porter B.
Published: February 2007

The method of D-partition is used to analyse the stability of a two-degree-of-freedom system subjected to a delayed restoring force of the kind which causes chatter in certain types of machine tool. The central feature of the analysis is the reduction of a stabliity problem involving a transcendental characteristic equation to a much simpler problem concerning the roots of a related algebraic equation. The results of the exact analysis are compared with approximate results obtained by assuming that the normal modes of the two-degree-of-freedom system can be decoupled.
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.
Response of a Single/Two-Pass, Liquid-Liquid heat Exchanger to Disturbances in Flow Rate
Authors: Finlay I. C. , Smith J.
Published: February 2007

Transfer functions, relating outlet temperature responses to disturbances in flow rate, are presented for a single/two-pass heat exchanger with distributed wall and fluid thermal capacitance. Good agreement is shown between the measured and predicted outlet temperature responses of both shell and tube-side fluids. The accuracy of an overall lumped model as an approximation to such a system is examined.
Approximate Analytic Expressions of the Thermodynamic Functions of Dissociating Steam
Authors: Kmoníček V. , Hoffer V.
Published: February 2007

The paper presents relatively simple approximate analytic expressions showing the dependence of the compressibility factor, specific enthalpy and specific entropy of dissociating steam on pressure and temperature. The range covered by these expressions extends from 1000 to 5000°K, and from 0·01 to 100 bar. The deviations of the approximate analytic expressions deduced in the paper, from data obtained through complete thermodynamic calculations, are of the order of 1·5 per cent, i.e. practically the same as the errors of the complete calculation. The advantages offered by the use of the approximate expressions are a computation time of about 50 per cent and a digital computer storage occupation of about 60 per cent of the values corresponding to the complete calculation, while the fact that the approximate expressions are not generally thermodynamically consistent within the whole range constitutes a certain shortcoming.