bluuebunny/crossref_metadata_2025_split huggingface dataset:
Some Experiments on the Alternating Stress Fatigue of a Mild Steel and an Aluminium Alloy at Elevated Temperatures
Authors: Forrest P. G. , Tapsell H. J. 
Published: October 2007

Alternating-stress-fatigue tests have been carried out at several speeds of between 10 and 8,000 cycles per min. on a normalized 0.17 per cent carbon steel at air temperature, 400, 450, and 500 deg. C. and on the aluminium alloy R.R. 58, in a fully softened condition, at 200 deg. C. It has been shown that for the mild steel the fatigue strength at air temperature depends mainly on the number of cycles of stress irrespective of the cyclic speed, but at 400–500 deg. C. failure at a given stress range occurs after a certain time which is approximately independent of the speed. For the aluminium alloy at 200 deg. C. there is evidence of a small speed effect, but fatigue failure depends mainly on the number of stress cycles applied and not on the time of the application. In addition, a study has been made of the dynamic stress-strain relations, and these are shown to be useful as a guide to the variations of fatigue strength with temperature and speed. They also provide a means for the determination of the stress redistribution when plastic strain occurs in bending fatigue, and it is shown how this, together with the effect of size of test piece may account for the difference between bending and direct-stress fatigue strengths. A description is given of the special apparatus designed for the work.
The Fatigue Strength under Bending, Torsional and Combined Stresses of Steel Test Pieces with Stress Concentrations
Authors: Thurston R. C. A. , Field J. E. 
Published: October 2007

In previous investigations (Gough, Pollard, and Clenshaw 1951)§ under the same general research programme, determinations were made of the intrinsic and vee-notched fatigue strengths of the first seven steels here investigated, under various combinations of bending and torsion. The intrinsic fatigue limits were found to fit reasonably to an ellipse quadrant, and the notched fatigue limits to a two-constant displaced ellipse or ‘ellipse arc’. The bulk of the present paper concerns the behaviour under combinations of bending and torsional stresses of test pieces with transverse holes, for the same seven steels. The fatigue limits under the various stress combinations have been found to fit reasonably to an ellipse arc of the same form as for the vee-Notched Specimens. The similarity in form of the ellipse arcs for the seven materials supports the theoretical conclusion that the shape of the curve is dependent only on the shape of the hole, and is independent of the nature of the material. The information given on strength reduction factors under various combinations of bending and torsion, together with the tables of results of supplementary static tests, should be of use in such problems as crankshaft design. The paper also includes the results of flexural and torsional fatigue tests on an aircraft crankshaft steel, with other forms of stress concentration. These results are compared with those on two other steels of similar composition.
A Correlation of the Resistance to Air Flow of Wire Gauzes
Authors: Grootenhuis P. 
Published: October 2007

The resistance to the flow of air through different assemblies of wire gauzes has been correlated to a common basis. Single gauzes, closely-packed assemblies, sintered packs, and assemblies of spaced gauzes have been considered, although the actual correlations have been restricted to square-mesh gauzes with a single-wire diameter, as these are used most in practice. Experimental data for the sintered packs are presented and compared with the published data for the other types of assembly. The flow of air through a gauze is considered as analogous to flow through passages or pipes, and the resistance as being due mainly to the friction between the flow and the surfaces of the voids in the gauze, in contrast to the previous approaches of treating the resistance of a gauze as being due to a combined drag of the wire cylinders. The range of Reynolds number (based on hydraulic mean diameter) covered by the correlation is from 0.1 to 5,000.
Convective Heat Transfer to Gas Turbine Blade Surfaces
Authors: Wilson D. G. , Pope J. A. 
Published: October 2007

Results are given of experiments into the variation, with chordwise position, of the heat transfer between the surface of a typical gas-turbine blade in cascade and in the air stream. The principal variables investigated are the blade's Reynolds number and the incident angle of the air stream, while the air/temperature ratio of the blade is kept near unity. It is shown that, with certain provisions, the results should be broadly applicable to similar blades under normal operating conditions. The extent of the correlation of the results with values obtained by available theoretical methods is shown. The laminar boundary-layer heat-transfer theory due to Squire (1942)‡ gives good agreement, but the predictions of heat transfer in the regions of turbulent boundary-layer flow, particularly under negative pressure gradients, leave much to be desired. In addition, knowledge of conditions at transition to turbulence and at laminar separation of the boundary layer is scanty, with consequent uncertainty in any overall heat-transfer forecast. Minor suggestions in this respect have resulted in slightly improved correlations. The experimental method employed involved the manufacture of a wind tunnel having a form of contraction based on the theoretical work of Cheers (1945), which gave excellent results; also a novel process was developed for the manufacture of the cascade blade which, it is considered, possesses certain advantages over the more traditional methods.
Factors Influencing the Continuing Development of the Steam Turbine
Authors: Dollin F. 
Published: October 2007

The Parsons Memorial Lecture was instituted in 1935 under the auspices of The Royal Society. It is delivered each year in one of the branches of science to which Sir Charles Parsons contributed, and is sponsored by the Institution or Society appropriate to that subject. The range of Parsons' activities included marine engineering, naval architecture, civil, electrical, and mechanical engineering, and optics.
Modern Developments in the Use of Large Single-entry Centrifugal Pumps
Authors: Anderson H. H. 
Published: October 2007

In parallel with the electric motor and the steam turbine, which provide suitable high-speed power, the centrifugal pump has been developed to a high degree of reliability and efficiency. This paper describes a recent step in this development, namely, the research manufacture and adoption of single-entry pumps, combined with their driving mechanisms, for medium and large power duties.
Development of the Lost-wax Process of Precision Casting, 1949–53
Authors: Turnbull J. S. 
Published: October 2007

The paper describes the limitations of the original lost-wax process (1945–49) and describes improved methods developed in the Precision Casting Shop of the Metropolitan-Vickers Electrical Co., Ltd., by which the process has extended its application in industry. In the technique of wax injection, methods are described for eliminating ‘draw’ in wax patterns, and for making accurate patterns considerably larger in size. Wax-injection machines are also described. In the manufacture of moulds, the new Investment X technique of shell moulding is described with full details of its technical and economic advantages. Methods of improving progressive solidification in castings are discussed. The application of centrifugal and vacuum casting is discussed. Attention is drawn to the mechanical properties of S.80 castings with higher consistency resulting from a combination of Investment X and centrifugal casting. Distortion of patterns and of castings are described and methods of correction suggested. The economics of lost-wax castings are considered and, finally, the scale of manufacture is reviewed with a view to mechanization.
Pulsating Flow Measurement by Viscous Meters, with Particular Reference to the Air Supply of Internal-combustion Engines
Authors: Kastner L. J. , Williams T. J. 
Published: October 2007

The problem of measuring the mean rate of mass flow of a fluctuating stream is one which has attracted the notice of many investigators but, although a limited degree of success has been achieved by more than one method, it may be said that a simple, inexpensive, and compact device which is capable of dealing with flows subject to severe pulsations without loss of accuracy and without ancillary apparatus has yet to be described. Meters of the orifice type, used in conjunction with large smoothing capacities, have been widely employed, in particular for the measurement of the air consumption of reciprocating internal-combustion engines, but the smoothing capacity often requires to be inconveniently great and too small a volume will lead to surprisingly large errors (Watson and Schofield 1912; Kastner 1947)‡ whilst the range of flows covered by a single orifice is rather restricted since the rate of flow is proportional to the square root of the head. Electrical methods, depending on the transfer of heat from an electrically heated wire to the stream, have been tried (Moss 1924) but are also not free from errors when velocity fluctuations are present. Other methods adapted to particular circumstances have had some success (Bailey 1939; Cornelius and Caplan 1952) but do not represent a satisfactory general solution of the problem. So-called ‘viscous meters’ in which the pulsating stream is directed through a number of narrow passages across which the pressure difference is measured and in which the Reynolds number is kept so low that the flow is laminar (Alcock and Ricardo 1936) may be shown theoretically to have certain advantages, notably that of a straight-line law between head and mass flow even when the instantaneous velocity is subject to fluctuations. Within limits these advantages have been confirmed in practice but under conditions of severe pulsation such meters have shown large and puzzling errors. The investigation described below was undertaken with the primary aims of studying the performance of viscous meters under the most severe conditions of pulsating flow, with special reference to the measurement of the air consumption of reciprocating internal-combustion engines, and of developing an accurate meter suitable for use under such conditions. It is believed that these aims have been at least partly achieved and, whilst many of the experiments relate to engine air-flow measurements, it is considered that the results are capable of wider application and that they will be of value in a variety of problems concerned with fluctuating flows.
Report on Investigation into the Failure of Two 100-MW. Turbo-generators
Authors: Gibb Claude 
Published: October 2007

It has often been said of engineering that ‘Progress is made by solving the problems resulting from the making of progress’. This paper describes the investigations made following the failure of two generators each of 100 MW. capacity installed in the Richard L. Hearn Generating Station at Toronto of The Hydro-Electric Power Commission of Ontario. The author details some general considerations affecting the design of alternator rotors, the selection of materials used, past troubles which had to be avoided, reasons for certain features incorporated in the original design and modified as the result of the failures, and safeguards introduced into current practice to avoid the possibility of a repetition of the failures.
Experiments on the Effect of Rate of Testing on the Criterion of Failure of Certain Mild Steels When Subject to Dynamic Torsion and Static Tensile Stresses
Authors: Calvert N. G. 
Published: October 2007

Torsional impact tests have been carried out on a range of mild-steel specimens subjected in addition to various intensities of axial tensile stress. Tests have been carried out at a low speed (time to yield about 002 second) and at a high speed (time to yield about 0001 second). In each case the stresses observed are compared with those predicted by various of the criteria of failure. With this particular type of stressing the effect of increasing the speed of the torsional component is to move the criterion of yield in a direction away from that of constant shear strain energy (Mises-Hencky) toward that of constant maximum tensile stress. The maximum observed torsional stresses lie between the constant maximum shear stress and the constant maximum tensile stress and they are apparently unaffected by the rate of straining within the range investigated. The angles endured to fracture diminish progressively as the axial tension is increased and they tend to be slightly reduced by an increase in speed.
Southampton Docks
Authors: Biddle R. P. 
Published: October 2007

Since the Institution of Mechanical Engineers last held their Summer Meeting at Southampton in 1928 many important developments at the Docks have taken place, notably the building of the New Docks, one of the largest reclamation schemes ever undertaken in Britain, and the provision of the King George V drydock. A commentary on the increase in the size of vessels using the Docks is provided by the fact that although in 1954 slightly fewer vessels used the Docks than in 1928 the gross tonnage of shipping has increased by 21 per cent. In passenger traffic 1928 was at that time a record year but 1954 showed an increase of 23 per cent.
An Investigation into the Accuracy of the Industrial Measurement of Sizes up to 80 Inches
Authors: Harrison P. W. 
Published: October 2007

The need to formulate proposals for the extension of the I.S.A. system of Limits and Fits above 500 mm. (20 inches) has required an improved knowledge of the accuracy of industrial measurement of such sizes. In an investigation conducted by the National Physical Laboratory (N.P.L.) this information has been obtained for diameters up to 2,000 mm. (79 inches) from a number of firms who have made measurements upon a special set of work-pieces circulated amongst them, these measurements being compared with those made at the N.P.L. The industrial measurements tended to be too small, especially at the larger diameters. Both this tendency, expressed as the algebraic means of the measurements, and their standard deviation about this mean, bore an approximately linear relationship with diameter in this range of size. Supplementary information on measuring equipment did not suggest that, among the techniques more commonly used, there was one which provided particularly accurate results, but indicated that some refinement in existing equipment and methods could do much to improve accuracy of measurement.
A Slip Line Field for the Hot Rolling Process
Authors: Alexander J. M. 
Published: October 2007

By using a geometrical representation, recently proposed by Prager (1953)†, of the equations defining the flow in plane strain of a plastic rigid material, it is possible to obtain a solution to the statically undetermined problem of hot rolling. The geometrical method facilitates adjustment, by inspection, of the slip line field until both velocity and stress boundary conditions are satisfied. Accuracy of the method is ensured by continual reference to the stress plane, in which an orthogonal family of identical cycloids defines the slopes of both slip lines and hodograph characteristics at corresponding points. To allow for the effect of rotation of the roll surface it has been necessary to consider the effect of rotation on hodographs in detail. The main assumptions which have to be made are that the yield stress of the material is constant throughout the plastic zone, and that the shear stress along the boundary between roll and material attains the yield shear stress of the material. This latter assumption corresponds with Orowan's condition of ‘sticking’ throughout the complete arc of contact (Orowan 1943), and implies that the slip lines of one family meet the roll surface orthogonally. An interesting feature of the solution is the occurrence of a thin slice of rigid material adjacent to the roll surface at the entry point having a large velocity discontinuity along its boundary.
The Value of the Notch Tensile Test
Authors: Baker J. F. , Tipper C. F. 
Published: October 2007

A History of the development at Cambridge of a notch tensile test for the investigation of brittleness in structural mild-steel is described. The test procedure and the methods of assessing the temperature limit at which the material becomes brittle are outlined in Part I. Investigations of material from an oil storage tank and from ships which fractured in service show that this notch tensile test gives good correlation with these casualties whatever the nominal stress in the plates at the time of the fracture. The results of Charpy V-notch and Izod tests are given for comparison, and it is shown that the energy absorption criterion used in these tests may be misleading (Part II). In Part III experiments are described in which the tensile test has been used to predict performance in test-pieces of more complicated geometric form. Criticisms of the notch tensile test are dealt with in Part IV. In the conclusions, attention is drawn to the fact that the designer of orthodox fabricated structures must be provided with material which is ductile at all operating temperatures and at all stress levels.
An Experimental Study of Air-Entraining Vortices in Pump Sumps
Authors: Denny D. F. 
Published: October 2007

The factors affecting the formation of air-entraining vortices in sumps are enumerated, and their relative importance assessed from experiments with a number of different sumps. It is established that vortices are caused by rotation of the mass of water within the sump arising primarily from the entry conditions. Their severity, measured in terms of the minimum safe submergence to avoid air entrainment was also found to depend greatly on the velocity in the suction inlet; air entrainment rarely occurred below a velocity of 2 ft. per sec., and above 15 or 20 ft. per sec. the severity of the vortices did not increase substantially. The shape and disposition of the suction inlet only slightly affected the vortices, but sump boundaries were found to reduce appreciably the tendency for vortex formation when closer than 8 diameters to the suction pipe: with the walls very close to the pipe, vortices did not occur. Small sumps may thus be more satisfactory than spacious ones. Tests with scale models of existing or proposed pump installations are described, and for one sump, where vortices formed within the working range, it is demonstrated that suitably placed boundary walls would be considerably more effective in preventing vortices than modifications to the suction inlets. Measurements of the quantity of air drawn into the pump through a vortex showed that air entrainment of this type could seriously impair pump performance. Severe vortices could lead to depriming of pumps operating with suction lift.
The Dynamics of the Ball Mill: Part I: Power Requirements Based on the Ball and Shell System
Authors: Rose H. E. , Evans D. E. 
Published: October 2007

In Part I the relation between the relevant dynamic variables and the power requirements to drive a ball mill, containing the ball charge but without powder charge, has been investigated by means of experiments upon small-scale models. Dimensional analysis is used to obtain the equations in the form of dimensionless groups, and the functional relations between the groups are given analytically, or by means of graphs. This analysis indicates that, so far as power input is concerned, the mill with lifters and the mill without lifters are best treated as separate cases, since the motion of the ball charge is different in the two systems, but that the variation in the number and size of the lifters has little effect upon the power required to drive the mill. By means of the results of this work, the power input required to drive a mill grinding powder may be calculated with reasonable accuracy, and examples of the application of these calculations to large mills are given.
Part III: An Investigation into the Surging of Ball Mills
Authors: Rose H. E. , Blunt G. D. 
Published: October 2007

The problem of surging in ball mills has been investigated by the use of small-scale models and, although a complete analysis of all the variables has not been made, a criterion has been obtained by use of which it is possible to determine, whilst the design is still on the drawing board, whether the charge of a proposed mill is likely to surge. The validity of the proposed criterion has been demonstrated by comparison with the published results relating to industrial mills; this comparison showing that all the mills considered are operated under conditions which are in accordance with those laid down in the present work. So far as is known, such a criterion has not previously been propounded, and it is believed that it is of considerable value to the designer and to the mill operator. For the purpose of predicting the existence or non-existence of surging in a mill, it is only necessary to establish within which of two possible zones on a certain graph the point corresponding to the operating conditions of the mill falls; the relevant graph having for the abscissae the value of the ratio of the mill diameter to the ball diameter and for the ordinate the product of the mill filling and the mean coefficient of friction of the ball and powder charge of the mill. Thus, in order that a mill shall not surge, it is necessary that the mill filling and the ratio of mill diameter to ball diameter shall be so chosen in relation to the coefficient of friction, which is fixed by the nature of the material being ground, that the operating point for the mill shall fall within the non-surging zone on the graph mentioned. It is suggested that if a mill can be operated under ‘non-surging’ conditions, then, for lower first costs and maintenance costs, plain liners should be adopted, but if the mill cannot be operated under these conditions, then heavy lifters should be provided to suppress surging—even though the cost is thereby increased.
Bending of Plating with Widely Spaced Stiffeners
Authors: Chapman J. C. , Slatford Jean E. 
Published: October 2007

This paper is concerned with stiffened plating to which a bending moment is applied in the plane of the stiffener webs. Owing to the initial or imposed curvature there is a radial component of force which tends to deflect the plating from its original position, and the effects of this deflexion may be considerable. There is a change in the distribution of longitudinal stress across the plate, and a transverse bending stress is induced which may exceed the longitudinal stress. The effects of initial deflexion of the plating, and of lateral load, are also considered. A numerical example illustrates the application of the analysis to the transverse bending of a ship's side. An experiment is described which confirms the theoretical conclusions for an initially flat plate.
Effect on the Local Heat-Transfer Coefficient in a Pipe of an Abrupt Disturbance of the Fluid Flow: Abrupt Convergence and Divergence of Diameter Ratio 2/1
Authors: Ede A. J. , Hislop C. I. , Morris R. 
Published: October 2007

The effect of an abrupt convergence, diameter ratio 2/1, on the local heat-transfer coefficient for water flowing in a straight pipe has been determined for Reynolds numbers from 800 to 100,000 in the smaller pipe, which had an internal diameter of 1 inch. The pipe was heated by the longitudinal passage of a heavy direct current through the wall. The variation in local coefficient, which was comparatively small, is presented and discussed; it does not differ greatly from the variation found in the entry regions of pipes under more normal entry conditions. The effect of an abrupt divergence, diameter ratio 1/2, has also been determined for Reynolds numbers from 3,700 to 45,000 in the larger (2-inch) pipe. The variation in local coefficient was considerable.