bluuebunny/crossref_metadata_2025_split huggingface dataset:
The High Temperature Properties of Four Wrought Steels Used in the Chemical Industry
Authors: Connolly B. J. , Boyd G. 
Published: October 2007

The paper presents data on the short-time high-temperature tensile properties and creep properties of four steels which are in common use in the chemical industry, these data having been recently obtained from tests done at the Imperial Chemical Industries (I.C.I.) Creep Test Station. The steels tested were: (1) low-carbon 1 per cent chromium-molybdenum (Cr-Mo) steel; (2) medium-carbon 1 per cent Cr-Mo steel; (3) low-carbon 3 per cent Cr-Mo steel; (4) 18/10/Mo/Ti chromium-nickel (Cr-Ni) austenitic steel. Information is also given on the effect of long-term heating under stress on the micro-structure of the steels, and in the case of the austenitic steel the effect on the room-temperature mechanical properties is discussed. The application of the data to design, and their relation to existing specifications is also discussed.
Theoretical Assessment of the Performance Characteristics of Inward Radial Flow Turbines
Authors: Wallace F. J. 
Published: October 2007

While the simple centrifugal compressor has been widely used over a considerable period of time and in a variety of applications, in particular aircraft gas turbines and aero-engine superchargers, and its behaviour is therefore reasonably well understood, the inward radial flow gas turbine has only recently begun to attract the attention of engineers. As a result, its characteristics are not understood as fully as those of the centrifugal compressor. Inward radial flow turbines have a number of attractive features, such as robustness, cheapness, and relative immunity from thermal stresses, which render them particularly suitable, where the mass throughput and overall pressure ratio are moderate. While the assessment of performance and flow conditions at the design point presents no very great difficulties, the evaluation of performance under conditions of reduced speed and pressure ratio, knowledge of which is essential in most applications, does not appear to have been attempted hitherto. An analytical treatment of part-load conditions is outlined in this paper. In addition, the influence of the various design parameters on the overall characteristics is examined, and tentative suggestions are made for the best combination of these parameters for particular applications.
Management and the Engineer
Authors: Smith Ewart 
Published: October 2007

I am very conscious of the honour and responsibility involved in presenting the Graham Clark Lecture, particularly as I am the first engineer to do so. These feelings are enhanced because I had the privilege of knowing Graham Clark personally, and because I greatly admired his humanism and breadth of vision. I share his belief that it is not less important to study people, and to organize them effectively for co-operative endeavour, than it is to study the material factors which affect the life of mankind and in which engineering science plays such a vital part. It is on the subject of the interrelation of the technical and human problems of modern life that I wish to talk today. Like my precursors, I have elected to deal with a very wide theme but, I fear, without their clarity of mind or of expression. Before talking about engineers in particular, I should like to say something about the problems we face, about management in general, and about the form of education and training conducive to a high level of managerial ability. If I oversimplify, state what is obvious, or lose my way in attempting to follow byways of thought, I can only ask for your indulgence. My hope is that I may, in some respects at least, provoke controversy, for any constructive conflict of ideas may help us on the road of progress.
The Forty-Fifth Thomas Hawksley Lecture: The Transmission and Radiation of Acoustic Waves by Structures
Authors: Beranek Leo L. 
Published: October 2007

Of major interest to architects, designers of vehicles, and acousticians is the control of structure-borne sound. Walls and panels are set into vibration by airborne waves or by vibrating mechanisms. The panel so excited will radiate sound and it may carry the vibrations to other panels or bodies. In this lecture, the author will treat the problem of acoustic transmission through walls and panels in the audible frequency range. At low frequencies the panel vibrates as a plate or a stretched membrane. At higher frequencies the panel may behave as a quasiinfinite sheet. Above a particular ‘critical’ frequency, the wavelength of the bending waves in the panel will be longer than the compressional waves in air at the same frequency. The two wavelengths may be brought into coincidence provided the airborne wave impinges on the panel at an angle θ determined by cos θ = ca/ cb where c a and cb are the speeds of sound in the air and panel, respectively. At the coincidence angle, an airborne wave striking one side of a panel will set it into a level of vibration such that the magnitude of the airborne wave radiated from the other side may be only a few decibels below that of the incident wave. This effect will be discussed both for airborne waves impinging at individual angles of incidence and for waves at many angles of incidence simultaneously. Measurements on plates, concrete sheets, and masonry walls will be presented and analysed. Analysis of the different types of response to airborne wave excitation will be made. Rules for the selection of simple and complex structures for buildings and vehicles will be suggested. Means for reducing the response of structures to airborne wave and mechanical excitation include the use of damping materials in or on the structure, the introduction of discontinuities and the use of sound-absorbing blankets in the structure. Recent data on damping materials and means for utilizing them to produce maximum reduction of flexural waves will be presented. It will be shown that by proper utilization of such materials a structure-borne wave may be attenuated in a given distance by a factor of 10 or more than when utilized in a conventional manner.
Economic Design of Light-Alloy Castings
Authors: Broadbent P. A. 
Published: October 2007

Light-alloy castings can already be produced to consistently close limits by well-established die-casting methods, so the post-war developments of precision moulds are of more benefit to the other non-ferrous and ferrous foundry industries. Furthermore, the special light- alloy foundry techniques, the heat treatment and other processes, and the free-cutting properties of light alloys should be related to design and costs of production. Test-bar specifications for a number of aluminium and magnesium alloys are given, and are discussed in relation to strength and weight of castings, and also to certain features of design, and to the cost of a machined casting in cast iron and various light alloys. High-tensile steel bolts are necessary to shear screw threads in light alloys, and results of tensile tests on inserts and fastenings are given, together with estimates of cost of each method of assembly. Where inserts and fastenings are used, precautions to avoid galvanic action between dissimilar metals are necessary only on exposed junctions, whilst for corrosion generally, precautions are just as necessary for the common light alloys as for the common iron and steels.
Experimental Investigation into the Stress Distribution in a Band-Reinforced Pressure Vessel
Authors: Mantle K. G. , Marshall N. , Palmer P. J. 
Published: October 2007

A model of a band-reinforced, cylindrical, reactor pressure vessel has been manufactured and tested. The vessel dimensions were 5 ft inside diameter by 9 ft overall length, with hemispherical ends, nominal plate thickness being 1 in. throughout. Hoop reinforcement on the barrel consisted of 3-in. wide circumferential bands, each band being built up of 13 layers of -in. strip, giving a total band thickness of 1 [Formula: see text] in. Full details of design, construction, and method of manufacture are given. A complete experimental investigation into the stress distribution in the vessel has been carried out, using electrical resistance strain gauges, both at its design pressure of 1000 lb/in2 and also at twice this pressure. The stress distribution on the inner surface of the barrel, on the outer surface of the bands, and local to the tangent line has been measured. These results are compared with theoretical calculations. Finally, the vessel was pressurized to destruction. The results show that, as would be expected, the band reinforcement was not fully effective. However, the general stress level was maintained within acceptable limits, the theoretical stresses being exceeded by about 20 per cent. The bursting pressure of 3940 lb/in2 confirms the safety of the design, that is, a design factor of safety of 3·94. It is considered that the results of the investigation fully demonstrate the safety and merits of the design.
The Response of a Loaded Hydraulic Servomechanism
Authors: Turnbull D. E. 
Published: October 2007

When a hydraulic servo controls the position of a load the force required to move the load is produced by a pressure drop across the actuator. This pressure drop decreases that available to drive fluid through the control ports of the valve with the result that the speed of response is reduced. This paper examines the effects of various types of load on the dynamic behaviour of the system for both step and sinusoidal input signals. Analytical solutions to most of the response equations are obtained but graphical methods are occasionally used. When an inertial load is present it has been found necessary to consider the step response in the velocity-displacement or ‘phase’ plane.
Vibrations of Pre-Twisted Cantilever Blading
Authors: Carnegie William 
Published: October 2007

This paper reports a study of the vibrations of pre-wisted cantilever blading. The blading is pre-twisted linearly about the centroid of its cross-section up to an angle of π/2 rad and is considered to be mounted encastré at the root. Accurate prediction of the frequencies of vibration of such blading is of considerable practical importance. Two theoretical approaches to the problem are discussed. The first one, involving a direct solution of the equations of motion, is not made use of, although the characteristic equations are derived in an appendix for reference. The second approach is based on the application of Rayleigh's principle. For blades of uniform rectangular cross-section, frequency equations are derived for the fundamental mode of lateral motion and all the modes of torsional motion. Similar types of equation are shown to apply to aerofoil cross- section blading since direct coupling effects between bending and torsion, being extremely small, can be neglected. Vibration tests were conducted on sets of blades of both uniform rectangular and uniform aerofoil cross-section pre-twisted between 0 and π/2 rad, the objects being to determine the frequencies and corresponding nodal patterns contained within a specified frequency band. The effect of pre-twist on the measured frequencies of the lateral, torsional, and, for the aerofoil cross-section, coupled modes of vibration is shown, with certain exceptions, to be considerable. For the modes of motion where a theoretical solution is provided, reasonable agreement is shown to exist between the calculated and corresponding measured frequencies. Hence, the use of Rayleigh's method is justified, giving, as it does, relatively simple expressions for the natural frequencies of vibration. The torsional frequencies of pre-twisted blades are dependent on the torsional stiffness values. Hence, a theoretical study of torsional stiffness variation with pre-twist is presented, the results obtained being confirmed experimentally by a series of simple torsion tests.
An Experimental Investigation of the Pressurized Air-Lubricated Journal Bearing in the High-Speed Range
Authors: Rieger N. F. 
Published: October 2007

Experimental apparatus has been developed and used to study the friction characteristics of an externally pressurized air-lubricated journal bearing. The effects of variations in speed, load, diametral clearance, and inlet pressure have been studied over a wide range at high speeds. The experimental friction coefficients have been compared with those given by the well-known Petroff (1)† formula, and a reasonable degree of correlation has been found. Bearing air consumption has been measured and a linear relationship between air-mass flow and inlet pressure is indicated. Curves relating load-carrying capacity to various ratios of inlet pressures are included, the applied loads being carried by hydrostatic flotation in all cases. The bearings used were plain, cylindrical bushes of diameter in. and length in. Compressed air was admitted through three sets of radial-inlet holes around the bush circumference, pressures being adjusted to keep the shaft and bush as close to concentric as possible.
Discharge Coefficient of Small Submerged Orifices
Authors: Spikes R. H. , Pennington G. A. 
Published: October 2007

This paper deals with the variation in discharge of small submerged orifices used in aero-control systems. It is shown that the effects of cavitation can be high and can cause changes of discharge coefficient greater than those associated with Reynolds number when the flow is turbulent. The orifice length was altered and it was found that the most unstable conditions occurred when the length was half the diameter. Further tests were carried out with inlet chamfer in order to determine the optimum angle and depth of chamfer for cavitation suppression.
Centrifugal Stresses in Turbo-Alternator Rotors
Authors: Fessler H. 
Published: October 2007

The frozen stress photo-elastic technique was used to determine the peak stresses occurring in rotating discs which represented rotor sections. A large range of shapes of winding slots was tested and a simple empirical relationship was obtained from which the peak stresses at the necks of the teeth can be readily calculated. It was shown that these results are directly applicable to steel rotors. Semicircular subslots (inward from the winding slots) and interslots (between the winding slots) reduced the peak stresses. The largest possible cooling slots with semicircular roots are recommended. The stresses in the tips of the teeth due to the thrust of the winding-slot wedges were studied with static models in which the centrifugal force due to the windings was replaced by a tensile force. From these results recommendations were made for the least highly stressed shapes of tooth tips in rotors containing interslots.
Strength of Thick Cylinders Subjected to Repeated Internal Pressure
Authors: Morrison J. L. M. , Crossland B. , Parry J. S. C. 
Published: October 2007

In April 1956 the authors presented to the Institution of Mechanical Engineers a paper entitled ‘Fatigue under Triaxial Stress: Development of a Testing Machine and Preliminary Results’, and in September 1956 a supplementary paper was presented at the International Conference on Fatigue of Metals. In these papers the authors reported tests carried out on cylinders made from a 2 1/2 per cent nickel-chromium-molybdenum steel, which were subjected to (up to) 10 million repetitions of internal oil pressure of (up to) 20 ton/in2. Since these papers were published a considerable amount of testing has been carried out on cylinders made from a mild steel, a 3 per cent chromium steel, an austenitic stainless steel, a light alloy, a nearly pure titanium, the nickel-chromium-molybdenum steel in a harder state, and both the nickel-chromium-molybdenum steel and the chromium steel in the nitrided condition. In addition, tests of more academic significance have been carried out on the nickel-chromium-molybdenum steel in an attempt to achieve a better understanding of the extraordinary results which have been obtained. The present paper is concerned mainly with the presentation of results (supported, of course, by ancillary tests on each material) which are of importance in design. Points of academic interest are discussed only when they are relevant to the practical problem. To make the paper reasonably self-contained, a brief summary of the previous work has been given.
Creep and Rupture Properties of Carbon Steels
Authors: Smith A. I. , Jenkinson E. A. , Armstrong D. J. 
Published: October 2007

In earlier N.P.L. work on the strength of carbon steels at high temperatures, steels showing ‘normal’ and ‘abnormal’ creep properties were assessed from tests extending to 1000 hours. Further results on the same steels indicate that the order of merit of these particular steels is not altered in tests extending to 100 000 hours. The rupture properties of carbon steels are reviewed in the light of the N.P.L. results and other published data. A wide range of strength properties is shown to exist. The pattern of results, however, appears reasonably consistent. At the lower end of the strength scale are almost pure irons and at the upper end are steels of moderate carbon content and not low in manganese and silicon. Heavy deoxidation with aluminium of conventional carbon steels results in lower creep and rupture properties than are observed in similar steels deoxidized with silicon; the part played by nitrogen in this effect is considered. The rupture ductility of carbon steels is discussed and in the types covered by the N.P.L. researches, low ductility in long-time service appears unlikely. Further work required in this field is considered and the need for long-time, low-strain creep properties of mild steels for use in nuclear power plants is emphasized.
Blaenau Ffestiniog and other Medium-Head Pumped Storage Schemes in Great Britain
Authors: Headland H. 
Published: October 2007

The lecture deals briefly with: (1) The general features and the mechanical aspects of the 300-MW Blaenau Ffestiniog Pumped Storage Scheme, which will be commissioned in 1961. This station is conventional in layout but nevertheless the vertical arrangement of the four 75-MW machines and other design considerations introduced some interesting and unusual problems. (2) Recent developments in Great Britain where high output reversible pump-turbines for 600-1200 ft head are contemplated. Problems associated with design and performance of this type of machine are mentioned, together with those of a more general character for coastal pumped storage schemes using sea-water, which introduce fresh civil engineering questions. These are interrelated with agricultural and maritime interests and more specialized problems such as the performance of plant and steel structures exposed to wave action, salt-water corrosion, resistance of concrete to high velocities, cavitation, and possibly marine growths.
Control of Water Level in Marine Boilers during Rapid Changes of Load
Authors:   Steam Plant Group, Morton A. J. 
Published: October 2007

Conditions in a boiler and steam range during manoeuvring are analysed in order to identify the factors affecting boiler water level, making reference to the Y.E.A.D.1† naval boiler whose behaviour was closely observed during recent shore trials. It is shown that a boiler steaming alone responds to control actions and load changes quite differently from a boiler steaming in parallel with others. A simple theory is developed and used to establish the characteristics ideally required of a feed regulator, and this leads to the conception of a regulator incorporating an unusual type of steam flow element. Comparative estimates of the performance of this regulator and others of conventional design, applied to the Y.E.A.D.1 boiler, indicate that the proposed modification would be very beneficial, but that a conventional two-element regulator is likely to give a poorer performance than simpler types dependent upon water level only. It also appears that feed regulation is easiest when the boiler is steaming in the region of half load. Common design and commissioning procedures are criticized and gaps in knowledge pointed out.
Behaviour of Metallic Thick-Walled Cylindrical Vessels or Tubes Subject to High Internal or External Pressures at Elevated Temperatures
Authors:   Applied Mechanics Group, Johnson A. E. , Henderson J. , Khan B. 
Published: October 2007

An analysis of the stresses and strains in a thick-walled cylinder, under internal and external pressure giving rise to purely elastic strain, was made initially by Lamé (1)† and subsequently several authors have dealt with the same problem. An analysis of stress and strain in similar cylinders at elevated temperatures, in which creep strain was regarded as being of major importance and the elastic strain of relatively trivial significance, was made by Bailey (2). This analysis has been much used by engineering designers. However, in practice cylindrical pressure vessels or thick-walled tubes may be subject at elevated temperatures to internal and external pressures in such circumstances that, over the whole or a considerable portion of the intended life of the structure, creep strains and elastic strains are both of significant order. Accordingly, it is obviously of practical importance that an analysis be made of the changes of distribution of stress and strain or strain rate with time, in such cases, and the current paper is directed towards this end. In the first portion of the paper, theoretical relations between stress, strain rate and time are derived, and in the second portion the application of these relations to a number of metallic alloys at temperatures within their practical working ranges is examined. A complete example of this application is worked out in detail for one material and temperature, as an aid to designers who may wish to use the methods described. It is to be emphasized that this work has become possible in view of the very considerable information regarding the complex stress-creep strain-time relations of a variety of engineering materials at elevated temperatures gained in the previous work of the authors.
Discontinuity Effects at the Junction of a Pressurized Cylinder and End Bulkhead
Authors:   Applied Mechanics Group, Houghton D. S. , Chan A. S. L. 
Published: October 2007

An analysis is made to assess the forces and moments arising at the junction of a pressurized circular cylindrical shell and end bulkhead which forms part of a hollow sphere. Expressions are developed for the stress distributions for two cases: (1) When the end bulkhead is joined rigidly and directly to the cylinder. (2) When a jointing ring is introduced at the junction. The necessary and sufficient geometric conditions for the existence of pure membrane stress in the structure are then examined.
A Novel Anti-Seizure Surface Treatment: Diamond Impregnation
Authors:   Lubrication and Wear Group, Wells James 
Published: October 2007

Tests of an exploratory nature into a novel process, which improved the load-carrying capacity of sliding surfaces and significantly reduced friction, are described Particles of a hard material, for example, diamond, were impregnated into the sliding surface, the projecting sharp edges being subsequently removed to leave numerous small pads of diamond above the surface. The experimental programme was limited mainly to bronze sliding on hardened steel and lubricated with aviation paraffin, but a few tests under conditions of high Hertz stress (hard steel sliding on hard steel) and synthetic-oil lubrication showed similar, beneficial effects. Only the hardened steel was impregnated in the bronze on steel tests Endurance running of the impregnated surface (bronze on steel lubricated with fuel) at loads up to 300 per cent of the failing load of a conventionally lapped surface was satisfactorily performed with coefficients of friction of the order of 0.001. Excellent repeatability of control tests was obtained Silicon carbide was shown to be a suitable substitute for diamond One instance of impregnation of the surfaces within a fuel pump with a subsequent reduction in wear rate is also described