bluuebunny/crossref_metadata_2025_split huggingface dataset:
A Review of Applications of Radioisotopes to Engineering
Authors: Putman J. L. 
Published: October 2007

Radioisotopes are radioactive versions of the natural chemical elements, differing from these only in their nuclear mass and in their ability to emit radiations. They are produced mainly by neutron bombardment of ordinary materials in a nuclear reactor. The most important radiations are beta particles (fast electrons of nuclear origin) and gamma rays (penetrating electromagnetic radiations). These are detected with ionization chambers, Geiger counters or scintillation counters. In production control, the absorption or scattering of radiations is used as a measure of material thickness, and in some cases, of its atomic number. Radioactive tracers aid in production research in rapid determination of mixing efficiencies and hold-up times. Tracers are also used in the non-destructive testing of materials and components and in more basic research into alloy structure. In this latter research, photographic films are used to produce autoradiographs which show the microscopic distribution of radioactively labelled constituents. Radioactivation by neutron irradiation enables certain impurities to be assayed at sub-microgram levels without chemical separation. The wear of engine parts can be measured, in a fraction of the time taken for orthodox methods, by making the parts in question radioactive and measuring the worn radioactive debris in circulating lubricant. Cutting tools can be measured similarly by assaying radioactive debris attached to the swarf. For many purposes gamma radiography supplements X-radiography or replaces it as a cheaper alternative. The greater manoeuvrability of gamma-ray sources is of especial advantage in the radiography of assembled engines.
Stress and Deflexion Studies of Pipeline Expansion Bellows
Authors: Turner C. E. , Ford Hugh 
Published: October 2007

In the design of pipelines for high-temperature service, allowance has to be made for the thermal expansion of the heated pipe. One particular aspect of this problem is the use of bellows expansion joints which, particularly on board ship, can transmit the pipe movements through bulkheads whilst providing a watertight flexible anchorage. An approximate theory has been developed for the compression of a bellows, the convolutions of which have a cross-section formed by circular arcs subtending any semi-angle α. Numerical results have been calculated for the two cases α = π/2 and α = 3π/4. Experiments have been carried out on six bellows, four corrugated-pipe type α = π/2, one S-type α = 3π/4, and one flat-plate type which was not analysed theoretically. Deflexion and resistance strain-gauge readings were taken on each bellows, and reasonable agreement was found between the theoretical and experimental results for the five bellows in which these could be compared. It has been found that for certain design conditions optimum relationships exist between bore, wall thickness, and radius of convolution for the maximum flexibility. Stress intensification and flexibility factors have been calculated to cover a range of bellows proportions.
Effect of Heating and Cooling on the Mechanical Properties of an Alloy Steel
Authors: Kenneford A. S. , Williams T. 
Published: October 2007

An investigation has been made of the effect of heating to, and cooling from, a temperature above the critical range on the mechanical properties of an alloy steel to specification B.S. En 29. It has been shown that, on rapid cooling from a temperature above the critical range, the steel possessed poor mechanical properties (low yield and tensile strengths) at all temperatures down to the commencement of martensite formation at about 300 deg. C. (572 deg. F.). Below this temperature, there was a sudden increase in yield and tensile strengths, accompanied by a marked decrease in ductility. The relation between these mechanical properties and the incidence of cracking after repeated heating and rapid cooling is briefly discussed.
Flow Measurement by Square-Edged Orifice Plates: Pipe Roughness Effects
Authors: Clark W. J. , Stephens R. C. 
Published: October 2007

This paper presents the results of experimental work carried out recently to determine the effects on the discharge coefficient of various degrees of pipe roughness adjacent to and at different distances from an orifice plate. Experiments were carried out for air flow in 12-, 6-, and 3-inch pipes and water flow in 3-inch pipes. Downstream, severe incrustation has no significant effect. Upstream, the effects vary with degree of roughness, pipe diameter, m value, and Reynolds number. For an m value of 0·5 and severe conditions of roughness, the combined effects of roughness and pipe diminution produce disturbance factors of the order of 1·40, 1·17, and 1·08 respectively for 3-, 6-, and 12-inch pipes. A length of two diameters of rough pipe immediately upstream from an orifice plate gives an effect close to that which would be obtained for a very long rough pipe. It has been found possible to extrapolate the results to very large pipes. One of the most important findings is that cleaning a rough upstream pipe adjacent to an orifice plate for a relatively short distance reduces errors which may be otherwise very considerable to within known small limits. A table detailing the extent of such cleaning for various pipe sizes, mvalues, and degrees of roughness is given. It is recommended that, where reasonable accuracy is required in the flow measurement of dirty fluids, installations should be designed for easy periodic inspection and cleaning of the upstream pipe adjacent to the orifice plate.
Vacuum Techniques in the Atomic Energy Industry
Authors: Kronberger H. 
Published: October 2007

Vacuum techniques are used in two distinct fields: (1) applications where a vacuum is required as an essential part of the process, and (2) applications in which vacuum techniques are merely used to ensure the tightness of plant (which may not finally be required to operate under high-vacuum conditions). Advances in vacuum technology have made the construction and testing of plant to vacuum standards a relatively simple matter. Examples are given showing how vacuum techniques are used in the uranium 235 diffusion plant, in plant handling liquid metals at high temperature, in experimental work for pressurized water reactors, and in the testing of the Calder Hall heat exchangers. The success of vacuum techniques in large-scale applications depends on three factors: correct design of plant, the availability of simple and reliable testing methods, and on efficient managerial control of construction and test work. Basic design rules are given and illustrated by examples of flanges, valves, and other components used in the applications mentioned above. Vacuum testing methods are discussed. The charcoal-Pirani technique of testing is favoured for most applications; tests can be carried out on components before they are degassed and ‘clean’; equipment and operation are simple. The management of vacuum work is discussed and a method of quality control by means of binomial distribution charts is described which has been useful in improving systematically the vacuum tightness of manufactured components.
Statistical Methods Applied to Engine Testing
Authors: Buckland W. R. 
Published: October 2007

In presenting the application of some statistical methods to problems in the field of research and development testing of internal-combustion engines, this paper attempts to stimulate interest in the use of modern statistical techniques in this important area of engineering practice. Owing to the wide range of possible applications the paper is selective and, besides saying little or nothing about many worth-while statistical methods, it also has to pass over the statistical approach to the control of quality and the inspection of the finished product. After an introduction in which the need for the statistical approach is outlined, the paper considers an engineer faced with the problem of making an estimation from a few test observations. The outlying observation is dealt with followed by the desirability and value of ‘Confidence Limits’, ‘Tolerance Limits’ and the use of statistical inequalities. The third section moves one step further and considers two sets of observations. This deals with relationships, the scatter chart, and differences which must be tested for statistical significance: some attention is paid to the risks associated with drawing inferences from small samples of observations. The final section generalizes the position to many groups of data leading directly to the statistical technique of analysis of variance and the principles of statistical design of experiments. Some examples are given suitable for laboratory and bench tests as well as controlled trials and service tests. A brief glossary of statistical terms is given together with references to guide further reading.
Design and Development of Four Light-Weight High-Speed Marine Gas Turbines for Electric Generator Drive
Authors: Pope A. W. 
Published: October 2007

During the last eight years, four high-speed marine gas turbines for driving generators have been designed, developed and put into operation. Two were base-load machines designed for operating at full tropical ambient temperature (100°F), and two were simple emergency and stand-by sets. The two base-load sets and one emergency were built under contract for the Admiralty while the other emergency set was built for the Merchant Navy. A brief description of the most important features of these engines is followed by the main body of the paper which deals with the six most outstanding problems that were encountered during their design and development.
Developments in Methods of Measuring Stresses in Compressor and Turbine Blades on Test Bed and in Flight
Authors: Drew D. A. 
Published: October 2007

An organization is described that has been operating for some years in connection with investigating vibratory and transient stresses in aero-engines. A large proportion of the work is being done on compressors and turbines and information is given upon some of the factors controlling the life of high-temperature gauges on them both. Some techniques are described that are being currently used for a very big volume of testing at the Rolls-Royce works in Derby and are generally those which have been developed since the author's paper on turbine measurements read in America in 1951 (Drew 1952)†. The system used at Rolls-Royce for a large proportion of tests of vibratory stresses is viewed by having one, and more recently two, recording rooms connected to all experimental test beds and a number of rigs by permanently installed cables. Particular reference is made to the various forms of slip-rings in general use. The relative advantages of telemetering signals from aircraft to the ground and of obtaining flight measurements with an airborne multi-channel recorder are discussed. Reproductions of records of rotating stall bands with their associated bands of high stress in the compressor are given, together with a brief description of the nature of rotating stall and the methods available for reducing troubles caused by it. A small change in the running conditions to move the working point of the compressor has a very marked effect upon compressor blade stresses and in studying this either on the test bed or in flight it is vital to have a very precise knowledge indeed of the instantaneous fuel flow, rev/min and blower pressure at the instant of high compressor blade stress during a rapid acceleration. A brief note on the results of the numerous tests which are being made is given, with a reference to a much fuller paper (Pearson 1953).
Nuclear Reactor Dynamic Analysis
Authors: Parr R. , Wordsworth D. V. 
Published: October 2007

To investigate aspects of safety of control of a nuclear reactor system requires a method of analysis of the dynamic behaviour of the system following postulated disturbances or during particular operating conditions. The paper derives equations which indicate the dependence of reactor power dynamics on fundamental design parameters, the ‘reactivity’, and the delayed neutrons, for a static fuel thermal reactor, a static fuel fast reactor, and a circulating fuel thermal reactor. A method of analysis of component temperature variations is presented, with particular reference to a solid-fuel element, clad in a sheathing material, cooled on the outer surface by a flowing coolant. The coolant channel is formed in a solid moderator. A comparison of theory and experiment for the BEPO reactor shows a fair agreement, there being a maximum difference of 10 per cent at maximum power during a transient resulting from a sudden increase in reactivity of 200 × 10−5.
A Study of Shrink-Fitted Assemblies Loaded in Torsion with Special Reference to Damping Capacity
Authors: Ørbeck Finn 
Published: October 2007

Damping in shrink-fitted assemblies has been investigated and found to be of considerable practical importance. It has been possible to give this damping a fundamental explanation related to elastic deflections and conditions of the mating surfaces of the assemblies. Thus, the study of damping also yielded information about other characteristics, such as differential slip and stiffness.
Some Bearing Tests Made with a Machine Producing Impulsive Loading
Authors: Russell A. E. 
Published: October 2007

It was considered that an assessment of the comparative performance of plain bearings subject to the impulsive type of load produced in compression-ignition engines would be a useful contribution to bearing knowledge. A machine for testing bearings under these conditions of loading was developed. The use of such a machine obviates the disadvantages that the use of an engine entails in respect of accurate measurement of the actual load on the test bearing, replacement of damaged journals, facility for changing journal materials and ease of examination of bearings. The use of a machine also allows the bearing to be assessed on its own merit by freeing the bearing from the influence of deleterious factors which are introduced when a bearing is housed in an engine, for example, indeterminate and variable misalignment, contaminated oil. A description of the development of a prototype machine and of the machine in its final form is given. The procedure for assessing the load capacity of bearings is described and the relative load-carrying capacities of various kinds of bearing material are given. The effects of changes in the lubrication conditions and also the effects of a certain amount of misalignment were determined. The changes of the running surface with increasing load and the effects of increased speed and of rate of loading (applied separately) were examined.
Some Factors Influencing the Stability of Piston-Type Control Valves
Authors: Noton G. J. , Turnbull D. E. 
Published: October 2007

The reaction force on an open, spool-type, control valve acts in such a direction as to close the valve. For this reason a four-way valve, having its closed position at the centre of its stroke, can overshoot if the reaction force imparts sufficient energy to it during closure. If there is insufficient damping on the spool a continuous oscillation may arise and the present work investigates the dynamic behaviour of a common type of hydraulic position-control system in which such an oscillation has been found to occur. Good agreement is obtained between the predicted and experimental minimum amplitudes and frequencies of oscillation and also between the theoretical and measured pressure fluctuations in the system. A graphical solution of the equation of motion of the system is included in the results and with the aid of ‘Describing Functions’ the approximate dynamic behaviour of the system considered may be derived.
A Large-Range Pneumatic Extensometer
Authors: Svensson N. L. 
Published: October 2007

This paper describes the design and development of a pneumatic extensometer suitable for the measurement of axial strains of the order 10-5 over a range of ±20 per cent, using a 1-in. gauge length. The pneumatic gauge is capable of measuring strains less than 10˜-5 over a range of approximately 4 times 10-3 thus ensuring adequate measurement of elastic and initial plastic strains. A micrometer screw is used for adjustment to cover the large range and is suitable for measurement of gross plastic strains. The mechanism of the instrument was designed to comply with the following requirements: (1) magnification linear with strain, (2) nozzle and micrometer spindle to be maintained parallel, (3) insensitive to bending strains, and (4) accommodate changes in specimen diameter without adjustment. Consideration of these requirements led to the choice of a parallel-motion mechanism made in two halves to allow for changes in specimen diameter. The measuring units were so placed as to measure the mean strain between the gauge points. The method of calibration is described and also the method for analysing the results for comparison with the theoretical expression derived. This calibration and subsequent use of the instrument have shown that all the requirements listed above have been adequately satisfied.
Stress and Deformation Studies for Sandwich Rolling Hard Metals
Authors: Arnold R. R. , Whitton P. W. 
Published: October 2007

The cold working of high-strength metals and alloys into sheet and strip form at the thinner gauges allows the metal manufacturer two alternatives: (1) high capital expenditure on a specialized mill of the Sendzimir or planetary type or (2) where demand does not justify the capital outlay, the application of new techniques utilizing existing equipment. In the latter class, the method of sandwich rolling is examined by theory and by experiment and it is shown that reductions in load up to 60 per cent can be achieved for rolling thin hard strip. The method allows greater reductions than for rolling the metal alone and decrease in finished thickness is obtained. A method of adapting current cold-rolling theory for the calculation of loads involved in planning production schedules is set out, based upon a criterion of simultaneous yielding in the hard and soft metal layers. Optimum conditions of metal thickness ratio and hardness ratio for the sandwich metals are discussed.
Asymmetrically Ring Reinforced Circular Hole in a Uniformly End-Loaded Flat Plate with Reference to Pressure Vessel Design
Authors: Hicks Raymond 
Published: October 2007

General expressions are obtained for the stress distribution in an infinite flat plate end- loaded by equal principal stresses and containing a circular hole reinforced by a compact ring. The ring reinforcement being placed on one side of the plate only so that the other side of the plate remains flush. It is shown that the effect of an asymmetrically placed reinforcement is to induce in the plate and reinforcement bending stresses which are not negligible compared with the externally applied direct stress. Furthermore, from particular examples considered, it is found that reinforcements having practical dimensions can give rise to stress concentrations in the same order of magnitude as those in a similarly loaded plate containing an unreinforced hole. Thus, a reinforcement designed to satisfy B.S. 1500:1949 has a small compensating effect compared with a symmetrically placed reinforcement having the same cross-sectional area. For practical purposes, data have been obtained which enable the designer to determine quickly the stress distributions associated with reinforcements and plates having a reasonably representative range of dimensions.
Experimental Study of Some Variables of the Tube-Expanding Process
Authors: Culver L. E. , Ford Hugh 
Published: October 2007

This paper deals with certain aspects of the tube-expanding process, which have been investigated using the test rig previously developed as part of a research sponsored by the British Shipbuilding Research Association. The factors investigated are (1) retubing, (2) the starting position of the roller cage within the tube, and (3) the initial clearance between tube and seat. A few tests are also reported on the relaxation of the joint with time. In the retubing tests, further tubes were expanded into seat plates used in previous tests, from which the original tube had been removed. The main conclusion was that seat pressures can approach the theoretical maximum in retubing, and that if an extra pass is made to take advantage of the work-hardened seat, a stronger joint than in a first expanding results. To study the effect of the starting position of the rollers within the joint, four complete tests were made. The results show conclusively that a much stronger joint is obtained with less work, if the rollers start with their front ends almost at the back of the joint. Tests to study the effect of the initial clearance between tube and seat showed that clearance is not a major factor in joint strength.
The Behaviour of Narrow-Faced, Bolted, Flanged Joints under the Influence of Internal Pressure
Authors: Donald M. B. , Salomon J. M. 
Published: October 2007

A narrow-faced, bolted, flanged joint is a highly complicated stress-system. When internal pressure is applied, the stress-system changes. In order to establish, quantitatively, what these changes are, a series of experiments were carried out on a pair of -in. nominal bore screw-on hubbed flanges. The apparatus was assembled as shown in Donald and Salomon (1, Fig. 1)† An accurate measure of bolt stress and, hence, the stress on the gasket was obtained by attaching a total of four electric resistance strain-gauges to two ‘measuring’ bolts. As the nuts were all tightened carefully by means of a torsion wrench, an average of the readings of the four gauges gave the average bolt stress of the eight bolts. Care was taken that the gauges were cemented to diametrically opposite sides of the bolts and that two of the gauges were pointing toward the centre of the flange while the other two were pointing in the opposite direction. From the readings of the two pairs of strain-gauges, it was possible to calculate the extent of bending of the bolts during application of internal pressure and, hence, the rotation of the flange-rings due to pressure. The results of the experiments indicated: (1) (a) There is a linear relationship between bolt load and internal pressure. (b) The slope of the line giving this relationship depends on the elastic properties and the dimensions of the components of the joint. (c) This slope can be predicted mathematically. (d) This slope can, in the case of pseudo-elastic gasket materials such as compressed asbestos composition, be positive, negative, or zero; the slope in any particular joint depending only on the initial load on the gasket. (2) (a) The rotation of the flange rings due to pressure increases as the slope of the bolt load versus internal pressure line changes from negative to positive. (b) The rotation, as calculated from strain-gauge measurements agrees fairly well with that calculated by use of the theory of Wesstrom and Bergh. (3) The circumferential strain in the flange and pipe assembly is at a maximum in the pipe at the back of the hub. This result is in agreement with that reported by several other investigators and is not discussed in this paper.