bluuebunny/crossref_metadata_2025_split huggingface dataset:
Slip-Line Field Analysis for Orthogonal Machining Based upon Experimental Flow Fields
Authors: Roth R. N. , Oxley P. L. B. 
Published: February 2007

An experimental flow field for slow speed (0·5 in/min) orthogonal (plane strain) machining was analysed using slip-line field techniques. Although the experimental streamlines were not sufficiently accurate to determine a slip-line field directly by calculating the directions of maximum shear strain rate from the velocity gradients, they were found to give sufficient information together with the measured cutting forces for an approximate step-by-step method of constructing a slip-line field. In this way a slip-line field was constructed not only for the plastic zone in which the chip is formed but also for the plastic flow along the tool-chip interface. It is shown that for most of the flow the slip-line field is satisfactory for both stress and velocity. An interesting feature of the analysis is that at the start of plastic deformation where the work material enters the plastic zone in which the chip is formed the increase in flow stress caused by strain-hardening is appreciable and must be taken into account in analysing the stresses, that is, in the stress equilibrium equations. However, along the tool-chip interface where the material has been severely strained there is little strain hardening and the slip lines in this region are shown to be consistent with the Hencky stress equilibrium equations for a material of constant flow stress.
Characteristics of Inversion Tubes under Axial Loading
Authors: Al-Hassani S. T. S. , Johnson W. , Lowe W. T. 
Published: February 2007

A thin wall tube, when axially compressed over a radiused die, either inverts, or buckles or tears. The phenomena associated with the external or internal inversion of tubes of aluminium, copper, mild steel and brass are described and load-tube shortening curves are presented for speeds of compression between 0·05 in/min and 20 in/min; some results for high speed compression using a drop hammer are also described. Thickness changes during inversion are reported and experiments to establish the effect of die angle and die radius on the inversion load are given. For the inside-out inversion of tube, a simple theoretical analysis to predict the steady inverting load and the optimum die radius for a strain hardening material is given, the basic assumption being that no change in the wall thickness takes place.
Numerical Solutions of Flow between Rotating Cylinders
Authors: Launder B. E. , Ying W. M. 
Published: February 2007

The paper presents solutions of the laminar flow of a Newtonian fluid between cylinders with non-coincident axes, where the core cylinder rotates about its axis. The solutions have been obtained by means of an adapted version of the finite-difference procedure of Gosman et al. (1). The results show that the inclusion of convective transport terms (which in previous analyses have been neglected or included only approximately) may have an appreciable effect upon the flow field and, in particular, upon the pressure field around cylinders.
Flow through Moving Cascades of Lifting Lines with Fluctuating Lift
Authors: Hawthorne W. R. 
Published: February 2007

The use of generalized functions to analyse the potential, two-dimensional, incompressible flow past singularities representing stationary and moving lifting lines is explained and developed. It is shown that the time mean stagnation pressure change in the flow through a moving cascade with fluctuating lift is normally zero, except when the lift fluctuations are in phase with the motion, so that a stationary system of shed vortices is produced in the downstream flow (the stationary, phased, fluctuating lift case). Then the time mean stagnation pressure is a function of position in the absolute co-ordinate system. Expressions are obtained for the kinetic energy produced by the vortices shed off a row of blades with fluctuating lift. Idealized losses or drags due to these effects may amount to ½ or 1 per cent of the work or lift effects produced by the cascade.
Improved Convective Heat Transfer in a Fluid with Artificially Modified Turbulence
Authors: Boothroyd R. G. , Haque H. 
Published: February 2007

Although a flowing gas loaded with fine particles can give a considerably higher wall heat transfer coefficient compared with the flow of gas alone, earlier studies have shown that this improvement is less than might be realized due to dampening of turbulence near the heat transfer surface by the particles. This paper reports an investigation into off-setting the effect by adding fine fibres to a suspension of 5–40 μm particles in air flowing in tubes of 1, 2 and 3 in diameter. The results indicate that in most situations a fibre-particle suspension is likely to be superior as a coolant compared with a suspension of particles flowing alone. The purpose of the fibres is (1) to induce a large-scale vortex motion near the pipe wall where normal turbulent fluid mixing is inadequate; (2) to promote controlled residence time of wall-contact of particles of high thermal conductivity and high thermal capacity and (3) to keep heat transfer surfaces clean with the minimum erosion effect.
Transmission of a Continuous Square Wave down a Pneumatic Line
Authors: Tyack Susan C. , Hughes T. 
Published: February 2007

Using the electrical analogy, a solution for the transmission of a continuous square wave down a pneumatic line has been obtained. The results are compared with experiment and show good agreement. Using the theoretical results, it is possible to calculate the maximum separation between pneumatic (fluidic) devices that will still ensure satisfactory operation. Typically, it can be shown that at a frequency of 100 Hz, the output from a fluidic OR gate or bistable (see Appendix 1) may be transmitted 8 m and the amplitude of the signal will still be large enough at that point to switch a second OR gate or bistable.
Absolute Viscosity of Air down to Cryogenic Temperatures and up to High Pressures
Authors: Latto B. , Saunders M. W. 
Published: February 2007

The absolute viscosity of gaseous air was determined experimentally for the general pressure and temperature range 100–15 000 kPa and 90–400 K respectively, using a series capillary transpiration-type viscometer which has been developed by the authors. The accuracy of the experimental data is believed to be better than ± 1 per cent. Two general correlating equations, one for atmospheric pressure and the other for medium high pressure (i.e., densities up to 400 kg/m3), have been obtained.
On the Parameters of the Magnetic Forming Process
Authors: Al-Hassani S. T. S. , Duncan J. L. , Johnson W. 
Published: February 2007

The present state of forming and of the development of analytical design techniques for the process is reviewed briefly. A comprehensive analysis of the expansion of a tube by means of an internal solenoidal coil is given; this contains new expressions for the circuit parameters and magnetic pressure and takes account of the depth of the coil conductors. The analytical method is tested by obtaining numerical solutions and comparing these with the results of experiments in which aluminium, copper and steel tubes were formed with various discharge energies and using coils having different conductor dimensions. It is shown that the analytical method gives accurate results and is convenient to use for design purposes to optimize the process.
Fatigue and Creep Rupture of an Acetal Copolymer
Authors: Crawford R. J. , Benham P. P. 
Published: February 2007

Part 1 of this paper describes the uniaxial fatigue testing of injection-moulded cylinders made of acetal copolymer at various frequencies between 0.167 and 10 Hz. The influence of mean stress and cycle control (stress or strain) has also been studied. Two mechanisms of failure were observed: cyclic thermal softening, above certain limits of stress and frequency, and traditional crack propagation fatigue, which was found to be independent of cyclic frequency. Strain cycle control tests were thermally stable and stress range became stable after the initial 1 per cent of the total endurance. Creep rupture tests were also performed. Part 2 considers the fatigue and creep rupture of tubular specimens containing geometrical stress raisers. These were injection moulded under the following conditions: (a) single-end gated, (b) side gated, (c) double-end gated, (d) ‘rough’ mould and polished mould. Moulding defects such as weld lines, presence of voids and sprue, poor surface finish, etc., are compared for fatigue-strength reduction with machined circumferential notches and transverse holes of known theoretical stress concentration.
The Stress Distribution in a Wedge-Shaped Metal-Cutting Tool for Triangular Distributions of Load on the Rake-Face Contact Length
Authors: Thomason P. F. 
Published: February 2007

Solutions for the isothermal stress distribution in a two-dimensional infinite wedge are obtained for negative-gradient triangular distributions of normal and tangential stress, acting over a segment of the wedge surface adjacent to the apex. The general stress-field equations are obtained in integral form by Tranter's method, which involves the application of the Mellin transform, and these equations are evaluated numerically to give the distributions of radial stress at the surfaces of a x/2 wedge. A superposition method is used to obtain the surface stresses for truncated triangular distributions of boundary loads, and the results are applied to the problem of estimating the surface stresses in a metal-cutting tool.
Fluid Film Damping of Rolling Contact Vibrations
Authors: Dareing D. W. , Johnson K. L. 
Published: February 2007

The magnitude of mechanical vibration and noise generated within machinery depends on damping. However, little is understood about how damping is distributed among the various possible damping sources. The results given in this paper isolate and quantify lubrication film damping between rolling discs and show that damping within the lubrication film contributes significantly to the total damping. A comparison of laboratory measurements with computer calculations shows that lubrication film damping is greatest under conditions of contact separation and thus indicates that fluid film damping is generated primarily by the squeeze film mechanism.
Conical Diffusers with annular injection
Authors: Duggins R. K. 
Published: February 2007

An experimental investigation was made of the possible benefits to be gained from injecting a secondary supply of fluid into a wide-angled conical diffuser through an annular slot at the inlet. The diffuser discharged through a parallel tailpipe and attention was focused on the overall pressure recovery in the cone and the tailpipe together, and on the non-uniformity and asymmetry of the flow. The results showed that annular injection had a very favourable effect on both the pressure recovery and the flow non-uniformity. In addition, the effects of cone angle and slot width were assessed and the optimum rate of injection was established.
A Study of Tensile Stresses in a Journal-Bearing Oil Film
Authors: Dyer D. , Reason B. R. 
Published: February 2007

Tensile stresses of 740 kN/m2 have been observed in the oil film of a steadily loaded journal bearing. A critical eccentricity ratio has been suggested below which, for a particular clearance, a tensile stress may be generated. An extensive literature survey indicates the sensitivity of the liquid's tensile strength to such factors as gas content, viscosity, particle content and the surface finish at the liquid/bearing material interface. It is suggested that previously attempted observations of liquid tensile stresses in journal bearings may have been limited by the configuration of the pressure-measuring device. The possibility of bearing Babbitt damage arising from transient and steady-state liquid tensile stresses is postulated.
A Solution of the Low-Speed Wheel Flutter Instability in Motorcycles
Authors: Roe G. E. , Thorpe T. E. 
Published: February 2007

Motorcycles are subject to two dynamic steering instabilities, a low-speed ‘flutter’ at 6–8 Hz. and a high-speed ‘weave’ at 2-3 Hz, both of which are increased by adding a tail load, or by decreasing the rider mass. This paper is concerned with the low-speed instability, and describes work which resulted in the elimination of this potentially dangerous phenomenon from a current large-capacity motorcycle. The cause was found to be twofold: a fundamental castor instability at the front wheel, coupled to a resonance in the upper section of the main frame. Recommendations on future frame design are made, and fundamental limitations of the ‘telescopic’ front fork are demonstrated.
Slot-Entry Bearings for Hybrid Hydrodynamic and Hydrostatic Operation
Authors: Rowe W. B. , Koshal D. , Stout K. J. 
Published: February 2007

Slot-entry bearings are compared with conventional hydrodynamic bearings and also with recessed hydrostatic bearings. Whereas recessed bearings are not ideal for hybrid operation, improvements in load capacity can be achieved by the use of non-return valves in the supply lines. However, it is shown that a much improved performance may be obtained from slot-entry bearings. Slot-entry bearings have additional advantages of manufacturing simplicity and compactness when compared with other hybrid bearings. Experimental results for recessed bearings and for slot-entry bearings justify computer solutions at moderate values of eccentricity ratio and speed parameters.
Platen Deceleration as a Mechanism of Noise Production in Impact Forming Machines
Authors: Hodgson D. C. 
Published: February 2007

The very rapid deceleration on impact of the platen (tup) in a drop forging machine is shown to be an important source of impulsive noise. An ‘explicit’ finite-difference method is used to calculate the sound pulse radiated by a platen in the form of a solid cylinder undergoing a deceleration given by where T is the impact time. The results are presented in dimensionless form, enabling the pulse to be calculated for a wide range of platen sizes and impact times.
The Use of Interferometry as an Aid to Studying Flapper-Valve Flow Characteristics
Authors: Tanner L. , Peckham R. G. , Burrows C. R. 
Published: February 2007

A technique is described for visualizing the air flow over a surface by means of an oil film. The technique is used in conjunction with experimentally determined flapper-plate pressure profiles to examine the flow characteristics of a flapper-nozzle valve used to control air at 425 kPa (4.25 bar). The oil film shows clearly the points of separation and reattachment of the air boundary layer resulting from shock wave and boundary layer interaction. Possible applications of the technique are discussed and attention is focused on the use of the oil-film technique in conjunction with interferometry as a tool for the rapid determination of the effects caused by changes in nozzle geometry.
Free Vibration of Blade Packets
Authors: Thomas J. , Belek H. T. 
Published: February 2007

The free-vibration characteristics of shrouded blade packets are studied using the finite-element method. The effects of various weight ratios, flexural rigidity ratios and length ratios between the blades and shrouds on the frequencies of vibration of the blade packet are investigated. It is shown that the vibration characteristics of a multibladed packet can be predicted with reasonable accuracy from the inference diagram of a two-bladed packet. The theory developed can be easily adapted for more complex blade packet configurations. The results presented for the frequencies of vibration are compared with experimental results and show good agreement with those of other investigators.
Interferometric Study of the Temperature Field Created by a Quasi-Plane Cold Air Jet and an Adjacent Flat Plate
Authors: Hammond G. P. , Fung W. S. , O'Callaghan P. W. , Probert S. D. 
Published: February 2007

The Chilowsky effect, whereby a jet initially inclined to a flat plate subsequently becomes attached to it, thereby forming an enclosed region of recirculation, has been studied. A quasi-plane cold air jet (at about 0°C) issued parallel or inclined to an adjacent adiabatic flat plate, with a slot-exit Reynolds number <5 times 103, into quiescent ambient air (at about 16°C). The temperature field in and around the jet was mapped using a 15-cm field-of-view Mach-Zehnder interferometer for a downstream distance of 90 slot widths and compared with predictions from Glauert/Seban-Back theoretical model for turbulent wall jets. Transverse velocity and temperature profiles downstream of the attachment point were found to be near-similar for inclination angles up to 40°. The attaching inclined jets exhibited two wall-temperature decay rates, similar to those observed for three-dimensional wall jets. To utilize the Chilowsky phenomenon, continuous linear air-conditioning diffusers need to be designed with exit angles of less than 50°, thereby ensuring jet attachment to the ceiling and so avoiding discomfort to human occupants.
Pressure-Distribution Measurements in Rotary Forging
Authors: Hawkyard J. B. , Gurnani C. K. S. , Johnson W. 
Published: February 2007

Experiments on the rotary forging of discs are described in which measurements are taken of pressure distribution under the rocking die using a pressure-sensing platen. The results suggest a deformation mechanism for the spread of the disc, involving the development of plastic hinges away from the immediate die contact area. This would explain central tensile failures and related phenomena observed previously.
The Measurement and Interpretation of Flow within Rotating Stall Cells in Axial Compressors
Authors: Day I. J. , Cumpsty N.A. 
Published: February 2007

Detailed flow measurements obtained by a new measuring technique are presented for the flow in a stalled axial-flow compressor. Results were obtained from a wide range of compressor builds, including multi-stage and single-stage configurations of various design flow rates and degrees of reaction. Instantaneous recordings of absolute velocity, flow direction and total and static pressures have been included for both full-span and part-span stall. With the aid of these results, it has been shown that the conventional model of the flow in a stall cell is erroneous. An alternative model is proposed, based on the observation that the fluid must cross from one side of the cell to the other in order to preserve continuity in the tangential direction. An investigation of the experimental results also reveals the finer details of the flow in the cell and shows how these details are related to the design flow rate of the compressor. The influence of these cell details on the power absorbed by a stalled compressor are investigated, and consideration is given to the complex pressure patterns encountered in the compressor.
An Analysis of the Yield Criteria and the Stress-Strain Relationships of a Pre-Strained Commercially Pure Aluminium
Authors: Daneshi G. H. 
Published: February 2007

An analysis of the stress path and the strain trajectory of a pre-strained engineering material in the deviatoric plane is presented. The deviatoric stress vector, which for a pre-strained material is initially at an angle to the strain trajectory, is shown to coincide with it after the ‘recoverable’ energy is consumed. Experimental work is carried out on the yield criteria and the stress—strain relationships of a pre-strained commercially pure aluminium. The significance of the isotropic hardening rule in relation to a metal's straining memory is demonstrated. It is shown that beyond a stress level associated with an isotropic hardening rule based on the Mises yield criterion, the representative stress—strain curves of a pre-strained specimen run parallel to that of an annealed material.
The Response of a Hooke's-Joint Gyroscope to Linear Vibration
Authors: Burdess J. S. , Fox C. H. J. , Maunder L. 
Published: February 2007

The response of an unbalanced Hooke's-joint gyroscope to linear vibration is considered. Six major resonant frequencies are identified. It is shown that, if the gyroscope is subjected to linear vibration either along the spin axis at the spin frequency, or perpendicular to the spin axis at twice the spin frequency, measurement errors may be generated as a result of mass unbalance. These errors are shown to depend not only upon the degree of unbalance but also upon the amplitude and phase characteristics of the vibration. Compensation by the application of suitable control torques is shown to be possible.
The Effect of Mass Flow Rate on the Reflection Behaviour of Small-Amplitude Pressure Waves from Duct Terminations
Authors: Ali M. A. , Gill K. F. , Imrie B. W. 
Published: February 2007

This paper describes an investigation of the reflection characteristics of small-amplitude pressure waves in the presence of steady flow in a duct. A correlation technique employing pseudo-random binary-sequence (p.r.b.s.) pulses is introduced. A theoretical model of the process is presented together with considerations of correlation analysis. The results show agreement between the experimental results and the model; they further indicate that, in the presence of a steady flow component, there is a significant effect on the reflection behaviour of plane pressure waves for a reduction in the area terminating a duct. The experimental technique is effective at very low flow velocities (Mach number = 0·02, Reynolds number = 30 times 103) and establishes a linear relationship between a reflection coefficient and a non-dimensional mass flow number. A reflection coefficient of flow is introduced as an appropriate parameter for such conditions. The procedure could be applied to a wide range of industrial processes to determine flow coefficients of duct elements in situ, to optimize flow processes and to locate leakage flows.
The Effect of Taylor Vortex Flow on the Development Length in Concentric Annuli
Authors: Simmers D. A. , Coney J. E. R. 
Published: February 2007

Results are presented of an investigation into a developing, combined axial and rotational flow in an annular gap formed by a stationary outer cylinder and a rotatable inner cylinder for an annulus radius ratio of 0–8 and an axial Reynolds number of 1200. These results show that, in the Taylor vortex flow régime, the development length decreases with the parameter Re2a/Ta and that the greatest development length in an annular gap, for a given axial Reynolds number, occurs when the Taylor number is near to its critical value. Consideration of isothermal heat transfer through the outer wall of the annular gap suggests that, in the development of the flow, the Nusselt number rises to a high value before falling to a constant value, at full development.
Parameter Plane Studies of Car-Steering Stability with Combined Lateral and Previewed Error-Sensing by the Driver
Authors: Thompson A. G. 
Published: February 2007

Parameter plane curves of the driver's minimum preview distance for stability ( P) versus his gain ( KD) are derived. These curves represent the boundaries for absolute or relative stability of the complete car—driver system. The driver's error input is assumed to be a weighted sum of his lateral position error and predicted error at the preview distance, P. This results in a simple steering strategy which, in simulation studies, will permit the car to be driven on winding roads. Part 1 is restricted to straight roads and compares the parameter plane and gain-crossover theories. Tracking accuracy in a steady turn is improved by a steering strategy in which the driver acts on both the lateral and previewed errors. It is shown that the lateral error becomes zero if the preview, P, equals an optimal value, Pm, depending on the speed and radius of the turn. The stability plots for straight roads are adapted to the determination of stability in turns. A computer simulation of a car driven on a road S-bend provides information on stability, tracking accuracy and optimal preview distances which correlate with the results of the other studies in Part 2.