bluuebunny/crossref_metadata_2025 huggingface dataset:
The application of immersive virtual reality for layout planning of manufacturing cells
Authors: Korves B , Loftus M
Published: October 2002

Immersive virtual reality (VR) is a new form of human-computer interaction, which has the potential to support a range of engineering applications. A recent review of the methods of planning and implementing manufacturing cells indicates that the visual capability of VR could assist the planning process. Current planning methods are restricted by two-dimensional and three-dimensional modelling systems, which provide visual representation of the cells but lack the full user interaction. This paper describes the framework of an immersive VR approach to the planning and implementation of manufacturing cells in which the planner enters the modelled world of the application.
Diagnostic benchmarking for small- and medium-sized enterprises
Authors: Nelder G P , Skandalakis A
Published: October 2002

Benchmarking can be described as an alliance between partners to share information on practices, processes and measures to stimulate innovative improvement in corporate performance. Small- and medium-sized manufacturing enterprises are reluctant to participate in benchmarking studies due to lack of time, financial and personnel resources, and difficulty in selecting partners. A diagnostic benchmarking process has been developed to meet the requirements of smaller enterprises. The process involves a business needs analysis, which provides participating companies with a fresh perspective on their strengths and weaknesses. The analysis connects to business performance, and is supplemented by a benchmarking study to help the company progress towards best practice excellence.
Modelling and simulation of the milling action
Authors: Martin K F , Ebrahimi M
Published: October 2002

The paper describes the mathematical modelling and simulation of the whole milling action in a milling machine. The mathematical model includes: (a) a model of the dynamics of the X axis drive, (b) a model of the dynamics of the spindle drive, (c) a model of the dynamics of the cutting process itself with cutting forces and torques and (d) the interconnection of (a), (b) and (c) to form the complete model of the milling action. The model uses both z and s plane transfer functions in order to model discrete and continuous parts of the system. The models of the X axis drive dynamics and spindle drive dynamics include models of the digital filter and analog converter in the velocity and position loop control. Friction is modelled in the machine table (part of the X axis drive) as a combination of stiction, coulomb and viscous friction. The model of the X axis drive dynamics is explained in detail whereas the model of the spindle drive dynamics is derived from the former. The model of the cutting process dynamics, which connects the other two models, is based upon a relatively simple analysis of the forces generated during face milling. The model is designed to be simulated by an existing computer simulation package and for this reason some dynamic equations are reoriented in order to avoid differentiation. This part of the paper concludes with an overall block diagram to represent the model of the whole milling action. The simulation of the mathematical model is then described, as are the tests carried out on the model and the actual machine in order to validate the model.
The identification of non-rigid errors in a vertical machining centre
Authors: Ford D G , Postlethwaite S R , Blake M D
Published: October 2002

Errors in machine tools can be categorized into three broad areas: (a) geometric errors, (b) thermally induced errors and (c) non-rigid errors. The categories cover imperfections in the machine tool structure, deviations caused by both internal and external heat sources and deflections due to loading of the structure respectively. This paper describes research into measurement strategies for the separation of the geometric and non-rigid errors into a suitable form to be utilized in a correction algorithm. The developed strategy was validated against machines of a similar configuration but varying in size.
Tolerance optimization in assembly stacks based on capable design
Authors: Swift K G , Raines M , Booker J D
Published: October 2002

There is probably no other design effort that can yield greater benefits for less cost than the careful analysis and assignment of tolerances. However, the proper assignment of tolerances is one of the least well understood activities in product engineering. The paper introduces a knowledge-based statistical approach to tolerance allocation, where a systematic analysis for estimating process capability levels at the design stage is used in conjunction with statistical methods for the optimization of tolerances in assembly stacks. The method takes into account failure severity through linkage with failure mode and effects analysis (FMEA) for the setting of realistic capability targets. The application of the method is fully illustrated using a case study from the automotive industry through the use of interactive software.
Intelligent tool wear identification based on optical scattering image and hybrid artificial intelligence techniques
Authors: Li X Q , Wong Y S , Nee A Y C
Published: October 2002

Tool wear monitoring is crucial for an automated machining system to maintain consistent quality of machined parts and prevent damage to the parts during the machining operation. A vision-based approach is presented for tool wear identification in finish turning using an adaptive resonance theory (ART2) neural network embedded with fuzzy classifiers. The proposed approach is established upon the fact that the optical scattering image of a turned surface is related to the wear of the cutting tool. By applying the technique of the ART2 neural network embedded with fuzzy classifiers, the state of wear of the turning tool is determined from captured images obtained by laser scattering from the machined surfaces of the workpiece. This approach is not unlike the visual inspection of the surface of a machined workpiece to determine the state of wear of a cutting tool by an expert machinist. However, experimental results indicate that the conventional technique of measuring surface finish does not give values that correlate well with tool wear. On the other hand, the laser scattering image provides a good indication of the tool wear as it is not readily affected by buildup edge or cold-welded material, scratches and other disruptive defects on the turned surface as the tool wears. In this paper, the theory on the laser scattering image and the principle of tool wear identification are described. Based on the scattering images, the proposed approach can correctly identify the condition of ‘significant wear’ prior to the rapid tool wear stage for the cutting tool.
A comparative study on the behaviour of free-fall lifeboat launching from a skid and from a hook
Authors: Khondoker M Reaz H , Arai M
Published: October 2002

There are two commonly used launching methods of free-fall lifeboats: from a skid and from a hook. A free-fall lifeboat, whether it is released from a skid or from a hook, experiences tremendous impact when it enters the water. This impact force, together with other hydrostatic and hydrodynamic forces and moments, affects the motions and accelerations of the boat considerably. In this paper, a comparative study on the behaviours of the skid and hook launching of free-fall lifeboats has been presented. Numerical simulation for different launching methods has been used as a tool to obtain trajectories of the lifeboat for different launching conditions. Also polar diagrams of accelerations are drawn using the data computed for the same conditions. Dynamic response criteria have been used in order to evaluate the risk of injury to the occupants during water entry of the lifeboat.
Shape factors and material indices for dimensionally constrained structures Part 1: Beams
Authors: Burgess S C
Published: October 2002

Shape factors and material indices have been recently developed for the optimal design of load-bearing beams and shafts. These shape factors and material indices are generally only applicable where there are no dimensional constraints. However, dimensional constraints are very common in mechanical design because of the integrated nature of modern machinery and equipment. This paper extends the methodology of a previous paper by Ashby by developing the shape factors and material indices for the case of constrained height in beams. The paper also shows that dimensional constraints can have a very significant effect on the optimal selection of material and shape.
Shape factors and material indices for dimensionally constrained structures Part 2: Shafts
Authors: Burgess S C
Published: October 2002

Shape factors and material indices have been recently developed for the optimal design of load-bearing beams and shafts. These shape factors and material indices are generally only applicable where there are no dimensional constraints. However, dimensional constraints are very common in mechanical design because of the integrated nature of modern machinery and equipment. This paper extends the methodology of a previous paper by Ashby by developing the shape factors and material indices for the case of constrained diameter in shafts. The paper also shows that dimensional constraints can have a very significant effect on the optimal selection of material and shape.
Non-circular gears—graphic generation of involutes and base outlines
Authors: Lozzi A
Published: October 2002

Base and involute contours associated with non-circular pitch outlines were generated by graphic construction and implemented by computer algorithms. The singular unambiguous definitions of a base circle and involute for circular gears lead to multiple interpretations when applied to non-circular pitch outlines. Four different base outlines were generated for each pitch outline presented here. These were arrived at by combining two means of fixing the pressure angle and two means of terminating the conjugate line. Involutes were then generated by applying the principle of unrolling a hypothetical cord from the base outlines and by tracing a point moving along the conjugate lines. Because of the difficulties associated with dealing analytically with generalized non-circular pitch outlines, the approach taken was the numerical equivalent of geometric constructions, reflecting the application of the principles of gearing. The outlines used were ellipses of the first three orders.
Fast and accurate inclusion of steam properties in two- and three-dimensional steam turbine flow calculations
Authors: Hill P G , Miyagawa K , Denton J D
Published: October 2002

The Denton time-marching method for turbomachinery flow calculation has been modified for rapid and accurate access to the properties of steam in equilibrium dry and wet states and in the metastable dry region. Transition between metastable dry and equilibrium wet states is accomplished either at the stable equilibrium boundary or by allowing metastable equilibrium expansion followed by a condensation shock whose location depends on the local degree of subcooling of the metastable vapour and the local expansion rate. Steam properties and their derivatives are obtained from a wide-ranging Helmholtz representation of equilibrium (stable and metastable) thermodynamic properties and stored for use in an accurate Taylor series representation. Comparisons have been made of flow development in a low-pressure steam turbine blade row for three expansion assumptions:

equilibrium stable and metastable dry, stable equilibrium, dry and wet, and dry expansion prior to a condensation ‘shock’ which is followed by equilibrium wet expansion. Inclusion of real steam properties extends calculation time for one iteration cycle by about 5 per cent and has little effect on the number of cycles required for convergence in the absence of a condensation shock; however, inclusion of the shock may double the time required for convergence.
Chaos and bifurcation analysis of a flexible rotor supported by short journal bearings with non-linear suspension
Authors: Yau H-T , Chen C-K , Chen C-L
Published: October 2002

The bifurcation and chaos of the unbalanced response of a bearing-rotor system with non-linear suspension are investigated on the basis of the assumption of an incompressible lubricant together with short bearing approximation. Numerical results show that, owing to the non-linear factors, the trajectory of the journal centre demonstrates steady state symmetric motion even when the trajectory of the bearing centre is in a state of disorder. Poincaré maps, bifurcation diagrams and power spectra are used to analyse the behaviour of the bearing centre in the horizontal and vertical directions under different operating conditions. A unidirectional bifurcation phenomenon is detected in the bearing-rotor system in this study. The fractal dimension concept is used to determine whether the system is in a state of chaotic motion. Numerical results show that the dimension of the bearing centre trajectory is fractal and greater than 2 in some operating conditions. This indicates that the bearing centre is in the state of chaotic motion at these operating conditions.
Optimum control of a mechanical drive for a weapon platform
Authors: Whalley R , Ebrahimi M
Published: October 2002

Remote positioning drive systems for weapon platform slewing are investigated. A linear, multivariable system model is derived. Regulation strategies based on polynomial functions generated by the controller model are proposed. Conventional, frequency domain, relative stability techniques are employed in conjunction with phase lead-lag compensation. An optimum, minimum control effort solution is presented.
Numerical analysis of the dynamic growth of droplets in gas metal arc welding
Authors: Zhang Y M , Liguo E
Published: October 2002

Feedback control of droplet transfer is pursued as a solution to produce sound welds in gas metal arc welding. In previous work, a real-time visual system has been developed to monitor on line the droplet size and geometry. To realize feedback control of metal transfer, this study addresses the dynamic process of droplet growth and detachment. The droplet is subjected to gravitational force, electromagnetic force, plasma drag force and surface tension force. The geometry of the droplet is determined by these forces through the static force balance. However, the forces acting on the droplet continuously change as the melting electrode wire changes the droplet geometry. Because of this interdependence between the droplet geometry and the forces, the model must be solved dynamically and iteratively. A numerical program has been developed to acquire its dynamic numerical solution. Hence, the dynamics of the metal transfer process can be understood and simulated. Currently, this model is being used to simulate theclosed-loop controlled metal transfer process using different advanced control technologies.
Detection of multiple solutions using a mid-cell back substitution technique applied to computational fluid dynamics
Authors: Kendall S R , Rao H V
Published: October 2002

Computational models for fluid flow based on the Navier-Stokes equations for compressible fluids led to numerical procedures requiring the solution of simultaneous non-linear algebraic equations. These give rise to the possibility of multiple solutions, and hence there is a need to monitor convergence towards a physically meaningful flow field. The number of possible solutions that may arise is examined, and a mid-cell back substitution technique (MCBST) is developed to detect and avoid convergence towards apparently spurious solutions. The MCBST was used successfully for flow modelling in micron-sized flow passages, and was found to be particularly useful in the early stages of computation, optimizing the speed of convergence.
Adaptive Product Manuals
Authors: Pham D T , Setchi R M
Published: October 2002

This paper extends the concept of Intelligent Product Manuals (IPMs) which provide just-in-time support to users during the life of the product. The paper advocates the concept of Adaptive Product Manuals (APMs) that generate virtual documents corresponding to the current information needs of users. The key elements of this concept are specification of user information needs, development of a knowledge-based (KB) system with models and algorithms for processing of user requests and generation of active Web pages matching user profiles and information goals.
Static weight estimation and system design for multiple-sensor weigh-in-motion
Authors: Stergioulas L K , Cebon D , Macleod M D
Published: October 2002

A probabilistic estimation method for multiple-sensor weigh-in-motion (MS-WIM) based on the maximum likelihood (ML) estimator is presented. The theoretical analysis is based on two generic vehicle models: a ‘quarter-car’ model, the tyre force spectrum of which can be idealized as a single sine wave, and a ‘walking beam’ model corresponding to the sum of two sine waves. The range and distribution of the model parameters (as derived from previous knowledge of vehicle dynamics) are taken into account and used as prior information (‘priors’) in the implementation of the method.

The technique is able to determine the static axle load of high-speed vehicles with considerably better accuracy than previous theoretical analyses. A detailed investigation of simulation results is given, the advantages of the method are discussed and its ability to estimate the static loads accurately is demonstrated. Finally, the probable success rate of the algorithm is calculated and a new design procedure for multiple-sensor weigh-in-motion is introduced.
Estimating optimal open-loop controls for industrial batch heating plant
Authors: Ford J , Griffiths A J , Brandon J A
Published: October 2002

A mathematical model of a gas-fired heater is used to estimate fuel input trajectories that minimize fuel consumption. The model has distributed parameters and an active surface temperature constraint. Optimal control theory is used to establish a two-point boundary value problem that is solved by a combination of shooting and relaxation. The shooting algorithm is an extension of the algorithm previously reported by the same authors [3]. The relaxation algorithm is based on a method for inverting a sparse band diagonal matrix. The calculations confirm that as the time available to warm a batch plant increases so the amount of fuel necessary for the task decreases.
A general method for the stiffness analysis of manipulator mechanisms
Authors: Sanger D J , Chen J Q , Zhang S J , Howard D
Published: October 2002

This paper is concerned with the displacement of the end effector of a manipulator, when subjected to an externally applied force system, which arises because of the flexibility of the actuator drives. General results are developed for the end effector infinitesimal stiffnesses (and compliances) in terms of the actuator infinitesimal stiffnesses (and compliances) for serial and parallel manipulators. It is shown that these quantities are dependent upon the instantaneous force system applied to the end effector, so that the relationship between the applied force system and the resulting displacement is non-linear, even for a given manipulator configuration.

These results are of interest for a number of reasons. For example, the accuracy of a manipulator is directly related to its stiffness, and knowledge of the stiffnesses (or compliances) can be used to develop means of simultaneously controlling the force and displacement for a partially constrained end effector.

Examples are provided to demonstrate the application of the general results to specific manipulator mechanisms, including both serial and parallel types.
Calculations of non-linear waves generated by complex body motion
Authors: Chen T , Chwang A T
Published: October 2002

A structured and unstructured hybrid overlapping grid method is developed for simulating free-surface waves generated by submerged arbitrary bodies undergoing rigid body motion in multi-degrees of freedom. Exact boundary conditions are applied to the transient free and body surfaces. The accuracy, efficiency and generality of the present two-dimensional code for potential flows are validated by comparisons with available theories and experiments. Numerical experiments are reported in this paper to investigate the non-linear behaviour of waves due to the complex rigid body motion, in terms of wave patterns and the pressure distribution. Combining the best features of both grid systems for finite elements and finite differences, the present method provides a promising alternative in computational fluid dynamics for the design and analysis in marine engineering.
Evaluation of non-linear wave forces on a fixed body by the higher-order boundary element method
Authors: Sung H G , Hong S Y , Choi H S
Published: October 2002

A numerical method is developed to evaluate non-linear waves diffracted by a fixed body and the resulting wave force acting on it. The entire boundary and all the variables are discretized by means of isoparametric biquadratic elements. To resolve the difficulty of describing the flow in the intersection region with regular elements, discontinuous elements are introduced. The generalized minimal residual (GMRES) algorithm is implemented to solve the reduced linear algebraic equations. Non-linearity of the free surface is integrated accurately in time by the fourth-order Runge-Kutta method with minimum truncation error. A new numerical radiation condition for non-linear diffraction is suggested, which resolves accurate non-linear diffraction around the body. Non-linear diffraction problem of a bottom-mounted circular cylinder is exemplified. The non-linear wave used by Rienecker and Fenton is chosen as the incident wave field. Based on the numerical results, it is believed that the present method is quite promising.
Non-linear simulations of wave-induced motions of a floating body by means of the mixed Eulerian-Lagrangian method
Authors: Kashiwagi M
Published: October 2002

A non-linear calculation method based on the mixed Eulerian-Lagrangian (MEL) method is presented for wave-induced motions of a two-dimensional floating body. Attention is focused on an effective calculation of the hydrodynamic force associated with the temporal derivative of the velocity potential in the Bernoulli pressure equation. Unlike other existing methods, the acceleration field can be computed simultaneously with the velocity field, which contributes greatly to a reduction in the computation time. Computations are performed for a wall-sided model and a flared model, and numerical results of the waves at upwave and downwave positions and the body motions (sway, heave and roll) are compared with corresponding experiments. The overall agreement is very good, confirming the validity of the present method. The parametric oscillation in roll, observed for the flared model, is also discussed.
The dynamics and limits on the scaling of a flexible kinetic sculpture
Authors: Gooch S D , Raine J K
Published: October 2002

Highly flexible structures may be scaled up by different criteria that lead to different degrees of structural integrity as the scale increases. This paper first explores the effects of different scaling rules, focusing in particular on a double-size version of the Len Lye kinetic sculpture Blade, whose aesthetic performance characteristics must be preserved as the size is increased. Stresses in the sculpture increase, reaching first an economic limit beyond which frequent fatigue failure makes the sculpture too costly to operate. As the scale further increases, a size is reached where the sculpture will collapse. A dimensional parameter for comparing the values of the life to failure for different construction materials is also developed. The second part of the paper summarizes the results of different analytical approaches to the dynamics of Blade, both with and without the inclusion of an axial acceleration load due to gravity. The results of analyses are found to be in good agreement with experimental data. The paper closes by discussing some of the design implications of implementing the drive system for a double-size version of Blade that has been built and is now on public display.
Evaluation of deflection in semi-infinite bodies by a differential method
Authors: Evans H P , Hughes T G
Published: October 2002

The paper presents a procedure for evaluating the Laplacian of the deflection of a semi-infinite body subject to pressure loading using suitable quadrature expressions. Both line contact and point contact situations are considered. The validity of the treatments is verified by consideration of the Hertzian pressure distributions, and it is shown for each case that the deflection can be obtained numerically by solution of the resulting differential equation. The effect of the pressure distribution in this ‘differential deflection’ method is shown to be extremely localized in comparison with direct evaluation of the deflection. A companion paper clarifies how this important property can be exploited to enable a fully coupled approach to the elastohydrodynamic problem to be constructed without the need to consider the solution of the fully populated matrix that has hitherto been thought to be necessary. The technique developed in this paper thus forms the key to exploiting the acknowledged benefits of full coupling in these problems.
Bubble size and system pressure effects on the phase distribution for two-phase turbulent bubbly flows
Authors: Kuo T-C , Yang A-S , Chieng C-C
Published: October 2002

The coupled Eulerian-Lagrangian approach was used to study the effects of bubble size and high-pressure transport behaviour on the phase distribution mechanisms in vertically upward air-water two-phase bubbly flows. The approach solves the conservation equations of liquid phase in Eulerian space and equations of motion in conjunction with the random walk method for dispersed air bubbles in Lagrangian space. Numerical calculations were performed under conditions of three bubble diameters (2.8, 4.0 and 5.0 mm) and two different pressure levels (0.1 and 7.17 MPa) to explore the flow and void fraction development phenomena. Simulation results indicate the tendency of higher slip ratios and the movement of the void fraction peak towards the flow core for larger gas bubbles. In the pressure range 0.1-7.17 MPa, predictions reveal that the effect of high-pressure transport behaviour on the phase distribution is insignificant.
Dynamic modelling and motion planning for a hybrid legged—wheeled mobile vehicle
Authors: Lee K Y , Dissanayake M W M G
Published: October 2002

This paper presents the dynamic modelling and energy-optimal motion planning of a hybrid legged-wheeled mobile vehicle. The equations describing the dynamic behaviour of such vehicles are complex. Kane's method and the Autolev symbolic manipulation package was used in the dynamic modelling. A state parameterization method is used to synthesize the leg trajectories for the hybrid vehicle. The resulting energy-optimal gait is experimentally evaluated to show the effectiveness and feasibility of the path planned.
Two-stage sliding mode controller for vibration suppression of a flexible pointing system
Authors: Park J-H , Kim K-W , Yoo H-H
Published: October 2002

The performance of pointing systems mounted on top of a vehicle can be affectedby the bending vibrations as the vehicle runs on a bump course. In order to improve the pointing performance, the vibrations of the pointing structure should be suppressed. In this paper, a non-linear controller is designed to control the tip position of the pointing system while actively suppressing the vibrations. To cope with high-order dynamics and non-linearity of the plant and the hydraulic actuating system, a two-stage sliding mode controller is designed. The desired actuating pressure is obtained in the first stage and then the input current to the hydraulic servo system is computed to generate the pressure. The simulation results show the effectiveness of this scheme and the improvements obtained in pointing accuracy.
Augmentation of the magnitude of the impulsive wave discharging from a tube
Authors: Kim H-D , Setoguchi T , Kashimura H , Raghunathan R S
Published: October 2002

The present paper describes experimental and computational work to augment the magnitude of the impulsive wave generated at the exit of a pipe. An experiment was performed using a simple shock tube with an open end, and numerical calculations were carried out to solve the unsteady, axisymmetric, inviscid, compressible governing equations that represent the experimental flowfield. The control strategy applied was to alter the exit geometry of a straight tube to a sudden enlargement tube and a flare tube. The effects of the configurations of the tube exit on the magnitude of the impulsive wave were investigated over the range of weak shock Mach numbers from 1.01 to 1.10. Various types of geometric parameter were explored for the configurations of the tube exit. The results obtained were compared with those of the straight tube tests. The numerical result predicted the magnitude of the experimented impulsive waves with a good accuracy. The present passive control technique enabled the magnitude of the impulsive wave to be augmented by about 24 per cent, compared with that of the straight tube with no control.
Coagulation of particles in oil by an a.c. electric field (observation of the coagulation process under various mechanical conditions)
Authors: Yanada H , Kikuchi M , Nishimura N
Published: October 2002

This paper describes an experimental investigation of the coagulation of particles in oil under the action of an a.c. electric field. The investigation is carried out to acquire fundamental data to develop an electrostatic liquid filter with higher performance. The coagulation process of spherical silica particles in oil is observed by tracking a certain particle arbitrarily chosen and using a video-microscope with a charge coupled device (CCD) camera under various mechanical conditions. The observations show that particles are coagulated by approaching one another, in particular, owing to the velocity gradient of flow and entering the region where attractive forces are exerted among them, and that the velocity gradient in the direction of the electric field is more effective for particles to be coagulated than that in the direction perpendicular to the electric field. The experiment shows that a certain frequency of the a.c. electric field at which the coagulation is most promoted exists, and that the frequency increases with increase in the strength of the a.c. electric field and the zeta potential of particles. The experimental results suggest that the mean amplitude of oscillation of particles in the direction of the a.c. electric field may dominate the degree of coagulation.
Numerical modelling of defect formation on copper wire surfaces during the wire drawing process
Authors: Phelan P , Brandon J , Hillery M
Published: October 2002

The crowsfoot defect, a characteristic surface cracking defect in wire drawing, usually occurs at fine wire diameters. This paper reports a numerical simulation of the wire drawing process where copper wire is reduced in diameter under varying conditions of friction, die angle and reduction ratios. The results of this analysis show that, contrary to existing theoretical models, the largest drawing stress and von Mises equivalent stress occur at the outer surface of the wire and not along the central axis as previously postulated.
Damping characteristics of particle dampers—some preliminary results
Authors: Tomlinson G R , Pritchard D , Wareing R
Published: October 2002

Particle dampers offer considerable potential for suppressing structural resonant conditions over a wide frequency range compared with tuned mass dampers or tuned vibration absorbers. However, they exhibit non-linear behaviour which relates to the motion of the particles that in turn is dependent on the excitation level. This communication describes some preliminary experimental results on the damping characteristics of a particle damping device which clearly show that the damping levels are dependent on the geometry of the device and the resulting motion of the particles arising from the level of the input excitation.
The surface geometry of rollers with skew rolling of steel balls
Authors: Yang S-C , Chen C-K
Published: October 2002

The ball shaping process is considered from a geometric viewpoint as a meshing pair of conjugate surfaces at the precise rolling stage. This viewpoint offers a simple method and procedure for determining the groove design of each forming roll in the skew rolling process of steel balls. Based on the envelope theory, a shape design of the forming roll is a composite of two helical grooves with constant pitch and variable pitch. Through this method, the mathematical model of the forming rolls for skew rolling, which can be used to design and manufacture a skew roller for manufacturing steel balls, can be derived and simulated. Finally, the required cutter path is provided for a spherical-end cutter in the manufacturing process. The size of the spherical-end cutter may be identical with or smaller than that of the steel ball.
Bending behaviour of double-acting hydraulic actuators
Authors: Baragetti S , Terranova A
Published: October 2002

The buckling behaviour of hydraulic actuators is often established by using simple analytical models. However, existing research does not take into account rectilinear imperfections and friction effects at the restrained ends and in the area of the rod-cylinder connection (the port through which the rod enters the cylinder). Recent research has tried to establish the effects of actual geometrical imperfections and friction on plunger-rod actuators, thus enabling better use of these very common mechanical components. This paper analyses the bending behaviour of hydraulic piston-type actuators using analytical models, able to take into account friction, rectilinear imperfections and the actual geometric configuration of piston-type actuators. The reliability of these analytical models was confirmed by means of experimental tests carried out on full-scale equipment.
An energy recovery system for a hydraulic crane
Authors: Liang X , Virvalo T
Published: October 2002

In this paper an energy recovery system for a hydraulic crane is presented. An assistant system with an accumulator is used to drive one joint of an example crane together with an electro-hydraulic load-sensing (ELS) system. The practical system is tested. The hydrostatic analysis of energy transfer is based on the experimental process and an assumed typical duty cycle. The experimental and theoretical results show that the application of the assistant system with the ELS crane system can recover and reutilize energy, save pump supply energy and improve energy utilization of the crane system. The success of its design and test in an example hydraulic crane will encourage its extension to different commercial applications in other lifting machinery.
Modelling and analysis of a high-speed circuit breaker mechanism with a spring-actuated cam
Authors: Ahn K Y , Kim S H
Published: October 2002

The dynamic model of a high-speed circuit breaker mechanism with a spring-actuated cam is derived, and its validation and appropriateness for an analysis of high-speed motion behaviour are checked through experiments. In particular, the characteristics of the friction on the camshaft are investigated using the non-linear pendulum experiment. The parameters of the friction model are estimated using an optimization technique. The analysis shows that the friction of the pendulum depends on stick-slip, the Stribeck effect and viscous damping. The simulation results of derived dynamic models for the rapid closing and opening operations are compared with actual responses using a high-speed camera and are investigated to validate their usefulness. The spring motion, which has much influence on the closing responses, is observed.
A shrink-fitted peg subjected to cyclic loading
Authors: Mugadu A , Hills D A
Published: October 2002

The plane problem of a peg, shrink fitted into a cavity and subjected to an oscillating/fluctuating axial load, is studied. Firstly, the conditions ensuing complete adhesion, analogous to the elastic limit in plasticity, are found. For conditions where adhesion is not achieved everywhere in the first cycle, the stick-slip regime is tracked and the conditions under which frictional shakedown will occur are deduced. A frictional equivalent to the Melan principle is then applied to give identical results. The results summarized are of practical relevance to the design of shrink-fitted joints, and demonstrate the extension of plastic shakedown to frictional problems.
Function generation utilizing an eight-link mechanism and optimized non-circular gear elements with application to automotive steering
Authors: Dooner D. B.
Published: October 2002

A procedure is presented for generating any desired function using an eight-link mechanism incorporating optimized non-circular gear elements. Non-circular gears are synthesized to regulate the relative displacements between two of the eight links. The coordinated steering of automobiles is presented as an illustrative example of function generation incorporating eight links and optimized non-circular gears. Minimization of the non-circularity of the gear elements for certain linkage parameters is included. A graphical display of the linkage along with the corresponding non-circular gear elements is given.
Bending fatigue testing of gear teeth under random loading
Authors: Hanumanna D , Narayanan S , Krishnamurthy S
Published: October 2002

The gears in a gear box fitted in an armoured tracked vehicle for the purpose of power transmission and positioning of rotating heavy mass to the desired angle with high accuracy are subjected to fluctuating loads that are random in nature. One of the important modes of failure in cyclic loading conditions including random loads is fatigue failure. It is thus important from the design point of view to estimate the life of the gears under these conditions. The fatigue life of components subjected to sinusoidal loading can be estimated by using cumulative damage theories. Their extension to random load fatigue, though straightforward, may not be very accurate owing to inherent scatter exhibited by the fatigue phenomenon. It is therefore necessary experimentally to determine the fatigue life of randomly loaded components and establish the validity of the theoretical model. An electrohydraulic test rig has been designed and fabricated that is capable of generating different types of load pattern by adopting a suitable electronic circuit in the test rig. This paper presents the details of the test rig for random load generation, the test fixture for mounting the gear and the technique for testing the gear for bending fatigue life under random loading. A gear has been tested in the test rig under random loading conditions and also under constant amplitude conditions for bending fatigue, and the life of the gear has been obtained experimentally. Fatigue lives of the gear have also been estimated theoretically by employing linear cumulative damage theory using the peak count method.
Analytical solution for thermal stresses during the laser pulse heating process
Authors: Kalyon M , Yilbas B S
Published: October 2002

Laser pulse heating of surfaces initiates thermal stress generation in the region irradiated by a laser beam. Depending on the level of thermal stresses, structural changes occur inside the substrate material. In the present study, laser step input pulse heating and thermal stress generation are considered. The governing equations of heat conduction and momentum are solved analytically. In the analysis, two cases are considered, namely a stress-free surface (σx = 0 at x = 0) and a zero stress gradient at the surface (ϑσx/ϑx = 0 at x = 0). The temperature and stress fields are computed using the closed-form solution, which is derived using a Laplace transformation method. It is found that considerably high stress levels developed at some depth below the surface. The stress-free surface condition suppresses a rise in thermal stress in the surface vicinity of the substrate material, while the zero stress gradient condition at the surface results in compressive stress levels in the surface vicinity.
The development of a three—dimensional imaging system and its application in fluid mechanics
Authors: Stickland M T , McKay S , Scanlon T J
Published: October 2002

This paper details the application of a three-dimensional imaging system known as planar contour imaging (PCI) to the presentation of experimental fluid mechanics data. The experimental datasets consisted of pseudo three-dimensional particle image velocimetry (PIV) vector maps of the flowfield around an air bubble growing at the base of a water column. The vectors from the experimental datasets were projected into three-dimensional space and the ease of their interpretation was assessed. It was found that the selection of the correct type and amount of data presented to the viewer was critical. However, when the image was refined, the three-dimensional image was found to produce an impressive representation of the flowfield contained within the experimental dataset.
An investigation of an ion drag pump using a needle-mesh electrode configuration
Authors: Yanada H , Hakama S , Miyashita T , Zhang N
Published: October 2002

This paper deals with an ion drag pump consisting of a needle-mesh electrode system. The effects of the number of needles of the emitter, the configuration of the collector and the type of oil on the pump performance are investigated experimentally, and some of the experimental results are compared with one-dimensional theoretical analysis. It is shown that the pump performance is not significantly influenced by the number of needles on the emitter but is significantly enhanced by attaching needles to the collector mesh in a similar manner to the emitter, and that the type of oil has a significant influence on the pressure-flowrate characteristic. Furthermore, it is revealed that no correlation can be seen between the stalled characteristic and the flow characteristic.
Control of multifrequency rotor vibration components
Authors: Cole M O T , Keogh P S , Burrows C R
Published: October 2002

A method is developed for the control of rotor lateral vibration using multiple frequency components. The control strategy uses a generalized algorithm for the real-time calculation of the amplitude and phase of the vibration components. The complex amplitudes are evaluated successively at the controller sample frequency and can therefore be used for dynamic feedback control. Parallel control of all frequency components is achieved using frequency-matched control signals with amplitude and phase dictated by the control algorithm. The strategy is evaluated experimentally using a flexible rotor system with magnetic bearings. The controller gain matrices are calculated from frequency response identification. The controller sample frequency is the rotational frequency, but the vibration frequencies that are controlled simultaneously include harmonics and subharmonics of the rotational frequency. The controller is shown to be effective in reducing rotor vibration arising from various sources and having a number of discrete frequency components.
Innovative high-speed machines with active magnetic bearings for special submerged gas processing
Authors: Mhango L M C , Perryman R
Published: October 2002

The combination of advances in active magnetic bearings, recent developments in power electronics technology, new design techniques of electrical machines and advances in magnetic materials is contributing to innovative forms of submerged high-speed electric drives which will be suitable for special gas processing applications well into the twenty-first century. Typical applications include submerged industrial high-pressure and high-temperature gas processes, calibration of gas meters, gas circulation in nuclear power plants, etc. This paper looks at the results of case studies of high-speed drives and discusses their benefits and advantages.
Elastic deflection of the sliding bearing interface in the tangential direction
Authors: Ni J , Zhu Z
Published: October 2002

The elastic deflection of the sliding bearing interface of machine tools in the tangential direction is important for ultraprecision positioning applications. This study focuses on investigating the magnitude of such tangential elastic deflection through experiments. A nanoprecison linear piezomotor is used to apply tangential force, and capacitance sensors of submicron resolution are used to measure displacements. Experimental results show that the bearing interface features linear elastic characteristics in the tangential direction when the range of tangential displacements is less than 50 nm. When the range is larger than 50nm, the interface only retains a certain amount of tangential deflection in an unloading cycle. The tangential force has a linear relationship with the tangential displacement only in the stage of elastic deformation which is submicron in magnitude.
Finite element analyses of flow in a cavity with internal blockages
Authors: Fawehinmi O B , Gaskell P H , Thompson H M
Published: October 2002

Although studies of flows in cavities without internal blockages are extremely common, those in which blockages arise are correspondingly rare. The present work describes a numerical study of one such flow using two complementary finite element approximations to the governing Navier-Stokes equations. Two formulations are adopted: the first employs a streamfunction-vorticity representation that has proven effective in elucidating fine flow detail in related cavity flows while the second is expressed in terms of primitive variables. The advantages and disadvantages of each formulation in relation to ease of application of boundary conditions and efficiency of numerical solution are compared and contrasted. In both cases, results for the chosen test problem are found to be in excellent agreement and reveal that previously reported data for this problem are in error. Moreover, results are presented that demonstrate the rich variety of flow patterns, recirculation regions and stagnation points that can arise as the cavity geometry and external wall speeds are varied.
Carton manipulation analysis using configuration transformation
Authors: Liu H , Dai J S
Published: October 2002

This paper investigates the folding process of packaging cartons and characterizes the manipulation of automatic carton folding by converting the problem into that of a motion sequence of an equivalent, metamorphic mechanism. The mechanism makes an analogy with a carton by taking carton creases as joints and carton panels as links. Hence the mechanism analysis can be applied to carton motion study, the loop can be analysed using the graph theory and the active guiding joints can be identified using the adjacency matrix. The folding sequence is thus produced and a general representation of carton manipulation is presented with a hereditary connectivity matrix and a configuration matrix. The methodology and algorithm are applied to an origami-type carton folding with simulation.
General linearized equations of wave propagation in strained elastic solids of cylindrical shapes using a simple perturbation method
Authors: Sinaie A , Ziaie A
Published: October 2002

The equations of particle motion in an elastic isotropic stressed medium are first derived in Cartesian coordinates and then transformed into cylindrical coordinates. The three components of the equations of motion are non-linear partial differential equations and cannot be of use in practical applications. However, noting that the particle displacement is composed of a small dynamic part superimposed on a large static part, these equations are linearized via a simple perturbation method. The linearized equations are presented in closed form. They contain variables, which may be measured and experimented upon in practice, in the field of acoustoelasticity.