bluuebunny/crossref_metadata_2025_split huggingface dataset:
Parametric Excitation Instability of a Rigid Unbalanced Rotor in Short Turbulent Journal Bearings
Authors: Russo M , Russo R 
Published: February 2007

The influence of oil-film turbulence on the parametric excitation instability of a symmetrical unbalanced rotor in short bearings is analysed for different values of Reynolds number. The method of calculating the journal orbit is described together with the method for predicting the synchronous orbit whose stability is to be evaluated. In addition to examples of calculated and predicted orbits, stability maps are given for dimensionless unbalance values equal to 0.2, 0.3 and 0.4 and for the Reynolds numbers of 2500, 5000 and 10000.
Mechanical Cooling Systems for use in Space
Authors: Bradshaw T W , Orlowska A H 
Published: February 2007

This paper describes the development of long-life cooling systems for use in spacecraft. The original single-stage coolers were developed by the Rutherford Appleton Laboratory (RAL) and Oxford University for the Improved Stratospheric and Mesospheric Sounder (ISAMS), an Oxford University instrument that will be part of the National Aeronautics and Space Administration's (US) (NASA's) Upper Atmosphere Research Satellite. Since then RAL has continued development of these coolers to produce lower temperatures and the technology has been transferred to industry via the British Technology Group (BTG). This has been possible by the award of contracts from the European Space Agency (ESA) and internal funding. The coolers are now available from industry and have been baselined for a variety of future instruments both in Europe and the United States.
A Better Than Average Stress Model—Photoelastic Analysis for Airbus Design
Authors: O'Brien E W 
Published: February 2007

A high level of structural efficiency is required in order to help achieve competitive performance from modern commercial aircraft. Quality data is essential to confidently optimize complex structures with respect to stress, weight and cost. One response to the challenge has necessitated the development of improved analysis techniques involving photoelasticity as a design tool—‘a better than average stress model’ (unfortunately the phrase is not original). Linear-elastic epoxy stress models can quickly determine precise stress levels and distributions of the required quality using reflective photoelasticity and may be supplemented by strain gauges.
Design and Performance of Vaneless Volutes for Radial Inflow Turbines: Part 2: Experimental Investigation of the Mean Line Performance—Assessment of Empirical Design Parameters
Authors: Whitfield A , MacGregor S A , Noor A B Mohd 
Published: February 2007

The non-dimensional design procedure described in Part 1 assumed a one-dimensional compressible flow and as such relied on the empirical specification of the dissipation of angular momentum, the dissipation of energy and the deviation of the swirling flow from that of a free vortex. This was based largely on data available in the published literature. In order to develop and substantiate the empirical procedures further an experimental study was carried out in parallel with the development of the design procedure. The experimental investigation described here had the specific objective of assessing and developing appropriate empirical models and coefficients for application to the design procedure. The study concentrated on the application of a five-hole probe located in the centre of the volute passage and at a series of azimuth angles around the discharge. The probe provided stagnation and static pressure measurements, from which the gas velocity was derived, together with the flow angle. When taking measurements at the volute discharge a stationary dummy rotor was used to carry the five-hole probe.
On the Retrospective Balancing of Installed Planar Mechanisms
Authors: Davies T H , Niu G H 
Published: February 2007

The paper closely follows the work described in the preceding paper by Chiou and Davies (1) and shares with it the nomenclature and illustrative example. The results of that paper are used here to investigate the feasibility of providing retrospective balancing of existing machines on site. In reference (1) it is shown that unbalance of frequency that is a multiple k of driveshaft rotational frequency can be represented by contra-rotating force vectors Fk+, Fk- rotating about centres Sk+, Sk-, one of which can be chosen arbitrarily. As explained in reference (1) there are advantages in adding balance mass to existing shafts that rotate at driveshaft speed, notably of course the driveshaft itself, or shafts that rotate at an exact multiple k of that speed. The extrusion press machine described in reference (1) has a driveshaft balance mass. Space is available on the driveshaft to add additional mass as a retrofit measure, but the force exerted by the supplemented balance mass remains less than the first-order unbalance of magnitude F1+ that rotates in the same sense as the driveshaft. The residual unbalance still requires two contra-rotating forces to represent it, but one of these is less than it would otherwise have been without driveshaft balance mass. It will usually be found that there are boundaries to the regions where additional shafts can be located. This is particularly so within the frame of a machine where it is, to say the least, inconvenient to install shafts that span the width of the machine as a retrofit measure. Attention is therefore directed to balancing one or more frequency terms of the unbalance by additional masses installed external to the frame of the machine. Several means by which this can be done are described: they include the use of two or more additional shafts carrying balance masses and the use of dummy mechanisms. Means of driving the shafts and mechanisms are also briefly discussed.
Precise Robotic Chamferless Peg-Hole Insertion Operation Without Force Feedback and Remote Centre Compliance (RCC)
Authors: Qiao H , Dalay B S , Parkin R M 
Published: February 2007

Robots can be widely used in the industrial assembly operation if the task can be performed with high precision, high speed and with low cost. Peg-hole insertion is a fundamental operation whose problems have been the focus of much work. In the passive accommodation solution, remote centre compliance (RCC) is used to perform chamfered peg-hole insertion). The principle exploited involves using RCC as a mechanical map which transfers the translational and angular errors, between the peg and the hole, into corrective motion. The potential advantages of minimized cycle times are offset by the limited precision. This contrasts with techniques exploiting active accommodation which use a force sensor to arrive at the deviation, between the peg and hole axes, to achieve chamferless insertion. A strategy is developed here that uses neither of these additional accessories but instead exploits features of both techniques with defined initial conditions. The immediate advantages of reduced hardware complexity are supplemented by evidence of trials. These were based on a 31.99 mm diameter peg and a hole with a diameter clearance of 0.02 mm. The results showed that the algorithm operated reliably with small clearances and with minimum cycle times. This confirms its potentially wide application in industry where its simplicity can be fully exploited.
Prediction of Electro-Rheological Valve Performance in Steady Flow
Authors: Peel D J , Bullough W A 
Published: February 2007

Previous work has indicated that electro-rheological (ER) fluid in steady valve flow can be approximately characterized by the dimensionless parameters friction coefficient, Reynolds number and Hedström number and the Bingham plastic constitutive equation, and has pointed towards a relationship between tests on valves of various dimensions at different excitations and speeds of flow and comparatively small volume, quick, static clutch mode tests. In this paper, the position is extended and developed more precisely. The generalized valve flow characteristic is taken, together with simple static clutch determinations of fluid yield properties, zero volt viscosity and valve dimensions to predict valve pressure/flow performance for comparison with valve test data. The static clutch test rig and test procedure are described, and the relationship between static clutch and valve flow determinations of yield stress is then further examined.
A Method for Assessing the Rollover Stability of Articulated Tipping Trailer Units under Tipping Conditions
Authors: Hyde T H , Fessler H , Pickering S G 
Published: February 2007

Because the chassis, suspension and tyres of a tipping trailer unit are flexible, when standing on sloping ground, the body tilts more than the sideways slope of the ground on which it is standing. This changes the positions and directions of the resultant forces due to self-weight, payload and sideways wind relative to the hinge bar which allows the body to be tipped. These changes alter the magnitudes of the forces exerted on the chassis at the hinges and by the lifting ram; this changes the forces exerted through the air suspension on to the rear wheels. When the force exerted by a rear wheel becomes zero, rollover is imminent. All of the above changes have highly non-linear effects. Further non-linearities are due to the operation of the airbag suspension. This paper defines these effects and describes iterative methods to predict the position of the body relative to the ground for any trailer unit under specified conditions and to predict the ram length at which rollover would occur.
Meeting the Challenge of Low Emissions and Fuel Economy with the Ricardo Four-Valve High-Speed Direct Injection Engine
Authors: Needham J R , Whelan S 
Published: February 2007

In order to investigate and demonstrate the potential of the high-speed direct injection (HSDI) diesel engine, Ricardo have undertaken a programme of research and analysis into the performance and emissions of a four-valve/cylinder combustion system. Analytical studies were based on a computational fluid dynamics investigation to model in-bowl events of fuel spray/air interactions and to improve understanding of the mixing processes. The major variables studied during the test programme included swirl ratio, combustion bowl geometry, nozzle configuration, contemporary and advanced electronic rotary fuel injection pumps and the effects of exhaust gas recirculation (EGR). A systematic optimization programme provided a fixed swirl configuration capable of achieving in excess of 15 bar b.m.e.p. (brake mean effective pressure) while providing less than 1.0 Bosch smoke unit. R49 EURO II NOx levels were met with competitive smoke, particulate emissions and fuel economy, demonstrating excellent potential for full EURO II compliance with further development. Vehicle emissions and fuel consumption simulations have shown that the combustion system has the potential to meet both the heavy and light duty emissions legislation planned for the 1990s.
An Experimental and Numerical Analysis of Riveted Single Lap Joints
Authors: Fung C-P , Smart J 
Published: February 2007

Countersunk and snap riveted single lap joints have been examined both experimentally and numerically. A total of 11 specimens were fatigued to failure with failures occurring in either the plate or the rive***r. The failures have been metallurgically examined to determine the cause of failure. The joints have also been analysed using the finite element method. Initially a single lap joint has been modelled as a ‘stepped plate’ and the results for the stress concentration factor found to be in reasonable agreement with published data. However, the stress concentration for this joint occurred at a point away from the point of failure of a riveted joint. A fuller three-dimensional finite element model has been constructed and the stress patterns around the rivet determined. These stress patterns are discussed in relation to the results from the metallurgical examination.
Axisymmetric Finite Element Analysis of Hip Replacement with an Elastomeric Layer: The Effects of Layer Thickness
Authors: Strozzi A , Unsworth A 
Published: February 2007

Finite element analysis of compliant layered artificial hip joints has been used to study the mechanical response of four different layer thicknesses from 0.5 to 3 mm. The results have been compared with a classical asymptotic model in terms of maximum contact pressure and contact width, and of maximum shear stress at the layer-backing interface and its location. The surface deformations and load capacities have also been compared. The best thickness was found to be 2 mm; though a marginal reduction in stresses would be found in the 3 mm layer, the penetrations would be greater and these might have implications for the fatigue life of the material. A formula for the thickness of the fluid film has been derived on the basis of the inverse hydrodynamic theory and the results show good correlation with existing theories.
The Design and Heat Pipe Tests for a Line Focus Solar Stirling Domestic Generation system
Authors: Trolove H P , Raine J K 
Published: February 2007

This paper outlines the methodology used in the design of a line focus solar Stirling power generation system for remote locations. Tests of potential working fluids for the heat pipes, used to transport energy from the solar concentrator focus to the Stirling engine heater heads, are also described. At the optimum achievable solar absorber temperature, very few heat pipe working fluids are available. Those tested were a sulphur iodine system, the organic fluid dioctyl phthalate and mercury These were designed to deliver energy to an already developed compact hermetically sealed Stirling engine battery charger of 200 W electrical power output. The only fluid to show promising performance was mercury, but safety considerations may rule mercury out for application in numerous dispersed small domestic systems. The line focus system efficiency tends to be low because of the low Stirling engine heater head temperature at optimum system conditions and the greater losses associated with a larger focal area than that used in a point focus system of similar power output. Predicted system efficiency was 4.9 per cent for the prototype 200 W generator and 12.5 per cent for a 3 kW full-scale system on which better insulation of the heat pipe is possible. The size and cost of the 200 W unit in relation to output are likely to be too high to be economically attractive, but development of the 3 kW system may still be viable if alternator efficiency can be maximized and heat pipe thermal losses kept to a minimum.
Efficiency Improvement Options for Municipal Waste-Fired Power Generation—Recent Development Activities in Japan: A Review
Authors: Haneda H 
Published: February 2007

The development of high-efficiency municipal waste-fired power plants, although not yet developed for practical use because of the technical difficulties involved, has recently come to be considered quite important, reflecting strong public demand for conservation of the global environment and preservation of energy resources. Development of such plants is now being actively promoted in various national projects in Japan. This paper first reviews the current status and technical issues concerning (a) municipal waste disposal plants and (b) municipal waste-fired power plants in Japan. Then each of the three approaches that are currently being proposed and vigorously promoted as national projects in Japan for realizing high-efficiency municipal waste-fired power plants is discussed. Although a high percentage of the municipal waste in Japan is incinerated, only a relatively small amount of electricity is generated at present. The paper shows that increasing the proportion of waste used to provide electricity could lead to savings of up to 30 per cent of the annual cost consumption in Japan, with accompanying substantial saving in CO2 emissions. The more effective utilization of municipal waste as an energy source would thus have a significant effect on global environmental conservation and in saving primary energy sources.
Engineering Success Using Teamwork
Authors: Price F Christopher 
Published: February 2007

The incoming President reviews his career which has primarily been in the development of shoemaking machinery and materials with British United Shoe Machinery Limited, subsequently USM Texon Limited, and also in the automobile components industry with Rearsby Automotive Limited. He focuses on the process of using teamwork in achieving successes in these businesses and describes two recent successes in highly sophisticated shoemaking machinery—a family of computer-controlled machines used in the process of bonding soles to shoes and an automatic stitching machine using an integrated vision system to identify and locate workpieces. He reflects on his involvement in the Institution running almost continuously from student membership to his election as the youngest President for 100 years and recommends active involvement as a good contributor to personal and professional development, especially for younger engineers. At a time when the new relationship within the engineering profession is being crystallized, Mr Price discusses the opportunities and challenges for the profession in the light of the ongoing need for strengthening of engineering and manufacturing in the United Kingdom. He concludes that progress has to be achieved by effective teamworking, both within the Institution, with other engineering institutions, with government and with other key organizations in the wider community.
Development of a Micro-Positioning Grinding Table Using Piezoelectric Voltage Feedback
Authors: Kim J-D , Nam S-R 
Published: February 2007

Micro-positioning systems using piezoelectric actuators have a very wide range of applications including ultra-precision machine tools, optical devices and measurement systems. In order to ensure a high-precision displacement resolution, they use a position sensor and error feedback. From a practical point of view, a high-resolution displacement sensor system is very expensive and it is difficult to guarantee that such sensitive sensors work properly in the harsh operating environments of industry. In this paper, a micro-positioning grinding table has been developed which does not require a position sensor but instead uses piezoelectric voltage feedback. It is driven by a hysteresis-sensitive reference input voltage calculated by computer using the actuator/sensor characteristics of piezoelectric materials. The experimental results illustrate the fast and stable response of the micro-positioning system, and the paper suggests a more efficient technique for controlling piezoelectric actuators.
An Energy Error Estimation Method for Improving Analytical Models Using Vibration Modal Test Data
Authors: Guo S , Hemingway N G 
Published: February 2007

When improving analytical dynamic models using modal test data, correct localization of the poorly modelled areas in the analytical model is essential for ensuring the accuracy of the model improvement obtained. In this paper, a method referred to as the energy error estimation (EEE) method is proposed. Firstly, this method is capable of effectively distinguishing the correctly modelled mass and stiffness elements from those poorly modelled regions by using a limited number of test modes. This results in an accurate localization of the analytical modelling errors. Secondly, a set of correction factors can be obtained for improving those elements that are identified as having been poorly modelled. The improved analytical model will also retain its original matrix configuration, size and physical explanation, which is desirable. In order to verify the efficiency and accuracy of this proposed method, beam examples using both simulated and experimental modal test data are demonstrated. Excellent model improvement is shown in these examples.
Friction Materials—Black Art or Science?
Authors: Smales H 
Published: February 2007

This address highlights some of the experiences of the Chairman in his career at Mintex Don Limited, a member of the BBA Group of companies, concerning the development and installation engineering of friction materials. Work on specific component design to overcome problems in both transmissions and brake systems is described; an outline is given of how testing has developed over the past 40 years; and the influence of regulations on testing is described, as well as how the change from asbestos-based to asbestos-free friction materials was achieved. Modern analysis techniques, electronic instrumentation and computational methods have increasingly assisted in this work and it is shown that friction materials have ceased to be developed by ‘black art’ and are now a well understood science.
Modification of a Heavy Vehicle Suspension to Reduce Road Damage
Authors: Cole D J , Cebon D 
Published: February 2007

A test rig for measuring the quasi-static performance of tandem suspensions in the laboratory is described. Measurements on a standard tandem leaf-spring suspension show it to have high effective stiffness in bounce and poor static load equalization. A method for eliminating the spring-end friction is investigated, and found to improve the performance significantly. A two-dimensional articulated vehicle simulation is validated with measurements from a test vehicle. The simulation is then used to study the effect on dynamic tyre forces of three modifications to the trailer suspension: softer springs; elimination of spring-end friction; and hydraulic dampers. The r.m.s. dynamic loads generated by the trailer axles are predicted to decrease by approximately 31 per cent and the theoretical road damage is predicted to decrease by about 13 per cent. The trailer suspension of the test vehicle is adapted to incorporate the three modifications and the measured reductions in dynamic tyre forces are found to be about half those predicted by the simulation.
Modelling of the Behaviour of Dynamical Gas Seals: Calculation with a Finite Element Method Implicitly Assuring the Continuity of Flow
Authors: Hernandez P , Boudet R 
Published: February 2007

The objective of this paper is to present a model of the behaviour of dynamical seals and the corresponding numerical results. These seals are used in the mechanism to realize partial sealing when the relative rotating speeds are too high for usual solutions. The studied seals mainly include two discs: one is attached to the shaft and the other to the body, the last one being pushed and the first being attached by springs. During operation, a gaseous film is created between the discs, preventing any contact. The control of the film thickness allows the leakage flow to be controlled. For the behaviour of such mechanisms, an analytical formulation of the problem is firstly presented. Then a geometrical and kinematical model having one degree of freedom is proposed to model the mechanism having two discs in relative rotation, one of which is spirally grooved. A dynamical model associated with the motion of the disc attached to the body has been developed and the mechanics of thin viscous films is used to study the behaviour of the gaseous film at the interface. Utilization of the finite element method in the mechanics of thin viscous films is introduced and a description of the elements used is presented. The influence of the groove's angle and the groove's depth is shown through numerical results concerning leakage mass flow through the mechanism and the loading capacity of the fluid film, as well as the coefficients of stiffness and damping associated with the dynamical model.