bluuebunny/crossref_metadata_2025 huggingface dataset:
Vehicle Sideslip Angle Estimation Through Neural Networks: Application to Experimental Data
Authors: Melzi Stefano , Sabbioni Edoardo , Concas Alessandro , Pesce Marco
Published: September 2008

This work explores the possibility of using a non-structured algorithm as a sideslip angle valuer: on the basis of a preliminary numerical analysis, a neural network was designed and trained with experimental signals of lateral acceleration, vehicle speed, yaw rate and steer angle. The network was applied to experimental data in order to verify its capability of self-adaptation to changes in friction coefficient and to provide accurate estimations for manoeuvres sensibly different from the ones used during the training stage. The simple architecture joined with an appropriate training set conferred good self-adaptation properties to the neural network which was able to provide satisfying estimation of side slip angle for a wide range of manoeuvres and different friction conditions.
Fluid Dynamic Design Optimization of the Intake of a Small Turbojet
Authors: Amirante Riccardo , Catalano Luciano A. , Dadone Andrea , Daloiso Vito S. E. , Manodoro Dario
Published: September 2008

This paper proposes an efficient gradient-based optimization procedure for black-box simulation codes and its application to the fluid-dynamic design optimization of the intake of a small-size turbojet, at high load and zero flight speed. Two simplified design criteria have been considered, which avoid to simulate the flow in any turbojet components other than the intake itself. Both design optimizations have been completed in a computational time corresponding to that required by eight flow analyses and have provided almost coincident optimal profiles for the intake. The flow fields computed with the original and the optimal profiles are compared to demonstrate the flow pattern improvements that can be theoretically achieved. Finally, the original and the optimal profiles have been mounted on the same small-size turbojet and experimentally tested, to assess the resulting improvements in terms of overall performances. All numerical and experimental results can be obviously extended to the intake of a microturbine for electricity generation.
Remote Controlled Underground Robot for Landfill Drainage
Authors: Belotti Vittorio , Michelini Rinaldo C. , Zoppi Matteo
Published: September 2008

The environmental policy of EU, acknowledged by the Economics Ministers in June 2001 meeting, establishes a set of priorities. The present paper deals with urgent demands in these fields, with attention on pollution decreasing/removal. A survey of European Topic Centre on Waste, based on partial data only, points out the risk of sewage and leachate contamination of subsoil and waterbed for 13500 landfills. The European Council, in the Directive 97/C_76/01, requests the member states to take the necessary measures to ensure, to fullest practicable extent, that old-landfills and polluting-sites should be rehabilitated. This request is specifically addressed, with the Microdrainage project, EVK4-CT-2002-30012, successfully achieved building the robotic prototype, properly operative from mid 2005. The paper presents the innovative developments undertaken by the project. A new drilling equipment is built, suited for autonomous operation, with fully automatic effectors and rods feeding and with multi-function boring/drilling head, to comply with complex work-task schedules. The mechanical architecture needs proper sophistication, to deal with rods supplying along the micro-tunnel, local buffering to complete the lay-down of a draining line, and mast feeding by the purposely designed arm. The system implementation, thereafter, tackles with the severe technical specifications for the micro-tunnel surroundings, and exacting performance requirements in rig levelling, mast attitude accuracy and work-task sequencing. By this project, the successful deployment of these enabling technologies helped in developing the novel robotic device, capable to solve the de-pollution requirements of the EU environmental policy.
Damage Criterions in Thermo-Mechanical Fatigue Models
Authors: Delprete Cristiana , Rosso Carlo , Sesana Raffaella
Published: September 2008

In the present paper different damage criterions, recorded in literature, are compared, distinguishing the philosophical approach to thermo-mechanical fatigue (TMF) in energetic methods and phenomenological methods. TMF is the combination of mechanical and thermal stresses that takes place in most of mechanical components, especially in automotive engines. The presence of thermal together with mechanical cycling can worsen fatigue and ageing phenomena. In order to describe the TMF behavior of a material or of a component it is necessary to take into account different phenomena contributing to progressive damage as plastic strain, thermal strain, creep and oxidation. In literature it is possible to find different definitions of damage: strain accumulated energy, volume unit damage, residual life. Many papers on TMF are available like experimental studies, analytical investigations, analytical models of damage, life prediction models. The present paper aims to make a first selection of TMF life assessment criteria by means of literature critical analysis. Then, by means of numerical model of actual TMF component, i.e. an exhaust manifold, a comparison between the selected methods is done. Using a set of experimental and numerical analyses of exhaust manifolds collected in literature papers, a comparison and results discussion are done.
Optimal and Robust Design of Ground Vehicle Systems
Authors: Gobbi Massimiliano
Published: September 2008

A new approach for the design of vehicle subsystems is addressed in the paper. The new approach is based not only on the theory of multi-objective optimisation but also on robust design. The method is characterised both by the optimisation of the objective functions (corresponding to system performance indices) and by the reduction (or minimisation) of the sensitivity (variance) of the performance indices to stochastic perturbations. Such variances are computed (very quickly) by means of an original procedure based on the global approximation of the objective functions. Additionally, with respect to the mentioned features, the new approach is based on both a special study to explore all of the feasible design solutions, and on a global sensitivity procedure to analyse (in a stochastic context) the influence of each design variable on each objective function. Pareto-optimal design solutions for different levels of “robustness” can be computed in a very short time. The optimisation method has been tested on a relatively simple problem and applied with successful results to a complex design problem related to vehicle design.
Experimental Analysis of Orifice Type Thrust Bearing
Authors: Malhi Charanjeet Kaur , Cherian Trupti
Published: September 2008

A single pad thrust bearing with central orifice restrictor, was fabricated and tested with a loading frame design for varying loads and supply pressures. One of the objectives of conducting the test was to obtain load verses air-gap curves for different supply pressures. The air bearing was supplied with different diameters of orifice. Another objective was to measure recess pressure at different supply pressures and loads and obtain a three dimensional plot. The recess pressure in the bearing is measured by the Smart Pressure Device. The testing of the thrust bearing enabled to validate the measurement system used. The results obtained were in good agreement with the investigations made in this field by other investigators. The sensor used also showed good repeatability and linearity, which approves its use for the measurement system.
On the Use of Fast-Response Pressure Transducers in a Common-Rail Diesel Injection System
Authors: Amirante R. , Catalano L. A. , Dadone A. , Lombardo V.
Published: September 2008

The aim of this paper is to investigate the use of fast-response pressure transducers for measuring the instantaneous pressure in different sections of a common-rail diesel injection system, both for a single injection and for multiple injections. The influence of the pressure transducer onto the measured pressure is evaluated numerically by comparing the pressure history computed without the pressure transducer and that computed with the presence, and thus with the disturbance, of this sensor. A new electric circuit is proposed in substitution of the standard electronic central unit, which allows to modify the injection parameters and to perform injections on a test rig, as done in the automotive applications. Experimental results are provided both for a single injection and for multiple injections, to demonstrate the capabilities of the proposed test bench for the unijet injectors.
Integrated Modeling of Vehicle and Driveline Dynamics
Authors: Cheli Federico , Pedrinelli Marco , Zorzutti Andrea
Published: September 2008

In the last years automotive industry has shown a growing interest in exploring the field of vehicle dynamic control, improving handling performances and safety of the vehicle, actuating devices able to optimize the driving torque distribution to the wheels. These techniques are defined as torque vectoring. The potentiality of these systems relies on the strong coupling between longitudinal and lateral vehicle dynamics established by tires and powertrain. Due to this fact the detailed (and correct) simulation of the dynamic behaviour of the driveline has a strong importance in the development of these control systems, which aim is to optimize the contact forces distribution. The aim of this work is to build an integrated vehicle and powertrain model in order to provide a proper instrument to be used in the development of such systems, able to reproduce the dynamic interaction between vehicle and driveline and its effects on the handling performances. The developed models have been validated through comparison with experimental results obtained with a 4WD vehicle.
Hot Drilling of 6082 Aluminium Alloy
Authors: Santo L. , Trovalusci F. , Tagliaferri V.
Published: September 2008

In traditional machining drilling is a major and common holemaking process in which lubrication and cooling are very important to improve the machining. The idea proposed in this paper regards the metal heating during the drilling operation by means of an infrared lamp. In this way a reduction in thrust force and torque is expected, since the material properties have been changed. Some experimental tests are carried out on Al 6082 in dry drilling operation, using a conventional milling machine and cobalt-coated HSS twist drills 2.5, 5, 7 mm in diameter. The spindle speeds range from 5000 to 15000 Rpm, the feeds range between 0.0076–0.042 mm/rev, the temperature is varied in the range of 40–140°C. Besides, Flat-top cylinder Indenter for Mechanical Characterization (FIMEC) tests for material characterization are carried out to obtain the yield stress of material varying temperature. The main result is a significant reduction of the thrust force (from 10 to 34% depending on the process conditions). By analysing the data of forces as a function of temperature, a minimum value of force is always found in correspondence of a temperature depending on drill diameter and feed. The influence of each parameter is investigated. The experimental data in terms of force are also correlated to the measured yield stresses to study the influence of material properties on drilling machining. Further study must be developed to investigate the torque, the mechanisms of chip formation and the tool wear.
Torsional Analysis of a 20-Cylinder Hypercompressor Train
Authors: Giacomelli Enzo , Mazzali Carlo , Campo Nicola , Battagli Paolo , Falciani Fabio
Published: September 2008

The capacity of plants for the production of low-density polyethylene is increasing worldwide and is continuing to challenge designers to provide the larger compression machinery required. The expected level of reliability and availability is very high, and the cylinders and frames of these reciprocating compressors are specially designed to withstand this heavy-duty service. All design aspects have to be properly considered, including the torsional analysis that represents a very critical element. This article considers a train with 2 compressors, each configured with 10 cylinders, with an electric motor drive between them. One machine is directly coupled to the motor while the other has a flexible coupling. This represents the largest reciprocating compressor train in the world, with a total motor power of 33 MW.
Microstructural Effects on the Wear Resistance of Co-Cr Implant Alloys
Authors: Affatato S. , Leardini W. , Jedenmalm A. , Zavalloni M. , Ruggeri O. , Tarterini F. , Viceconti M.
Published: September 2008

Modern metal-on-metal articulation have been proposed to reduce the incidence of osteolysis due to polyethylene particles debris, as a late complication. The tribology of large metal-on-metal articulations allows theoretical advantages with respect to other configurations, especially for the lubrication regime. This study was aimed to compare the wear performances of different diameters of clinically available acetabular metallic components manufactured in a cast cobalt-chrome alloy. To evaluate the influence of the material properties of wear and microstructure, metal-on-metal components were tested in a hip joint simulator for five million cycles with bovine calf serum as lubricant. In particular, three different configurations of metal-on-metal components (28-mm, 36-mm, 54-mm) were tested. After the test all specimens were examined with optical and electronic scanning microscope. A statistical difference were observed among the three groups tested in the run-in and steady-state wear rates, favoring the larger femoral heads. The results of this study indicate that the 54-mm diameter femoral heads prove a better wear behavior than the smaller configurations.
Effect of Head Surface Roughness and Sterilization Method on Wear of UHMWPE Acetabular Cups: Preliminary Hip Joint Simulator Results
Authors: Jedenmalm Anneli , Leardini Walther , Zavalloni Mara , Affatato Saverio
Published: September 2008

More than one million hip joint replacements are performed each year in the world. However, the implants do not last forever due to material limitations, even though the operation is successful. The most common material combination used today is a CoCr head articulating against an UHMWPE (Ultra High Molecular Weight Polyethylene) acetabular cup. Several investigations have shown that the metal head is roughened inside the body and thus accelerating wear of the polymer cup. The sterilization method is also known to have effect on the wear properties. In vitro wear tests are however usually performed with as new implants. This investigation aimed at study the impact of head surface roughness on wear of both sterilized and non-sterilized acetabular cups. A total of nine acetabular cup and head pairs were wear tested in a hip joint simulator for 2Million cycles (Mc) with bovine calf serum as lubricant. Wear was determined by weighing of all cups. The heads were of CoCrMo and the average initial head surface roughness was 15nm (Ra), measured with a white light interference profilometer. The roughening was produced with a SiC paper producing circular multidirectional wear tracks to a surface roughness of about 400nm (Ra). The cups were of UHMWPE and the sterilized cups were 3Mrad gamma-radiated in nitrogen. The surface roughness after wear test was unchanged for the roughened heads, while the initially smooth heads were slightly roughened. Preliminary results show that the rough heads increase the wear of the cups 2-fold. The γ-irradiation affected both wear- and soak rate.
Vehicle Dynamics Control System Actuating an Active Differential
Authors: Cheli Federico , Pedrinelli Marco , Campo Sebastiano , Fortina Andrea , Martella Paolo
Published: September 2008

In the last years automotive industry has shown a growing interest in exploring the field of actively controlled differentials due to the promising expectations of their application for the improvement of handling performances. The differential here considered has two clutches, which connect each driveshaft with a second part that, through a gear, always rotates faster. This device allows the control system to transfer torque from one wheel to the other one, almost independently from their relative velocity. The results of this preliminary modeling phase are shown in the first part of the paper. The control algorithms development has been carried out using a vehicle model that can precisely simulate the handling response, the powertrain dynamics and the actuation system behavior. To obtain a representative powertrain response, the development of a customized library in Simulink has been required. Applying a methodology commonly shared among car manufacturers, for this research a two-steps approach has been adopted: firstly an intensive simulation campaign has been executed to design and tune the controller in the virtual environment; secondly the logic has been tested using HIL techniques. The second part of the paper introduces the general structure of control system developed and its main algorithms. Vehicle performance improvements, evaluated through simulation and HIL tests, are underlined.
Theoretical Basis of Generation of Face Worm Gear Drive With Duplex Worm
Authors: Gessner Andrzej
Published: September 2008

New type of face worm gear drive with double-lead worm is proposed. The advantages of that gear in comparison to contemporary known gears are also mentioned. The shaping process of the face worm gear is carrying out by means of a single point tool. The same insert is used for cutting the duplex worm. Using a single point tool instead of hobbing cutter considerably reduces the manufacturing cost, in which the share of tool production plays the main role. The shaping process is performed on a CNC milling machine with or without additional equipment. Two main methods of shaping depended on setting up the tool machine are presented. One of them requires no special equipment but a single point tool with insert of specific tool included angle, whilst the second uses a constructed tooling. There are also described 3 methods of shaping the face toothing, which depends on the used technology. Geometry of that face worm gear drive is presented and described. The tooth depth is constant along the whole tooth line. Nominal width of tooth section as well as its location depends on the lead difference of the worm. Provided scheme can be used to calculate those parameters. The total length of the duplex worm is calculated by taking into consideration the internal and external diameters of the worm gear and the additional length which is needed to reduce the backlash. The shape and size of the single point tool is determined according to the worm and the necessary geometric model is provided. There are also given criteria, which limit the maximum length of worm and its maximum lead angle. A complete algorithm describing the designing process of that type of gear is presented in the final part of the article.
Experimental Investigation of Water Jet Orifice Efficiency by a Novel Laser Doppler Velocimetry Technique
Authors: Annoni Massimiliano , Cristaldi Loredana , Norgia Michele , Svelto Cesare
Published: September 2008

The problem of efficiency evaluation of water jet nozzles has been dealt in the present work and a novel Laser Doppler Velocimetry (LDV) technique has been proposed in order to acquire high-speed water velocity at the exit of the cutting head nozzles. A standard LDV technique has been implemented for the first experimental trials with the aim of applying the theoretical approach to measured velocity values. A novel LDV technique has been proposed outlying of the critical aspects to be taken into account for future developments and improvements in measurement dynamic range, resolution, and accuracy.
Vapour Compression and Liquid Desiccant Hybrid System for Air Conditioning
Authors: Bergero Stefano , Chiari Anna , Nannei Enrico
Published: September 2008

The present study examines the performance of a hybrid air-conditioning system in which a vapour compression inverse cycle is integrated with an air dehumidification system working with hygroscopic solution and hydrophobic membrane. This approach may prove to be a valid alternative to the traditional summertime air-conditioning system, which involves cooling the air to below its dew point and subsequently reheating it. The system examined simultaneously cools and dehumidifies the air in an air-LiCl solution membrane vapour exchanger before it enters the conditioned environment. The LiCl solution is cooled by means of a vapour compression inverse cycle that uses the refrigerant KLEA 407C. The heat rejected by the condenser is used to regenerate the solution. A SIMULINK calculation programme was used to simulate the system in steady-state conditions. The performance of the system was analysed on varying significant operating parameters and was compared with that of a traditional direct-expansion air-conditioning plant. The results of the simulations revealed significant power saving which, in certain operating conditions, was as much as 50%.
Experimental Analysis of a Soft Compliant Tactile Microsensor to be Integrated in an Anthropomorphic Artificial Hand
Authors: Beccai L. , Roccella S. , Ascari Luca , Valdastri P. , Sieber Arne , Carrozza M. C. , Dario P.
Published: September 2008

This paper presents the experimental analysis of a high shear sensitive 1.4mm3 three-axis force microsensor embedded in a soft, compliant and flexible packaging with minimum thickness of 2mm. The study is aimed at investigating the response of the tactile microsensor when it is stimulated with a combination of normal and shear loads. Experimental analysis is focused on the transient phenomena when a change of static to dynamic friction occurs at the packaged microsensor surface during interaction with an external object. According to a bioinspired design approach that is based on the emulation of natural mechanoreceptors of the human skin for providing appropriate tactile event encoding, the transient behaviour quantitative analysis is fundamental for assessing if the sensor is applicable in an artificial hand for controlling grasping and manipulation of an object.
On the Design of Three Links Robot for Drawing Epicycloid and Hypocycloid Curves
Authors: Hsu Meng-Hui , Tsai Zong-You , Hsieh Long-Chang , Liu Jen-Yu
Published: September 2008

An epicycloid or hypocycloid mechanism is capable of drawing an exact epicycloid or hypocycloid curve. Similar mechanism designs can be found abundantly in industrial machines or educational equipment. Currently, the major type of epicycloid or hypocycloid configurations is planetary gear trains, which contain a binary link that has one fixed and one moving pivot, and a singular link adjacent to the moving pivot. The main feature of the configurations is that any point on the singular link may describe an epicycloid or hypocycloid curve when the binary link is rotated. Presently, the major types of configurations of epicycloid (hypocycloid) mechanisms have one degree of freedom. However, at present, as far as the authors are concerned, there appears to be no approach in designing epicycloid (hypocycloid) mechanisms with two degrees of freedom. Thus, the main aim of this paper is to develop a new design method in designing new configurations of epicycloid (hypocycloid) mechanisms. This paper analyses the characteristics of the topological structures of existing planetary gear train type epicycloid (hypocycloid) mechanisms with one degree of freedom. The equation of motion and kinematical model of the mechanism was derived and appropriate design constraints and criteria were implemented. Subsequently, using the design constraints and criteria, this work designs a new and simple epicycloid (hypocycloid) mechanism that is a three-links robot and has two degrees of freedom. We can easily control the angular velocities of the binary and singular links to satisfy the criterion to draw an epicycloid (hypocycloid) curve. Additionally, an epicycloid (hypocycloid) path of a point on the three links robot is simulated by computer drawing to prove the feasibility of proposed theory. Finally, a prototype of three links robot for drawing an epicycloid (hypocycloid) path is done well. We know the methods of design and manufacture of the proposed epicycloid or hypocycloid mechanism in linkage is easily done.
A Numerical Procedure for Obtaining the Static and Pull-In Deflection and Voltage of Capacitive Microcantilever Beams
Authors: Ghaemi Oskouei Seyed Babak , Alasty Aria
Published: September 2008

A numerical procedure is proposed for obtaining the static deflection, pull-in (PI) deflection and PI voltage of electrostatically excited capacitive microcantilever beams. The method is not time and memory consuming as Finite Element Analysis (FEA). Nonlinear ordinary differential equation of the static deflection of the beam is derived, w/wo considering the fringing field effects. The nondimensional parameters upon which PI voltage is dependent are then found. Thereafter, using the parameters and the numerical method, three closed form equations for pull-in voltage are developed. The results are in good agreement with others in literature.
An Integrated Approach With Innovative NDTS for Thermal Barrier Coating Assessment: Optical and Frequency Scanning Eddy Current Testing (F-SECT) Combination With Pulsed Thermography
Authors: Rinaldi Claudia , de Maria Letizia , Cernuschi Federico , Antonelli Giampiero
Published: September 2008

The components of the hot gas path in gas turbines can survive to very high temperatures because they are protected by ceramic Thermal Barrier Coatings (TBC); the failure of such coatings can dramatically reduce the component life. A reliable assessment of the Coating integrity and/or an Incipient TBC Damage Detection can help both in optimising the inspection intervals and in finding the appropriate remedial actions. In this paper the potential of three different NDT techniques applicable to the metallo/ceramic coatings of hot parts are discussed in the light of both results obtained on laboratory aged specimens and in field measurements on operated components. An investigation of the NDTs capability to detect damage evolution was performed on thermal-cycled specimens coated with TBC (both EB-PVD and pseudocolumnar APS) by means of an F-SECT eddy current system, by an innovative portable Piezospectroscopic system and by pulsed thermography. The observation of metallographic sections of the thermal cycled specimens allowed to give the right interpretation to the results of each NDT methodology and enlightened its specific characteristics and potentiality. Moreover in field applicability is discussed for each technique. Finally it is shown how an integrated approach of suitable coating evolution models and complimentary NDT techniques can provide an interesting assessment of the damage level of the metallo/ceramic coatings of operated rotating blades.
1D Modelling and Simulation of a Piezo Injector for Spray Guided Gasoline Direct Injection Systems
Authors: Antonelli Marco , Martorano Luigi , Nuti Luca , Provenzale Michele , Matteucci Luca
Published: September 2008

The aim of this work was the modelling and the simulation of the Piezo injector, developed by Siemens VDO Automotive for “spray guided” Gasoline Direct Injection (GDI) systems. The development of the model was based on a 1D lumped parameter approach, which was performed in the AMESim environment. The injector was accurately modelled in its three subsystems, namely the piezo actuator, the thermal compensator and the valve body, in order to have a complete control on its behaviour. The reliability and the accuracy of the models of each subsystem were evaluated through comparisons with experiments for various operating points. The last part of this work describes some applications where the model was used and it demonstrates how accurate modelling and simulation may allow a real contribution in the understanding and optimization of the injector behaviour, reducing time and costs that are involved in an only experimental analysis.
Design of Noncircular Gears to Minimise Shaft Accelerations
Authors: Vanegas Useche Libardo V. , Abdel Wahab Magd M. , Parker Graham A.
Published: September 2008

This paper presents a novel pair of noncircular gear profiles for minimising shaft accelerations of the driven gear. The proposed profiles are developed based on an “exponential” function that is valid for a portion of gear rotation, and this function is extended to the remaining parts of the rotation of both gears. The exact shapes of the centrodes of the toothed bodies, which depend on a “smoothness” parameter, b, constitute a trade-off between the maximum shaft acceleration and the smoothness of the centrodes, so as to control the maximum tooth dynamic forces and stresses. A comparison between the derived noncircular gears and a gear pair that provides a sinusoidal variation of the angular velocity is presented. Results indicate that, for two-lobule gears, the maximum and minimum values of the polar radii, the velocity at the contact point, and the gear ratio are the same for both profiles. In contrast, there are significant differences in the angular acceleration of the driven gear, the tangential acceleration at the contact point, and the pressure angle, especially in the first one. It is concluded that the derived pair not only can provide low shaft accelerations, but also low tangential accelerations and small pressure angles.
Observer Design for Active Suspension Control for Passenger Cars
Authors: Cheli Federico , Resta Ferruccio , Sabbioni Edoardo
Published: September 2008

An observer for controlled suspension is presented in this paper based on acceleration measurements. The proposed observer allows to estimate the system states and can be profitably used in a state-derivative feed-back control. This kind of control, designed in the reciprocal-state-space framework (RSS), is based on the optimal control theory and consists in minimizing the derivative of the state vector instead of the state vector itself.
Brush Dynamics: Models and Characteristics
Authors: Vanegas Useche Libardo V. , Abdel Wahab Magd M. , Parker Graham A.
Published: September 2008

This paper reviews investigations into the dynamics and modelling of brushes. They include brushes for surface finishing operations, removal of fouling, post-CMP brushing processes, air duct cleaning, and street sweeping. The methods that have been proposed to model brush dynamics are described, and the results of the research into brush mechanics are presented and discussed. Some conclusions of the paper are as follows: brush dynamics is very complex, as it depends on the interaction among many phenomena and variables. The bristle oscillations that occur in some brushes constitute a complexity for modelling brush behaviour and are not normally addressed. Additionally, the literature reveals that the coefficient of friction is not a constant value that depends only on the materials and surface roughness of the two contacting bodies. Frictional behaviour strongly depends on many variables, such as brush setup angles and rotational speed, which play a part in the development of stick-slip friction cycles. Finally, it is concluded that brush behaviour and the phenomena involved in brushing have not been fully studied or understood and more research into this field is needed.
Development and Assessment of Defrosting Strategies for Transport Refrigeration Systems
Authors: Donnellan Wayne J. , Lohan John , Gleeson Ken
Published: September 2008

When commercial transport refrigeration systems operate at temperatures of 0°C frost accumulates on the surface of the evaporator coil. Occasionally, defrost cycles are required to remove frost from the coil to sustain effective operation of the refrigeration system. This paper details results of an experimental investigation undertaken to characterise the performance of an existing defrost strategy that was in turn modified to improve its performance and effectiveness. Results are reported for two significant modifications, the first of which utilises new criteria for terminating the defrost cycle and the second that employs higher compressor speeds during defrost. Results show that the number of defrosts required was reduced by 20 to 40% yielding more stable temperature control and reduced fuel consumption during defrost.
Development of a Laser Based Dual-Axial Five-Degrees-of-Freedom Measurement System for an X-Y Stage
Authors: Jywe Wen-Yuh , Liu Chien Hung , Teng Yun-Feng , Chen Chun-Jen , Shen Jing-Chung , Hsieh Wen-Hsiang , Wang Yung-Cheng
Published: September 2008

This paper presents a new precision multi-DOF measurement system which has been developed and implemented for the simultaneous measurement of 5DOF motion errors (two linear positions, as well as pitch, roll and yaw) of an X-Y stage. In this paper, the 3DOF laser interferometer was produced by designing the optical path from the one-degrees-of-freedom laser interferometer. The system employs two three-degree-of-freedom interferometers to detect two position errors and three angular errors of the X-Y stage. The experimental setups and measuring procedure and a systematic calculated method for the error verification are presented in the paper. The resolution of measuring the angular errors component is about 0.055 arcsec.
Finite Element Analysis of Side-Load Springs for McPherson Front Suspensions
Authors: Frendo Francesco , Sarra Vincenzo , Spina Michele
Published: September 2008

In the present work, the operating conditions of “side-load” springs, which are typically employed in McPherson suspensions, were analysed by finite element analysis. The finite element model, including the spring and the upper and lower spring seats, is firstly described in the paper; the spring geometry was accurately obtained by a reverse engineering procedure based on two video cameras and a video projector. Surface to surface contact elements were defined between spring and seats; the initial assembling phase of the spring between the seats was also included in the finite element analysis. The experimental rig, employed for spring characterisation, and the performed numerical analyses are then presented; results are discussed in comparison with experimental data, in terms of spring characteristic, side-load force and thrust axis spatial position, as a function of spring compression. A fully satisfactory agreement was generally observed between numerical results and experiments. The effect of lower spring seat orientation on results was also investigated by numerical analysis. A higher inclination of the lower seat appeared to increase the side-load force; at the same time, for a given configuration, the thrust axis orientation, remained almost constant during suspension compression.
High-Pressure Rotary Pump Performance in Multi-Jet Common Rail Systems
Authors: Catania Andrea Emilio , Ferrari Alessandro , Mittica Antonio
Published: September 2008

The high-pressure hydraulic circuit of the Multi-jet Common Rail (C.R.) system has thoroughly been investigated in the last few years by researchers of the automotive field. However, shortage of knowledge is still present about the high-pressure pump performance. Hydraulic-mechanical efficiency of the pump is only known as mean value and no published data are available on the Radial-jet compression volumetric efficiency. Due to the fact that part of the pumped fuel is partially expelled by the pressure-control valve and because of the presence of the oil flowing in the cooling and lubrification circuit, the determination of the compression volumetric efficiency seems to be a hard task. In the present paper a detailed description of the Radial-jet performance has been provided. The dependence of the flow rate sucked by the high-pressure pump, on speed and load has been studied and the characteristic curve of the cooling-lubricant circuit has been determined. A special procedure was designed and applied for the experimental evaluation of the fuel leakages from the pumping chambers, so as to allow the calculus of the volumetric efficiency. The actual head-capacity pump curves at different revolution speeds were plotted and compared with the electroinjector flow-requirements so as to allow the evaluation of the efficiency of the pressure-control strategy. Furthermore the pump mechanic-hydraulic efficiency dependence on head and speed was also experimentally assessed.
Modelling a Friction Damper: Analysis of the Experimental Data and Comparison With Numerical Results
Authors: Firrone Christian M. , Botto Daniele , Gola Muzio M.
Published: September 2008

High cycle fatigue is one of the main causes of failure of blades in turbomachinery. The negative impact of HCF on turbomachinery blades can be reduced by dry friction vibration damping. A typical application of dry friction damping in gas turbine is the so called “underplatform damper”. In this work a ‘real life’ asymmetric underplatform damper is experimentally tested with two real blades. A static test rig is used to obtain the nonlinear frequency response function of a mock-up made with two real blades with an underplatform damper between them. This paper addresses an underplatform damper model taking into account damper rotation. The proper mathematical formulations have been developed and forced response calculation of the system have been performed. Comparison with experimental data are carried out for different values of excitation forces and for pre-load similar to real centrifugal force values.
Analytical Shock Response of a Transversely Point-Loaded Linear Rectangular Plate
Authors: Hampton R. David , Nygren Kip P. , Li Ting H.
Published: September 2008

Ballistic shock, the strong vibrations that propagate through a vehicle structure after a ballistic impact, can damage electronic components that are mounted on various interior locations of the vehicle. To protect onboard critical electronic components from ballistic shock damage, predicted shock response spectra (SRS) are used as design guidelines in the selection of shock isolation devices. Current technology to predict shock response intensity at component mounting locations includes Finite Element Analysis, Statistical Energy Analysis, and various other modeling approaches. The Army Research Laboratory is implementing a process to determine component damage probability based on a numerical modal superposition method. This process allows detailed modeling of an entire vehicle (including instrumentation racks) but requires months of effort to perform skillful FEA modeling. Such an expenditure is acceptable only for unique high value vehicles, and is impractical for analysis of many vehicles. Therefore it is desirable to investigate alternative shock analysis methods that are simple and general (i.e., independent of specific vehicle configurations). Although such methods could entail reduced accuracy, for situations that are applicable they would eliminate the need of time-consuming finite element modeling, and could used in a variety of vehicles. As such, the methods could be used for “screening” for rapid identification of potential shock-damage issues. If necessary, further detailed analysis could be accomplished subsequently. When an armored vehicle is subjected to a non-perforating large-caliber munitions impact or blast, direct mounted components that are near the impact location will always risk the highest damage potential. Live fire ballistic tests and laboratory experiments as well as numerical modeling have proved this observation. The research presented in this paper develops, from an exact continuous model, a constant- and lumped-parameter, linear matrix model of a homogeneous, rectangular, simply-supported plate subject to transverse ballistic shock. The model is provided in a form suitable for eigen-analysis intended to yield kinematic responses for SRS determination. Damping can be included in either Rayleigh or modal form. The enabled “same-plate” shock analysis, while not encompassing an entire military vehicle, would treat the most severe cases of shock response, for components mounted directly on the impacted plate.
Characterization of Material Properties Using Strain Mapping and Reverse Engineering
Authors: Lin Lianshan , Li Haiyan , Fok Alex S. L.
Published: September 2008

For simplicity, the material properties used in engineering analysis are often assumed to be linear elastic, isotropic and homogeneous. These simplifications may lead to erroneous stress and failure predictions if the materials involved are highly nonlinear, anisotropic and inhomogeneous. Based on the techniques of strain mapping and reverse engineering, a simple finite-element-based method has been devised with the aim of characterizing the properties of such materials under load. The method has been implemented into the commercial finite element code ABAQUS, via its User Material Subroutine (UMAT), to allow material characterization to be performed easily. Verification of the method has been carried out using simulated examples and the results showed rapid convergence of the method with good accuracy. The method has also been applied successfully to actual mechanical testing of graphite.
An Experimental and Numerical Study to Analysis and Design of Sheet Hydroforming Process for an Automobile Fender Shell
Authors: Habibi Parsa Mohammad , Darbandi Payam
Published: September 2008

A new approach for manufacturing of shell fender is proposed and has been examined numerically and experimentally. The new suggested method is based on sheet hydroforming process, which has a lot of advantages over conventional deep drawing process. After defining the shape of initial blank using an inverse finite element program, numerical evaluation of the proposed sheet hydroforming process for production of shell fender has been carried out using an explicit finite element code considering fluid pressure, boundary conditions and tools. Then experimental evaluation has been carried out using down sized specimen and the results have been compared with results of previous simulations. It has been shown that there are similar trends between finite element and experimental results.
Innovative Air Estimation and Luenberger Observers in Model Based A/F Control
Authors: Cannavo` Cecilia , Cipollone Roberto , Pinamonti Silvio Antonio , Sciarretta Antonio
Published: September 2008

In this paper it has been demonstrated as the closed loop air fuel ratio (A/F) control system, equipped with a linear oxygen sensor (UEGO), can be improved with an innovative reformulation of the fuel injection control by means of a model based approach. The A/F control, within a rigorous speed-throttle logic (which avoids the use of the air flow-meters and of the pressure sensors inside the intake manifolds), can be designed using a Luenberger-type observer which includes the dominant dynamics of air, fuel and oxygen lambda sensor. The control has been developed and experimented on a research one-cylinder spark ignited engine (AVL 5401). The air mass reference can be supplied either by a stationary map, or, in substitution, by a physical gas dynamic code (Method of Transfer Function, MTF) which is able to compute cycle by cycle the pressure pumping fluctuation and the cylinder filling (volumetric efficiency) giving rise to an effective estimate of the volumetric efficiency during transients, avoiding in this way the use of experimental stored data. The experimental campaign on AVL 5401 has tested the control performances in transient conditions determined by moderate and severe unsteady maneuvers concerning both the load and the engine speeds, demonstrating the robustness of the proposed observer-based control strategy and the possibility to replace the map with the MTF code. The control is able to keep the A/F in the most part of transients around the stoichiometric, with transient control errors bounded within 3–4% in presence of critical throttle maneuvers which are more severe than in the usual operative conditions.
HEAC and THYCS Projects
Authors: Mola Stefano , Martini Stefania , Parodi Maria Laura , Lo Presti Giulio , Malvicino Carloandrea
Published: September 2008

Due to its more and more widespread diffusion, Air Conditioning (A/C) systems in automobiles will face two main challenges in the near future: to improve the evaluation and control of perceived thermal comfort, and to reduce the fuel consumption increase due to its use (up to 70% in urban operation under hot weather [1]). In view of future regulations and heightening environmental concern, rapid action is needed to reduce such negative A/C impact. Moreover, the A/C system has also an important role in safety, since it has to assure the driver’s visibility by avoiding fogging formation on the windshield in any condition of use. This function has to be assured in the most reliable and automatic way, minimising the interaction of the driver with the A/C system itself. The two research projects described in the present paper have the following goals: • To improve the perceived thermal comfort evaluation. • To lower the impact of air conditioning system on fuel consumption. • To detect incipient fogging conditions in a reliable and predictive way. The research activity has been performed with the following constraints: • To minimize the number of sensors. • To reduce the cost of the air conditioning system.
Crash Structural Improvements in Automotive Vehicles Using Metallic Foams
Authors: Bassan Daniele
Published: September 2008

More and more stringent requirements in passive safety lead automotive manufactures to explore new ways to improve present passengers cars performances. Material engineering could contribute to the development and application of improved materials with higher performance with respect to the conventional metals applied in car design. Aluminium foams are currently monitored as application from automotive manufactures thanks to their potential in terms of contribution for energy absorption and stiffness improvement. Several application studies have been proposed from major automotive research branches and the potential in terms of performance improvement has been exploited. Up to now, nevertheless, many studies have been performed only from the performance point of view, most of the time on simplified demonstrators, without taking into account a global vision in terms of process compatibility with common automotive manufacturing lines. In the present paper a detailed investigation of metallic foam application as structural vehicle reinforcement has been accomplished. Starting from finite element analysis (FEA) a metallic foam reinforced version of a Multipla car vehicle has been redesigned and manufactured in standard manufacturing line. The experience obtained both from the manufacturing and from the experimental crash test has allowed a deeper knowledge of metallic foam behaviour. The present works represents a step forward with respect to the current investigations on real applications in cellular materials.
Diesel Engine Combustion Monitoring Based on Acoustic Measurement of Exhaust Systems
Authors: Gennish R. , Jiang J. , Albarbar A. , Harris G. , Gu F. , Ball A.
Published: September 2008

This paper presents a novel monitoring approach to diesel engine combustion based on acoustic measurement of exhaust systems. It investigates the acoustic characteristics from the measurements of individual sensors and their combination based on a linear one port acoustic source model. It has been found that the strength, in terms of pressure, of the acoustic source gives a more accurate representation of engine acoustics because it is obtained by minimizing the reflection effects in the exhaust system. Therefore, the pressure waveform produces more accurate monitoring results for abnormal combustions such as those caused by faults in engine fuel injection systems.