bluuebunny/crossref_metadata_2025 huggingface dataset:
3D Thermal Analysis of a Power Supply Busbar Structure
Authors: Plesca Adrian , Scintee Alina
Published: January 2011

Busbar technology is more and more used to realize connections within power supply systems in answer to the need of compactness. The integrated problem on heat conduction and radiation-convective heat exchange describes the temperature regime in current conductors and current carrying busbars of power electrical apparatus such as circuit breakers or high breaking capacity fuses. Beside steady-state conditions, the transient thermal regime of busbar has an important influence upon whole power supply system from thermal behaviour point of view. Hence, a 3D thermal analysis of a power system including fuse, low voltage circuit breaker and busbars connections, using a specific software package based on Finite Element Method, has been done. From 3D thermal modelling and simulations, the thermal transient impedance for the busbar has been computed. This allows a better correlation between protection characteristics of the fuse and circuit breaker and busbar design.
Cavity Flame Holding for High Speed Reacting Flows
Authors: Tuncer Onur
Published: January 2011

Combustion phenomena in a ramjet combustor with cavity flame-holder is studied numerically. Combustor follows a constant area isolator and comprises of hydrogen fuel injected sonically upstream of the cavity. Secondary fuel injection is performed at the cavity backwall. A diverging section follows the cavity to prevent thermal choking. These concepts are also utilized in practice. Calculations were performed for an entrance Mach number of 1.4. Stagnation temperature is 702 K, corresponding to a flight Mach number of 3.3 at an altitude of 12.5 km. Detailed chemical kinetics are taken into account with a reaction mechanism comprising of 9 species and 25 reaction steps. Turbulence is modeled using Menter’s k–ω shear stress transport model, which is appropriate for high speed internal flows. It is observed that flame anchors at the leading edge of the cavity, and the flame is stabilized in the cavity mode rather than the jet-wake mode. Numerical simulation captures all the essential features of the reacting flowfield.
Improving Performance of an Artificial Neural Network Based Gearbox Fault Diagnosis System
Authors: Hajnayeb Ali , Ghasemloonia Ahmad , Khadem Siamak Esmaeelzadeh , Moradi Mohammad Hasan
Published: January 2011

The automatic vibration monitoring methods of gears and gearboxes due to their extensive applications in industry are improving. Hence, their vibration signal and its derived features, has been an interesting topic for researchers in this field. On the other hand, optimizing the number of vibration signal features used in the detection and diagnosis process is crucial for increasing the fault detection speed of automatic condition monitoring systems. In this paper, a system based on multiple layer perceptron artificial neural networks (MLP ANNs) is designed to diagnose different types of fault in a gearbox. Using a feature selection method, the system is optimized through eliminating unimportant features of vibration signals. This method is based on a simple and fast sensitivity evaluation process, which results in a considerable estimation, despite its simplicity. Consequently, the system’s speed increases, while the classification error decreases or remains constant in some other cases. An experimental test rig data set is used to verify the effectiveness and accuracy of the mentioned method. Four different types of data which are generated through the test rig setup are: no fault condition, 5% fault (5% eroded tooth) gear, 20% eroded tooth gear and the broken tooth gear. The results verify that eliminating some input features of gear vibration signal, using this method, will increase the accuracy and detection speed of gear fault diagnosis methods. The improved systems with fewer input features and higher precision, facilitates the development of online automatic condition monitoring systems.
An Axiomatic Design Approach to Multi-Objective Optimization
Authors: Tarcan Esin , Kar A. Kerim
Published: January 2011

In this study, a methodology is suggested by applying axiomatic design theory to multi-objective optimization of engineering design problems. In axiomatic design, Semangularity (S) and Reangularity (R) are utilized to decide which design is better. However it is not used for optimization purpose. This proposed methodology is applied on two case studies, as theoretical and thermal system multi-criteria optimization problems. It is foreseen that this methodology will reduce the degree of coupling in design optimization.
Study of the Burn-Through During In-Service Welding of T Joint Branch Connections
Authors: Daei-Sorkhabi A. H. , Saeimi-Sadigh M. A. , Vakili-Tahami F. , Zehsaz M. , Behjat B.
Published: January 2011

In this paper, the effect of three main parameters: a) welding speed, b) cooling rate of fluid flow through the main pipe; and c) number of welding passes, have been studied to obtain an effective method to reduce the burn-through risk during the in-service welding of AISI-316 pipe branch connection to perform hot-tapping. In addition, important patents regarding the new methods of hot-tapping have been reviewed. To carry out numerical simulation, a 3D Finite Element (FE) based thermo-mechanical model has been developed. Using this model, thermo-mechanical stresses and temperature distribution along the main-pipe wall-thickness have been obtained with maximum and minimum allowable welding speeds; and with two high and low level of steam flow rate through the main pipe. The Von-Mises yield criterion using the temperature dependent yield stress has been used to check the main pipe failure during the welding process. The results show that current techniques, including API recommendations, which only rely on the observation of the main-pipe inner wall temperature, does not take into account the effect of mechanical or thermal stresses due to the inline pressure or other working parameters which have significant role in burn-through. In addition, the results show that the increase of welding speed reduces the risk of burn-through but it increases the risk of hot cracking. On the other hand, decreasing the steam flow rate has the opposite effect. It has also been shown that using smaller electrode size is the most effective way to decrease burn-through risk.
Effects of Geometric Hystersis in Lung Deformation on Irreversibility in Trajectories of Fine Inhaled Particles
Authors: Zendehbad Mohsen , Saidi Mohammad S. , Sani Mahdi
Published: January 2011

In order to perform the drug delivery via lung, tracking the trajectories of fine inhaled particles in the acinar airways is of high importance. The causes of irreversibility in the motion of fine particles (0.1–1 micron) and chaotic flow deep in the acinar region of lung has been always under investigation. In this study we demonstrate the importance of geometric hystersis and asynchrony of lung deformation on the issue. We adapted a 2D axisymmetric geometry of alveolated duct from recent relative works and deformed it in a way that some hystersis would appear in a respiration period. The overall deformation of duct was corresponding to the transpulmonary pressure of lung reported in physiological books and the Re number was matched with the actual flow in acinar airways. The geometric hystersis had the same amount as the measured hystersis in rat lungs available in relative literature. We performed a lagrangian particle tracking for different cases with and without geometric hystersis. Results confirm that as soon as some asynchrony appears in wall motion the trajectories of particles become extremely irreversible and hence we propose that the geometric hystersis can be a principal reason for observed irreversibility in acinar airways.
Closed Die Forging of Turbine Blades
Authors: Nacy Somer M. , Ali Alaa H.
Published: January 2011

This paper comprises a theoretical and experimental investigation dealing with the simulation of closed die forging of turbine blades. The theoretical part was achieved numerically via the well known finite element package (ANSYS). For simulation purposes, the material used for blade manufacture was high purity lead (99.99%), which was pressed between two dies with the required shape of the turbine blade. An optimum flash-less die shape was obtained with a parting line angle of 16°.
Numerical Study of the Workpiece Rotation Effect on the Strain and Residual Stress Distribution in the Cold Radial Forging Process
Authors: Afrasiab H. , Movahhedy M. R.
Published: January 2011

Radial forging is an open die forging process used for reducing the diameters of shafts, tubes, stepped shafts and axels, and for creating internal profiles in tubes. In this study, the effect of the workpiece rotation (the circumferential feed) on the strain and residual stress distribution in the inner surface of the tube in the cold radial forging process is investigated using nonlinear three dimensional finite element modeling. To verify the model, the predicted radial forging load is compared with the published experimental data which shows a good agreement. It is shown that for achieving a more favorable residual stress distribution in the workpiece inner surface, the rotation angle associated with each stroke should be reduced. Furthermore, a total rotation angle of 90° seems to be sufficient for finalizing the strain and residual stress distribution in the workpiece inner surface and using additional rotation is just a waste of time and energy in this respect.
A Search Algorithm for Particle Laden Flows: Application to Nanofluids
Authors: Afshar Hossein , Shams Mehrzad , Nainian Seyed Mojtaba Mousavi , Ahmadi Goodarz
Published: January 2011

Evaluating the particle location in particle-laden flows is the most important parameter for calculating the two-phase flow parameters and also controls the computational time. In heat conducting nanofluids the volume fraction of particles is typically less than 3%. Nevertheless the their effect on heat transfer is important. In this paper, a new method for coupling thermal effects of dispersed and continuum phases is introduces. The L-N-R search algorithm, which can be used in complex geometries and unstructured grid is used for specifying particle location. For low volume fractions, particles-fluid interaction is considered only for the energy exchange. This exchange is done using a binary search tree. It is shown general usage of nanofluids in microchannels should be done by special considerations.
Presenting a Multi-Level Superstructure Optimization Approach for Mechatronic System Design
Authors: Pedersen Henrik C. , Andersen Torben O. , Hansen Michael R. , Bech Michael M.
Published: January 2011

Synergism and integration in the design process is what sets apart a Mechatronic System from a traditional, multidisciplinary system. However the typical design approach has been to divide the design problem into sub problems for each technology area (mechanics, electronics and control) and describe the interface between the technologies, whereas the lack of well-established, systematic engineering methods to form the basic set-off in analysis and design of complete mechatronic systems has been obvious. The focus of the current paper is therefore to present an integrated design approach for mechatronic system design, utilizing a multi-level superstructure optimization based approach. Finally two design examples are presented and the possibilities and limitations of the approach are outlined.
Non-Isothermal Fluid Flow in a Continuous Casting Tundish
Authors: Boudjabi Amel F. , Bellaouar Ahmed , Lachi Mohammed , El Wakil Nadim
Published: January 2011

Temperature variation phenomena observed inside the metallurgical tundish in the continuous casting is principally due to several factors, high temperature of the ladle metal jet, important thermal losses, heat transfer between molten steel and tundish walls and more still, in contact with the slag layer at bath surface and if necessary cooling or warming in refining composition operations. A numerical simulation using the CFD code “Fluent” is realised. Investigation of heat transfer—which has a great importance in the natural convection and the inclusions floating at slag surface—, is proposed. Results are presented for three arrangements of the tundish, where the interest and role of the control devices is improved.
Engine Durability Test Cycle for Heavy-Duty Engines
Authors: Akc¸a Serdar , Demir Serdar , Pennington Ian , Ataman Okan
Published: January 2011

Dynamometer durability testing plays a very important role in engine design verification process as it is still the most reliable method to ensure the product quality before starting mass production. To ensure that the new engine as designed and manufactured will perform in a manner that increases customer satisfaction, the stresses present in the dynamometer durability test has to be representative of those an engine will meet in customer usage. Thus, it is an important task to derive proper test cycles for dynamometer tests as they should definitely be correlated to customer usage in order not to under/over-test the subject. Customer-Correlated General Durability (CCGD) test, which targets system-to-system interactions rather than component-specific or subsystem-specific failure modes, is developed in this manner. In current CCGD cycles used in engine companies, state speed/load residencies reflecting the overall lifetime driving of the engine of concern is taken into account with randomized ramp-up and ramp-down stages to cover transient driving conditions. The cycle creation method can be divided into two phases: Data Collection & Data Analysis. Also there are two types of data used: Vehicle Data & Customer Field Data to obtain real world customer usage profile.
Dynamics of CVT Metal Pushing V-Belt Co-Simulating With Feedback Control and Finite Element Analysis
Authors: Saito Toshihiro
Published: January 2011

A simulation technology has been developed to predict the transmission efficiency of a metal pushing V-belt and pulleys that make up the drive system of a continuously variable transmission (CVT). When a CVT operates in an actual vehicle, pulley thrust pressure is adjusted by feedback control to maintain a speed ratio. This feedback control has been implemented, for the first time, in an existing simulation that predicts the dynamic behavior of a metal V-belt using explicit structural analysis. The new simulation enables stable control of a target speed ratio when appropriate gains are set for each analysis condition. Using this simulation, the following values can be obtained: 1) pulley thrust pressure that is necessary for maintaining a specified speed ratio but could previously be derived only from physical testing, 2) transmission efficiency of a CVT drive system, consisting of a metal pushing V-belt and pulleys, at each operating condition, and 3) belt friction losses calculated from sliding velocities and friction forces applied to element contact surfaces.
A Method for Thermal Loading Design to Reduce Stresses
Authors: Soltani H. , Hematiyan M. R. , Jafarpur K.
Published: January 2011

Thermal loading is one of the most important issues which results in thermal stresses in different bodies. Thermal stresses may be large and have to be considered in the design processes. Although thermal stresses are usually treated as non-desired factors, in this paper we proposed to use thermal stresses in a body with elastic loading to reduce elastic stresses and consequently increase the maximum allowable loading. In the proposed method, thermal loading is generated by applying a heat flux on parts of the boundary of the body or heat generation inside a portion of its domain. In each case the distribution of the thermal load is obtained so that the maximum stress in the body becomes minimum. To determine the unknown distribution of the thermal load, first we modeled it as a multi-parameter function with some unknown parameters; then, by a sensitivity analysis and some mathematical operations, the optimized values of the parameters are found. To see the application, in this paper, several examples are presented to show the performance and the efficiency of the proposed method. The cases which are studied in the current work show that the proposed method for reducing elastic stresses by employing thermal loading is effective and the maximum stress can be decreased considerably.
Visualisation of Burring Operation in Virtual Surgery Simulation
Authors: Onbasıog˘lu Esin , Atalay Bas¸ar , Goularas Dionysis , Soydan Ahu H. , S¸afak Koray K. , Okyar Fethi
Published: January 2011

Virtual reality based surgical training have a great potential as an alternative to traditional training methods. In neurosurgery, state-of-the-art training devices are limited and the surgical experience accumulates only after so many surgical procedures. Incorrect surgical movements can be destructive; leaving patients paralyzed, comatose or dead. Traditional techniques for training in surgery use animals, phantoms, cadavers and real patients. Most of the training is based either on these or on observation behind windows. The aim of this research is the development of a novel virtual reality training system for neurosurgical interventions based on a real surgical microscope for a better visual and tactile realism. The simulation works by an accurate tissue modeling, a force feedback device and a representation of the virtual scene on the screen or directly on the oculars of the operating microscope. An intra-operative presentation of the preoperative three-dimensional data will be prepared in our laboratory and by using this existing platform virtual organs will be reconstructed from real patients’ images. VISPLAT is a platform for virtual surgery simulation. It is designed as a patient-specific system that provides a database where patient information and CT images are stored. It acts as a framework for modeling 3D objects from CT images, visualization of the surgical operations, haptic interaction and mechanistic material-removal models for surgical operations. It tries to solve the challenging problems in surgical simulation, such as real-time interaction with complex 3D datasets, photorealistic visualization, and haptic (force-feedback) modeling. Surgical training on this system for educational and preoperative planning purposes will increase the surgical success and provide a better quality of life for the patients. Surgical residents trained to perform surgery using virtual reality simulators will be more proficient and have fewer errors in the first operations than those who received no virtual reality simulated education. VISPLAT will help to accelerate the learning curve. In future VISPLAT will offer more sophisticated task training programs for minimally invasive surgery; this system will record errors and supply a way of measuring operative efficiency and performance, working both as an educational tool and a surgical planning platform quality.
Pressure Field in Liquid Phase Nanomembrane System
Authors: Maftouni N. , Amininasab M. , Kowsari F.
Published: January 2011

Nanomembrane is a very important part of living systems. Alive cells have lipid bilayer nanomembrane in liquid phase. The lateral pressure profile, or stress profile, across a cell nanomembrane is the result of the inhomogeneous nature of the interactions within a nanomembrane. It has been shown that the work exerted by the pressure profile when a protein conformational change takes place is significant, of the order of 10kBT, and that the lateral pressure profile averaged over the whole nanomembrane is modified by the inclusion of a protein. Indeed, understanding the full coupling for stress arising from protein-lipid interactions is of profound importance and calls for elucidation. Here proper ensembles for molecular dynamics simulation of inhomogeneous nanoscale system of nanomembrane-cytotoxin protein are introduced. The Virial pressure theorem together with using molecular dynamics simulation data are proposed to use to calculate pressure filed. The predicted pressure tensor of system without cytotoxin is compared with that of system including this protein. Finally deformation of nanomembrane is related to the variation of pressure tensor.
Thermal Hydraulic, Exergy and Exergy-Economic Analysis of Micro Heat Sinks at High Flow Rates
Authors: O¨zdemir Mehmed Rafet , Kos¸ar Ali , Demir Orc¸un , O¨zenel Cemre , Bahc¸ivan Og˘uzhan
Published: January 2011

Recently, micro/nanofabrication technology has been used to develop a number of microfluidic systems. With its integration to microfluidic devices, microchannels and micro scale pin fin heat sinks find applications in many areas such as drug delivery and propulsion in biochemical reaction chambers and micro mixing. Many research efforts have been performed to reveal thermal and hydrodynamic performances of microchannel based micro fluidic devices. In the current study, it is aimed to extend the knowledge on this field by investigating heat and fluid flow in micro heat sinks at high flow rates. Moreover, thermodynamic and thermo-economic aspects were also considered. De-ionized water was used as the coolant in the system. Flow rates were measured over pressures of 20–80 psi. A serpentine heater was deposited at the back of the micro pin fin devices to enable the delivery of heat to these devices. Two micro-pin fin devices each having different geometrical properties (Circular based and Hydrofoil based) were used in this study. In addition, the performances (thermal-hydraulic, exergy, exergo-economic) were also experimentally obtained for a plain microchannel device. Thermal resistances, exergy efficiencies and thermo-economic parameters were obtained from the devices and their performances were assessed.
Experimental and Numerical Investigation of Grooved Thin-Walled Steel Cylinders Under Axial Compression
Authors: Pakizehkar Arshia , Sarkarfarshi Mirhamed , Masomi Abolfazl
Published: January 2011

In this study, axial compression behavior of grooved thin-walled steel cylinders is investigated using experimental and numerical methods. Circumferential grooves are generated by means of a special forming tools and the effect of interval between the grooves and their total number on the load-displacement curve, energy absorption-displacement curves and initial buckling load are investigated. It is revealed that having circumferential grooves on the tubes can decrease the initial peak load in load-displacement curve and also increase the amount of absorbed energy. Then explicit Finite Element Model of aforementioned grooved tubes under axial loading are generated using ANSYS software and solved utilizing LSDYNA solver. Result of the FE models (containing the amount of absorbed energy, the peak load and the load-displacement curve during axial compression) are validated by comparing them with those of experimental test. The outcome of comparisons confirms the FE model to be in a good agreement with experimental results.
The Effects of Ausforming on the Precipitating Process and Mechanical Properties of 17-4PH Stainless Steel
Authors: Amirkamali M. , Aghaie-Khafri M.
Published: January 2011

In this study, the effects of ausforming on the precipitating process and mechanical properties of 17-4PH stainless steel were investigated. For doing ausforming, samples were solution treated at 1050°C for an hour, and then quenched into a salt bath furnace at 400°C. Rolling at 400°C in different percents was done for achieving different mechanical works. After finishing ausforming process, samples were tempered for precipitating at 300,400,500 and 600°C for 1, 2, 4, 8, 16 and 32h. Microstructural studies were done for finding the changes on precipitating process and tensile and hardness test done to study mechanical properties. Scanning electron microscope was used to show precipitates and other phases. Also EDS method used to analyze the elements in each phases.
Experimental Results of a Vertical Axis Wind Turbine
Authors: Fortunato Bernardo , Camporeale Sergio Mario , Torresi Marco , De Fazio Davide , Giordani Mauro
Published: January 2011

In the present paper the new wind tunnel located in the Fluid-dynamic Laboratory of the Dipartimento di Ingegneria Meccanica e Gestionale (DIMeG) of the Bari Polytechnic will be shortly described and the first experimental measurements on a vertical axis wind turbine (VAWT) will be shown. The DIMeG wind tunnel has been designed by the research group on wind energy of the Department. It is a subsonic, closed loop, wind tunnel with a transparent test part where small scale models can be analyzed. A four bladed axial fan is driven by an asynchronous three phase electric motor, which is connected to an inverter in order to change the wind speed. Angular blades have been inserted at the two curves between the fan and the test section in order to increase the uniformity of the velocity profile after the two curves. An optimization fluid-dynamic study has been carried out in order to find the best blade profile. A honeycomb has been also inserted upstream the test section in order to destroy the still existing small vorticity generated by the fan and the curves. A three-axis traversing, called Cartesian robot, has been designed and built above the test section, in order to move the hot wire probe, for wind speed measurements, by means of four step by step electric motors controlled by a personal computer. A data acquisition system has been set up. All the principal commands and controls can be performed by a dedicated personal computer, which has been programmed using LabVIEW® G-programming language. The first experimental activity has been performed on a VAWT model, of the Giromill type with parallel blades. The turbine has been connected to an AC brushless servo, able to control the braking torque. Experimental results of the flow field in two horizontal planes have been set up using a two component hot wire probe (Dantec 55R51) calibrated with the manual system Dantec 54H10. The measurement grid adopted is formed by 20 nodes in the Y direction (main flow direction) and 10 nodes in the X direction.
Improvement of Mechanical Properties and Microstructure of Al-Fe-Si Alloy by ECAP Semisolided Method
Authors: Azimi-Yancheshmeh D. , Aghaie-Khafri M.
Published: January 2011

ECAP is one of the Severe Plastic Deformation methods for reducing the grain size. With this process we can achieve ultrafine grains and consequently high strength. In this study, ECAP process was done on Al-Fe-Si alloy. This alloy was considered because of Fe effect on refining grain size. All samples were ECAPed into 1 pass in ECAP mold with 2 equal channels (1 cm × 1 cm) with 90 degree between them. By this method, around 1.05 as strain was applied on each samples. ECAPed specimens were heat treated (Semisolided) in different times and temperatures for achieving good toughness. Compression and hardness tests were done for finding the mechanical properties. As a result of these test, specimens that tolerate both ECAP and Semisolid have better toughness and strength than received and only ECAPed samples. Based on the microstructural evaluations spheroid solid phase was observed in the Semisolid specimen.
Design of Novel Nanocomposite Nitride Coatings for Severe Tribological Applications
Authors: Erdemir A. , Eryilmaz O. L. , Urgen M. , Kazmanli M. K. , Ezirmik V.
Published: January 2011

Nanocomposite coatings have lately been attracting a lot of attention mainly because of their superior mechanical and tribological properties even under very severe operating conditions (such as high loads, speeds, temperatures, starved or marginal lubrication, etc.). These coatings may consist of multiple crystalline and/or amorphous phases that make them truly composite and hence multi-functional. In this paper, we primarily focus on the chemical and structural design of such coatings for superior friction and wear properties under lubricated sliding conditions that are typical of various engine applications. As an innovative approach for the design of such coatings, we employed a crystal-chemical model that can be very useful for the selection of right kinds of coating ingredients that are essential for their unique structures and superior property and performance characteristics under severe tribological conditions. Novel MoNx−Cu coatings produced according to this model could provide friction coefficients as low as 0.04 under boundary lubricated sliding regimes and they could not be scuffed or worn through under the heaviest loading conditions of a block-on-ring test machine.
Forming Line Design for Hooks Production
Authors: Kosˇtˇa´lova´ Miroslava , Mecˇiar Sva¨topluk
Published: January 2011

The article points out on new trends in the bending technology, elimination possibilities of defects originating in bending and it deals with designing of forming line for hooks production by bending technology. It was suggested change of previous manner of production and material of produced bearing hooks as well. In previous manner of production the unfinished surface of semi product in form of roll sheet was galvanic zinc coated, it was thereafter sheared on needed length with shearing machine, followed punching in fixture, roll bending by sequence bending by help of fixture. Suggested forming line is dedicated for processing of zinc coated roll strip in automation production cycle. Forming line enables the automation work flow which includes the uncoiling of strip, feeding and leveling of strip, punching of holes and shearing of strip, roll bending of pressed part, repeated feeding of strip by leveler. Forming line consists of two-sided uncoiler without drive, feeding leveler, block of forming tools, rotary roll head. It is possible to set production of hook according to required dimensions, forming line is able to produce several dimensions of hooks with several numbers of holes. The bearing hooks from suggested original zinc coated roll strip have higher surface quality without defects. Production innovation with feeding of automation in comparison to previous manner of production enables savings of four or five workers, increasing number of produced parts per hour, to achieve repeated pressed part precision,, less manual work, increasing operation safety, minimized noise level, reducing of production costs and production of time.
Modeling of Non-Newtonian Fluid Flow Within Simplex Atomizers
Authors: Rezaeimoghaddam Mohammad , Elahi Rasool , Modarres Razavi M. R. , Ayani Mohammad B.
Published: January 2011

In this paper the Volume-of-Fluid (VOF) method is used to simulate Newtonian and non-Newtonian fluid flow within simplex (pressure-swirl) atomizers. The two-dimensional axisymmetric swirl Navier-Stokes equations coupled with the VOF method is employed for accounting the formation mechanism of the liquid film inside the swirl chamber and the orifice hole of the pressure swirl atomizer. For verification of the code, the numerical results were compared with experimental data for large scale prototype injector with water (Newtonian fluid) as injection fluid in various constant inlet mass flow rate. By using power-law equation to calculate shear stress terms in the Navier-Stokes equations, the code is extended to compute Newtonian and non-Newtonian fluid flow inside the atomizer. The time-independent purely viscous power-law fluids flow in pressure-swirl atomizers is simulated. The effects of shear-thinning fluids (0.5 < n <1), viscous Newtonian (n = 1) fluids and shear thickening fluids (1< n < 1.5) on atomizers performance (discharge coefficient and spray cone angle) were investigated. Results were shown that with increasing the power-law index the spray cone angle decreases and the discharge coefficient increases.
Modeling and Control of a Teletruck Using Electronic Load Sensing
Authors: Hansen Rico H. , Iversen Asger M. , Jensen Mads S. , Andersen Torben O. , Pedersen Henrik C.
Published: January 2011

In mobile hydraulic application the actuating fluid power system is most commonly controlled using a hydro-mechanical control scheme called Hydraulic Load Sensing (HLS). However, with the demands for increased efficiency and controllability the HLS solutions are reaching their limits. Motivated by availability of electronic controllable fluid power components and the potential of increased dynamic performance and efficiency, this paper investigates how HLS can be replaced with electronic control, i.e. Electronic Load Sensing (ELS). The investigation is performed by taking a specific application, a teletruck, and replace the HLS control with ELS. To aid the controller design for the ELS system, a complete model of the teletruck’s articulated arm and fluid power system is developed. To show the feasibility, a preliminary control structure for the ELS system is developed. The controller is tested on the machine, validating that features such as pump pressure control, flow sharing and over pressure protection can be implemented using ELS and with improved energy efficiency.
Investigating Optimum Procedures Needed to Maintain a Model Satellite’s CG Stable About Design Point, Under Subsystem Configuration Changes
Authors: Dastoom Laatleyli Hassan , Abedian Ali , Teimouri Hessamodin
Published: January 2011

During design, microsatellites are subject to different changes like the changes in weight, location and dimension of parts and elements of subsystems and the payload. These changes should be accumulated by the structure subsystem in a way that some key structural parameters like the center of gravity (CG) and inertia moments remain unchanged. This subject is also important regarding the design of a modular structure of a satellite. In the present study it is tried to accommodate any changes in weight and location of any part(s) and element(s) of a microsatellite by optimum (minimum) rearrangement of other parts on their plane of rest in order to keep the CG and inertia moments unchanged. This is performed by a special mathematics modeling considering the existing constraints. Of course, no addition or subtractions of weight from the remaining parts are assumed. Also, in order to keep the original structural design intact, no movement of the parts except in the close neighborhood of their original location is allowed. At the end, this study shows that it is possible to move other subsystems on some suitable paths as a result of changing one subsystem mass from −100% (omitting that element) to 100% (doubling the weight of that element) to maintain the overall CG position in its previous position.
Kinematics Modeling of a Family of Pure Translational 3-P^UR Parallel Linear Manipulators
Authors: Boschetti Giovanni , Caracciolo Roberto , Trevisani Alberto
Published: January 2011

This paper introduces a simplified kinematic model for a family of parallel linear manipulators with three degrees of freedom of pure translation. The P^UR topology of the limbs and the adjustable layout of the linear actuators are the main characteristics of such a family. The analytical solutions of the forward and inverse position and velocity kinematics are presented. Then the variations of the manipulator features in terms of workspace and performance indexes are investigated as functions of the actuators arrangement.
Mathematical Modeling of Abrasive Waterjet Turning of Ductile Materials
Authors: Zohourkari Iman , Zohoor Mehdi
Published: January 2011

In this paper, an erosion-based model for abrasive waterjet (AWJ) turning process is presented. In the AWJ turning process a particular volume of material is removed by impacting of abrasive particles to the surface of the rotating cylindrical workpiece. This volume is estimated according to the modified Hashish erosion model; thus radius reduction at each revolution is calculated. The distinctively proposed model considers the continuous change in local impact angle due to change in workpiece diameter, axial traverse speed of the jet, the abrasive particle roundness and density. The accuracy of the proposed model is approved by experimental tests under various traverse speeds. The final diameters estimated by the new model are in good accordance with the experiments.
Whiplash Protection by Energy Absorbing Car-Seat Concepts
Authors: Himmetoglu Selcuk , Acar Memis , Bouazza-Marouf Kaddour , Taylor Andy J.
Published: January 2011

Whiplash injury/disorder is a common neck-injury in road traffic accidents. This paper introduces energy absorbing car-seat concepts which can reduce the risk of whiplash injuries. Computational multi-body models of a generic car seat and a biofidelic 50th-percentile male human model for rear impact are developed to assess the effectiveness of the proposed car-seat concepts. The numerical sled-test-simulations show that the proposed car-seat concepts can successfully mitigate whiplash injuries for a wide range of crash severity by utilising energy absorbing devices which can remain reusable after a rear-impact. A physical model of a proposed car-seat concept is built and tested to verify the computational models.
Surface Characterization of Polymer Composite Using Bearing Area Curve
Authors: Deleanu Lorena , Andrei Gabriel , Maftei Laura
Published: January 2011

This paper presents an analysis of several 3D parameters based on bearing area curve in order to use the information for establishing the influence of sliding regime against steel on the tribological behavior of a composite class with polyamide matrix and 1% of black carbon. There were done pin-on-disk tests for different concentrations of micro glass spheres (MGS): 2.5, 5, 10, 20, 30 and 50% (wt), respectively. The polymer was tested under similar conditions in order to have a reference basis and to point out the improvement in tribological behavior when adding this reinforcement material. The surface topographies were registered with the help of PRO500 3D (stylus) Profilometer. The test parameters in dry regime were: sliding speed 0.5, 1.0 and 1.5 m/s, average pressure 1, 2 and 3 MPa, respectively. There were analyzed the influence of MGS concentration and sliding regime on wear as mass loss of the composite discs, after 10,000 m of sliding, the friction coefficient and several 3D parameters related to the bearing area curve, determined from raw profiles (surface bearing index – Sbi, core fluid retention index – Sci, valley fluid retention index, Svi, reduced summit height, Spk, core roughness depth, Sk, and reduced valley depth, Svk).
Interior-Point Method for the Computation of Shakedown Loads for Engineering Systems
Authors: Simon Jaan-Willem , Weichert Dieter
Published: January 2011

A new interior-point algorithm for the computation of shakedown loads has recently been developed by the authors. The analytical formulation is based on the statical shakedown theorem by Melan which leads to a nonlinear convex optimization problem. The algorithm’s efficiency results from the close adaption of the solution procedure to the specific problem of shakedown analysis. This paper focuses on algorithmic aspects of the proposed method. A numerical example of practical interest is used for validation purposes.
Solving Free Vibration of Stepped Beam by Using the Adomian Decomposition Method
Authors: Farshidianfar Anooshiravan , Tabassian Rassoul , Khoee Omid Kazemzadeh , Noei Sayed Javadorreza
Published: January 2011

This paper studies the free vibration of Euler-Bernoulli stepped beam with different cross-sections and also different materials for each section. In this work, a new approach called Adomian decomposition method (ADM) is used to deal with vibration problem. Natural frequencies of stepped beam are obtained with high accuracy using this method. Numerical results are validated by ANSYS.10 and proper convergence is observed between results. Effects of various parameters like step ratio on natural frequency are discussed. Applying this method on free vibration of stepped beam constructs a systematic procedure which is completely straightforward and could calculate both low and high mode frequency with appropriate accuracy.
A Compact Nanostructure Enhanced Heat Sink With Flow in a Rectangular Channel
Authors: Sesen Muhsincan , Kosar Berkay Arda , Kosar Ali , Khudhayer Wisam , Ahishalioglu Berk Ahmet , Karabacak Tansel
Published: January 2011

This paper reports a compact nanostructure based heat sink. The system has an inlet and an outlet valve similar to a conventional heat sink. From the inlet valve, pressurized deionized-water is propelled into a rectangular channel (of dimensions 24mm×59mm×8mm). This rectangular channel houses a nanostructured plate, on which ∼600 nm long copper nanorod arrays with an average nanorod diameter of 150 nm are integrated to copper thin film coated on silicon wafer surface. Forced convective heat transfer characteristics of the nanostructured plate are investigated using the experimental setup and compared to the results from a flat plate of copper thin film deposited on silicon substrate. Nanorod arrays act as fins over the plate which enhances the heat transfer from the plate. Excess heat generating small devices are mimicked through a small heat generator placed below the nanostructured plate. Constant heat flux is provided through the heat generator. Thermocouples placed on the heater surface are utilized to gather the surface temperature data. Constant pressure drop across the heat sink and constant heat flux values are varied in order to obtain the correlation between heat removal rate and input power. Volumetric flow rate was measured as a function of the constant pressure drop. In this study, it was proved that nanostructured surfaces have the potential to be a useful in cooling of small and excessive heat generating devices such as MEMS (Micro Electro Mechanical Systems) and microprocessors.
Experimental Application of Friction Stir Welding (FSW) on Thermo Plastic Medium Density Polyethylene Blanks
Authors: Saeedy S. , Besharati Givi M. K.
Published: January 2011

The feasibility of friction stir welding has been studied on medium density polyethylene blanks. The design and analysis of experiments have been performed with Taguchi method. The mechanical properties of the joints have been analyzed based on two parameters of rotation speed and tool tilt angle. The optimum welding condition has been determined. It has been demonstrated that rotation speed and tool tilt angle have key roles in the seam elongation and strength respectively. By applying this method of welding on polyethylene blanks 70% of the base material strength is achieved. SEM micrographs show microstructural changes of the weld zone which result in the reduction of the seam weld strength and elongation.
Experimental Investigation of Double Side Friction Stir Welding (FSW) on High Density Polyethylene Blanks
Authors: Saeedy S. , Besharati Givi M. K.
Published: January 2011

The effect of double side technique in friction stir welding of polyethylene blanks has been studied. Experiments have been designed and analyzed with the full factorial method. The process parameters were rotation speed and tool tilt angle. The optimum welding condition has been determined. It has been demonstrated that double side FSW can improve the weld quality by decreasing the problem of stress concentration in the root of the joint. By applying this technique, 80% of the base material strength is achieved. Considerable reduction in elongation and toughness of the seam weld is due to crystallinity changes of the weld zone which are indicated in the DSC test results.
Thermal and Fluid Dynamic Analysis on Impinging Jet for Aircraft Anti-Icing
Authors: Andreozzi Assunta , Lucibello Fabio , Manca Oronzio , Nardini Sergio , Roma Mario
Published: January 2011

Ice formation on airplane wing profile is a very dangerous condition because of the change in the profile aerodynamic, so it’s necessary to avoid ice formation on the wings. The hardest condition ice formation are at altitudes between 10.000 and 15.000 ft and at temperature between 0° C and −15° C, because they are particularly suitable for ice formation. In this paper an anti-icing system based on hot air impinging jets on internal wing surface is analyzed in order to check the efficiency of the system. A numerical model is given in order to evaluate the thermal and fluid dynamic behaviors of the impinging jet inside the wing panel. A wing profile with an angle of attack of 4.50° is taken into account with a free stream temperature of 258 K. A piccolo tube with a diameter of 1.00 inch and air temperature of 523 K and at variable distance from the wall of the wing profile, is considered for anti-icing system. A structured mesh is used in the discretization of the computational domain for the two-dimensional and three-dimensional case. A steady state solution with k-ε RNG turbulent model has been found. Numerical simulations of a two and a three dimensional model of an aircraft wing has been carried out taking into account the external convective exchange by means of an average coefficient on the external surface and thermo-fluid dynamic field inside the wing due to the anti-icing system. The analysis is performed by means of the FLUENT code in order to find the optimal geometrical configuration to avoid the ice formation on the external wing surface. Results are presented in terms of temperature fields and wall temperature and air velocity profiles along the wing surfaces.
Adaptive Fuzzy Sliding Mode Control Approach for Swarm Formation Control of Multi-Agent Systems
Authors: Ranjbar Sahraei Bijan , Nemati Alireza , Farshchi Mehdi , Meghdari Ali
Published: January 2011

In this paper, an adaptive control scheme for multi-agent formation control is proposed. This control method is based on artificial potential functions integrated with adaptive fuzzy sliding mode control technique. We consider fully actuated mobile agents with completely unknown dynamics. An adaptive fuzzy logic system is used to approximate the unknown system dynamics. Sliding Mode Control (SMC) theory is used to force agents’ motion to obey the dynamics defined by the simple inter-agent artificial potential functions. Stability proof is given using Lyapunov functions, which shows the robustness of controller with respect to disturbances and system uncertainties. Simulation results are demonstrated for a multi-agent formation problem, illustrating the effectiveness of the proposed method. Experimental results are included to verify the applicability of the scheme for a test-bed of six real mobile robots.
Comparison of Contact Force Control Strategies on Different Robot Arm Types
Authors: Yaltirik Hu¨seyin , Kar A. Kerim , Ekici Bu¨lent
Published: January 2011

Nowadays robots are used in various areas. There are extremely important applications where the robot arm tip comes in contact with the environment or an object. During controlling an object, static or in motion, the object or the robot arm should not be damaged. The interaction forces are important in such conditions. Whether the task succeeds or fails depends on how accurate the interaction forces are controlled. The interaction forces are changed depending on the motion of the robot arm. Therefore, to control interaction forces a force control algorithm must be developed. In this research a force control algorithm will first be developed for the quasi-static contact tasks, then it will be extended to the dynamic cases. The goal of this study is to compare force control strategies to achieve the desired interaction forces between the robot arm tip (end-effector) and the environment during contact tasks. Taguchi L9 method is used for comparison of selected force control algorithms which are modeled in SIMULINK MATLAB program.