bluuebunny/crossref_metadata_2025 huggingface dataset:
Promoting Inventive Design and Problem-Solving Competencies
Authors: Barak Moshe
Published: July 2009

What can education do to foster students’ inventive design and problem-solving competencies? On the one hand, it is widely agreed that accomplishing this end is one of education’s main objectives today. On the other hand, many people regard creativity as a ‘God-given’ ability, something an individual either has or does not have but can hardly be learned or enhanced. Therefore, it is of no surprise that only little has been done to introduce the teaching of creative thinking into traditional schooling, either in K-12 education or in engineering education. In the current paper, however, I present a different viewpoint. The literature on design and problem-solving in engineering shows that while novices tend to follow a routine design approach or use the trial-and-error method, experts are likely to use domain-specific strategies, schemes and heuristics, move flexibly from one working method to another, combine given strategies in new ways, and solve problems by using shortcuts or rules-of-thumb rather than work according to a specific method. Therefore, it could be useful to teach students several heuristic methods for inventive design and problem-solving that have been used increasingly in engineering, for example, SCAMPER, TRIZ, Systematic Inventive Thinking (SIT) and the Eight-Dimensional method. This paper briefly reviews some of these methods and addresses the outcomes of several studies about teaching the methods to engineers and designers in industry, junior high school students, and science and technology teachers. The findings indicate that the participants often improved their achievements in suggesting original solutions to problems in comparison to a control group, and successfully utilized the method they had learned in their final project. The implications to engineering education are also discussed.
Fatigue Life Prediction in Rapid Die Casting
Authors: Ng Chuan Huat , Grote Karl-Heinrich , Ba¨hr Ru¨diger
Published: July 2009

During a die casting process, it is very difficult to achieve efficient and correct casting tooling endurance results by the casting designer and foundry man. However, it is very costly and time consuming to predict the tooling endurance with a trial and error method based on expertise and experience. After an extensive fatigue design study, it was possible to develop specimen design models for the simulation of the time and temperature dependent stress-strain and fracture models to determine the thermal fatigue prediction. In this research, stress-strain approach, heat transfer concept and life time calculation methods were used to predict the casting tool endurance by a computer simulation. The thermal stress and heat transfer behaviour analysis were performed using RWP casting numerical simulation software. It is shown that numerical simulation techniques can simulate stress concentration on the specimen surface to thermal behaviour. Furthermore, the result from the specimen based simulation model associated with fracture indicators permits the construction of a life time design curve independent of time and temperature. The fatigue life predicted by simulation based models and the results from experimental testing on real components are very similar. The simulation results showed that they match the experimental results, including a design safety factor.
Techniques for Assessment of Wear Between Human Cartilage Surfaces
Authors: Verberne Gabi , Merkher Yulia , Halperin Gregory , Maroudas Alice , Etsion Izhak
Published: July 2009

Osteoarthritis (OA) is a disease of joints, affecting a large number of people worldwide. One of the symptoms of OA is wear of articular cartilage; it is thought that among other factors this may be due to failure of lubrication. Injection of bio-lubricants into a joint may remedy this problem. Wear of cartilage and its prevention is a focus of much interest. The present paper describes wear tests performed using cartilage on cartilage under various working conditions. Several techniques assessing wear are described, such as changes in surface morphology using optical profilometry and variation in the concentration of proteoglycans (PG) and hydroxyproline in the lubricating solution.
Direct Wire-Bonding to Silicon Devices Without the Use of Metallic Layers
Authors: Hirshberg Arnon , Elata David
Published: July 2009

We present a novel method of direct wire-bonding of Silicon MEMS devices that does not require any metal bond-pads. We demonstrate that the strength and the conductivity of direct wire-bonds are comparable with those of standard bonds on metal bond-pads. Direct wire-bonding eliminates the metallization step, thus alleviating the constraint of consecutive high-temperature micromachining processes.
On the Applicability of Newton’s, Poisson’s and Stronge’s Collision Hypotheses
Authors: Djerassi Shlomo
Published: July 2009

This paper deals with collision with friction. Equations governing a one-point collision of planar, simple non-holonomic systems are generated. Expressions for the normal and tangential impulses, the normal and tangential velocities of separation of the colliding points, and the change of the system mechanical energy, are written for three types of collision in connection with Newton’s hypothesis, and for five types of collision in connection with Poisson’s and Stronge’s hypotheses. These, together with Routh’s semi-graphical method and Coulomb’s coefficient of friction, are used to show that the algebraic signs of five, newly-defined, configuration-related parameters, not all independent, span eleven cases of system configuration. For each, the ratio between the tangential and normal components of the velocity of approach, called α, determine the type of collision which, once found, allows the evaluation of the associated normal and tangential impulses and ultimately the changes in the motion variables. The analysis of the eleven cases with Newton’s hypothesis indicates that the calculated mechanical energy may increase if sticking or reverse sliding occur, and that regions of α exist for which there is no solution or there are multiple solutions. Regarding Poisson’s hypothesis, there are regions of α, narrower than with Newton’s hypothesis, for which there is no solution. However, whenever a solution exists it is unique, coherent and energy-consistent. The same applies to Stronge’s hypothesis, however for a narrower range of application. It is thus concluded that Poisson’s hypothesis is superior as compared with Newton’s and Stronge’s hypotheses.
Cooperative 3D Parametric Design of Large Structure
Authors: Wang Chonghua , Liang Chengji
Published: July 2009

Large structure such as container crane is small amount manufacturing and made for order. A lot of designers must work cooperatively to bring it to success as early as it is needed. Besides, collecting and identifying customers’ needs and understanding their idea are essential tasks in the development process. In this paper, a 3D parametric design system based on hybrid pattern of Client/Server and Browser/Server is introduced to achieve the coordination between the design team and close communication with the customers. In Client/Server architecture, a framework is presented to support integration of CAD/CAE. The effective management of mail and message can ensure swift, safe and effective communication between designers and avoid useless working and wrong result. Based on the top-down design method, skeleton model, technologies of parametric 3D modeling, finite element analysis, integrated CAD/CAE and engineering database, the CAD platform of 3D parametric model family for crane design is set up. That let the cooperation of the design team possible. In Browser/Server architecture, standard Internet Explores act as the browsers, which will exchange the desired information as well as dynamically display the CAD models in VRML format according to request.
A DOE Approach for Sensitivity Analysis of a Shape Partitioning Algorithm
Authors: Gandini Martina , Ruffa Suela
Published: July 2009

In the field of geometrical product specification and verification, one of the main problems is classification and segmentation of 3D shapes. Shape recognition and segmentation is a widespread research area with different application fields (image processing, shape searching, pattern recognition, reverse engineering, etc.). Many methodologies and algorithms have been developed within such different fields, each one exhibiting optimized performances with respect to the set of objects and targets in each application [1, 11, 12]. Nevertheless, for manufactured parts a unique description of shape during the whole product lifecycle is still envisaged, and GPS (“Geometrical Product Specification and Verification”) project seems to be the most promising approach, but it should be stated that the partitioning process is still to be improved both theoretically and operationally. The ISO Technical Committee 213 (TC213), entrusted to develop the GPS project, founded the partitioning process on the classification of shapes based on symmetrical properties of surfaces [5, 6]. The aim of this paper is to describe the method proposed by Gelfand and Guibas [4] and analyze its performances on sampled surfaces by varying parameters of the method that basically affect its efficiency. In fact, the ISO research is currently devoted to identify a segmentation method characterized by efficiency, reliability, robustness and applicability with the aim to standardize the methodology for the verification phase of the manufacturing process. In this paper, a DOE analysis has been performed, in order to search an optimal parameter configuration, necessary to consider the method as a standard for shape partitioning.
Parametric Study of Installed Fogging Systems Using CFD Model
Authors: Hain Y. , Litinetski V. , Litinetsky A.
Published: July 2009

Water fogging of inlet air has become widely acceptable for gas turbine power augmentation. Fogging systems are generally designed for a specific set of conditions called the design point. As a rule, the design point is specified to provide the maximum capacity of the fogging system at extreme ambient temperatures, when gas turbine power output is maximally decreased. Since the extreme ambient conditions rarely occur, the fogging system primarily operates at partial loads, when only a part of the installed cooling stages is in operation. At partial loads the fogging system does not provide uniform fogging of the inlet air, which could result in insufficient fog evaporation, less air-cooling and entrainment of non-evaporated water into the compressor. Prolonged operation at such off-design conditions requires careful tuning of the system in order to maximize cooling efficiency and eliminate a possible impact on gas turbine maintenance. This requires clear understanding of conceptual features of thin droplets evaporation and fog cloud behavior inside gas turbine inlet ducts. To this purpose, computational fluid dynamics (CFD) analysis was used. A CFD model is described, which comprises a straight duct equipped with fog nozzles operating in conditions similar to field conditions at design point, as well as, at partial load operation of the fogging system. The study focused on problems, which are critical in design and operation of real fogging systems, namely: single droplet, mono- and poly-fraction fog evaporation; influence of flow turbulent intensity; fog cloud shape and dimensions; polyfraction fog evaporation in the wide range of ambient conditions; over-spray and under-spray operation of the fogging system. The study results were helpful in the tuning of the installed fogging systems to site specific ambient conditions that provided efficient cooling with safe compressor operation. These results should be useful to both designers and operators of the fogging systems.
Axially Loaded Timoshenko Rotors From a Prestressed Continuum Approach
Authors: Mahadevan Pradeep , Chatterjee Anindya
Published: July 2009

We consider an axially loaded Timoshenko rotor rotating at a constant speed and derive its governing equations from a continuum viewpoint. The primary aim of this paper is to understand the source and role of gyroscopic terms, when the rotor is viewed not as a Timoshenko beam but as a genuine 3D continuum. We offer the primary insight that macroscopically observed gyroscopic terms may also, quite equivalently, be viewed as external manifestations of internally existing spin-induced prestresses at the continuum level. To demonstrate this idea with an analytical example (the Timoshenko rotor), we have studied the reliable equations of Choi et al. (Journal of Vibration and Acoustics, 114, 1992, 249–259). Using a straightforward application of our insight in the framework of nonlinear elasticity, we obtain equations that exactly match Choi et al. for the case with no axial load. For the case of axial preload, our straightforward formulation leads to a slightly different set of equations that have negligible numerical consequence for solid rotors. However, we offer a macroscopic, intuitive, justification for modifying our formulation so as to obtain the exact equations of Choi et al. with the axial load included.
Improved Materials for Dielectric Elastomer Actuators
Authors: Opris Dorina , Molberg Martin , Lo¨we Christiane , Nu¨esch Frank , Plummer Christopher , Leterrier Yves
Published: July 2009

Dielectric elastomers are an emerging class of electroactive polymers for electromechanical transduction. A broad application of dielectric elastomer actuators (DEA) is limited by the high voltage necessary to drive such devices. The development of novel elastomers offering better intrinsic electromechanical properties is one way to solve the problem. Therefore we prepared composites from thermoplastic or thermoset silicone elastomers and organic fillers as phthalocyanines or doped polyaniline (PANI). We studied the mechanical properties of silicones, synthesized, modified and characterized phthalocyanines and doped PANI. The influence of humidity onto the dielectric properties of CuPc(COOH)8 and ZnPc(COOH)8 was analyzed in detail. First measurements of silicone/PANI blends results in a hundredfold increase for the dielectric constant and an electromechanically strain of 8.5%.
Full Field Strain Measurement in Split Hopkinson Bar Experiments
Authors: Gilat Amos , Schmidt Tim , Tyson John , Walker Andrew
Published: July 2009

A method for full field measurement of strain (and strain rate) in split Hopkinson bar experiments (compression, tensile, and shear) is introduced. The measurements are done by using the Aramis three-dimensional image correlation system. The system uses two digital high-speed cameras that provide a synchronized stereo view of the specimen. Depending on the number of pixels used, the system is capable or recording frames at a rate of up to about 110,000 per second. Before conducting a test, a random dot pattern is applied to the surface of the specimen. The image correlation algorithm uses the dot pattern to define a field of overlapping virtual gage boxes. The 3-D coordinates of the center of each gage box is determined at each frame, interpolated to better than 1/100 of a pixel. The coordinates are then used for calculating the deformations, strains, and strain rates throughout the surface of the specimen.
Least Squares Fitting of Analytic Primitives on a GPU
Authors: Panyam Meghashyam , Kurfess Thomas R. , Tucker Thomas M.
Published: July 2009

Metrology systems take coordinate information directly from the surface of a manufactured part and generate millions of (X, Y, Z) data points. The inspection process often involves fitting analytic primitives such as sphere, cone, torus, cylinder and plane to these points which represent an object with the corresponding shape. Typically, a least squares fit of the parameters of the shape to the point set is performed. The least squares fit attempts to minimize the sum of the squares of the distances between the points and the primitive. The objective function however, cannot be solved in the closed form and numerical minimization techniques are required to obtain the solution. These techniques as applied to primitive fitting entail iteratively solving large systems of linear equations generally involving arithmetic intensive operations. The current problem in-process metrology faces is the large computational time for the analysis of these millions of streaming data points. This paper presents a framework to address the bottleneck using a Graphical Processing Unit (GPU), to optimize operations and obtain significant gain in computation time.
Optimal Design of Horizontal Axis Wind Turbine Blades
Authors: Gur Ohad , Rosen Aviv
Published: July 2009

The optimal aerodynamic design of Horizontal Axis Wind Turbine (HAWT) is investigated. The Blade-element/Momentum model is used for the aerodynamic analysis. In the first part of the paper a simple design method is derived, where the turbine blade is optimized for operation at a specific wind speed. Results of this simple optimization are presented and discussed. Besides being optimized for operation at a specific wind speed, without considering operation at other wind speeds, the simple model is also limited in the choice of design goals (cost functions), design variables and constraints. In the second part of the paper a comprehensive design method that is based on a mixed numerical optimization strategy, is presented. This method can handle almost any combination of: design goal, design variables, and constraints. Results of this method are presented, compared with the results of the simple optimization, and discussed.
Direct Observation of Frictional Contacts on a Sliding Interface
Authors: Rubinstein Shmuel M. , Cohen Gil , Fineberg Jay
Published: July 2009

Two blocks in frictional contact, are supported by a multitude of microscopic contacts whose real contact area, A, is much smaller than the nominal one. We measure the spatial and temporal behavior of A along a rough spatially extended interface. Using high speed imaging we record, both slow nucleation processes as well as rapid, crack like events that eventually lead to overall sliding of an entire frictional interface. We report that a discrete sequence of crack-like precursors propagating within the interface is excited by a slowly increasing shear force applied to the blocks, when the shear force is applied to a single edge of the sample. The precursors are triggered at shear stresses well bellow those usually associated with the static friction coefficient. They increase systematically in length and significantly redistribute the real area of contact. Thus when the critical shear force for sliding is reached, the initially uniform contact area along the interface has already evolved to one that is highly non-uniform in space. These results suggest a fundamentally new view of the processes leading to frictional motion with ramifications to earthquake dynamics and material failure.
Robot Competitions: Curricula, Projects, and Educational Research
Authors: Ahlgren David J. , Verner Igor M.
Published: July 2009

This paper discusses the role and significance of robot competitions in engineering education with focus on experiences with the Trinity College Fire-Fighting Home Robot Contest, a mature international event that has attracted teams from more than 115 universities around the world. We consider development of effective learning environments for robot design projects, including first-year undergraduate engineering design courses and upper-level robot research and development teams. With regard to the latter, we describe our instructional strategies of choosing team projects, imparting competences and teamwork skills, reporting results, and assessing progress. We also consider achievement of ABET outcomes through competition-based design projects, and means to maximize student self-efficacy beliefs through mastery experiences in robotics. Finally we present methods for effective assessment and evaluation.
Uncertainty of Wear Rate and Coefficient of Friction for a Polymer Wear Experiment in a Pad-On Disc Tribotester
Authors: Aksulu Murat , Palabiyik Mehmet
Published: July 2009

In this study, for dry sliding wear of some polymers against stainless steel discs in a pad on disc tribotester, uncertainties of wear rate and coefficient of friction were calculated according to ISO “Guide to the Expression of Uncertainty in Measurement”. In the uncertainty budget of wear rate, the uncertainty of the slope of the regression line which was fitted to the wear volume-sliding distance curve, was added. In addition, the uncertainty of taking moisture of polymer pins while weighing was determined, and it was added to the uncertainty budget. So an attempt is made to calculate proper uncertainty for experimental results. It was seen that the most important uncertainty contribution was the repeatability of experiments.
Analytical and Numerical Study of Crushing of Syntactic Foams Under Uniaxial Compression
Authors: Marur Prabhakar
Published: July 2009

Syntactic foams are a class of particulate composites made with hollow microspheres dispersed uniformly in a matrix. By the inclusion of hollow spheres in the matrix, the bulk mechanical properties are improved by limiting the bending of cell edges and localization of inelastic deformation, which is the cause of failure in the case of low-density foams. For the general class of cellular materials, several analytical and experimental methods are available in the literature to characterize the material. In the case of syntactic foams, relatively few methods exist for the computation of effective elastic properties and methods for analyzing the crush behavior of the syntactic foams are rather limited. In this research, the quasi-static crushing behavior of syntactic foam under uniaxial compression is investigated using analytical and numerical methods. To better understand the bulk behavior of syntactic foam, a micromechanical study is conducted to analyze the crushing of hollow spheres in dilute concentration. Initially the stress fields around dilute concentration are derived using continuum mechanics principles and subsequently a limit analysis is performed. To gain further insight into the deformation fields and deformations of cell walls leading to densification, a finite element (FE) analysis is performed. Assuming a periodic repetition of a representative volume of the material would correspond to the bulk material, axisymmetric and 3D finite element models are developed. The numerical computations are compared with the analytical results obtained in this study, and with experimental data reported in the literature. Using the FE models, a parametric study is conducted to investigate the influence of microsphere strength and elastic mismatch between the matrix and the inclusions on the crush behavior of syntactic foam.
Vibration Reduction of Laminated Plates With Various Piezoelectric Functionally Graded Actuators
Authors: Pietrzakowski Marek
Published: July 2009

The aim of the present study is to develop models of active laminated plates containing monolithic piezopolymer sensor layers and a new type of actuator layers made of Piezoelectric Functionally Graded (PFG) material, which is a mixture of piezoceramics and polymer or epoxy matrix. The electromechanical properties of the PFG layers can be tailored varying continuously the piezoceramic volume fraction across the thickness during the manufacturing process. The analysis and numerical simulations are focused on the relationship between the material compositional gradient and electromechanical properties and also dynamic responses of the structure obtained. Three types of functions, which describe the volume fraction distribution of constituents, are considered: exponential, parabolic and sigmoid. The effective properties of the PFG material, i.e. the Young’s modulus and piezoelectric coefficient gradations, are determined using to the rule of mixtures. A constant velocity feedback algorithm is used for the active damping of transverse plate vibration. The dynamic analysis concerns steady-state behavior of rectangular symmetrically laminated plates and is based on hypothesis of the classical plate theory. The numerical simulations are performed to recognize the influence of the applied pattern of the piezoceramic fraction distribution and its parameters on the gradient of elastic and piezoelectric properties within the PFG actuators and, as the final result, the active plate structural response presented in terms of amplitude-frequency characteristics. The changes in both the natural frequencies and resonant amplitudes are compared and the influence of the piezoceramic gradation on the control system operational effectiveness is also indicated and discussed.
Computer Aided Manufacturability Analysis Closing the CAD-CAM Knowledge Gap
Authors: Molcho Gila , Schneor Ronit , Zipori Yaron , Kowalsi Pawel , Denkena Berend , Shpitalni Moshe
Published: July 2009

Due to rising demands in efficiency of design and manufacturing of industrial products, collaboration and exchange between designers and process planners is a permanent challenge. In an industrial survey carried out as part of this research, all participants emphasized the lack of collaboration and cooperation between designers and process planners. Although evolving CAD, CAM, CAPP and PLM tools provide the backbone for such cooperation and collaboration, additional structured supporting tools and processes are still required. This paper presents a holistic approach and supporting software tools for closing the knowledge gap and capitalizing on available manufacturability knowledge. Two complementary tools have been developed and implemented to ensure the efficiency and effectiveness of product and process design. The first is CAMA (Computer Aided Manufacturability Analysis), a system for capturing available “know how” and providing designers easy and effective insight regarding the manufacturability of their design. The system has been designed to facilitate upstream manufacturability validation and identification of areas of a design that are difficult, expensive or impossible to machine. The second tool is a process plan evaluator expert system tool capable of evaluating alternative process plans. The insight enabled by the evaluation is then also fed back to the designer and to CAMA, thus further initiating organizational learning.
Improved Tracking Systems With Adaptive Gates
Authors: Berman Arie , Dayan Joshua
Published: July 2009

Range and bearing navigation is commonly used in many autonomous systems such as autonomous guided vehicles and freely moving platforms. The measurements obtained are accompanied by noise and are subjected to possible errors, which consequently may lead to wrong decisions made by the control and guidance system. An improved method is applied for filtering unexpected high measurement noise due to clutter, glittering, or shaking of the measuring system. Optimal correlation gates around the predicted values of the signal states — the position of the target — reduce the unexpected noise effect. The optimal threshold for the correlation gates is determined off-line by simulation or, adaptively, by online estimations. Values of measurements not in the gates are ignored and the integration of the prediction model for the tracked signal continues until a new measurement is received within the gate opening. The dimensions of the correlation gates are determined by the filter predictions and the normal error variances of the measurement.
Discontinuity-Induced Bifurcations in Systems With Hysteretic Force Interactions
Authors: Dankowicz Harry , Paul Mark R.
Published: July 2009

This paper presents the application of the discontinuity-mapping technique to the analysis of discontinuity-induced bifurcations of periodic trajectories in an example piecewise smooth system in which changes in the vector field associated with the crossing of a discontinuity-surface depend on the direction of crossing. The analysis is motivatived by a hysteretic model of the capillary force interactions between an atomic-force-microscope cantilever probe tip and a nanoscale sample surface in the presence of a thin liquid film on the tip and the surface and operating in intermittent-contact mode. The analysis predicts the sudden termination of branches of periodic system responses at parameter values corresponding to grazing contact with the onset of the hysteretic force interactions. It further establishes the increase beyond all bounds of the magnitude of one of the eigenvalues of the linearization of a suitably defined Poincare´ mapping indicating the destabilizing influence of near-grazing contact.
A New Tool to Improve Enterprise Modelling Utilisation and Development
Authors: Wahid Bilal , Ding Chenghua , Weston Richard
Published: July 2009

In recent decades technological innovation has induced very significant change on the way that Manufacturing Enterprises (MEs) operate and compete. In general MEs are very complex entities: designed, managed and changed by people, by deploying people and technological resources in systematic, timely and innovative ways that generate competitive behaviors. Prerequisites to respond such change and deal with complexity are firm understandings of; the processes that are the focus of improvement, and effects of change decisions. However, implementing change and dealing with associated effects can prove difficult when such an understanding is not intrinsic i.e. domains lacking structure and documentation. This paper introduces a new approach to support enterprise decision making using Computer Integrated Manufacturing Open Systems Architecture (CIMOSA) modeling principles and constructs and enhanced stencils created in MS Visio® and MS Visual Basic®. Current approaches offer little benefit above and beyond paper based solutions and merely serve to provide a visual representation of processes. Such models require that the end user have an understanding of the modeling methodology deployed in creating the diagrams, leaving models prone to misinterpretation. From a model developers perspective, current approaches do not provide support for the capture of modeling decisions or background information, implying that robust understandings can not be had by those not directly involved with the modeling efforts. The added functionality exhibited by the newly developed approach offers great extensions over those currently in use, in terms of; efficient model development, increased data and application integration, and enhanced end user interactivity.
Electromagnetic Microactuators With On-Chip Resin-Bonded Permanent Magnets
Authors: Schreiber David , Krylov Slava , Shacham-Diamand Yosi , Sibgatullin Timur
Published: July 2009

In this work we present modeling, fabrication and characterization of novel electromagnetic microactuators with integrated resin-bonded hard magnets embedded in the handle of silicon-on-insulator (SOI) wafers. Trenches etched through the handle of the SOI wafers are filled with the resin-bonded magnet material and allowed to cure at ambient temperature. Clamped-clamped beams fabricated from the single crystal silicon device layer of the SOI wafer are fabricated above the resin-bonded magnet filled trenches. Applying alternating current through the beam produces steady out-of-plane displacements due to resistive Joule heating and excites in-plane resonant vibrations due to Lorentz force coupling. The 8 mm long, 32 μm wide beams produced a maximum in-plane amplitude of 4.2 μm under an applied 2.4 mA current while the resonant frequency was tuned by changing the current amplitude. The results provided by the coupled thermo-electro-mechanical model of the beam and backed by experiments suggest that the integrated resin bonded magnets can be efficiently used for the actuation of micro structures.
Experimental Validation of a Special Locking Drum Brake for Robotic Applications
Authors: Moschella Demetrio , Gatti Gianluca , Vitelli Emiliano , Lecce Albenzio , Perrelli Michele , Pace Calogero , Danieli Guido A.
Published: July 2009

The paper presents the development of a novel type of drum brake capable of locking a joint exploiting the effect of self excitation characteristic of this type of brake. A theoretical analysis based on the Reye assumption on wear is first presented, were conditions for self excitement are determined. An initial version of the brake was designed and tested, but it was soon discovered that actuation with solenoids was not appropriate. A second version was then developed where solenoids were replaced by a small motor and reducer placed inside the brake itself, but the resulting drum was too big for the application. Finally a version were the motor and reducer were placed outside the drum was designed. An ad hoc experimental test bed was built using a Maxon motor to control rotation and toque of the drum and to allow an initial wear of the ferodo in order to obtain compliant surfaces. Finally an electronic control of the brakes has been developed.
Pull-In Dynamics of Variable-Width Electrostatic Microactuators
Authors: Joglekar Manish M. , Pawaskar Dnyanesh N.
Published: July 2009

Determination of pull-in parameters is vital in the design of electrostatically actuated microdevices. Moreover, it is important to devise some means to gain a control over the pull-in parameters in order to establish the customized microactuator design practice. In this paper, we analyze the influence of the beam geometry on the dynamic pull-in parameters of electrostatically actuated microbeams. Novel width functions are proposed for the microcantilever and the fixed-fixed beam, which smoothly vary the width of the microbeam along its length. We demonstrate the use of these width-functions by comparing six different microbeam geometries, three for cantilevered beam and three for fixed-fixed beam along with their constant width rectangular counterparts. All configurations are analyzed using an energy technique which gives an upper bound on the critical amplitude of the microbeam displacement, which is subsequently used to extract a lower bound on the applied voltage at the point of dynamic pull-in instability. For every case, a comparison is made between the static and the dynamic pull-in parameters. Results indicate a greater pull-in range for concave beam geometries, while the convex geometries exhibit a reduction in the pull-in range. Actuation voltage requirement is found to be proportional to the increase in the travel range. In all cases, the dynamic pull-in displacement is found to be greater than the static pull-in displacement, while the dynamic pull-in voltage is found to be less than the static pull-in voltage.
On Self Intersections of Freeform Curves and Surfaces
Authors: Elber Gershon
Published: July 2009

The computations of curve-curve and surface-surface intersections are considered difficult problems in geometric design. Numerous results were annually published on these topics for the last several decades. Moreover, the detection and more so the computation and even elimination of self-intersections in freeform curves and surfaces is viewed by many as a far more challenging problem, with much fewer satisfactory results. In recent years, several methods were developed to robustly detect, compute and even eliminate self intersections in general freeform (typically NURBs) curves and surfaces, exploiting intrinsic and/or geometric properties, on one side, and the algebraic structure of the shape, on the other. Other methods are specific and employ special properties of the problem in hand, as is the case of offset computation. In this work, we will survey some of our results and others, and provide a birds view of the current state-of-the-art research, on the self-intersections problem, in the freeform domain.
Damage Identification by Computational Model Updating
Authors: Link Michael , Weiland Matthias
Published: July 2009

Computational model updating techniques have been developed in the past for adjusting selected parameters of large order finite element models in order to make the models compatible with experimental data. Numerical optimization procedures are applied for minimizing the differences of analytical and experimental data, for example, natural frequencies, mode shapes and/or frequency response functions. Since long these techniques have also been investigated with regard to their ability to localize and quantify structural damage. The success of such an approach is mainly governed by the quality of the damage model and its ability to describe the structural property changes due to damage in a physical meaningful way. The change of such parameters identified from test data taken continuously or temporarily over the time may serve as a feature for structural health monitoring. It is well known that low frequency vibration test data or static response data are not very well suited for detecting and quantifying localized small size damage. Exploitable results can only be expected if high spatial resolution of the response data is available. Time domain response data from impact tests carry high frequency information which usually is lost when experimental modal data are utilized for damage identification. Even so only little literature was found addressing the utilization of experimental time histories for model updating in conjunction with damage identification. The theoretical background and examples for using both types of experimental data, high resolution modal data as well as time domain data with high frequency content will be presented in the paper. These data are used in conjunction with a new technique of localizing and quantifying the damage parameters using the test data and the models of the damaged and the undamaged structure simultaneously (“multi model updating”) which is regarded as an attempt to reduce the effects of the unavoidable non-uniqueness of structural damage models.
Strategic Project Selection in the Pre-Development of Manufacturing Industry
Authors: Oertelt Stephan , Grote Karl-Heinrich
Published: July 2009

This paper focuses on the evaluation of project proposals within the innovation management of manufacturing industries. The goal is to define a strategy-oriented project program within a budgetary framework. This task requires a systematic approach which structures the wide range of information and makes the complexity of decision making controllable. Within the process framework of decision preparation and decision making, a coherent combination of adequate methods, processes and tools is indispensable. For this reason, a set of standardized methods comprised of ABC-analysis, value analysis, portfolio analysis, paired comparison and expert discussion is suggested. Moreover, the central decision-making supporting element is the evaluation of alternative projects with regard to their potential and risk.
Hydraulic Analysis of a District Heating Network
Authors: Popescu Daniela , Serban Elena , Panaite Carmen-Ema , Herna´ndez-Guerrero Abel
Published: July 2009

The aim of this work is to study the influence of pressure loss parameters from a district heating system on the distribution of fluid flow rates. The research was finalized by improving the mathematical model of a district heating network, which comprises an algebraic non-linear system that synthesizes flow balance equations of a stationary flow. This enhanced model indicates the influence of every consumer’s heat demand supplied from a district heating network on the fluid flow rates distribution based on the means of the implicit function theorem. The originality of the method consists of considering the network a sensitive system that responds to the variations of input parameters (pressure loss parameters) by variations of output parameter (fluid flow rates). The main advantage is that the engineer in charge with exploitation of the heating system may understand what happens with the flow allocations when pressure loss parameters of the network are different from the nominal ones, without making any measurements on the field or computations using new scenarios. The method presented in this paper facilitates the choice of the best decision concerning balancing and practical management of radial heating networks.
MBARS2: A New Design for a 3- Degrees of Freedom Parallel Structure for Joint Arthroplasty
Authors: Wolf A. , Amir S. , Mor A. B.
Published: July 2009

In this report we present the second prototype of a 3-degrees-of-freedom active, miniature bone-attached, robotic system. The report focuses on the mechanical structure, workspace analysis and inverse kinematics solution. The robot is capable of preparing the bone cavity for an implant during joint arthroplasty procedures. This system, just as its predecessor is image-free and all planning is performed intraoperatively in the robot coordinate system, eliminating the need for external tracking systems in the OR. Experiments were conducted using the first robot prototype to evaluate its accuracy and the results supported the feasibility of the concept.
Control of Knee Frontal Plane Moment via Modulation of Center of Pressure: A Prospective Gait Analysis Study
Authors: Haif Amir , Wolf Alon
Published: July 2009

Objectives: Footwear-generated biomechanical manipulations (e.g., wedge insoles) have been shown to reduce the magnitude of adduction moment about the knee. The theory behind wedged insoles is that a more laterally shifted location of the center of pressure causes a smaller distance of the moment arm of the knee joint adduction moment during gait. However, the relationship between the center of pressure and the knee adduction moment remains to be determined. The aim of this study was to assess the effect of the location of the center of pressure and the magnitude of the knee adduction moment during gait in healthy men. Methods: A novel foot-worn biomechanical device which allows controlled manipulation of the center of pressure location was utilized. Successive gait analysis testing was performed on 12 healthy men under four different conditions: control, neutral sagittal axis, center of pressure shifted medially and laterally from the functional sagittal axis. Results: The knee adduction moment during the stance phase significantly correlated with the shift of the center of pressure from the functional neutral sagittal axis in the frontal plane (i.e., from medial to lateral). The moment was reduced with the lateral sagittal axis configuration and augmented with the medial sagittal axis configuration. Conclusions: The study results confirm the hypothesis of a direct correlation between the coronal position of the biomechanical elements (location of the center of pressure) and the coronal kinetics of the knee.
Deep-Cryogenic Treatment and Effect of Austenizing Temperature on Tribological Performance of P/M High-Speed Steel
Authors: Podgornik B. , Leskovsˇek V. , Vizˇintin J.
Published: July 2009

The aim of our work was to investigate the influence of deep-cryogenic treatment parameters (treatment time and temperature) and austenizing temperature on the tribological performance of powder-metallurgy (P/M) high-speed steel. Special emphasis was put on abrasive wear resistance and resistance to galling under dry sliding conditions. Abrasive wear resistance was tested under reciprocating sliding conditions using alumina ball, while galling resistance against austenitic stainless steel was determined in a load-scanning test rig. Tribological test were evaluated in terms of high-speed steel wear volume, coefficient of friction under reciprocating sliding, friction variation with load, and critical load for galling initiation and stainless steel transfer layer formation.
Lifecycle Monitoring for the Automotive Eco-Sustainability
Authors: Belotti Vittorio , Razzoli Roberto P. , Michelini Rinaldo C.
Published: July 2009

The growth sustainability requires dramatic changes to lower the natural resources consumption and the surroundings pollution, by recovery/remediation processes. The EU policy aims at the extended producers/suppliers responsibility, with effective charges on the products allowed to be put on the market, used and called-back, in view of the properly small impact and transparent lifecycle acknowledgement. This leads to «extensions» in designing the new offers with integrated monitoring and service functions. The design for the lifecycle eco-effectiveness is accomplishment, better qualifying the far-seeing companies according to the EU eco-policy. The idea is to reach the duty visibility, by the extended plug-and-play concept, based on series of integrated design options, assigning the structural and functional modules, for the operation monitoring, the reliability assessment and the impact appraisal. This instrumental setting includes intangible information/communication aids, to confer ambient intelligence abilities. This way, the on-process visibility is assured, and exploited for on-duty servicing and end-of-life processing. The example case chosen deals with the critical situation of the parts manufactured in plastics, which are deemed to represent most relevant portion in the cars to come. The following recovery options are possible: - the reuse of the reconditioned items, according to suitably assessed life-extension opportunities; - the recycling of the warn-out components, with the regeneration and reusing of the materials; - the thermal recovery of residual stuffs, within careful handling and pollution-safe warnings; - the reduction to registered ASR, automobile shredding residue, within the EU directives limits. The on-board information system includes, as innovative feature, the resort to identifying tags or labels, to be read and written through wireless links. The technology exploits cheap and compact supports, allowing the labelling of the component, from production, to lifecycle, with an identifying code. The RFID, Radio Frequency Identification Device, is privileged, as ideal means for the component traceability and the history, use modes/styles and cumulated issues storing.