bluuebunny/crossref_metadata_2025 huggingface dataset:
Application of Photostrictive Actuators to Photonic Control of Shallow Spherical Shells
Authors: Shih Hui-Ru , Lucas Calvin , Saypuri Manov , Tzou Horn-Sen
Published: April 2008

The direct conversion of photonic energy to mechanical motion by photostrictive effect can lead to a new photoactuation technique for active control of flexible structures. It offers the advantage of generating distributed actuation strain without connecting any electric lead wires. In this paper, photonic control of flexible spherical shells using discrete photostrictive actuators are investigated. This paper presents a coupled opto-piezothermoelastic shell theory that incorporates photovoltaic, pyroelectric, and piezoelectric effects, and has the capability to predict the response of a spherical shell driven by the photostrictive actuators. In this study, the effects of actuator locations as well as membrane and bending components on the control action are analyzed. Analytical results indicate that the control forces are mode and location dependent. Analysis also shows that the membrane control action is much more significant than the bending control action.
Design and Development of a Convection Heating System in a Glass Tempering Furnace
Authors: Coe William , Nasr Karim , Mahoney Gary
Published: April 2008

Glass tempering has relied on radiant heaters to transfer heat to glass sheets. This has a direct correlation to the length of time that the glass is subject to heating in the furnace and its related line speeds. This paper presents the design and development of a supplementary convection heating system with the objective of reducing glass residence time and increasing production efficiency. It will document the methodology of retrofitting a current furnace in a cost effective manner while increasing heat transfer to the glass and increasing throughput. This study will address factors affecting the systems’ performance such as current draw, surface compression test, break pattern, warp configuration, and nozzle design. The retrofitted system has achieved design goals and promises to increase heat transfer rates to the glass as well as increase furnace productivity.
Development of a G-Code Free, STEP-Compliant CNC Lathe
Authors: Xu Xun W. , Wang Jun
Published: April 2008

The paper describes a STEP-compliant CNC lathe that demonstrated a G-Code free machining scenario. This research work was conducted in two parts. The first involved retrofitting an existing CNC lathe with a more open platform control system — Compumotor Motion Control system, which is capable of interfacing with other CAPP/CAM programs through languages such as Visual Basic, Visual C++ and Delphi. The control system is programmable using its own motion control language — 6K Motion Control language. A library of 6K functions has been developed to cater for different turning operations. The second part of the research is the development of a “STEPcNC Converter,” which can understand and process STEP-NC codes, and interface with the CNC controller through an interface. It makes use of STEP-NC information such as “Workplan,” “Workingstep,” machining strategy, machining features and cutting tools that is present in a STEP-NC file. The Application Interpreted Model (AIM) of STEP-NC has been used.
An Introduction to Intellectual Property
Authors: Rowland William C.
Published: April 2008

Patents are legal documents issued by the governments of almost every industrial country in the world. The scope and term of a patient may very from counry to country. A United States patient provides its owner with the legal right to prevent the unauthorized making, using, selling, and offereing for sale in the United States, and the importation into the United States, of the invention set forth and claimed in the patent.[2]
Influence of Intake Manifold Heat Transfer Effects on Accuracy of SI Engine Air-Charge Prediction
Authors: Deur Josˇko , Magner Stephen W. , Jankovic Mrdjan , Hrovat Davor
Published: April 2008

Estimation of the actual cylinder air charge and air-charge prediction several engine events into the future are needed to implement an air-fuel ratio feedforward controller. The estimator/predictor is usually based on the isothermal intake manifold model which assumes constant temperature of manifold air. However, fast thermocouple measurements have pointed to significant changes of manifold air temperature during typical tip-in/tip-out engine transients. In order to capture the temperature change effect, the manifold dynamics should be described by the so-called polytropic model. This paper presents an algebraic and simulation analyses of the influence of manifold modeling errors on the accuracy of air-charge prediction. The analysis is conducted for a typical predictor given in two variants depending on whether the throttle mass flow sensor or the manifold pressure sensor is used.
Validity of Environmental Indicators in Design of Products
Authors: Olson Walt
Published: April 2008

Environmental comparison of products and processes commonly use environmental indices such as Eco-Indicator 99 and/or other metrical indices. Extensive life cycle analyses of the product or process are the foundations for these indices. Then based on these indices, products are evaluated relative to other products for various decisions including design. Yet these metrics include little, if any, appreciation of the underlying distributions in making such estimates. This paper explores the cumulative effects of uncertainty by considering the values entering the computation of a metric such as Eco Indicator-99 as random variables. Since these indicators algebraically combine random variates, the resulting index is also a random variate. While the practitioners of life cycle analysis are well aware of the uncertainties of the analysis, there appears to be little appreciation for the value or uncertainties of algebraically combining random variates particularly when the fundamental distribution is lognormal as it is in most environmental instances.
Stress Intensity Factor Distributions and Crack Growth in Pressure Vessel Problems by the Frozen Stress Method
Authors: Smith C. W. , Liu C. T.
Published: April 2008

This paper describes the application of a laboratory based experimental method [1] to three dimensional cracked body problems in pressure vessels in order to determine the crack shape and stress intensity factor (SIF) distribution along the crack front when the crack shape is not known a-priori. Results for specific problems are presented and conditions and limitation of the method are described.
Measurement of Heat Transfer Coefficients for Non-Azeotropic Hydrocarbon Mixtures at Cryogenic Temperatures
Authors: Hughes Cory B. , Nellis Gregory F. , Pfotenhauer John M.
Published: April 2008

The use of non-azeotropic hydrocarbon mixtures in throttle-cycle refrigeration systems has resulted in large increases in the performance of Joule-Thomson type cryocoolers. However, there is very little data or theory currently available in the literature regarding the thermal-fluid behavior of multi-component, multi-phase mixtures at cryogenic temperatures. The design of these systems is therefore semi-empirical, relying heavily on experimental iteration. In this paper, an experimental apparatus is described that is capable of making precise and controlled measurements of the heat transfer coefficient over a range of cryogenic temperatures, compositions, geometries, and flow rates that are relevant to small-scale, throttle-cycle refrigeration systems. The experimental apparatus is used to carry out a study of the horizontal flow boiling heat transfer coefficient for a non-azeotropic hydrocarbon mixture in a circular cross-section with a constant wall temperature. The measurements are carried out over a range of cryogenic temperatures and the data is presented in the form of heat transfer coefficient as a function of temperature and thermodynamic quality. The experimental uncertainty of the measurements is theoretically estimated to be 10%. Measurements of the single-phase heat transfer coefficient for pure nitrogen fall within 10% of the Dittus-Boelter correlation.
How Do the Local Conditions Influence the Flame Synthesis of Carbon Nanostructures?
Authors: Arana Claudya P. , Puri Ishwar K. , Sen Swarnendu
Published: April 2008

Since prepared substrates offer an appropriate method for the selective production of uniform arrays of aligned CNTs and CNFs, it is important to illustrate the influence of different catalysts on the resulting nanostructures. This investigation characterizes the activity of three catalysts — iron in alloyed form as stainless steel, nickel, and platinum — on carbon nanostructure formation under identical conditions in an ethylene/air nonpremixed flame. We have synthesized well-aligned multi-walled CNTs (on Ni) and CNFs (on stainless steel). The third transition metal Pt produces CNF structures of a different kind and its activity has not been previously characterized in flames. The catalyst and gas-phase conditions leading to the formation of these different structures are discussed.
Short Shaped Copper Fibers in an Epoxy Matrix: Their Multifunctional Use — Fracture and Impact Toughening and EMI Shielding
Authors: Wetherhold Robert C. , Bagwell Renee M. , McManaman Joseph M.
Published: April 2008

Previous research has shown that short shaped copper fibers can significantly increase the fracture toughness of a thermoset matrix composite. This paper considers the effectiveness of adding these same short shaped copper fibers to improve the composite’s impact toughness. Further, the electromagnetic interference (EMI) shielding effectiveness (SE) of these shaped copper fibers will be analyzed. The matrices used in the impact experiments were two different types of epoxy, a low shrinkage epoxy (LS) and a high shrinkage epoxy (HS). Fiber shapes and lengths were chosen based on previous single fiber pullout experiments. The following shaped fibers were used: straight, flat end-impacted, rippled, and end-oxidized. The two fiber lengths tested were 6mm and 10mm. Results indicate that the largest influence on impact toughness is from the matrix fracture behavior. When the matrix failed around the fibers, the impact toughness was significantly less compared to matrices with the same fibers that had a planar fracture at the notch during impact. Fiber end modification and to a lesser extent the fiber length both also had an effect on the fiber pullout behavior and resulting toughness. Comparing the end-modified fibers to straight fibers, the largest increase in impact toughness was 17%. The matrix used for the EMI shielding experiments was HS epoxy and two fiber diameters were tested: 0.325 mm and 0.162 mm. The fiber shapes used in the experiments were: straight, flat end-impacted, rippled, and acid roughened. An EMI SE of > 40 dB at 1.5 GHz was attained using 15vol% of the 0.162 mm diameter shaped fibers. The composites with 15vol% of the 0.325 mm diameter shaped fibers showed poor EMI SE, < 20 dB, due to large fiber diameter that results in a lower skin depth volume and a lower number of fibers which results in a lower number of conducting paths for attenuation through the composite. Results indicate that besides improving the fracture and impact toughness of a thermoset polymer matrix, short shaped copper fibers can also significantly improve the EMI SE of the composite, resulting in a multifunctional material.
Effects of Laser Intensity and Ambient Conditions on the Laser Induced Plume
Authors: Zhang Zhaoyan , Gogos George
Published: April 2008

Laser ablation presents a promising technique for material processing. The quality of products is strongly influenced by the properties of the laser induced plume. In compressible flow, the ambient conditions can be transmitted upstream. Therefore, the laser ablation process is strongly affected by the ambient conditions. In this paper, the effects of laser intensity, back pressure and temperature on the laser induced plume were studied using a numerical model, which calculates the density, pressure and temperature of the laser induced plume at different laser intensity and ambient conditions. The results are in agreement with experimental results available in the literature and can be used for the optimization of the pulsed laser deposition process.
Pressure Drop Measurements for Air Flow Through Open-Cell Aluminum Foam
Authors: Dukhan Nihad , Alvarez Angel
Published: April 2008

Wind-tunnel pressure drop measurements for airflow through two samples of forty-pore-per-inch commercially available open-cell aluminum foam were undertaken. Each sample’s cross-sectional area perpendicular to the flow direction measured 10.16 cm by 24.13 cm. The thickness in the flow direction was 10.16 cm for one sample and 5.08 cm for the other. The flow rate ranged from 0.016 to 0.101 m3/s for the thick sample and from 0.025 to 0.134 m3/s for the other. The data were all in the fully turbulent regime. The pressure drop for both samples increased with increasing flow rate and followed a quadratic behavior. The permeability and the inertia coefficient showed some scatter with average values of 4.6 × 10−8 m2 and 2.9 × 10−8 m2, and 0.086 and 0.066 for the thick and the thin samples, respectively. The friction factor decayed with the Reynolds number and was weakly dependent on the Reynolds number for Reynolds number greater than 35.
Unsteady MHD Flow and Heat Transfer of Dusty Fluid Between Two Cylinders With Variable Physical Properties
Authors: Balasubramanian Nagarajan , Chen Yitung
Published: April 2008

A mathematical model for unsteady heat transfer and flow of an electrically conducting, viscous, incompressible dusty fluid in a channel formed between two concentric cylinders is developed. In the model, the fluid is driven along the channel by a constant pressure gradient, and an external magnetic field is applied in the direction perpendicular to the channel flow. The two cylinders are considered electrically insulated, and the surfaces maintained at constant but different temperatures with the outer cylinder being at a higher temperature. The viscosity and electrical conductivity of the fluid are considered varying with temperature. The equations governing flow and temperature distribution of both the fluid and the dust particles are a set of coupled momentum and energy equations. The derived system of non-linear partial differential equations is solved numerically on a two-dimensional computation grid using the Galerkin finite element method. The paper ends with discussions of the effect of the applied magnetic field and the variations in viscosity and electrical conductivity with temperature on the time development of the velocity and temperature distributions for both the fluid and dust particles.
Hybrid Micro-Meso Mechanical Switch Array for Tactile Displays
Authors: Enikov Eniko T. , Lazarov Kalin V.
Published: April 2008

Traditional MEMS actuators have limited stroke and force characteristics. This paper describes the development of a novel hybrid actuation solution, which utilizes a micro-machined actuator array to provide switching of mechanical motion of a larger meso-scale piezo-electric actuator. One motivating application of this technology is the development of a tactile display, where discrete mechanical actuators apply vibratory excitation at discrete locations on the skin. Specifically, this paper describes the development fabrication and characterization of a 4 × 5 micro-actuator array of individual vibrating pixels for fingertip tactile communication. The individual pixels are turned ON and OFF by pairs of microscopic thermal actuators, while the main vibration is generated by a vibrating piezo-electric plate. A thermo-electric and non-linear thermo-elastic models have been developed to account for the temperature dependence of the electrical resistance and the lateral buckling of the hot, respectively. Comparison between analytical and finite element models indicated very good agreement, confirming that the buckling of the hot arm has most significant impact in the overall actuator performance. The fabrication sequence and the actuation performance of the array are also presented.
Micro-Assembly and Packaging of MEMS Using Optically Transparent Electrostatic Gripper
Authors: Enikov Eniko T. , Minkov Lyubomir
Published: April 2008

This paper describes the assembly experiments with a novel miniature assembly cell for micro-electromechanical systems (MEMS). The cell utilizes a transparent electrostatic gripper and uses several disparate sensing modalities for position control: computer vision for part alignment with respect to the gripper, a fiber-coupled laser, and a position sensitive detector (PSD) for part to assembly alignment. Assembly experiments indicate that the gripping force and stage positioning accuracy are sufficient for insertion of 500μm wide parts in 550 μm wide slots etched in silicon wafers. Details on the cell operation, the control algorithm used and their limitations are also provided. Potential applications of the developed assembly cell are assembly of miniature optical systems, integration of optoelectronics, such as laser diodes with CMOS, and epitaxial lift-off (ELO) of thin films used in optoelectronic devices.
OSHA, EPA and Other Stakeholder Responses to the Conclusions and Recommendations of the Chemical Safety Board’s Report on “Improving Reactive Hazard Management” and Some Approaches Towards Resolving Remaining Recommendation Issues
Authors: Rosenthal Isadore
Published: April 2008

The USA Chemical Safety and Hazard Investigation Board (CSB) conducted a study of the chemical safety risks posed by the class of reactive hazards. This report, “IMPROVING REACTIVE HAZARD MANAGEMENT” (Report), was issued in October 2002 and its conclusions and recommendations have had significant impacts on how stakeholders view the adequacy of industry and government management of reactive hazards. The continued stream of high profile accidents due to reactive hazards such as Concept Sciences and Toulouse) cause people to also remember that realization of a reactive hazard also led to the accidents at Bhopal and Seveso and consequent major legal and social impacts in India, the United States and Europe. After a discussion of the congruence between the Report’s Objectives and Conclusions and the major thrusts of the Reactive Report’s ‘Recommendations’, to government agencies and other stakeholders, the paper will provide an update on the positive impacts that the CSB Report has already had on activities by professional societies, government and industry and examine some of the major unresolved recommendations, particularly those directed to OSHA to broaden PSM regulatory coverage of reactive chemicals. The paper will conclude with observations on various approaches to broadening coverage of reactive hazards along the lines recommended by the CSB to OSHA and EPA. Among the approaches reviewed will be the one embodied in New Jersey’s very recently modified TCPA regulation, selected proposals in the literature, and voluntary guidelines such as those under development by the newly formed Reactive Management Roundtable group of AIChE.
Course EC320: The Contemporary Economy of Japan Taught for Non-Japanese Students
Authors: Honda Hiroshi
Published: April 2008

Course EC320 “The Contemporary Economy of Japan” was taught by the author in Fall 2003 Semester for a total of fourteen American, Chinese, Korean, Vietnamese and Venezuelan undergraduate students who came to IES Tokyo to study Japanese language, culture, economics, social structure and politics among others. The subject of paper introduces the outline of Course EC320 and its teaching methodology such as collaborative learning approach and utilization of field studies, and discusses interests and motivations of the students in learning in general, and in writing semester reports, based on their performance, their comments, and the author’s observation.
Machine Guarding, Lockout/Tagout, and the Interlocked Guard
Authors: Rasnic Russ , Capps Joe A.
Published: April 2008

Unguarded or poorly guarded machinery claims many limbs and lives each year. Similarly, injuries from machinery undergoing maintenance and/or cleaning operations are far too numerous. Machine guarding and related machinery violations continue to rank in the top 10 in OSHA citations. The lists of types of machines and their associated hazards, as well as the types of injuries are too lengthy to mention. Maximizing the effectiveness of safeguards is essential for protecting workers from preventable injuries. One of the most effective means of machinery guarding is the interlocking guard, which is a device that shuts off or disables a machine function when a guard or cover is removed or opened. Interlocking guards are an important component of guarding safety. Often, an interlocked guard is the only type of guard that can be used. This paper presents several scenarios where the interlocking guard was the best available technology for handling the hazard. Interlocks are a rapidly developing field. The advantages and drawbacks of interlocks are discussed, as well as the different types of interlocks available.
Tactile Feedback Navigation Handle for the Visually Impaired
Authors: Bouzit M. , Chaibi A. , De Laurentis K. J. , Mavroidis C.
Published: April 2008

This paper presents a novel tactile navigation system for the blind. The device is portable and cost effective, and will allow visually impaired individuals to navigate through familiar and non-familiar environments without relying on the assistance of a guide. The “Tactile Handle” consists of an array of vibro-tactile actuators positioned to match the finger phalanxes, proximity sensors, and an embedded micro-controller. The handle processes sensor signals and outputs information to the user through variable and synchronized vibrations, which will enhance the sense of orientation and distance for the user. The prototype has an ergonomic design, is lightweight, compact, and adjustable to different hand sizes. This paper describes the concept of its use as a navigation system for the visually impaired and the preliminary results for the tactile perception of 30 sighted users of different genders and hand sizes.
Thermal Analyzing of Disc Type Winding With Directed Oil Flow
Authors: Peste Seyyed Mehdi , Abloo Mehdi
Published: April 2008

In this paper, a model of a disc type winding for a transformer with directed oil flow is presented which utilizes a network of oil flow paths. Along each path segment, oil velocities and temperature rises are computed. The model includes temperature dependent oil density, resistivity, and oil viscosity and temperature and velocity dependent heat transfer and friction coefficients. Because of the non-linearity, an iterative solution is necessary. Temperature and oil velocities are computed and compared with experiment values. From this, the average winding temperature rise and the hot spot temperature can be determined. The model assumes the oil flows in definite paths and ignores local circulation, since we assume the oil flow is guided by means of oil flow washers, this assumption should be fairly accurate. The disc type winding is assumed to be subdivided into directed oil flow cooling paths.
Computational Modelling of Flow in Idealised and Realistic Airway Bifurcations
Authors: Heraty Kevin , Quinlan Nathan
Published: April 2008

Understanding of the flow of air and particles in the lung is essential to the success of pulmonary drug delivery. The main objective of this work is to characterize the flow in a single geometrically realistic tracheobronchial bifurcation by computational methods. Much research to date (e.g. Comer et al [1]) is based on idealised geometry put forward by Weibel [2]. Another aim of this project, therefore, is to compare observed flows in realistic and idealised geometries in order to evaluate the validity of the simplified models. A computational model of a realistic geometry was generated using images obtained from the Visible Human data set (Banvard [3]), which comprises a three-dimensional anatomical picture of a human cadaver. Extracts from this data set were used with image processing and surface modelling software to generate a geometric description of a 4th generation bifurcation. The geometry of the idealised model is based on the Weibel model A. The unsteady flow of air through the bifurcation was then modelled computationally. A general purpose computational fluid dynamics package, CFX5®, was used to predict the entire three-dimensional unsteady flow field inside the bifurcation. It was assumed that the airflow was unsteady, incompressible and laminar at the location of the 4th generation airway in the lung. Computations were carried out for a Reynolds number of 510 (based on the average velocity in the parent branch of the bifurcation). The walls of the airway were assumed to be rigid. Computational results for air flow highlight the complex flow structure in the realistic geometry, and indicate major discrepancies between realistic and idealised geometry models.
Thermal Consideration of the Design of Multilayer Coated Tools for High Speed Machining
Authors: Attia Helmi , Kops Lucjan
Published: April 2008

Quantitative assessment of the thermal role of multi-layer coating in cutting tools was approached through the analysis of mechanical contact problem at the tool–chip interface and the constriction resistance phenomenon. The micro-contact configuration on the surface asperity level (size and density of contact points, and surface approach) and the macro-contact configuration (contact pressure distribution and the size of the adhesion and sliding zones) were defined. The effect of multi-layer coating on stiffness of the contact interface was experimentally investigated and used to estimate effective flow stress of contacting solids. Thermal constriction model, based on the concept of heat flow channel, was developed. Using FE simulation, the correlation between the contact pressure and the thermal contact resistance of uncoated and multi-layer coated tools were established and validated. The thermal interaction and heat redistribution in the workpiece–chip-tool system was then examined for multi-layer coated tools in conventional and high speed machining. Analysis of the results showed that the tool coating causes the reduction of the heat flowing into the tool and the reduction of the maximum temperature rise. The thermal constriction model developed in this work provides a methodology for the design of coated tools based on thermal considerations.
Real-Time Adaptive Modeling Approach to Compensate the Thermal Deformation of Nonlinear Machine Tool Structures
Authors: Fraser S. , Attia Helmi , Osman M. O. M.
Published: April 2008

Machine tool structures cannot be fully optimized at the design stage to cover the wide range of operating conditions. Therefore, reliable control systems emerge as the logical solution to compensate for thermal errors. Due to the difficulty of measuring the relative thermal displacement δ between the tool and the workpiece during machining, δ has to be accurately estimated in real-time. A new concept of adaptive modeling is introduced to develop control-based dynamic models to predict and compensate for thermal deformation of nonlinear complex machine tool structures. A key element of this approach is to replace the changes in the contact pressures along the joint by fictitious contact heat sources FCHS. This allows us to track the system nonlinearity through temperature measurements and real-time inverse heat conduction IHCP solution. The proposed approach dealt successfully with a number of challenges; namely, the non-uniqueness of the problem, and the lack of sufficient conditions to identify each of such unusual FCHS separately. The results showed that the models are capable of satisfying the accuracy, stability and computational efficiency requirements, even when the temperature measurement signal is contaminated with random noise. The results also showed that the thermal deformation transfer function behaves as low-pass filters, and as such it attenuates the high frequency noise associated with temperature measurement error.
Effect of Jet Pulsation and Duty Cycle on Film Cooling From a Single Jet on a Leading Edge Model
Authors: Ekkad Srinath V. , Ou Shichuan , Rivir Richard B.
Published: April 2008

The effect of jet pulsation and duty cycle on film effectiveness and heat transfer was investigated on a film hole located on the circular leading edge of a blunt body. A transient infrared technique was used to measure both heat transfer coefficients and film effectiveness from a single test. Detailed Frossling number and film effectiveness distributions were obtained for all flow conditions. Jet pulsing frequencies of 5 Hz, 10 Hz, and 20 Hz have been studied. The effect of duty cycle created by the valve opening and closing times was also set at different levels of 10%, 25%, 50%, and 75% of designated 100% fully open condition for different blowing ratios from 0.25 to 2.0. The combination of pulse frequency and duty cycle was investigated for different blowing ratios on a single leading edge hole located at 22-deg from geometric leading edge. Results indicate that higher effectiveness and lower heat transfer coefficients are obtained at the reduced blowing ratios which result from reduced duty cycles. The effect of varying the pulsing frequency from 5 Hertz to 20 Hertz is not discernable beyond the level of experimental uncertainty. Effective blowing ratio due to lowering of the duty cycle at a given blowing ratio seems to plays a more important role in combination with pulsing which provides improved cooling effectiveness at lower heat transfer coefficients.
A Generalized Impact-Sliding Fretting Wear Model Based on Fracture Mechanics Approach
Authors: Gessesse Yemane , Attia Helmi , Osman M. O. M.
Published: April 2008

Impact-sliding fretting wear is a complex phenomenon due to the random nature of the flow-induced vibrations, and the self-induced tribological changes. Available models, which relate wear losses to the process variables, are empirical in nature and bear no physical similarity to the actual mathematical and physical attributes of the wear process. A generalized model is developed in the present work to mathematically describe the fretting wear process under various modes of motion, namely, impact, sliding and oscillatory. This model, which is based on the findings from the fracture mechanics analysis of the crack initiation and propagation processes, takes into consideration the simultaneous action of both the surface adhesion and subsurface fatigue mechanisms. The model also accounts for the micro-, and macro- contact configuration of the tube-support system. The closed form solution requires the calibration of single parameter, using a limited number of experiments, to account for the effect of environment and the support material. The model was validated using experimental data that are generated for Inconel 600 and Incology 800 tube materials at room and high temperature environment, and for different types of motion. The results showed that model can accurately predict wear losses within a factor of < ±3. This narrow range presents better than an order of magnitude improvement over the current state-of-the-art models.
Identification of Dynamic Rates of Elastomeric Vibration Isolators in Automotive Vehicles
Authors: Nefske Donald J. , Sung Shung H. (Sue) , Feldmaier Douglas A.
Published: April 2008

Dynamic stiffness and damping rates of elastomeric vibration isolators used in automotive vehicles are identified from static isolator tests and the use of an isolator finite element model. Comparisons are made of the predicted versus measured dynamic stiffness and damping rates from 0 to 300 Hz of a rear suspension isolator to validate the technique. The identified dynamic rates of the elastomeric isolators of a representative vehicle are then input to the vehicle system finite-element model to compare the predicted versus measured vehicle vibration and interior noise response for laboratory shaker excitation.
Numerical Investigation of Laminar Flow in a Helical Pipe Filled With a Fluid Saturated Porous Medium: The Sensitivity of Secondary Flow to Parameter Variations
Authors: Cheng Liping , Kuznetsov Andrey V.
Published: April 2008

Laminar flow in a helical pipe filled with a fluid saturated porous medium is investigated numerically. The analysis is based on a full momentum equation for the flow in porous media that accounts for the Brinkman and Forchheimer extensions of the Darcy law as well as for the flow inertia. Accounting for the flow inertia is shown to be important for predicting secondary flow in a helical pipe. The effects of the Darcy number, the Forchheimer coefficient as well as the curvature and torsion of the helical pipe on the axial flow velocity and secondary flow are investigated numerically.
Challenges and Methods in the Quantification of Design Errors and Solution Elements
Authors: Chao Lawrence P. , Ishii Kosuke
Published: April 2008

To error-proof the design process, tools such as Design Process Failure Modes and Effects Analysis and Project Quality Function Deployment mitigate risk through thorough understanding of the consequences of both the process-level errors that can occur and the solution elements that mitigate them. However, the quantification of design errors and prioritization of other elements are complicated by the temporal and spatial distance of the decisions from the end-result. This paper discusses measures for design elements in the context of process-based analysis, including the design errors, tasks, and project resources. The Risk Priority Number is the standard measure of criticality of failure modes and their effects. However, alternatives to the traditional RPN have emerged in forms such as expected and life-cycle cost as well as QFD-based techniques. The paper explores the benefits and challenges of these traditional and new measures and concludes with a discussion into converting between the measures.
Single Crystal Piezoelectric Actuators for Advanced Deformable Mirrors
Authors: Jiang X. N. , Rehrig P. W. , Hackenberger W. S. , Moore J. , Chodimella S. , Patrick B.
Published: April 2008

In this paper, single crystal piezoelectric actuators are developed and demonstrated as a means of increasing actuator authority while maintaining strain precision for adaptive optics used large throw deformable mirror applications. Single crystal (PMN-PT crystal) stack actuators with foot print size of 5 mm × 5 mm and height varied from 16 mm to 21 mm have been designed, fabricated and tested. The actuation stroke larger than 50 μm is obtained under driving electric field of 15 KV/cm for single crystal stack actuators. In-plane actuation stroke is about 25 μm under 8KV/cm for single crystal plate actuators. The characterization results show that the single crystal piezoelectric actuators hold enhanced stroke and coupling coefficient (>0.83) under lower driving field comparing with PZT counterpart, while keep the nature of piezoelectric actuations with high precision, high resolution, fast response under high preload stress. The potential benefits of incorporating these actuators in a deformable mirror (DM) design were demonstrated by system modeling using the Integrated Optical Design Analysis Software (IODA) developed by SRS. The modeling shows that low order aberrations with peak to valley errors as large as 40 microns could be corrected to diffraction limited performance with a reasonable number of actuators and acceptable actuator forces and face sheet stresses. In the case of DM correction with 20 microns of 1st-Order Astigmatism-X error (Peak to valley: 38.74 μm, RMS error: 8.13 μm), the corrected wavefront error was reduced to PV of 0.26 μm and RMS error of 0.024 μm, which suggest promise for large throw DM applications.
System Identification and Optimal Control of a 6-DOF Magnetic Levitation Stage With Nanopositioning Capabilities
Authors: Shakir Huzefa , Kim Won-Jong , Verma Shobhit
Published: April 2008

A systematic procedure for modeling and optimal control of a multivariable 6-DOF (degree-of-freedom) magnetically levitated (maglev) stage has been described in this paper. In our previous publications, we have presented the design, SISO (single-input single-output) control, and testing of the maglev stage with nanometer-precision positioning capability and several-hundred-micrometer travel range. In the present work, we extended the current model to a more rigorous LQR (linear quadratic regulation) controller for the lateral control to reduce the coupling between axes. Independent lead-lag controllers have been used for the vertical control. The system equations have been derived using the Euler angle methodology and linearized about an operating point. The performance of this multivariable control has been analyzed and compared with all the six decoupled SISO controllers. The effect of adding the integrators to eliminate the steady-state error has also been discussed and the performance of the LQR controller with different weight matrices has been compared. In this paper, we also address the issues related to the stochastic modeling of the stage to analyze the coupling between different axes and transfer function identification.
Determination of Particle Size Distribution Using Laser Diffraction Technique
Authors: Jawad Badih A. , Riedel Chris H. , Bazzari Ahmad A.
Published: April 2008

Understanding the disintegration mechanism, spray penetration, and spray motion is of great importance in the design of a high quality diesel engine. The atomization process that a liquid would undergo as it is injected into a high-temperature, high-pressure air, is investigated in this work. The purpose of this study is to gain further insight into the atomization mechanism, the variation over time in droplet size distribution and spray penetration. This is done based on effect of chamber pressure, injection pressure, and type of fuel. A laser diffraction method is used to determine droplet mean diameters, single injection with synchronized time mechanism allowed the time dependent studies. Obscuration signals are obtained through a digital oscilloscope from which arrival time of spray can be measured. The spray penetration correlation obtained is compared to other correlation’s obtained from different other techniques used in the literature.
The Water Turbine Competition: A Hands-On Approach to Teaching Conservation Principles
Authors: Van Poppel Bret , McKay Michael D. , Arnas A. O¨zer , Boettner Daisie
Published: April 2008

For the past five semesters, the Water Turbine Competition has added significant excitement and motivation to the historically dreaded Fluid Mechanics course offered in the Department of Civil and Mechanical Engineering at the United States Military Academy. The Water Turbine Competition is an adaptation of the national Hydropower Contest. Teams of two or three students build a water turbine that will lift a weight using only the potential energy stored in a tank of water that is suspended above ground level. The water turbine project has proven to be an exciting and beneficial educational tool.
The Pigskin Professor: Video Presentations of Engineering Fundamentals
Authors: Schmitz Tony L. , Sawyer W. Gregory , Sinclair Arturo
Published: April 2008

This paper describes collaboration between the Department of Mechanical and Aerospace Engineering and Digital Worlds Institute at the University of Florida to develop a series of videos describing fundamental engineering concepts in the language of football. These videos, which were shown during the six home football games for the 2003 season, reached a diverse audience of over 84,000 fans at each game and provided a unique opportunity to discuss engineering in a high-profile forum. The objective was to stimulate excitement and interest in engineering education.
Impact Performance of Magnetorheological Fluids
Authors: Browne Alan L. , McCleary Joseph D. , Namuduri Chandra S. , Webb Scott R.
Published: April 2008

As part of an emerging effort in what is now termed the area of mechamatronics [1], an effort was begun to assess the suitability of MR (magnetorheological) material based devices for impact energy management applications. A fundamental property of MR materials is that their yield stress alters almost instantaneously (and proportionally) to changes in the strength of an applied magnetic field. Based on this property, MR based devices, if found suitable, would be desirable for impact energy management applications because of attendant response tailorability. However, it was identified that prior to adopting MR based devices for impact energy management applications several key issues needed to be addressed. The present study focused on one of the most significant of these, the verification of the tunability of the response of such devices at stroking velocities representative of vehicular crashes. Impact tests using a free-flight drop tower facility were conducted on an MR based energy absorber (shock absorber) for a range of impact velocities and magnetic field strengths. Results demonstrated that over the range of impact velocities tested — 1.0 to 10 m/s — the stroking force/energy absorption exhibited by the device remained dependent on and thus could be modified by changes in the strength of the applied magnetic field.
A Study of Fatigue and Failure Behavior of Conductive Adhesive Joints Subjected to Elevated Temperature and Humidity
Authors: Gomatam Rajesh R. , Sancaktar Erol
Published: April 2008

The use of conductive adhesives to replace solder joint connectors and other joining methods has enjoyed rapid growth in recent years. Major reasons for their use in electronic packaging are efficient load distribution over a larger area, comparable joint electrical conductivity, and environmental concerns for tin/lead solder. There are a number of issues that one needs to be concerned about in the design of joints bonded using conductive adhesives. One of these is the cyclic fatigue behavior of conductive adhesive interconnects under different environmental conditions, in which fatigue failure might occur due to either mechanical or thermal stresses varying in a cyclic manner. This paper addresses the effect of various environmental conditions, such as, elevated temperature, and humidity on the fatigue failure of conductive adhesive joints. For this purpose, conductive adhesive joints were prepared using stainless steel adherends, and tested using monotonic and cyclic mechanical loading in different environmental conditions. Furthermore, an in-depth analysis of the damage-path is also presented through a spectrum of experiments involving variable loading methodology.
Synergism of Binary Mixtures Wettability and Cover Porosity on Enhanced Pool Boiling Heat Transfer
Authors: Mele´ndez Elva , Reyes Rene´
Published: April 2008

The wettability of the system in capillary covers is an important element to increase the boiling heat transfer on the coverings. The sessile drop methodology allows the evaluation of either the surface energy of solids or the interfacial energy of liquids, and from both the system’s wettability. This methodology was tested with an experimental set up built for this study. The surface energies calculated for solids and metal foils used for construction of capillary coverings were in accordance with previous experimental results. The same methodology is used for measuring interfacial energies of the liquids used for increasing boiling heat transfer like ethanol-water mixtures. The mixture with 16% ethanol by weight had the lowest contact angle (associated to the lowest interfacial energy) and produced the highest convective heat transfer coefficient, h. Thus, the maximum for h correlates with an increase in the wettability of this system. This behavior is related to that observed as the critical micelial concentration (cmc) for surfactants, that produce the lowest interfacial energy of the liquid. Thus a set of experiments was developed to correlate the binary mixture behavior around the concentration with maximum heat transfer coefficient with the cmc boiling behavior. The surfactant sodium lauryl sulfate (SLS) produced an increase of the wettability of the solid surface with the addition of 100 ppm (or less) that is its cmc. The h values increase with the addition of SLS up to 100 ppm but do not change if the concentration of surfactant is higher than that value. The maximum heat transfer coefficient is obtained with the cmc of SLS in water, and with the 16% by weight ethanol-water mixture, both having the highest wettability. Porous coverings were tested with two covering’s thickness. A synergistic effect is found for the appropriate cover thickness combined with either a 16% by weight ethanol-water mixture or water with the cmc of SLS.
Nonlinear Response of the Macro Fiber Composite Actuator to Monotonically Increasing Excitation Voltages
Authors: Williams R. Brett , Inman Daniel J. , Wilkie W. Keats
Published: April 2008

This paper presents a nonlinear model which predicts the response of a piezoelectric continuum to a monotonic increase in electric field from some DC offset value under some constant mechanical load within the linear-elastic region. A general model is derived and then specialized for a piezoceramic-based material with anisotropic actuation and mechanical properties, for example, the Macro Fiber Composite (MFC) actuator. This specialized formulation includes the linear-elastic mechanical response, as well as linear and second-order piezoelectric behavior and a second-order electromechanical cross term. Thus, there are many required linear and nonlinear material parameters, namely the elastic compliances, piezoelectric strain coefficients, electrostrictive, and elastostrictive coefficients. Using previously published work dealing with the mechanical response of the MFC [1], this rather large set of material properties is determined experimentally in order to predict the response of the Macro Fiber Composite device to given external loading conditions.
Ideas Into Action: Using Learning Objectives to Revitalize a Mechanical Engineering Laboratory Sequence
Authors: Layton Richard A. , Mech Andrew R. , Mayhew James E.
Published: April 2008

This paper describes specific steps to develop and implement improvements to a mechanical engineering lab sequence by paying close attention to the learning objectives appropriate to engineering laboratories. The result is a proposed sequence of three new courses in the junior and senior years: Measurement Systems, Experiment Design, and Laboratory Clinic. In this paper, we provide the reader with a specific approach to implementing laboratory improvements based on learning objectives and an example of how those objectives are met in the proposed sequence.
Generation and Propagation of Thermoacoustic Waves in Mildly Supercritical Carbon Dioxide
Authors: Lei Zhiheng , Aktas Murat K. , Farouk Bakhtier , Oran Elaine S.
Published: April 2008

The generation and propagation of thermoacoustic waves in mildly supercritical carbon dioxide are investigated by solving the fully compressible form of the Navier-Stokes equations. Mildly supercritical fluids have high thermal conductivity; however the diffusion of heat in such fluids is very slow. Due to the high compressibility of the mildly supercritical fluids, the boundary layer along any heated surface expands and compresses adiabatically the whole fluid. We investigate these interesting phenomena via a high order numerical scheme. A square enclosure filled with supercritical carbon dioxide is considered as the computational domain. Thermally induced pressure waves are generated by heating the left wall. The thermodynamic properties of the slightly supercritical carbon dioxide are calculated via the NIST Standard Reference Database 12 [1].