bluuebunny/crossref_metadata_2025 huggingface dataset:
Manufacturing and Analysis of 3-D Woven Sandwich Composite Under Compressive Loading With Acoustic Emission Monitoring
Authors: Islam M. , Mahfuz H. , Motuku M. , Saha M. , Ayorinde E. , Salekeen S. , Jeelani S.
Published: June 2008

Composite sandwich panel with 3-d woven fabric preform were manufactured through a vacuum assisted resin transfer molding (VARTM) process. The 3-d sandwich fabric preform known as Parabeam, consist of two bi-directional woven E-glass fabric surfaces, which are inter connected mechanically with several vertical woven piles. Parabeam provides a new type of sandwich composite that possess several multifunctional benefits in addition to light weight, bending stiffness and core skin debonding resistance advantages. After consolidation of the panels, polyurethane foam was injected into the core. Conventional sandwich panels were also fabricated with precast polyurethane foam and E-glass face sheet for comparison with the Parabeam sandwich. Edge wise compression tests were conducted and the corresponding acoustic emission (AE) responses were monitored by an advance AE system. Piezoelectric sensor was used to detect the AE signals. On the basis AE signals, the damage source of the specimen were identified, and classified. Furthermore, cracking size were estimated and used to determine the delamination events among the AE signals. Consequently, the AE signals were correlated to the load-displacement curve in the time domain in order to elucidate the types of damage in the specimen. Details of the manufacturing process, the compression tests, and the analysis of the AE signals are presented in this paper.
A Magneto-Hydrodynamic Micro Fluidic Network
Authors: Bau Haim H. , Zhu Jianzhong , Qian Shizhi , Xiang Yu
Published: June 2008

The magneto hydrodynamic fluidic network’s basic building blocks are conduits equipped with two electrodes positioned on opposing walls. The entire device is either subjected to an external uniform magnetic field or fabricated within a magnetic material. When a prescribed potential difference is applied across each electrode pair, it induces current in the liquid (assumed to be a weakly conductive). The current interacts with the magnetic field to produce a Lorentz force that is perpendicular to both the directions of the current and the magnetic field. Analogously with electric circuits, by judicious application of the potential differences at various branches, one can direct liquid flow in any desired way and rate without a need for mechanical pumps or valves. By equipping the network branches with additional, interior electrodes, the branches double as stirrers capable of generating chaotic advection. The paper describes the basic building blocks for such a network, the operation of these branches as stirrers, a general theory for the analysis and control of fluidic magneto-hydrodynamic networks, and an example of a network fabricated with low temperature, co-fired ceramic tapes.
Smooth Muscle Tissue Response to Applied Vibration Following Extreme Isotonic Shortening
Authors: Dhanaraj Nandhini , Pidaparti Ramana M. , Meiss Richard A.
Published: June 2008

The objectives of the present study are to investigate the response of a tracheal smooth muscle tissue to an applied longitudinal vibration following isotonic shortening, and, using experimental data, to simulate the mechanical response through a non-linear finite element analysis. The response of an activated smooth muscle tissue to forced length oscillations at 33Hz for 1 second was obtained. The response in terms of stiffness change and hysteresis was estimated from the experimental data. A finite element simulation was carried out to simulate the vibratory response under experimental conditions. The results obtained indicate that the approach and the vibratory response obtained may be useful for describing the cross-bridge deattachements within the cells as well as connective tissue connections characteristics of tracheal smooth muscle tissue.
Minimum Time Trajectory Planning Along Specified Tool Path With Consideration of Cutting Force Constraint and Feed Drive Dynamics
Authors: Tounsi Nejah , Bailey Trevor E. , Elbestawi Mohamed A.
Published: June 2008

This paper proposes an Optimized Feed Scheduling Strategy (OFSS). This strategy integrates the feed drive dynamics with the minimum-time trajectory planing to achieve the desired feed rate at the appropriate tool position along specified tool path. It optimizes the use of the feed drive capabilities and provides good tracking of the cutting geometry variations. The feed scheduling is applied to maintain near-constant cutting force magnitude. An integrated geometric and mechanistic force model is used to estimate the in-cut geometry and the cutting force. A methodology based on time series modeling and analysis is proposed to identify the low frequency feed drive dynamics. The resulting model is applied as an acceleration/deceleration processor (Acc/Dec) to relate the actual feed rate to the commanded feed rate specified in the G-Code file. The effectiveness of the OFSS is analyzed using ball end milling operations. Its performance in terms of productivity and machining safety is assessed based on comparison with other feed scheduling techniques where the trajectory planing does not consider the feed drive dynamics.
Aerothermoelastic Analysis of Cylindrical Piezolaminated Shells Using Multifield Layerwise Theory
Authors: Oh Il-Kwon , Lee In
Published: June 2008

For the aerothermoelastic analysis of cylindrical piezolaminated shells, geometrically nonlinear finite elements based on the multi-field layerwise theory have been developed. Present multi-field layerwise theory describes zigzag displacement, thermal and electric fields providing a more realistic multi-physical description of fully and partially piezolaminated panels. By applying a Hans Krumhaar’s supersonic piston theory, supersonic flutter analyses are performed for the cylindrical piezolaminted shells subject to thermal and piezoelectric loads. The possibility to increase flutter boundary and reduce thermoelastic deformations of piezolaminated panels is examined using piezoelectric actuation. Results show that active piezoelectric actuation can effectively increase the critical aerodynamic pressure by retarding the coalescence of flutter modes and compensating thermal stresses.
CMOS-Compatible Micro-Fluidic Chip Cooling Using Buried Channel Fabrication
Authors: Gaugel Daniel M. , Gabriel Kaigham J.
Published: June 2008

We present a CMOS-compatible method of fabricating burried channels within bulk single-crystal silicon serving as the substrate of CMOS circuitry. The channels were designed to provide a compact, forced convection heat transfer liquid cooling approach to microprocessor and integrated circuit thermal management. The baseline fabrication process consumers 8–10% of front-side surface area and serves as a foundation for incorporation of buried-channel cooling with CMOS electronics. Channels were fabricated with diameters ranging from 43–92 μm with sacrificial surface area trenches 10 μm wide. A microchannel heat transfer solution was designed, simulated, and tested with cooling of up to 21 W/cm2. Compatibility with CMOS electronics was investigated by evaluating the post-process transistor performance of a simple oscillator circuit.
Mechanical Implications of High Current Densities in Flip Chip Solder Joints
Authors: Ye Hua , Basaran Cemal , Hopkins Douglas
Published: June 2008

The electromigration damage in flip chip solder joints of eutectic SnPb was studied under current stressing at room temperature with the current density about 1.3×104A/cm2. The diameter of the solder joints was about 140μm. The mass accumulation near anode side and void nucleation near cathode were observed during current stressing. The nano-indentation test was first time done on solder joints for electromigration test. Surface marker movement was used to measure the atomic flux driven by electromigration and to calculate the product of effective charge number and diffusivity, DxZ*, of the solder at room temperature. The effective charge number can be extracted with the solder diffusivity at room temperature known.
Evaluation of Mini/Micro-Pumps for Micro-Chem-Lab™
Authors: Wong C. Channy , Flemming Jeb H. , Adkins Douglas R. , Plowman Michael A.
Published: June 2008

The performance of a selective group of mini and micro-pumps has been evaluated for use in gas phase detection for the Micro-Chem-Lab™. Our major assessment criteria are: flow rate, pressure drop across the pump, and electrical current drawn by the pump. Two pumping configurations have been investigated: (1) upstream pumping to build up pressure head and (2) downstream pumping to draw vacuum. Four mini-pumps (T-Square, SP 250 EC, SP 135 FZ-4, and KNF Neuberger) have been studied. Each of these pumps has been tested to determine whether they meet our requirements of high head pressure, high flow rate, and low power consumption. We have also assessed different mechanisms for pumping gas in micro-domains — specifically, a valveless diffuser/nozzle micro-pump, a LIGA diaphragm micro-pump and a micro drag pump. However our preliminary findings reveal that these micro-pumps do not meet our minimal requirements for use in the μChemLab™.
Free Air Ball Forming Process Parameter Analysis for Wire Bonder
Authors: Chen Jau-Liang , Chang Hsu-Yang
Published: June 2008

In this paper, we are focusing on the FAB forming technology for fine pitch wire bonding. The parameters that affect the FAB formation include: 1) tail length; 2) spark gap; 3) Electric flame-off (EFO) voltage, current, time; 4) relative position between electrode plate and tail; 5) wire material; and 6) type of capillary. Except the last two items, all the other parameters can be quantified for analysis. By using Taguchi method it was found that EFO time and EFO current are the most important parameters that affect the formation free-air ball. The error-back-propagation neural network was then used to predict suitable EFO time and current setting. The main objective in this research is to find a suitable rule for parameters setting in order to control the FAB ball size as required. The result can be used in the future for optimal parameter setting and prediction of FAB formation.
Molecular Dynamic Simulation of Nano-Sized Channel Flow
Authors: Lu M. C. , Hsieh H. M. , Tseng F. G. , Chieng C. C.
Published: June 2008

Liquid flow passes through two parallel plates are simulated using molecular dynamic method. The flowing systems consist of 2744, 5488, and 8232 Argon molecules inside channels with heights of 40Å, 80Å, and 120Å respectively and the liquid Argon is sandwiched between two solid walls. The wall is comprised of fcc <111> surface of 510 platinum molecules. The potentials between argon-argon and argon-platinum are well-known Lennard-Jones functions. The flow behavior is studied by two driven mechanisms: (1) pulling two parallel plates at a constant velocity with zero pressure gradients, and (2) pressure gradient. The phantom molecules are used to mimic the constant temperature boundary. Velocity profiles with slip boundaries and laminar friction constants are calculated to support the validation of continuous theory with appropriate modifications. This study finds that the channel size, driving mechanism and its magnitude are the factors determining slip/non-slip velocity and the laminar friction constant.
Mass Flow Measurements of Gases in Deep-RIE Microchannels
Authors: Jang Jaesung , Zhao Yabin , Wereley Steven T. , Gui Lichuan
Published: June 2008

We present mass flow measurements and pressure distributions in near unity aspect ratio microchannels using Deep Reactive Ion Etching (RIE). Almost all of the previous papers have dealt with only wide channels for gas flow measurements. We also adopt Spin-On-Glass (SOG) to bond Pyrex glass to silicon. Using the first order slip flow formula and experimental data, we extracted the tangential momentum accommodation coefficient (TMAC) of 0.425 for the case of SOG and Si microchannels and air, and the effective diameter of 57.67μm. Increased mass flow from the incompressible flow case is mostly due to compressibility rather than rarefaction, which is expected from the fact that the Knudsen number is 0.00115, the borderline of slip flows. The deviations from the linear incompressible pressure distributions get larger with increasing inlet pressures, and the dimensionless streamwise locations of maximum deviations are between 0.5 and 0.6, which is slightly downstream from the middle of the channels. It is notable that these experimental data are much closer to simulation results than the previous experiments in microchannels. The inlet pressure drops are almost linear with respect to pressure ratio of inlet to outlet. This type of near unity aspect ratio microchannel is more effective for heat exchangers than previous thin, wide channels.
Numerical Simulation of Sediment Transport Near Shipping Channels in Harbors
Authors: Amromin Eduard L. , Kovinskaya Svetlana I.
Published: June 2008

Numerical simulation of sediment transport is considered as a coupled problem based on computation of profiles of water velocity and suspended sediment concentration. Effects of the water velocity profile and turbulent pulsation on vertical motion of particles are emphasized. These effects allow explanation of amplified sediment deposit in viscous separation zones near both natural and manmade bottom irregularities (like walls of shipping channels). The unique numerical technique for separated flow computation is developed on the basis of viscous-inviscid interaction concept. This technique is validated by experimental data for turbulent flows over backward-facing steps. New results for conditions inherent to flow separation over seabed are obtained. A semi-empirical approach to determination of sediment concentration is suggested.
Quantitative Photothermal NDE of Composites: Numerical Analysis
Authors: Siegmund Thomas , Hattiangadi Ashwin
Published: June 2008

Photothermal non-destructive evaluation (NDE) of solids is a powerful method to detect subsurface cracks, inclusions and delaminations. To fully explore the use of this method, and to expand its capabilities a quantitative measurement model is required. Such a model provides the link between the actual damage processes in the material or structure under investigation and the measurement system response. In the proposed paper a numerical simulations of the photothermal non-destructive evaluation of unidirectionally reinforced composite materials. In the investigation, special focus is placed on the description of the interaction of the thermal field with the delamination to be detected. The model consists of two main parts: (1) a probabilistic crack advance and crack bridging model embedded in a full field solution of the actual loaded structure, and (2) a model describing the thermal characteristics of the bridged delamination in dependence of the loading state and the probabilistic fiber failure model. The paper will describe results on computationally predicted thermal response data in dependence of the type and magnitude of the applied loading for the case of ceramic matrix composite materials.
Embedded Ultrasonic Structural Radar With Piezoelectric Wafer Active Sensors for the NDE of Thin-Wall Structures
Authors: Giurgiutiu Victor , Bao Jingjing
Published: June 2008

Embedded-ultrasonics structural radar (EUSR) is a new concept and methodology for in-situ nondestructive evaluation (NDE) and structural health monitoring (SHM) of thin-wall structures. EUSR consists (a) an array of piezoelectric wafer active sensors (PWAS) embedded into the structure; and (b) electronic modules for signal transmission/reception, processing, and interpretation. EUSR utilizes guided elastic waves (Lamb waves) generated omnidirectionally into the thin-wall structure by surface-mounted permanently-attached PWAS. The paper starts with the general concepts of the EUSR algorithm: transmission beamforming, reception beamforming, and time of fight determination. Next, details of the Lamb wave generation with PWAS, verification of group-velocity dispersion curves, identification of optimal excitation frequency, and confirmation of wave front omnidirectionality are discussed. In the third part of the paper, the actual implementation of the EUSR method in a proof-of-concept demonstration is presented. The construction of the PWAS phased array is described, and detection of cracks located broadside and offside of the PWAS array is illustrated. The method is shown to be easy to use through a visually interactive LabView™ interface. Very good detection accuracy is observed. Though the proof-of-concept experiments presented in this paper were illustrated on metallic structures, the EUSR concept works just as well on composite and hybrid structures.
Significant Severity Reduction of Side-Impact Injuries by Using ITS Airbags: FE Simulation and Severity Analysis
Authors: Omar Tarek A. , Bedewi Nabih E. , Eskandarian Azim
Published: June 2008

The Inflatable Tubular Structure (ITS) airbag is a potentially life-saving device that has been implemented recently in some luxury vehicles. Its main objective is to provide head protection for the front seat occupants against upper side-interior car components. In a previous research conducted by the authors, a nonlinear Finite Element (FE) model for the ITS-airbag system was successfully developed and tested. In the current research, the developed ITS model is combined with a full-scale FE vehicle model and 50th percentile side-impact dummy (SID) model. The combined model is then used to conduct two series of side-impact simulations. The first series included side impacts with narrow objects, i.e. rigid poles, while the second series included side impacts with a Moving Deformable Barrier (MDB) as a wide and deformable object. The effect of the relative position between the dummy and the rigid pole was considered by conducting variety of simulations for two different rigid pole positions and three different dummy positions. The three dummy positions were considered in the side impacts with the MDB. For both impact series, the effect of the impact velocity was considered by conducting each impact scenario at three different velocities. The ITS model performance, in all FE simulations, was fairly similar to the actual ITS performance. The simulation results indicated a significant reduction in the Head Injury Criteria (HIC) of the dummy head due to the ITS-airbag deployment. The life-threatening severity for occupants is usually measured by the Abbreviated Injury Scale (AIS) that ranges from 1 (minor) to 6 (fatal). The AIS indices are calculated in all side impacts. The results demonstrated a significant reduction/elimination in fatalities and severe injuries due to the ITS-airbag performance. The results clearly indicated the great benefits expected from this promising safety device.
Flank Wear of Edge-Radiused Cutting Tools Under Ideal Straight-Edged Orthogonal Conditions
Authors: Kountanya Raja K. , Endres William J.
Published: June 2008

Understanding the effects of tool wear is critical to predicting tool life, the point at which tool performance, in terms of power requirement, dimensional error, surface finish, or chatter, is no longer acceptable. To achieve the long cuts that are required for wear testing while maintaining a clear view of the basic process geometry effects, ideal straight-edged orthogonal conditions are realized in a bar-turning arrangement by employing a specially designed two-tool setup. The data show that increasing edge radius tends to increase wear rate, especially at the initial cut-in wear phase. The data also show that when the uncut chip thickness is less than or equal to the edge radius, forces actually decrease substantially with flank wear until most of the edge radius has been worn away. At that point the forces begin to increase with flank wear in a power-law fashion. This decreasing-then-increasing trend is a result of the parasitic (non chip removing) wear-land force increasing more slowly than the chip-removal force is decreasing. The decrease in chip-removal force with an increase in flank wear results from the blunt edge being effectively sharpened as it is removed by the growing wear land. An empirical model structure is formulated, guided by specific elements of the data, to well represent the force trends with respect to wear and edge radius and to assist in their interpretation. The edge-sharpening concept is further supported by a special experiment in which the edge is sharpened without the presence of the wear land.
Computer Simulation of Three-Dimensional Chip Kinematics in Machining
Authors: Fang Ning
Published: June 2008

Effective chip control is an essential requirement of modern automatic and computer numerically controlled (CNC) machining operations. This paper asserts that the study of chip control can be divided into three branches—chip dynamics, chip kinematics, and chip breaking mechanics—each having different research emphasis. Chip kinematics is becoming a promising research area, serving as an essential bridge between the other two branches. In developing the mathematical formulation of chip kinematics, this paper introduces three patterns of chip curl, i.e., up-, side-, and lateral-curl, followed by the establishment of a Cartesian coordinate system. Chip form is measured by three geometric parameters: the resultant radius R of chip curl, the pitch P of the chip helix, and the inclined angle θ of the helical axis to the helical surface. It is revealed that the final chip form is determined by four governing variables: chip up-, side-, and lateral-curl radii (Ru, Rs, and Rl) and chip side-flow angle (ηs). The effect of Ru, Rs, Rl, and ηs on chip forms is investigated. A set of new chip kinematical equations and computer-simulated chip forms are also established in this paper.
Contact Zone Force Profile and Machining Performance of Filamentary Brush
Authors: Stango Robert J. , Cariapa Vikram , Zuzanski Mark
Published: June 2008

Filamentary brushing tools are used in a wide range of surface finishing processes, such as deburring, edge radiusing, polishing, and surface decontamination applications. Moreover, these tools are easily adapted to automation because the filament tips, which perform the machining operation, readily conform to the workpart surface without the need for sophisticated control systems technology. However, little is known about the material removal mechanics of filamentary brushes and, therefore, trial-and-error experimentation is often necessary before the tool is implemented in a production environment. This uncertainty of performance can be traced to a lack of understanding of the actual forces that are generated within the contact zone, that is, along the interface of the filament tip and workpart surface. Although previous experimental research has focused on the overall (i.e., resultant) brush force exerted onto the workpart, no information exists in the literature regarding the variation of force within the contact zone. Such information is essential for understanding the material removal profile within the contact zone, and could provide valuable information regarding the most active machining site along the contact surface. In this paper, a novel experiment is proposed for evaluating the force profile of filament tip forces that are generated within the contact region of a brushed surface. A specially designed workpart fixture is constructed and used in conjunction with a multi-axis force sensor for measuring the detailed force variation within the contact zone. The experiment is conducted using a wire brush at several different rotational speeds, which enables one to ascertain the role of filament inertia in the material removal process. Findings are reported which suggest that a significantly enhanced material removal rate can be achieved at a selective location within the contact zone at moderately elevated spindle speeds.
Passive Optoelectronics Component Manufacturing: A Case Study
Authors: Harvilchuck Laurence A. , Borgesen Peter , Kondos Pericles , Gopakumar Sunil , Srihari K.
Published: June 2008

The infrastructure required for fiber optic communication systems to become truly affordable includes a supply of individual components at a price that can only be achieved through full automation of the packaging processes. We illustrate the manufacturing of typical passive photonics components through the case of a polarization dependent optical isolator. Identification of the available options here requires an understanding of the underlying optical principles and functionality, as well as of the influences of process variations and part tolerances on performance. Issues relating to cost, ease of manufacturing and automation are discussed. These include component design and materials selection, as well as questions of intellectual property.
A Versatile, Fast and Inexpensive Microfabrication Technique Using a One Metal and One Silicon Dioxide Film
Authors: Lopez George C. , Gabriel Kaigham J.
Published: June 2008

A versatile fabrication process that allows users to quickly construct micromachined structures using a one metal, one silicon dioxide film stack on a silicon wafer is presented. This simplified process, which we have labeled Mock CMOS or M-CMOS, (a) starts from pre-processed wafers and requires only one photolithography step, (b) provides a conductor material for actuating electrostatic and thermal devices, (c) avoids electrical shorting between metal microstructures or to the silicon substrate by using silicon dioxide as an insulator, and (d) allows quick prototyping of true CMOS-MEMS structures similar to those designed at Carnegie Mellon University (CMU). Devices successfully microfabricated with M-CMOS include surface-normal and lateral electrostatic and thermal actuators, the majority of which were designed by forty students in an Introduction to MEMS course in Fall 2001 at Carnegie Mellon University.
Evaluation of a Conductive Adhesive Based Approach to Lead Free Flip Chip Assembly
Authors: Venkateswaran Muthiah , Borgesen Peter , Srihari K.
Published: June 2008

Electrically conductive adhesives are emerging as a lead free, flux less, low temperature alternative to soldering in a variety of electronics and optoelectronics applications. Some of the potential benefits are obvious, but so far the adhesives have some limitations as well. The present work offers a critical evaluation of one approach to flip chip assembly, which lends itself particularly well to use with a high speed placement machine. Wafers were bumped by stencil printing of a thermoset conductive adhesive, which was then fully cured. In assembly, the conductive adhesive paste was stencil printed onto the pads of a printed circuit board and cured after die placement. The printing process was optimized to ensure robust assembly and the resulting reliability assessed.
RF MEMS Switch Heat Dissipation in Discrete and Wafer-Level MEMS Packages
Authors: Mercado Lei L. , Lee Tien-Yu Tom , Kuo Shun-Meen , Hause Vern , Amrine Craig
Published: June 2008

In discrete RF (Radio Frequency) MEMS (MicroElectroMechanical Systems) packages, MEMS devices were fabricated on Silicon or GaAs (Galium Arsenide) chips. The chips were then attached to substrates with die attach materials. In wafer-level MEMS packages, the switches were manufactured directly on substrates. For both types of packages, when the switches close, a contact resistance of approximately 1 Ohm exists at the contact area. As a result, during switch operations, a considerable amount of heat is generated in the minuscule contact area. The power density at the contact area could be up to 1000 times higher than that of typical power amplifiers. The high power density may overheat the contact area, therefore affect switch performance and jeopardize long-term switch reliabilities. In this paper, thermal analysis was performed to study the heat dissipation at the switch contact area. The goal is to control the “hot spots” and lower the maximum junction temperature at the contact area. A variety of chip materials, including Silicon, GaAs have been evaluated for the discrete packages. For each chip material, the effect of die attach materials was considered. For the wafer-level packages, various substrate materials, such as ceramic, glass, and LTCC (Low-Temperature Cofire Ceramic) were studied. Thermal experiments were conducted to measure the temperature at the contact area and its vicinity as a function of DC and RF powers. Several solutions in material selection and package configurations were explored to enable the use of MEMS with chips or substrates with relatively poor thermal conductivity.
An Integrated Wafer-Scale Packaging Process for MEMS
Authors: Kenny Thomas W. , Candler Rob N. , Li Huimou J. , Park Woo-Tae , Cho Junghwa , Li Holden , Partridge Aaron , Yama Gary , Lutz Marcus
Published: June 2008

Packaging is well known to impose significant cost, performance and fabrication constraints on MEMS devices. We have developed a wafer-scale, integrated packaging process which enables a released MEMS device to be sealed within a thick layer of epi-polysilicon. This encapsulation may be tailored to withstand conventional dicing saws, pick/place chip handling equipment, and even high-pressure injection molding for plastic DIP packages. This architecture can be adapted to a variety of MEMS devices, and is compatible with integrated electronics. This paper will describe this packaging technique and discuss applications.
Low Frequency Operation of the P3 Micro Heat Engine
Authors: Whalen Scott A. , Thompson Michael R. , Richards Cecilia D. , Bahr David F. , Richards Robert F.
Published: June 2008

The development and low frequency testing of a micro heat engine is presented. Production of electrical power by a dynamic micro heat engine is demonstrated. The prototype micro heat engine is an external combustion engine in which thermal power is converted to mechanical power through a novel thermodynamic cycle. Mechanical power is converted into electrical power through the use of a thin-film piezoelectric membrane generator. This design is well suited to photolithography-based batch fabrication methods and is unlike any conventionally manufactured macro-scale engine. A peak-to-peak voltage of .84 volts, and power output of 1.5 microwatts have been realized at operating speeds of 10 Hz. Measurements are also presented for the engine operating at resonant conditions. Cycle speeds up to 240 Hz have been obtained, with peak-to-peak voltages of 70 millivolts.
Estimation of Gas and Liquid Flow Rates in Gas-Liquid Two-Phase System
Authors: Mori Koji , Ono Tetsumasa , Kaji Masuo , Sawai Toru
Published: June 2008

A new method of estimating gas and liquid flow rates is proposed for a gas-liquid two-phase flow system. The method involves measurement of pressure drops in horizontal and vertical flow channels, and calculation of flow rates by Lockhart-Martinelli correlation. The method does not require the insertion of sensing device into the flow channel and does not rely on previously calibrated correlations. Experiments are performed in slug, froth and annular flow regimes for an air-water system, and the usefulness of the proposed method is examined. The results reveal that gas and liquid flow rates can be estimated with the accuracies of 45% for gas phase and 37% for liquid phase with respect to mean values.
Schlieren and Shadowgraph Images of Transient Expanding Spherical Thin Flames
Authors: Matlo Matyas , Parsinejad Farzan , Metghalchi Hameed
Published: June 2008

Experimental facilities have been built to visualize transient expanding spherical flames. Facilities include a cylindrical chamber with two end glasses for optical observation. Shadowgraph and Schlieren pictures of flame propagation have been taken using a high speed Charged Coupled Device (CCD) camera. In this paper the optical behavior of spherical flames has been investigated using both Schlieren and Shadowgraph methods. A mathematical model has been developed to predict the intensity of refracted light beams interacting with a transient expanding thin flame. Experimental results are in very good agreement with theoretical model. Schlieren and Shadowgraph techniques have also been used to view smooth, cracked and cellular flames, which are useful in determining the stability of propagating flame.
A Novel Piezoelectrically Actuated Microvalve for Flow Control in a PEM Fuel Cell
Authors: Vipperman Jeffrey S. , Ayhan A. Fatih , Clark William W. , Thornton Jimmy D. , Gemmen Randall S.
Published: June 2008

A novel axial-flow piezoelectric microvalve for fuel cell applications has been designed and analyzed. Microvalves offer to improve flow maldistribution problems that have been identified in fuel cells. This paper will outline the design of an embeddable microvalve that has many novel features, including an axial flow characteristic, piezoelectric trimorph actuation mechanism, unlimited scalability, thermally-insensitive activation, and relative simplicity. Detailed electro-mechanical, thermal, and fluidic analyses of the design are conducted using ANSYS and MATLAB simulation packages. The valve geometry is heuristically optimized based upon the results of the analyses. Fabrication and testing of the valve is currently underway.
Thermoelastic Actuation: Solution for Circular Composite Plates With Application in MEMS
Authors: Chandrasekaran Venkataraman , Sheplak Mark , Cattafesta Louis N. , Sankar Bhavani V.
Published: June 2008

This paper presents the dynamic analysis of a thermoelastically actuated circular composite diaphragm, for MEMS applications. The diaphragm is used as an acoustic transmitter, actuated at ultrasonic frequencies via a diffused surface heater at its center. The principle of operation of the thermal actuator is the generation of an oscillating temperature gradient across the diaphragm cross-section due to Joule heating of the diffused heater, creating a thermal moment that results in out-of-plane bending of the diaphragm. The mechanical analysis of the diaphragm, modeled as a composite plate, is based on the classical laminated plate theory. The time harmonic heat conduction resulting from the Joule heating of the diffused surface heater, modeled as a surface heat flux input, is analyzed using the Fourier heat conduction model. Analytical expressions have been obtained for the temperature distribution, and the resulting thermal moment, and plate deflection.
Electrochemically Actuated Microvalves for Microfluidic Systems
Authors: Hua Susan Z. , Sachs Frederick , Chopra Harsh Deep
Published: June 2008

Electrochemical actuation is used to make active control elements for microfluidic applications that require no moving mechanical parts. Electrochemical bubbles were generated directly inside the micro-channels, which serve as valves. Bubble formation and its physical interaction with the fluid were visualized using epi-fluorescent microscopy, which shows that the valve completely stops the flow. Valve closing/opening was quantitatively characterized for flow rates ranging from ≈5 mm/s to 27 mm/s (inlet pressures 102 kPa to105 kPa). It was found that valves could be closed/opened in relatively short times (≈30 ms) and consume low power (≈10μJ). The current versus time curves measured at progressively higher voltages (from 3.8 V to 5.2 V) shows a linear relationship between the total charges transferred during electrolysis and the resulting bubble size. The large volume change associated with liquid to gas transformation can also be used to displace liquid for dosing or pumping.
Exploratory Studies on the Control of High-Speed Flows With Magnetogasdynamics
Authors: Gaitonde Datta V.
Published: June 2008

Magnetogasdynamics (MGD) has the potential to lift many of the constraints presently inhibiting sustained hypersonic flight and affordable access to space. Given the difficulty of ground-testing under the expected harsh conditions, numerical methods can provide insight into the physical phenomena, and thus complement experimental investigations in the development of future concepts. This paper describes the status of an effort to develop a high-fidelity, fully three-dimensional method to explore MGD flow control in complex configurations. The theoretical model includes several non-ideal effects and takes recourse to a blend of first principles and phenomenological approaches to enhance simulation efficiency. Boundary conditions are summarized and sample verification exercises are presented. Exploratory calculations on a reentry vehicle and flow-through scramjet flowpath with MGD-bypass demonstrate the versatility of the approach and yield insight into dominant flow control mechanisms.
Physical and Computational Modeling for Chemical and Biological Weapons Airflow Applications
Authors: Knight Kelly J. , Barringer Chris , Berkoe Jon M. , McCreery Glenn E. , Pink Robert J. , McEligot Donald M.
Published: June 2008

There is a need for information on dispersion and infiltration of chemical and biological agents in complex building environments. A recent collaborative study conducted at the Idaho National Engineering and Environmental Laboratory (INEEL) and Bechtel Corporation Research and Development had the objective of assessing computational fluid dynamics (CFD) models for simulation of flow around complicated buildings through a comparison of experimental and numerical results. The test facility used in the experiments was INEEL’s unique large Matched-Index-of-Refraction (MIR) flow system. The CFD code used for modeling was Fluent, a widely available commercial flow simulation package. For the experiment, a building plan was selected to approximately represent an existing facility. It was found that predicted velocity profiles from above the building and in front of the building were in good agreement with the measurements.
Diffusion and Performance of CAD/CAM in the U.S. Textile and Apparel Industry
Authors: Yan He , Fiorito Susan
Published: June 2008

This study examines the determinants of CAD/CAM adoption and diffusion in American textile and apparel industries. Innovation diffusion theory provided a conceptual framework and empirical base applicable to the study of technology adoption and implementation. A variety of sources were used to develop the survey which was mailed to a national random sample of 500 textile and apparel manufacturers. The responses of 103 manufacturers from 30 different states were analyzed. Factor analysis was used to identify the dimensions of reasons for CAD/CAM adoption. Hypotheses were tested with logistic regression analysis procedures. The diffusion of CAD/CAM practices was found to be driven primarily by the market and affected by the business-unit size. In addition, labor considerations affected recent CAD/CAM adoption.
Mechanical Properties of Square Braided Fabric
Authors: Ueda Takahisa , Otani Akio , Nakai Asami , Hamada Hiroyuki
Published: June 2008

Cyclic compression test was performed on square braided fabric and the effects of the type of fiber bundle were examined for aramid and glass square braided fabrics. Moreover, the strength of the fiber bundles from the square braided fabric after cyclic compression loading was investigated with tensile testing of fiber bundles. It was found that the strength of the glass fiber bundle was decreased with the increase of compression cycle, whereas the strength of aramid fiber bundle was not decreased. The decrease in strength of glass fiber bundle caused an increase in cumulative deformation with compression cycle.
Partially Miscible Hybrids Made From Chlorinated Polyethylene and 2,2′-Methylene-Bis-(4-Methyl-6-Tert-Butyl Phenol)
Authors: Liu Jitao , Yu Jianyong , Wang Shanyuan
Published: June 2008

Damping behaviors and miscibility between a polar polymer (CPE) and an organic small molecule (AO-18) are mainly discussed in this paper. It is well-known that mixing two partly compatible polymers can produce a material with a wide range of the glass transition temperature (Tg) and thus good damping behavior. In this paper, since CPE and AO-18 are partially miscible, adding AO-18 to CPE causes Tg of the mixture shifts to higher temperature, and the relaxation of AO-18 appears when AO-18 content is high in CPE/AO-18 alloy, similar to two partly compatible polymers. The damping properties around CPE glass transition are greatly improved compared with pure CPE, which can be attributed to the hydrogen bonds between CPE and AO-18 in CPE/AO-18 hybrids.
A Novel 3-D Braiding Technology, Complex Shape Preforms and Composites
Authors: Bogdanovich Alexander , Mungalov Dmitri
Published: June 2008

A brief overview of 3-D braiding technology and its two major branches, “row and column” and “rotary” braiding, opens the paper. An innovative 3-D braiding process that has been recently patented and implemented in a fully automated multi-modular industrial scale machine is introduced next. The machine enables producing complex, continuously variable shape preforms for composite structures. Each module of the machine incorporates some number of horngears with four yarn carriers placed on each of them. A novel gate switch mechanism, based on the gripping fork controlled rotation, provides smooth transfer of yarn carriers between adjacent horngears. Each gripping fork is controlled individually, thus allowing fabricating practically unlimited variety of complex cross section 3-D braided preforms. Examples of manufactured braided products include rectangular bars, T-, I- and J-stiffeners, box-beams, hollow tubes, etc. Results and discussion of mechanical characterization of 3-D braided carbon and E-glass composites conclude the paper.
On the Understanding of Tensile Elastic and Strength Properties of Integrally Woven 3D Carbon Composites
Authors: Dickinson Larry C. , Bogdanovich Alexander E.
Published: June 2008

There is significant literature reporting research on three-dimensional (3D) textile composites. Previous experimental and theoretical work has shown that small details of design and structure of 3D woven composites have a significant effect on strength and failure mechanisms. This work presents the results of an experimental study examining the effect of thickness (number of warp layers) on tensile behavior of 3D orthogonal woven carbon/epoxy composites. Three different preform designs resulting in three different thicknesses were examined. There is a significant difference between warp (x) and fill (y) tensile properties strength, and the difference is a function of thickness.
Experimental Evaluation on Solder Joint Reliability of PBGA Assembly Under Mechanical Drop Test
Authors: Lee Shi-Wei Ricky , Li Yin-Lai Tracy , Lui Hoi-Wai Ben
Published: June 2008

The present study is intended to investigate the board level solder joint reliability of PBGA assemblies under mechanical drop test. During the course of this study, a five-leg experiment was designed to investigate various combinations of solder materials and peak reflow temperatures. Two major failure modes, namely, solder cracking and copper trace breakage, were identified. In addition, the critical location of solder joints was characterized. It was found that Sn-Pb eutectic solder joints performed better than Pb-free solder joints under mechanical impact loading.
The Lead-Free Interconnection Movement: A Pro-Active Approach to Understand the Effects on COTS Usage in the Aerospace and Defense Industries
Authors: Rafanelli Anthony J.
Published: June 2008

Commercial-off-the-shelf (COTS) items continue to play a significant role in the development and production of defense systems under acquisition reform initiatives. With concerns focussing mainly on top-level performance specifications, end-users do not have the luxury of governing processes used in the manufacture of such items. Accordingly, as the electronics industry proceeds with ever-increasing initiatives in “green” technologies, end-users can expect to find new materials and processes present in COTS products. With respect to electronic interconnection, a specific case is the trend to use alternative materials to lead-bearing solders. Such alternative materials fall into two technology areas: non-lead solders and electrically conductive (polymeric) adhesives. Within commercial applications, these alternate materials have operated sufficiently in relatively benign environments. Since these materials are used as the sole electronic interconnection medium, aerospace and defense original equipment manufacturers (OEMs) need to concern themselves with the overall performance characteristics of these materials in harsher service environments. In this context, performance characteristics include operational and reliability requirements. Note that in surface mount technology, understanding of performance characteristics is of special concern since the interconnection also serves as the primary means of mechanical attachment. The objectives of this paper are: 1. To discuss lead-free evaluative efforts to date, 2. Discuss concerns and approaches, presently under consideration, regarding implementation of these “green” technologies, and 3. Prompt further dialogue in addressing these issues.
Advanced OEH Methodology for Evaluation of Microelectronics and Packaging
Authors: Furlong Cosme , Pryputniewicz Ryszard J.
Published: June 2008

With the microelectronics industry being one of the most dynamic, in terms of new technologies, electronic packages have to be designed and optimized for new and ever more demanding applications in relatively short periods of time. In addition, for certain applications, the nondestructive testing (NDT) of electronic packages may be needed, especially for applications requiring noninvasive, full-field-of-view, real-time testing the behavior of a specific package subjected to actual operating conditions. This type of NDT can be accomplished by application of optical techniques and, in particular, speckle phase correlation techniques in the form of optoelectronic holography (OEH). In this paper, advanced OEH techniques are described and representative applications of OEH for the effective characterization of microelectronic components and packages are presented.
Thermal Stress Induced Void Formation in Semiconductor Interconnect
Authors: He Xiaoling , Burda Clemens
Published: June 2008

Stress voiding is a common defect of the semiconductor interconnect. In thermal cycles, other defects such as the hillocks, delamination can also occur. For the Cu/low-k interconnect, simulation with Ansys is made to analysis the interconnect stress-strain distribution and deformation. Results indicate that stress induced void is prone to form in the via than in the metal lines. Flower defect appear at the via top can also be analyzed based on the stress distribution. It is found that Von-Mises stress represent the localization of the stress concentration, which cause delamination and over-stress failure at the interface of the different materials.
Electronics Spot Cooling With Liquid Nitrogen
Authors: Rada M. , Shooshtari A. , Ohadi M. , Franc¸a F. H. R. , Lawler J.
Published: June 2008

This paper describes an ongoing research to evaluate and characterize electrohydro-dynamic (EHD) meso- and micro-pumps for spot cooling of sensors. In the proposed concept, the localized cooling is achieved by means of a flow of liquid nitrogen that is driven by an ion-drag pump towards the heat source, where heat is directly removed. First, a numerical heat transfer model will illustrate the advantages of the proposed concept of spot cooling with liquid nitrogen against a conventional conduction cooling. Next, we will present experimental results for pumping of liquid nitrogen via (EHD) a pump at the meso-scale, as well as experiments with EHD micro-pumps for pumping of HFE-7100 at room temperature. The objective of this research is to establish the optimum operational and design conditions for micro-pumping of liquid nitrogen for spot cooling applications.