bluuebunny/crossref_metadata_2025 huggingface dataset:
A Robust True Direct-Print Technology for Tissue Engineering
Authors: Li B. , Roy T. Dutta , Smith C. M. , Clark P. A. , Church K. H.
Published: March 2009

Numerous solid freeform fabrication (SFF) or rapid prototyping (RP) techniques have been employed in the field of tissue engineering to fabricate specially organized three-dimensional (3-D) structures such as scaffolds. Some such technologies include, but are not limited to, laminated object manufacturing (LOM), three-dimensional printing (3-DP) or ink-jet printing, selective laser sintering (SLS), and fused deposition modeling (FDM). These techniques are capable of rapidly producing highly complex 3-D scaffolds or other biomedical structures with the aid of a computer-aided design (CAD) system. However, they suffer from lack of consistency and repeatability, since most of these processes are not fully controlled and cannot reproduce the previous work with accuracy. Also, these techniques (excluding FDM) are not truly direct-print processes. Certain material removing steps are involved, which in turn increases the complexity and the cost of fabrication. The FDM process has good repeatability; however, the materials that can be used are limited due to the high temperature needed to melt the feedstock. Some researchers also reported that the scaffolds fabricated by FDM lack consistency in the z-direction. In this paper, we will present a true direct-print technology for repeatedly producing scaffolds and other biomedical structures for tissue engineering with the aid of our Computer Aided Biological (CAB) tool. Unlike other SFF techniques mentioned above, our direct-print process fabricates scaffolds or other complex 3-D structures by extruding (dispensing) a liquid material onto the substrate with a prescribed pattern generated by a CAD program. This can be a layer-by-layer 2.5 dimension build or a true 3-D build. The dispensed liquid material then polymerizes or solidifies, to form a solid structure. The flexibility in the types of materials that can be extruded ranges from polymers to living cells, encapsulated in the proper material. True 3-D structures are now possible on a wide range of substrates, including even in vivo. Some of the advantages of the process are a) researchers have full control over the patterns to be created; b) it is a true direct-print process with no material removing steps involved; c) it is highly consistent and repeatable; and d) it is highly efficient and cost-effective. This paper will first give a detailed description of the CAB tool. Then, it will present a detailed process for printing polycaprolactone (PCL) into a defined 3-D architecture, where the primary focus for these constructs is for use in tissue engineering applications. Finally, mechanical characterization results of the printed scaffolds will be included in the paper.
Generation of High Aspect Ratio Micro Holes by a Hybrid Micromachining Process
Authors: Sundaram Murali M. , Billa Sridevi , Rajurkar Kamlakar P.
Published: March 2009

Drilling a micro hole with an aspect ratio above 10 is a challenging task for any-micromachining process. In micro electro discharge machining (micro EDM), a proven metallic micromachining process, this is due to the problems associated with debris removal. In such cases, where the capabilities of existing macro machining methods are constantly being challenged, innovative micro manufacturing approaches are required to make progress. Hybrid micromachining is one such approach in which the synergy of constituent processes is exploited to achieve desired results. In this paper, the results of ultrasonic vibration assisted micro electro discharge machining process are presented. This hybrid process is capable of deep hole drilling with aspect ratio of 20 in austenitic stainless steel by overcoming the limitations in the debris removal faced in the typical micro EDM process. Other benefits of ultrasonic vibration are the savings in machining time, and less tool wear. It is also noticed that the ultrasonic vibration causes some shape distortion and produces rougher machined surface.
Process Monitoring in Micro-Injection Molding
Authors: Kuek Soon-Chun , Angstadt David C.
Published: March 2009

Due to the micro-scale dimensions in the microinjection molding proces, it is difficult to inspect the part quality without using costly microscopic observation methods. To address this issue, a suitable process monitoring method such as cavity pressure monitoring can be employed to detect any process deviation that causes defects in part quality. The objective of this study is to investigate how cavity pressure responds to different molding conditions that lead to varying part quality of a molded hollow cap.
Dynamic Mechanical Behavior of Titanium Ti-6Al-4V at Transient Large Deformation Manufacturing Processes
Authors: Sun J. , Guo Y. B.
Published: March 2009

Titanium Ti-6Al-4V alloy has been widely used in the aerospace, biomedical, automobile and petroleum industries. However, Ti-6Al-4V is a typical difficult-to-process material owning to its unique physical and mechanical properties which are characterized by low thermal conductivity, low modulus of elasticity, and high yield strength at elevated temperatures. The rapidly rising demand for titanium components demands more efficient manufacturing processes. Material property of Ti-6Al-4V plays an important role in process design and optimization especially for transient large deformations processes such as forming and machining. However, the dynamic mechanical behavior is poorly understood and accurate predictive models have yet to be developed. To obtain meaningful results which reflect the physical mechanisms of large deformation processes, it is essential to study the dynamic mechanical behavior of Ti-6Al-4V. The Johnson-Cook (JC) model has shown to be effective for modeling strain-hardening behavior of metals and it is numerically robust and can easily be used in finite element simulation models. However, the determination of JC model parameters is determined mostly based on split Hopkinson bar pressure (SHPB) test at isothermal conditions, which is very different from those of transient large deformations characterized by quick and high temperature changes. This study focuses on the dynamic mechanical behavior of titanium in transient manufacturing processes. The mechanical behavior of Ti-6Al-4V at large strains and strain rates beyond the isothermal conditions has been studied using the JC model coupled with the adiabatic condition. Heat fraction coefficient and temperature parameter have great effect on Flow stress-strain relationship. A significant drop of the flow stress occurs at large deformations with high strain rates. The flow stress sensitivity to JC strength model parameters was also investigated. The effect of pressure-stress ratio on material failure strain has shown the material may exhibit super plasticity before failure at hydro compression mode.
Fabrication of TiO2 and SiO2 Thin Films by Room Temperature Liquid Phase Deposition
Authors: Tiwari Santosh K. , Paul Brian K.
Published: March 2009

Mesoporous and dense titanium dioxide (TiO2) and silicon dioxide (SiO2) films were deposited directly from nanoparticle colloidal suspensions on quartz using a liquid phase deposition technique. The quartz surface was pre-treated with an -OH group to activate the deposition surface for crack-free adhesion. The deposited films were characterized with the help of scanning electron microscope for microstructural evaluation. An optical profilometer was used to measure the optical properties of the SiO2 film. The reflectance and transmittance patterns of the film were analyzed to determine the index of refraction of the film.
A Miniature Linear Slide With Air Bearings and Its Implementation in a Mesoscale Precision Turning Machine
Authors: Ro Seung-Kook , Kim Byung-Sub , Park Jong-Kweon
Published: March 2009

In this paper, we propose a new miniature air-bearing stage with a moving-magnet slotless linear motor. This stage was developed to achieve the precise positioning required for submicron-level machining and miniaturization by introducing air bearings and a linear motor sufficient for mesoscale precision machine tools. The linear motor contained two permanent magnets and was designed to generate a preload force for the vertical air bearings and a thrust force for the stage movement. The characteristics of the air bearings, which used porous pads, were analyzed with numerical methods, and a magnetic circuit model was derived for the linear motor to calculate the required preload and thrust forces. A prototype of a single-axis miniature stage with dimensions of 120 × 120 × 50 mm3 was designed and fabricated, and its performance was examined, including its vertical stiffness, load capacity, thrust force, and positioning resolution. Two fabricated stages were then used for the X and Z-axes of a mesoscale micro-turning machine combined with an air-bearing spindle to investigate the effectiveness of the proposed system. A mirror surface was machined from an aluminum alloy with a single-crystal diamond tool.
Pulsed Laser Assisted Micromilling for Die/Mold Manufacturing
Authors: O¨zel Tug˘rul , Pfefferkorn Frank
Published: March 2009

Laser assisted machining is an alternative to conventional machining of hard and/or difficult-to-process materials which involves pre-heating of a focused area with a laser beam over the surface of the workpiece to cause localized thermal softening along the path of the cutting action. The main advantage that laser assisted machining has over conventional machining is the increased material removal rate and productivity. Laser assisted micromilling is a scaled down derivative of laser assisted machining assuming that the process effectiveness potentially exists at the meso/micro scale. It is well-known that continuous-wave (c.w.) lasers generate a wide and deep heat affected zone, and can cause microstructure alterations, potentially making laser assistance counter-productive at the meso/micro scale. The novel use of a pulsed laser in assisting micromilling enables processing of die/mold metal alloys that are typically hard and/or difficult-to-process in micro scale, while reducing the heat affected zone. A fairly innovative technique is introduced by thermally softening only the focused microscale area of the work material with induced heat from a pulsed laser, and material removal is performed immediately with micro mechanical end milling. The focus of this paper is to present a fundamental understanding of the pulsed laser assisted micromilling (PLAM), in particular, to investigate the influence of pulsing on microscale localized thermal softening by coupling with the finite element simulation of the micromilling process. Experiments and Finite element method-based process simulations for micromilling of AISI 4340 steel with and without the laser assistance are conducted to study the influence of the pulsed laser thermal softening on the reduction in cutting forces and its influence on the temperature rise in the cutting tool.
Implementing Point Assignment Using Octrees and GPU
Authors: Aravalli Koushik V. , Kurfess Thomas R. , Tucker Thomas M.
Published: March 2009

Data point set registration is an important operation in coordinate metrology. Registration is the operation by which sampled point clouds are aligned with a CAD model by a 4×4 homogeneous transformation (e.g., rotation and translation). This alignment permits validation of the produced artifact’s geometry. Registration is an iterative nonlinear optimization operation assigning points on the CAD model for the sampled points. The objective is to minimize the sum of the squares of the normal distances between each point in the point cloud and the closest point in the CAD model. State-of-the-art metrology systems are now capable of generating thousands, if not millions, of data points during an inspection operation, resulting in increased computational power to fully utilize these larger data sets. The execution time for assigning the point set in registration process is directly related to the number of points processed and CAD model complexity. A brute force approach to registration, which is often used, is to compute the minimum distance between each sampled point and its normal projection on the CAD model. As the point cloud size and CAD model complexity increase, this approach becomes intractable and inefficient. This paper proposes a new approach to efficiently identify the closest point in the CAD model for a given point. This approach employs a combination of readily available computer hardware, graphical processor unit (GPU) and a formulation of the point assignment problem, using an octree data structure that is suited for execution on the GPU.
Characterization of Polymer Flows in Very Thin Gaps
Authors: Panchal Rahul R. , Kazmer David
Published: March 2009

The flow of polymers in micromolding applications is dominated by shear stresses. At high flow velocities and small wall thicknesses, the shear rates can exceed the typical characterization scheme of 10,000 reciprocal seconds. Yet, the effective design of micromolded parts and micromolding processes requires a correct understanding of the flow dynamics. In this paper, analytical models assuming power law fluid behavior are developed and experimentally validated for wall thicknesses of 10, 20, and 100 micro meters. A design of experiments is conducted to consider the effect of wall thickness, channel width, melt temperature, and pressure on flow rate in an isothermal molding process. The results indicate that the power law model is a valid representation for viscous polymer flow in very thin gaps under isothermal conditions, though further work is required to validate the non-isothermal dynamics.
Multi-Phase Finite Element Modeling of Machining Unidirectional Fiber Reinforced Composites
Authors: Dandekar Chinmaya R. , Shin Yung C.
Published: March 2009

A multi-phase and a continuum based finite element model using the commercial finite element package ABAQUS is developed for simulating the orthogonal machining of composite materials. The materials considered for this study are a glass fiber reinforced epoxy composite and a ceramic matrix composite. The effect of varying the fiber orientation and tool rake angle on the cutting force, temperature distribution and damage during machining are considered. In the multi-phase approach the fiber and matrix are modeled as continuum elements with isotropic properties separated by an interfacial layer while the tool is modeled as a rigid body. The cohesive zone modeling approach is used for the interfacial layer. Bulk deformation and shear failure is considered in the fiber and matrix while the traction separation in the cohesive zone is used to ascertain the extent of delamination below the work surface. For validation purposes simulation results of the multi-phase approach are compared with experimental measurements. Parametric studies are conducted utilizing the equivalent homogenous (EHM) material model. The EHM simplifies the composite material into an anisotropic but locally homogenous material. External heating effect on the workpiece is considered in the EHM model to include preliminary results on Laser Assisted Machining. The model is successful in predicting cutting forces, temperature distribution entry and exit damage with respect to the fiber orientation.
Laser Cladding of Two Hardfacing Alloys Onto Cylindrical Low Alloy Steel Substrates With a High Power Direct Diode Laser
Authors: Schoeffel Kevin C. , Shin Yung C.
Published: March 2009

Blown-powder laser cladding is an efficient method for enhancing the surface properties of engineering components while preserving the properties of the base material. High power direct diode lasers (HPDDLs) offer wide beams with nearly uniform intensity distribution, allowing the deposition of wide clad tracks with flatter profiles than those produced with a Gaussian beam. In this work, a 4.0 kW HPDDL is used to perform blown-powder cladding on AISI 4140 and AISI 5150 steel shafts. The first part of the experiments concerns two-layer circumferential tracks created from two commonly used hardfacing alloys: Stellite 6 (Co-Cr alloy) and Nistelle 625 (Ni-Cr alloy). The effects of laser power and powder feed rate on the clad geometry are assessed. Increasing the powder feed rate and holding constant all other parameters decreases the track width-to-thickness aspect ratio. All tracks exhibit dendrite microstructures that are characteristic of powder-based clad tracks. The tracks exhibit no cracks or porosity. Energy dispersive X-ray (EDX) analysis reveals dilution of five percent or less between the clad and substrate materials. The second part of the experiments concerns overlapping of single-layer clad tracks in a continuous helical pattern on the substrate to form a layer that covers a large area. Clad layer thickness and inter-track porosity are measured to determine the optimum degree of overlap for producing a high-quality clad layer. The thickness of the resulting Stellite 6 and Nistelle 625 clad layers decreases as the overlap percentage decreases. No inter-track, interfacial, or bulk pores are present for any tests, comprising overlap percentages of 50% and lower.
Development of a Decision Support System for Unscheduled Maintenance MRO Component Safety Stock
Authors: Tsakatikas D. , Sfantsikopoulos M.
Published: March 2009

The paper presents a methodology for the establishment of the MRO (Maintenance, Repair and Operation) material criticality that is focused on the Industrial Unplanned Maintenance needs. The thus obtained criticality is used to rationalize the efficiency of the Plant MRO-material Inventory. Through an appropriately adapted Top-Down FMECA (Failure Modes Effects and Criticality Analysis) the concept of the Component Dynamic Criticality is introduced and calculated for all the functional components of an industrial production facility. The components are assigned with characteristic code numbers. MRO-material Inventory control is then carried out within the frame of the developed Decision Support System. A case study demonstrates the method. The use of the developed Decision Support System considerably increases not only the efficiency of the Plant MRO-Material Inventory and control of the Unplanned Maintenance Downtime, but also its continuously updated and highly constructive System Dynamic Database of Component Failure Modes and their Effects benefits the Conventional Maintenance Schemes, e.g. Scheduled and/or Predictive Maintenance, as well. MRO-Material Inventory control for rational Unplanned Maintenance Downtime has not been addressed to this date in a systematic way. By addressing this issue the present approach contributes to an increased availability of industrial production facilities and to a better performance of CMMS and/or ERP tools.
Application of Simulation Technology to Hollow Die Extrusion
Authors: Takatsuji N. , Inagaki T. , Murakami S. , Matsuki K.
Published: March 2009

In recent years, the application of various simulations in hot extrusion of aluminum alloys has proven useful. However, the most of them are generally applied in the field of steady metal flow conditions with solid die extrusion. In this paper, the simulation technology is applied to hollow die extrusion. Especially, the effects of the taper port-hole shapes on the extrusion pressure-stroke diagrams and the metal flows are investigated experimentally and theoretically. Taper port-hole shapes are useful for the reduction of the extrusion pressure in comparison with straight port-hole shape, because the extrusion pressure in the port-hole filling process is decreased by the reduction of the sliding friction, and the extrusion pressure in the welding chamber filling process is decreased by the reduction of equivalent strain rate in the port-hole and the welding chamber. FEM results by FEM analysis code added with special know-how show a close match with the experimental results. Therefore, we are able to predict the extrusion pressure and the metal flow through the port-hole and the welding chamber by this simulation technology.
Prediction of Forming Limit in Single Point Incremental Forming With the Ductile Fracture Criterion
Authors: Huang Y. , Wang Y. J. , Cao J. , Li M.
Published: March 2009

Many experiments have been conducted to investigate the forming limit in single point incremental forming (SPIF). The forming limit curve (FLC) generated from these experiments follows a linear line with a negative slope in the positive minor strain side of the forming limit diagram (FLD). It is also found that, in general, for the same material subjected to the SPIF process, the failure strain level greatly exceeds the traditional FLC based on theories of the plastic instability [Iseki and Kumon, 1994]. Currently, no theoretical work or no criterion was proposed to predict this FLC in the SPIF. In this paper, the criterion for the ductile fracture [Oyane, 1980] is introduced to try to predict the forming limit of the material in the SPIF. Based on the calculated stress and strain from the finite element simulation and the ductile fracture criterion, the fracture initiation site and the forming limit are predicted. The predicted results are compared with that from the SPIF experiment to verify the feasibility of the proposed method.
A Fundamental Investigation on the Formability of a Commercially-Pure Titanium Sheet-Metal in the Incremental Forming and Stamping Processes
Authors: Hussain G. , Gao L. , Hui Wang , Dar N. U.
Published: March 2009

In the present study, a basic comparison between the cold formability of a commercially-pure Titanium (CP Ti) sheet in the single-point incremental forming (SPIF) and stamping processes is presented. An attempt was made to evaluate the SPIF formability by employing two tests. In the first test, parts having continuously varying wall angles were formed. While in the second test, parts having fixed wall angles were formed. The stamping formability was determined by conducting the limiting dome height (LDH) test. It is concluded that the forming limit curve (FLC) in SPIF is located much higher than the stamping FLC, even higher than the fracture limit curve in stamping. Moreover, the SPIF formability shows dependence on the test employed.
Digital Sheet Metal Manufacturing System and Application
Authors: Wang J. B. , Liu C.
Published: March 2009

This paper develops digital aircraft sheet metal manufacturing technology. The architecture of digital sheet metal manufacturing system is proposed based on the classification of sheet metal manufacturing information. The essence of digital manufacturing is definition, management and transfer of information, and the key technologies are brought forward and described. It is pointed out that knowledge-based manufacturing elements design is necessary to make digital technology efficient. The management of all kinds of sheet metal manufacturing elements information is to build single source of manufacturing data. Multi-state model-based digital transfer and coordination method is presented to provide a foundation for digital manufacturing of sheet metal part. The application of digital sheet metal manufacturing is exemplified with an aircraft sheet metal part. The application result is compared to that of the traditional analog transfer technology. It is shown that the developed technology can improve part quality, shorten manufacturing time and lower manufacturing cost.
Endmill Condition Monitoring and Failure Forecasting Method for Curvilinear Cuts of Non-Constant Radii
Authors: Suprock Christopher A. , Roth John T. , Downey Larry M.
Published: March 2009

In this paper, an endmill condition monitoring technique is presented for curvilinear cutting. This algorithm operates without the need for prior knowledge of cutting conditions, tool type, cut curvature, cut direction, or directional rate of change. This technique is based on an autoregressive-type monitoring algorithm which is used to track the tool’s condition using a tri-axial accelerometer. Accelerometer signals are monitored due to the sensors relatively low cost and since use of the sensor does not limit the machining envelope. To demonstrate repeatability, eight life tests were conducted. The technique discussed herein successfully prognosis impending fracture or meltdown due to wear in all cases, providing sufficient time to remove the tools before failure is realized. Furthermore, the algorithm produces similar trends capable of forecasting failure, regardless of tool type and cut geometry. Success is seen in all cases without requiring algorithm modifications or any prior information regarding the tool or cutting conditions.
Maintenance Task Prioritization Using Data Driven Bottleneck Detection and Maintenance Opportunity Windows
Authors: Li Lin , Djurdjanovic Dragan , Ni Jun
Published: March 2009

Maintenance operations have a direct influence on production performance in manufacturing systems. Maintenance task prioritization is crucial and important, especially when availability of maintenance resources is limited. The decision on task assignment is often made through heuristic methods or experience, which could cause more downtime and the production losses. In this paper, a new maintenance task prioritization policy based on data driven bottleneck detection and reliability-based maintenance opportunity window calculation is introduced. An experiment in simulation of a real production line shows the proposed policy is able to improve the system reliability, increase the throughput and minimize the total cost of system operation.
Step-and-Grow Approach for Precisely Positioned Nanowire Array Structure Fabrication
Authors: Nam W. J. , Carrion H. , Park P. , Garg P. , Joshi S. , Fonash S. J.
Published: March 2009

A novel fabrication approach for forming precisely positioned nanowire array structures is introduced. The approach is suitable for potentially economical and environmentally safe manufacturing. For the demonstration of this approach, 100nm wide Sn nanowires and 150nm wide polyaniline (PANI) nanowires were synthesized using an electro-chemical deposition technique and a process we term the step-and-grow method. The nanowires produced exhibit the expected properties. For example, synthesized PANI nanowires showed reasonable ranges of electrical conductivities (e.g., 25S/cm for a 200nm wide, 200nm high, 10um long nanowire), and formed ohmic contact with electrodes on a substrate. It is shown that the polydimethylsiloxane (PDMS) stepping template mold used for our step-and-grow nanowire synthesis process can be used at least up to 40 times without degradation.
Grain Boundary Response of Aluminum Bicrystal Under Micro Scale Laser Shock Peening
Authors: Vukelic Sinisa , Kysar Jeffrey W. , Yao Y. Lawrence
Published: March 2009

Micro scale laser shock peening (μLSP) is a process in which compressive residual stresses are induced in a material surface to improve fatigue life and wear resistance under cyclic loading. Since the diameter of the laser spot used during the process is the same order of magnitude as grain size, the effects of anisotropy and heterogeneity have to be explicitly taken into account. In this study experimental and analytic work have been done in order to investigate the bicrystal aluminum response under Gaussian loading. Effects of heterogeneity under μLSP are studied through applying laser shocks onto the grain boundary of the aluminum bicrystal. μLSP on reference single crystals have also been performed for the purpose of comparison. The orientations of the crystals in the bicrystal as well as the reference single crystals have been chosen such that an approximate plane strain condition is achieved. A finite element model has also been developed based on single crystal micromechanics and a cohesive zone interface model. Simulation results are compared with experimental findings. The potential benefit of μLSP as a surface treatment for improvement of fatigue life is also discussed.
Production Validation of Agile Machining Fixture: A Machine-Automated Reconfigurable Tooling
Authors: Lin Yhu-Tin , Shen Chi-Hung , Bandyopadhyay Pulak
Published: March 2009

Agile machining fixture is a machine-automated reconfigurable tooling first introduced in 2003. The fixture is reconfigurable and programmable on a CNC machine. To evaluate its viability in production, the agile machining fixture is reconfigured from one machining operation to another for showing its flexibility to processing needs. The fixture is further tested and validated in a low volume production environment to address various challenges in product designs, machine conditions and process details. The good dimensional quality of the production parts machined in this study confirms that the agile machining fixture can perform as well as conventional ones on a regular CNC machine and thus deserves the consideration for future production implementation.
Vessel Sealing Using the Bipolar Electrosurgical Method
Authors: Chastagner Matthew W. , Miller Scott F. , Shih Albert J. , Geiger James D.
Published: March 2009

The electrosurgical sealing method has risen to prominence in recent years as more vessel sealing procedures are being conducted in minimally invasive surgery. Electrosurgical sealing works by applying electrical current to coagulate and denature proteins in the vessel, thereby creating a bond. In this study, experiments were conducted to seal 3 and 8 mm diameter vessels in a porcine model with a bipolar electrosurgical device and measure the electrical voltage and current, and temperature distribution in the vessel near the area of the seal. The vessel seal was modeled with finite element analysis (FEA) and compared to the experimental data. FEA allow for insight into the correlation of temperature to quality of the seal in the vessel. The maximum temperatures were 83°C and 63°C in the 3 and 8 mm vessels, respectively. Validation of the experimental results was attempted through the use of a simplified FEA model. The model showed similar thermal profiles near the electrode, but further downstream temperatures did not rise as fast as the experimental results. Further refinement to overcome limitations in the model is identified.
Experimental Investigations of Laser Micromachining of Metal Using Micro Thin Film Thermocouples
Authors: Choi Hongseok , Li Xiaochun
Published: March 2009

Laser-material interactions involved in laser micromachining are extremely complicated. In order to improve the fundamental understanding of the laser micromachining process, it is essential to investigate the complex phenomena and mechanisms of the physical processes within and close to the region of the interaction. Topographical characterizations of laser micromachining with various laser energy fluences were undertaken to correlate the resulting geometry changes with surface temperature measurements. Single pulses of laser beam with a nominal diameter of 47 μm were used. Possible changes of surface chemical composition induced by the laser micromachining process, in particular oxide formation, were also investigated around the laser spot. Moreover, C-type micro thin film thermocouples (TFTCs) with a junction size of 2 μm × 2 μm were fabricated to increase the maximum operation temperature and spatial resolution of temperature measurements. Surface temperature distribution around the laser spot was obtained in the range from 45 μm to 85 μm away from the center of laser spot. The result showed that there was a steep gradient of temperature in the radial direction and a superheated area around laser spot. It was also observed that the temperature profile matched the oxidation profile due to thermal effects.
Pressure-Assisted Sintering of Nanocrystalline Silver Lines Produced by Laser Ablation of Microparticle Aerosols
Authors: Kovar Desiderio , Albert Andre D. , Becker Michael F. , Keto John W.
Published: March 2009

The Laser Ablation of Microparticle Aerosol (LAMA) process provides a method for generating high yields of aerosolized nanoparticles (NPs) that are then accelerated through a nozzle and impacted onto substrates. The process allows nanostructured films and patterned lines to be directly written onto substrates at room temperature. Using the LAMA process, we have demonstrated the ability to produce thick patterned deposits with densities ranging from 60–70% in the as-deposited state. After deposition, the lines were densified using pressure-assisted sintering and the microstructures and strengths of the films were investigated. Pressure-enhanced sintering resulted in densification and strong bonding at processing temperatures of 100–175°C and pressures of 100–600 MPa. Mechanisms for sintering at low temperatures are discussed.
Agent-Based Integration of Collaborative Mobile Environment and Smartboard
Authors: Kadri Abdou Al-Rahim , Kermani Mohammad Mozaffari , Ghenniwa Hamada , Shen Weiming
Published: March 2009

Ubiquitous computing is a new emerging computing style which adapts various computing devices throughout our living and working spaces. These devices include mobile devices (such as PDAs, smartphones), traditional desktop, smart-board and so on. Mobile devices coordinate with each other and network services seamlessly, yet they are often inactive and even when in use they are most of the time disconnected from the network, which severely limits their use for ubiquitous interaction with the environment’s entities. In this paper we study the integration of Collaborative Mobile Environment (CoMoE) and interactive devices such as smart-board to overcome the pervious problems. The focus of this work is on the development of the integration architectural framework. This architectural framework is based on Coordinated Intelligent Rational Agent (CIR-Agent) model, which supports sophisticated real-time interaction among agents. Also we discuss the notion of personal assistant agents that allows the physical integration and interoperability of entities in an environment and in the same time provides assistance in achieving user’s goals.
A Parametric Study on Selective Ultrasonic Foaming of Porous Polymer for Biomedical Applications
Authors: Wang Hai , Li Wei
Published: March 2009

A selective ultrasonic foaming (SUF) process was developed to fabricate porous polymer for biomedical applications. The method employs a high intensity focused ultrasound (HIFU) transducer to selectively heat and implode gas-impregnated polymers. This acoustic method is solvent-free and capable of creating interconnected pores that have various topographical features at different length scales. In this paper, we investigate the effects of major process parameters of the SUF process, including the ultrasound power, scanning speed, and the specimen gas concentration. The pore size and interconnectivity of the porous structure were analyzed. The microstructures were characterized using the scanning electron microscopy (SEM) and a dye penetration test. It was found that the scanning speed of the ultrasound had a significant effect on the pore size control, and that low gas concentration was a necessary condition for interconnected porous structures.
Process Yield Improvement Through Optimum Design of Fixture Layouts in 3D Multi-Station Assembly Systems
Authors: Phoomboplab T. , Ceglarek D.
Published: March 2009

This paper presents a new approach to improve process yield by determining an optimum set of fixture layouts for a given multi-station assembly system which can satisfy: (i) parts and subassemblies locating stability in each fixture layout; and (ii) fixture system robustness against environmental noises in order to minimize product dimensional variability. Three major challenges of the multi-stage assembly processes are addressed: (i) high-dimensional design space; (ii) large and complex design space of each locator; and (iii) the nonlinear relations between locator positions, also called Key Control Characteristics, and Key Product Characteristics. The proposed methodology conducts two-step optimization based on the integration of Genetic Algorithm and Hammersley Sequence Sampling. First, Genetic Algorithm is used for design space reduction by determining the areas of optimal fixture locations in initial design spaces. Then, Hammersley Sequence Sampling uniformly samples the candidate sets of fixture layouts from the areas predetermined by GA for the optimum. The process yield and part instability index are design objectives in evaluating candidate sets of fixture layouts. An industrial case study illustrates and validates the proposed methodology.
Fuzzy Logic Control System for Micro-Hole Electrical Discharge Machining
Authors: Kao Chen-Chun , Miller Scott F. , Shih Albert J.
Published: March 2009

An advanced micro-hole electrical discharge machining (EDM) system with the adaptive fuzzy logic control and precision piezoelectric stage is developed in this study. A high-speed EDM monitoring system is implemented to measure the gap voltage, current, and ignition delay time, which are used to derive three input parameters, the average gap voltage, deviation of spark ratio, and change of deviation of spark ratio, for the fuzzy logic control. Servo displacement and speed of the piezoelectric stage during each data acquisition cycle are real-time synthesized by the adaptive fuzzy logic controller. Effects of the single and multiple input parameters, ignition delay threshold value, and maximum servo displacement and speed on the EDM drilling process are experimentally studied. Design of experiments (DOE) is applied to investigate the correlation of fuzzy logic control parameters. The optimal EDM parameter values are searched via the genetic algorithm. The optimal search result is experimentally validated. The fuzzy logic EDM control system has demonstrated the efficiency and stability in micro-hole drilling by reducing the frequency of irregular discharges and the drilling time.
Robust Machine Vision-Based Parts Inspection: Intelligent Neuro-Fuzzy Versus Threshold Based Classification
Authors: Killing Jonathan , Surgenor Brian W. , Mechefske Chris K.
Published: March 2009

Past experience with an industrial machine vision-based parts inspection system highlighted the need for a robust system, that is a vision system that could adapt to changes in the operating environment without requiring excessive retuning of the data analysis algorithm. With this need in mind, an intelligent neuro-fuzzy based image processing algorithm was developed and tested against a traditional threshold based algorithm. Experimental results indicate that the intelligent algorithm performs well when the data is not well segmented.
Coupled Multifield Finite Element Analysis Model of Upsetting Under an Applied Direct Current
Authors: Kronenberger Thomas J. , Johnson David H. , Roth John T.
Published: March 2009

Recent research studying the deformation of various metals in compression, while running an electric current through the material, has been quite promising. A problem occurs when trying to identify the specific mechanisms that cause the changes in the mechanical properties, however, since the flow of electricity produces resistive heating, which also affects the mechanical properties of metals. However, previous research has proven that not all of the effects on the properties can be explained through resistive heating, implying that the electron flow through the metal also causes changes to the mechanical properties. Therefore, this work develops a model capable of differentiating between the effects of resistive heating and the effects of the electron flow when deforming 6061-T6511 aluminum in compression. To accomplish this, a detailed finite element simulation has been developed using ANSYS® with two models in symbiosis. The first model predicts the temperature of the specimen and compression fixtures due to the applied electrical current. The resulting thermal data are then input into a deformation model to observe how the temperature change affects the deformation characteristics of the material. From this model, temperature profiles for the specimen are developed along with true stress vs. strain plots. This theoretical data is then compared to experimentally determined data collected for 6061-T6511 aluminum in compression. By knowing the exact effects of resistive heating, as obtained through the FEA model, the effects of the electron flow are isolated by subtracting out the effects of resistive heating from the data obtained experimentally. Future work will use these results to develop a new material behavior model that will incorporate both the resistive and flow effects from the electricity.
Extension-Based Clustering Method: An Approach to Support Adaptable Design of the Product
Authors: Zhao Yanwei , Tang Huijun , Su Nan , Wang Wanliang
Published: March 2009

Design for product adaptability is one of the techniques used to provide customers with products that exactly meet their requirements. Clustering methods have been used extensively in the study of product adaptability design. Of the clustering methods, the fuzzy clustering method is the most widely in the design field. The three main kinds of fuzzy clustering methods are the transitive closure method, the dynamic direct method and the maximum tree method. The dynamic direct clustering method has been found to produce design solutions with the lowest cost. In this paper, a new approach for obtaining adaptable product designs using the clustering method is proposed. The method consists of three steps. Firstly, the extension distance formula is used to determine the distance between two products in a product database. The product design space and the distances between individuals are used as grouping criteria in this step. Secondly, the minimal distance between products is used to obtain the clustering index. Thirdly, the threshold value is used to divide the products in the database into groups. Customer demands and the results obtained from the adaptable function (based on the extension distance formula) are used to evaluate the fitness of the groups and their corresponding products. The product with the largest adaptable function value to demand ratio is selected product. In order to the show the advantage of using the extension-clustering method, both the extension-clustering method and the dynamic direct method are presented and compared. The comparison indicates that the extension-clustering method leads to quicker evaluations of design alternatives and results that more closely match customers’ demands. An example of the adaptable design of circular saws tools is used to demonstrate that with the extension-clustering design method a high variety of intelligent configurations can be obtained with significant rapidity.
A Hull Normal Approach for Determining the Size of Cylindrical Features
Authors: Turek Steven , Anand Sam
Published: March 2009

In coordinate metrology, discrete data is sampled from a continuous form to assess the manufactured feature’s deviation from its design specifications. Although coordinate measuring machines have a high degree of accuracy, the unsampled portion of the manufactured object cannot be completely described. The definition of cylindrical size for an external feature as specified by ASME Y14.5.1M-1994 [1,2] matches the analytical definition of a minimum circumscribing cylinder (MCC) when Rule #1 is applied. Even though the MCC is a logical analysis technique for size determination, it is highly sensitive to the sampling method and any uncertainties encountered in that process. Determining the least-sum-of-squares solution is an alternative method commonly utilized in size determination. However, the least-squares formulation seeks an optimal solution not based on the cylindrical size definition [1,2], and hence has been shown to be biased [6,7]. This research presents a novel Hull Normal method for size determination of cylindrical bosses. The goal of the proposed method is to recreate the sampled surface using computational geometry methods and determine the cylinder’s axis and radius based upon the reconstructed surface. Through varying the random sample size of data from an actual measured part, repetitive analyses resulted in the Hull Normal method having a lower bias and distributions that were skewed towards the true value of the radius.
Collaborative Haptic Interfaces and Distributed Control for Product Development and Virtual Prototyping
Authors: Lin Shiyong , Lee Yuan-Shin , Narayan Roger J.
Published: March 2009

In this paper, we propose a collaborative product development and virtual prototyping framework based on distributed haptic interfaces along with the deformable object modeling. Collaborative Virtual Environment (CVE) is a promising technique in industrial product development and virtual prototyping for globalized manufacturing enterprises. Network control problems such as network delay have greatly limited CVE’s application. The problem becomes more difficult when high-update-rate haptic interfaces and computation-demanding deformable objects are both integrated into CVEs for intuitive manipulation and enhanced realism. A hybrid network architecture is presented to balance the computational burden of haptic rendering and deformable object simulation. An adaptive artificial time compensation is used to reduce the time discrepancy between the server and the client. Interpolation and extrapolation approaches are used to synchronize graphic and haptic data transmitted over the network. The proposed techniques can be used for collaborative product virtual prototyping, virtual assembly, remote surgical simulation and other collaborative virtual environments where both haptic interfaces and deformable object models are involved.
Bone Scaffold Fabrication System Study
Authors: Lu Lin , Wootton David , Lelkes Peter I. , Zhou Jack
Published: March 2009

Musculoskeletal conditions are a major health concern in United States because of a large aging population and increased occurrence of sport-related injuries. The need for bone substitutes is especially important. Traditional treatments of bone-defect have many limitations. Bone tissue engineering may offer a less painful alternative to traditional bone grafts with lower risk of infection. This research integrates biomimetic modeling, solid freedom fabrication (SFF), systems and control, and tissue engineering in one intelligent system for structured, highly porous biomaterials, which will be applied to bone scaffolds. Recently a new SFF-based fabrication system has been developed, which uses a pressurized extrusion to print highly biocompatible and water soluble sucrose bone scaffold porogens. The fabrication process for PCL scaffold implemented and tested using the newly developed porogen system. The resultant scaffold demonstrates the defined porous structure designed into the sucrose porogens. The viscosity of sucrose mixture has been tested and analyzed. The flow rate measurements of sucrose machine have been carried out. The input factor, which induced uncertainty in the flow rate of the microprinting system has been analyzed. The result showed that the reservoir pressure was dominant to determine the flow rate. This is very important for improving the quality control of our fabrication system.
Comparing Energy and Other Measures of Environmental Performance in the Original Manufacturing and Remanufacturing of Engine Components
Authors: Adler D. P. , Ludewig P. A. , Kumar V. , Sutherland J. W.
Published: March 2009

The remanufacturing industry is rapidly becoming a source of economic growth and environmental benefit. In the past, researchers have presented cost and energy savings due to remanufacturing a variety of products, largely based on the results of industry-wide surveys. However, little or no effort has focused on the life cycle assessment of remanufacturing. In fact, no study has performed a life cycle assessment of engine components, comparing the original component manufacture with remanufactured components. In this paper, a comparison of the original manufacture and remanufacture of components from a typical Caterpillar diesel engine is described. The “gate-to-gate” analysis considers components that represent a majority of the engine assembly by weight. The comparison is made in two measures of environmental performance: energy and material usage.