bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of Spinning Disk–Parking Ramp Collison on the Operational Shock Performance of a Mobile Hard Disk Drive
Authors: Rai Rahul , Bogy David B.
Published: April 2011

With the introduction of netbook computers two years ago, the demand for hard disk drives (HDD) for mobile applications has greatly increased. High shock resistance is an important requirement for the reliable performance of HDDs in such applications. In this paper we conduct a numerical investigation to understand the failure mechanism of the head disk interface (HDI) during an operational shock. Simulation results suggest that the excitation frequency spectrum has a strong influence on HDI failure. We also investigate the effect of the parking or load unload (LUL) ramp on shock resistance using a new spinning disk model. The results suggest that asymmetric excitations induced by ramp-disk collision causes failure of the HDI at lower shock magnitudes. This study can be helpful in improving the design of HDD components and air bearing sliders (ABS) for better shock performance.
Dynamic Skin Wrinkles: Geometry or Mechanics? A Probabilistic Finite Element Approach
Authors: Limbert Georges
Published: April 2011

Skin is the largest organ of the human body. Its main role is to ensure cohesion and protection of the internal body structures, acting as a physical and social interface to the external environment. The geometry and biophysics of this multi-layered biological structure are key elements in determining the nature and characteristics of these interactions [1]. Skin wrinkles [2], of particular relevance for skin care and shaving products, are the result of a complex interplay between material and structural properties, boundary and loading conditions the exact nature of which remains to be elucidated [3]. The variability of these properties/conditions according to the anatomical site, gender, race, from individuals to individuals or from experimental measurement techniques call for stochastic computational models [4]. The objective of this study was therefore to quantify the relative dependence of the wrinkling behavior of skin on these mechanical and geometrical factors by performing a stochastic finite element study accounting for 14 random variables. An integrated methodology combining design of experiment, solid modeling, finite element analysis and Bayesian meta-modeling was developed for this purpose. A three-layer finite element skin model including epidermis, dermis and hypodermis was designed. The sensitivity of the eigenvalues of the skin structure, number of wrinkles, amplitude of wrinkles, average roughness of the skin surface to the 14 probabilistic variables were calculated. It was found that the first four eigenvalues of the three-layer skin structure are mostly sensitive to the stiffness of the epidermis whilst this is no longer the case from the fifth eigenvalue. The thickness of the epidermis has the most significant effect on the number of wrinkles whilst the sensitivity of the average roughness to the length of the skin sample is maximum.
Effects of Varying Shoe Surface Roughness on COF Between Shoe and Floor Material in the Presence of a Liquid Contaminant
Authors: Moore Caitlin , Beschorner Kurt
Published: April 2011

Slip and fall accidents represent a serious occupational and public health concern. Yet, the tribological mechanisms that cause shoe and floor surfaces to be slippery are still not well understood. Previous attempts to model shoe-floor-contaminant friction under mixed-lubrication have ignored the effects of boundary lubrication. The purpose of this study was to examine the affect of roughness and viscosity on shoe-floor-contaminant lubrication by examining its effect on boundary and hydrodynamic lubrication. COF-velocity curves generated by a pin-on-disk tribometer were analyzed to determine the effects of roughness and viscosity on boundary and mixed lubrication. COF was collected under varying shoe roughness (7.3μm, 8.2μm, and 9.34μm), contaminant concentrations (water, 0.89cP; 1.5% diluted detergent, 1.28cP; 25% diluted glycerol, 1.9cP; 50% diluted glycerol, 5.54cP; and 75% diluted glycerol, 41cP), and speed (0.05–1.0m·sec−1). A single shoe material (polyurethane) and a single floor material (vinyl tile) were tested. Reduction in COF with increasing sliding speeds, consistent with regions of boundary and mixed lubrication were observed for all viscosities except the highest (41cP) and the lowest viscosity (water, 0.89cP). An exponential regression model was fit to the data to determine the effect of roughness and viscosity on the rate of COF decay, τhydro, and COF when velocity is 0, COFBL, indicative of boundary lubrication. τhydro was inferred to be a measure of the hydrodynamic lubricating effect. Fluid contaminant significantly affected both COFBL and τhydro. Post-hoc analyses revealed that COFBL decreased with higher concentrations of glycerol. τhydro was significantly higher under 1.28cP (diluted detergent) viscosity lubrication when compared to 1.9cP and 5.54cP (diluted glycerol) viscosity lubrication, indicating a slower rate of decrease. No significant effect of shoe material roughness on COFBL or τhydro was identified. Fluid contaminant had a significant effect on both boundary and hydrodynamic lubrication. The change in boundary lubrication coefficient of friction for varying lubricants was primarily attributed to a higher proportion of glycerol molecules, which is a much longer molecule than water, coating the shoe and floor surfaces. The hydrodynamic effect was significant between the glycerol-water lubrication compared to the lower viscosity, 1.5% detergent lubrication, which indicates that the higher viscosity fluids caused a greater rate of friction decrease. This effect is likely due to the wedge term effect of the Reynolds equation. Absence of roughness effects on both boundary and hydrodynamic variables could be due to the soft, shoe material deforming and therefore shoe roughness having a decreased affect on asperity interaction.
The Effect of Contact Conditions on the Onset of Plastic Yielding in a Spherical Shell Compressed by a Rigid Flat
Authors: Li Longqiu , Wang Lin , Etsion Izhak , Talke Frank
Published: April 2011

The effect of contact conditions on yield inception of a spherical shell compressed by a rigid flat is studied using finite element analysis. A wide range of material properties and shell thickness values, corresponding to the dimensionless shell parameter, were studied. This work provides the critical load ratio as a function of the shell parameter for different values of the Poisson’s ratio under both slip and stick contact condition. At small values of the Poisson’s ratio the behavior in stick is very different from that in slip. At high values of the Poisson’s ratio the yield inception in stick and slip is similar.
A 3D Finite Element Study on the Friction Effects on Material Flow Under the Cutting Edge in Superfinish Hard Milling H13 Tool Steel
Authors: Singh H. M. , Guo Y. B.
Published: April 2011

Milling hardened steels has emerged as a key technology in mold and die manufacturing industries. In cutting, a portion of work material is pushed upward by the tool rake face to form the chip while the other portion below this layer is ploughed under the cutting edge to become the machined surface. Although the ploughed material is a very small fraction of the uncut chip thickness, it determines surface integrity after machining. In this study, a 3D finite element simulation model of milling hardened AISI H13 tool steel (HRC 50) has been developed to study material deformation under the cutting edge of a milling insert. The ploughed depth in the range of 0.6 μm to 3.0 μm is used to study the material flow under the cutting edge. Friction between the cutting edge and workpiece surface has a significant influence on the ploughed depth. Different coefficients of friction are used to study their effects on stresses/strains and temperature during ploughing. The Johnson-Cook model is used to model the plastic behavior of workpiece material. The 3D finite element analysis gives an insight into some key issues in a milling process. The FEA model illustrates the effects of micro cutting edge geometry on pile-up in front of the cutting edge, transient stresses and temperatures, and a transition from ploughing to cutting in a milling process.
Synchronous Observation With Friction Measurement Prior to and During Occurrence of Scuffing
Authors: Yagi Kazuyuki , Sugimura Joichi , Kajita Seiji , Ohmori Toshihide , Suzuki Atsushi
Published: April 2011

In the current work, scuffing phenomenon was investigated by a direct observation of a contact area. A ball-on-disc test rig was used, which produced a point contact area between a rotating sapphire disc and a stationary steel ball. Sequence of the friction and photograph in the contact area was synchronously obtained prior to and during occurrences of scuffing. Experiments were conducted in a dry condition and a lubricated condition with hexadecane. In the lubricated condition, wear debris accumulated in the inlet zone entered suddenly into the contact area to sharply increase the friction coefficient. On the other hand, macro plastic flow occurred in the whole contact area in the dry condition during a rapid increase in friction coefficient.
Tribological Characterization of Polymeric Sealing Materials in High Pressure Hydrogen Gas
Authors: Sawae Yoshinori , Fukuda Kanao , Miyakoshi Eiichi , Doi Shunichiro , Watanabe Hideki , Nakashima Kazuhiro , Sugimura Joich
Published: April 2011

Bearings and seals used in fuel cell vehicles and related hydrogen infrastructures are operating in pressurized gaseous hydrogen. However, there is a paucity of available data about the friction and wear behavior of materials in high pressure hydrogen gas. In this study, authors developed a pin-on-disk type apparatus enclosed in a high pressure vessel and characterized tribological behavior of polymeric sealing materials, such as polytetrafluoroethylene (PTFE) based composites, in gaseous hydrogen pressurized up to 40 MPa. As a result, the friction coefficient between graphite filled PTFE and austenitic stainless steel in 40 MPa hydrogen gas became lower compared with the friction in helium gas at the same pressure. The chemical composition of worn surfaces was analyzed by using X-ray photoelectron spectrometer (XPS) after the wear test. Results of the chemical analysis indicated that there were several differences in chemical compositions of polymer transfer film formed on the stainless disk surface between high pressure hydrogen environment and high pressure helium environment. In addition, the reduction of surface oxide layer of stainless steel was more significant in high pressure hydrogen gas. These particular effects of the pressurized hydrogen gas on the chemical condition of sliding surfaces might be responsible for the tribological characteristics in the high pressure hydrogen environment.
Molecularly Thin Lubricant Layer Contact Model Accounting for Interfacial Slip
Authors: Vakis Antonis I. , Eriten Melih , Polycarpou Andreas A.
Published: April 2011

A model is presented that accounts for contact with a molecularly thin lubricant layer confined between a rigid sphere and flat substrate. The sphere is moving at a high lateral velocity inducing high shear rates and a significant increase of lubricant viscosity. Interfacial slip is modeled based on experimental and molecular dynamics data and includes effects of lubricant morphology and chemistry. The model is used to interpret experimental measurements of viscosity and slip and express them as functions of shear rate. These data can then be used in a typical head-disk interface in magnetic storage.
Tribological Performance of Polymer-Based Coatings for Oil-Less Piston-Type Compressor Applications
Authors: Yeo Seung Min , Escobar Nunez Emerson , Polycarpou Andreas A.
Published: April 2011

Due to thermodynamically adverse effects of liquid-type lubricants on the operation of air conditioning and refrigeration compressors, oil-less compressors are of current research interest. Under such conditions, advanced tribologically coatings are needed for critical interacting surfaces to ensure reliable operation under oil-less conditions. In this paper, seven commercially available polymeric coatings (PTFE-, PEEK-, resin- and fluorocarbon-based coatings) coated on gray cast iron were tribologically evaluated through unlubricated oscillatory experiments simulating a realistic wrist pin interface in a piston-type compressor. The experiments were performed in the presence of the environmentally friendly (as far as minimal global warming potential is concerned) carbon dioxide refrigerant, simulating oil-less piston-type compressors. It was found that polymer-based coatings exhibited excellent tribological performance, and in general PTFE-based coatings performed better than PEEK-based coatings. Also, their friction and wear behavior is affected by additives, which polymeric coatings were blended with. Specifically, PTFE coatings blended with pyrrolidone showed relatively low friction coefficient, and coatings blended with MoS2 had higher wear resistance.
Coefficient of Restitution Testing: Explicit Finite Element Modeling and Experiments
Authors: Marinack Martin C. , Gaudio Brian G. , Musgrave Richard E. , Rizzo Christopher E. , Lovell Michael , Higgs C. Fred
Published: April 2011

Particle based modeling approaches, such as the discrete element method (DEM) approach, require the definition of accurate contact (collision) models. An essential parameter within these models is the coefficient of restitution (e), which defines the ratio of post-collision to pre-collision relative velocity during the collision of two materials. In this study, e of various steel-material combinations is predicted through both physical experiments and explicit finite element modeling of a falling sphere colliding with a stationary plate, and examined against a theoretical formulation of e. Experiments are performed on various sphere materials including steel, brass, chrome steel, tungsten carbide, aluminum, polybutadiene, and nitinol 60, Experimental results for metals colliding with steel, match what is predicted by theory, as they show a decreasing trend in e with increasing impact velocities. Additional experimental results for polybutadiene rubber show no velocity dependence, remaining constant across the impact velocities examined; this matches with theory. Modeling results, obtained via the explicit finite element method (FEM) approach, are compared against experimental results for verification. Current explicit FEM results show very good quantitative agreement with experimental results for various materials (brass, steel, tungsten carbide, and chrome steel) impacting steel, but do not display the proper decreasing trend in e for increasing impact velocity, over the range of impact velocities examined (∼2 m/s–3.2 m/s). However, for simulations at impact velocities above this range, a decrease in e is witnessed. Current and future work focuses on refining the models to correctly display this qualitative trend within the current range of experimental impact velocities, as well as performing experiments on a wider range of impact velocities.
A Simple FEM Model for Foil Bearings Under Differential Pressure
Authors: Aksoy Serdar , Aksit Mahmut Faruk , Dogu Yahya
Published: April 2011

A bump-type foil bearing consists of a compliant corrugated sheet metal supporting structure that is covered by a thin top foil surface. Bumps serve as stiffener and damping elements to increase the stability of the system while top foil creates necessary wedge surface for aerodynamic film formation. Foil bearings are hard to analyze as flexible foil surface deforms and changes shape while aerodynamic film pressure forms. Iterative solutions required typical of EHL analysis. This work utilizes Reynolds Equation to solve aerodynamic film pressure by coupling structural deformation and the fluid film pressure formation. Bearing performance under various operating conditions and the effect of differential pressure boundary condition on sealing capacity is discussed.
Lubricant Effects in Hydraulic Motor Starting Efficiency
Authors: Michael Paul , Martini Ashlie , Bair Scott , Burgess Kelly , Garcia Jose
Published: April 2011

This paper presents an investigation of the fluid properties that affect starting efficiency in hydraulic motors. Starting efficiency is important because it often determines the minimum displacement of motors in mobile hydraulic systems. The boundary friction, thermophysical and pressure-viscosity coefficients of prototype fluids have been characterized. These hydraulic fluids have been evaluated in geroler, axial piston, and radial piston motors under constant torque starting conditions in accordance with the ISO 4392-2 standard test method. Correlations between starting efficiency and fluid boundary friction, thermophysical and pressure-viscosity coefficients have been identified. The relative impact of these fluid properties varied with motor design.
Studies on Friction and Transfer Layer Formation When Pure Magnesium Pins Slid at Various Numbers of Cycles on Steel Plates of Different Surface Texture
Authors: Menezes Pradeep L. , Kishore  , Kailas Satish V. , Lovell Michael R.
Published: April 2011

In the present investigation, various kinds of textures (undirectional, 8-ground, and random,) were attained on a set of steel plate surfaces. The roughness of the textures was varied using different grits of emery papers or polishing powders. Pins made of pure magnesium were then slid against the steel plates at various numbers of cycles (1, 2, 6, 10 and 20) using an inclined pin-on-plate sliding apparatus. In the experiments, it was observed that the coefficient of friction and the formation of a transfer layer depended on the die surface textures under both dry and lubricated conditions. The coefficient of friction increased with number of cycles under dry conditions for all of the textures studied. Under lubricated conditions, however, the coefficient of friction decreased for unidirectional and 8-ground surfaces and increased for random surfaces with the number of cycles. A stick-slip phenomenon was observed under both dry and lubricated conditions. Occurrence of the stick slip behavior depended on the surface texture, the load and the number of cycles. The variation in the coefficient of friction under both dry and lubrication conditions was attributed to changes in the texture of the surfaces during sliding.
Experimental Investigation on Marine Main Shaft Bearings With Reduced Length to Diameter Ratio
Authors: Litwin Wojciech
Published: April 2011

Water lubricated bearings are often installed on new and modernized ships. The main reasons are: unit simplicity, no danger of pollution and low price. One of the main problems connected with this the bearings of this kind is defining maximum hydrodynamic film capacity. Due to very thin hydrodynamic film and significant bearing bush deformation, the EHL model should be used for calculations. Experimental research conducted in the past was carried out on a single bearing test rig [1, 2, 3]. Unfortunately that test rig has some disadvantages. Its flexible support gives possibility of shaft misalignment for instance in case of asymmetric hydrodynamic pressure film in the bearing. The new test rig, presented in this paper gives wide research possibilities and working conditions are very similar to those on a real ship.
Tool Wear Analysis on Multi-Layered Coated Carbide Tools in Face Milling of AISI 1045 Steel
Authors: Park Kyung-Hee , Kwon Patrick Y.
Published: April 2011

Face milling tests on AISI 1045 steel were performed to study the flank wear of multilayered coated carbide tools. The cutting tools were dual (TiN/TiAlN) and triple (TiN/Al2O3/TiCN) layered, coated carbide inserts processed by PVD and CVD respectively. As expected, the depth of cut (DOC) did not play an important role on the development of flank wear while the cutting speed had a significant role in the development of flank wear. Using confocal laser scanning microscopy (CLSM) and wavelet transform, the flank wear evolution was analyzed and abrasive wear was found to be a dominant tool wear mechanism. Adhesion of the work material was also observed after the carbide substrate was exposed. Edge chipping and micro-fracture were additional tool failure modes. After comparing the performance of the two inserts, we concluded that the dual layer coating was superior to the triple layer coating under various cutting conditions mainly due to the benefit coming from the coating processes themselves. It was claimed that the superior performance of the multilayer coating came from preventing the gross crack-induced removal of coating materials by propagating the fracture along the coating interfaces. However, no such observations were found in our milling experiment. Therefore, the hardness of the coating materials is the most important criteria for the development of flank wear.
Fabrication of Al6061-CNT Composite by Mechanical Alloying Followed by Semi-Solid Powder Processing
Authors: Wu Yufeng , Kim Gap-Yong
Published: April 2011

Carbon nanotubes (CNTs) have been widely investigated as a reinforcement material to improve the mechanical, electrical and thermal properties of composite materials. Various routes have been employed to fabricate aluminum-carbon nanotube (Al-CNT) composites in the past few years. However, uniform distribution of CNTs in the metal matrix is still challenging. In this paper, a novel semi-solid powder processing (SPP) was used to incorporate CNT uniformly into the Al6061-CNT composite. Al6061-CNT powders mechanically alloyed for different durations were also examined to understand how the CNTs were dispersed in the Al6061 powders. As-received CNT cluster balls were crushed into dense thin CNT layers during mechanical alloying. As mechanical alloying time increased, CNTs were dispersed in the Al6061 particles. Well-densified microstructures with severely deformed grains were observed in the Al6061-CNT composite.
Virtual 3D Model Simulation for Design and Implementation of Automated Processes
Authors: Chiou Richard Y. , Kwon Yongjin James , Park Sang C. , Kizirian Robin , Yang Yueh-Ting , Dordai Matthew R.
Published: April 2011

This paper presents the integration and implementation of automated processes, based on the sequence control specifications and requirements of PLC (Programmable Logic Controller) systems to create a virtual test environment using a software simulation tool, PLCStudio. In order to meet the demands of the new manufacturing paradigm, PLCStudio is being designed as a next generation tool for digital production. This production solution set represents an integrated suite that provides manufacturing process design, tool and fixture design, factory and production systems design, visualization, and automation through 3D virtual simulation tools. The significant effect and benefit for the manufacturer from such a suite of tools would be a substantial reduction to the manufacturing lifecycle. This includes reduction of the assembly time and cut-down on the cost for a process development through the virtual validation and commissioning of production systems. In this paper, a process with quantifiable goals and efficiencies utilizing a robot and other devices is developed. PLCStudio is used to model the process. PLC logic control is developed to control the system and tested virtually using PLCStudio before it is used in a full scale physical test.
Predicting the Effect of Vibration on Machining Distortion in High-Speed Milling Aerospace Monolithic Components
Authors: Song Q. H. , Ai X. , Liu Z. Q.
Published: April 2011

Based on the stability lobe diagram of two degrees of freedom milling system obtained by using the numerical method, two kinds of cutting conditions (stable and unstable) are selected to perform the cutting tests of aeronautical monolithic components. Cutting distortion and secular distortion are measured and analyzed by using the MISTRAL 775 coordinate measuring machine (CMM), respectively. Influences of chatter on machining distortion are investigated. It is shown that, both machining distortion and secular distortion are smaller in stable case; in unstable case, machining distortion is also smaller, while secular distortion is very large, and torsion occurs in the workpiece end with larger box. Therefore, workpiece need be machined in stable conditions for subsequent assembly work, especially aeronautical monolithic components.
Database for Real-Time Loading Path Prediction for Tube Hydroforming Using Multidimensional Cubic Spline Interpolation
Authors: Ghosh Angshuman , Deshmukh Karan , Ngaile Gracious
Published: April 2011

Tube Hydroforming (THF) is a metal-forming process that uses a pressurized fluid in place of a hard tool to plastically deform a given tube into a desired shape. In addition to the internal pressure, the tube material is fed axially toward the die cavity. This process has various applications in the automotive, aerospace, and bicycle industries. Accurate coordination of the fluid pressure and axial feed, collectively referred to as a loading path, is critical to THF. Workable loading paths are currently determined by trial and error, which can be time consuming. This paper discusses an innovative technique for developing an interactive, real-time database that would be able to predict loading paths for typical classes of THF products and hence, reduce the computational time required. By classifying most of the commercial THF parts into families, parameters such as material properties, part geometry, and tribological factors were simulated by category and stored in the database. Multidimensional cubic spline interpolation was implemented to enable an end user to request from the database a loading path for a wide range of conditions. Test results from the database for different THF families were shown to approximate the simulated results. In addition, by reducing the computation time, the use of interpolation techniques eliminates the need for carrying out multiple simulations for similar THF parts.
Experimental Study of Micro Tools Fabricated by Electrochemical Machining
Authors: Mathew Ronnie , James Sagil , Sundaram M. M.
Published: April 2011

Accurate and precise micro tools are essential for the micromachining of highly complex features in a wide variety of engineering materials including metals and ceramics. Simple shapes like cylindrical rods with micrometer level dimensions are increasingly being used as micro tools in processes such as micro ultrasonic machining. High aspect ratio tools are necessary to produce deep micro holes and other high aspect ratio structures. Micro tools produced by the well known wire electro-discharge grinding suffer from deformation due to the thermal stresses. Therefore, alternate micro tool manufacturing techniques are being explored actively. In this paper, the manufacturing of micro tools by micro electrochemical machining (ECM) is discussed. The micro tools are made under different experimental conditions using an in-house built micro electrochemical machining system and analyzed for tool tip radii and cone angles. Further, the feasibility of extremely high aspect ratio micro tools is studied. Using micro ECM, micro tools having mean diameters of 10 microns with tips as small as 50 nm and aspect ratios of the order of 300 are achieved.
Nanosecond Laser Ablation of Titanium in Air and Water: The Time-Resolved Observation and Post-Process Characterizations
Authors: Zhou Yun , Gao Yibo , Wu Benxin
Published: April 2011

Titanium has lots of competitive applications in aerospace, biomedical and many other areas due to its special properties. However, the machining of titanium using conventional mechanical approaches often has serious tool wear and low efficiency. Laser ablation can potentially provide a good solution for titanium micromachining. In this paper, nanosecond laser ablation of titanium in air and water has been studied. The laser ablation rate, laser-induced plasma, the ablated surface profile and chemical composition change have been studied, and the results are discussed.
Study on the Influence of Different Tool Edge Radius on Milling Ti6Al4V
Authors: Liu Yueping , Li Jianfeng , Sun Jie , Jiang Feng
Published: April 2011

Short tool life is one of the bottleneck problems in Ti6Al4V machining. Edge preparation plays an important role on tool life. To investigate the influence of edge preparation on cutting force, cutting heat and chip morphology et al, Finite element model (FEM) is established. The software adopted in this study is ThirdWaveSystems AdvantEdge. Experiment is designed to verify the validation of the FEM model. Based on the validated FEM, optimized edge radius is obtained.
Experimental Investigation of Interactions Between Abrasive Tool and Workpiece in Honing
Authors: Feng Q. , Ren C. Z. , Zhao Y. , Pei Z. J.
Published: April 2011

Honing is a material removal process with a fixed-abrasive tool that has surface contact with the workpiece. The honed surfaces have a profound effect on the tribological performance of the workpiece. The interactions between abrasive tool and workpiece in honing determine the honed surfaces. This paper reports an experimental investigation on tool-workpiece interactions during honing. It studied the scratch number, scratch depth, real contact area, and honing force in honing of steel cylindrical workpiece by constant pressure with vitrified-bonded alumina stones. The results showed that abrasive grain size and honing pressure have significant effects on the tool-workpiece interactions.
Development of Self-Adhesive Bamboo Fiber Composite With Three-Dimensional Shape Using Fibers Extracted With Machining Center
Authors: Ogawa Sachiko , Ogawa Keiji , Hirogaki Toshiki , Aoyama Eiichi , Taniguchi Mitsuaki , Nobe Hiromichi
Published: April 2011

Bamboo is drawing attention as a sustainable and environmentally safe material because it is a renewable natural material and has a quick growth rate. Bamboo also has high specific strength and stiffness. Our research proposes a sustainable manufacturing system that focuses on the natural growth and properties of bamboo. One characteristic of this system is shape-controlled high quality fibers. This can be achieved by in-situ measurement and an end-milling extraction method with a machining center. Another characteristic is the potential to create a flexible composite shape thanks to controlled bamboo fiber shape and a press die. In this report, the fabrication of self-adhesive bamboo fiber composite is demonstrated by hot press forming. Proper forming temperature is investigated based on conditions and mechanical properties of the composites. A composite with three-dimensional shape is also fabricated using a press die with a three-dimensional curve. The forming was successful and good transcription could be obtained.
Forming Force Prediction in Two Point Incremental Forming Using Backpropagation Neural Networks in Combination With Genetic Algorithms
Authors: Garcia-Romeu M. Luisa , Ceretti Elisabetta , Fiorentino Antonio , Giardini Claudio
Published: April 2011

Process feasibility and material formability are two of the most concerning factors which are studied in Incremental Sheet Forming (ISF) process. They are two important matters under study of the scientific community with the final goal of improving the process performances and to make it reliable to allow its use for rapid prototyping and for small batch production. In recent years, the application of neural network techniques to forming processes has been a research topic for optimizing and predicting process parameters and ISF process has not been an exception. Unfortunately, there are some drawbacks in using Backpropagation (BP) neural networks, such as easily falling into local minimum point. Because of that, recently Genetic Algorithms (GA) are applied to BP networks in order to optimize them. This paper describes the application of BP networks and GA applied to BP networks for the prediction of the forming force in ISF process. These models have been developed using experimental data from several tests. The two point incremental forming (TPIF) tests were performed on a horizontal CNC milling machine and DC04 deep drawing sheets steel 0.8 mm thick were worked. The reliability of the proposed approach has been evaluated by testing the trained networks with unseen experimental data and the comparison between the two BP and GA-BP models are presented. All the details are accurately discussed in the paper.
Deburring of Micro-Scale Structures Machined in Milling
Authors: Matsumura Takashi , Konno Tsuyoshi , Tobe Shouta , Komatsu Takafumi
Published: April 2011

Recently micro cutting has been applied to manufacturing of micro devices. Burr formation is a troublesome problem in micro cutting. From the point of view of the required accuracy, burr removal in the micro manufacturing cannot be performed by the manual operations or the additional cuttings. The paper presents a deburring process to remove the burrs on the micro-scale structured surfaces, which are machined in micro milling. In order to remove the burrs on the pillars in the structures, the study examines burr removal milling, polishing and water jet finishing. Burr removal milling leaves the cutter traces with adhesion of the chips on the pillars. Polishing finishes the surfaces with removing the burrs on the top of the pillars. A supporting device is used for protecting the edge shapes of the pillars in polishing. Then, the burrs on the side of the pillars can be removed in water jet finishing. A water jet machine driven by a low pressure pump is developed to remove the burrs without losing their shapes. The process sequence of polishing and water jet finishing is effective in removing the burrs in micro milling. The presented process is discussed to manufacture the micro-scale structures in mechanical manner based on the axiomatic design.
Effects of Carrier Material and Design on Microalgae Attachment for Biofuel Manufacturing: A Literature Review
Authors: Cui Yan , Yuan Wenqiao Wayne , Pei Zhijian
Published: April 2011

Continuous use of petroleum derived fuels is widely recognized as unsustainable due to depleting supplies and the accumulation of greenhouse gases in the environment. Renewable, carbon neutral transport fuels are needed for environmental and economic sustainabilities. Algae have been demonstrated to be one of the most promising sources for biofuel production. However, large-scale algae production and harvesting for energy manufacturing are too costly using existing methods. The approach of growing algae on solid carriers is innovative and can potentially lead to cost-effective manufacturing of algae biofuels. As cells approach to the solid surface, many factors come in to influence microbial attachment such as the surface wettability, free energy, polarity, roughness and topography. Surface wettability plays an important role in the initial cell attachment. For further contact, surface free energy and polarity are more directly related to cell-substratum attachment strength. Surface roughness and texture are species-specific parameters and have been applied widely in attachment studies.
Ductility Enhancement in Pulsed Uniaxial Tension of Stainless Steel 304
Authors: Cullen Graham W. , Korkolis Yannis P.
Published: April 2011

It was recently demonstrated that significant increases in formability in tube hydroforming (THF) can be achieved if the load is applied in a pulsed, as opposed to the monotonic, manner. The frequency of such loading is of the order of 1 Hz, and the benefits can be observed in the case of free inflation of a tube (i.e., without a die), as well. Hence the mechanism of such improvements is not related to enhanced tribological conditions between the tube and the die, as is the case in the ultrasonic THF. In an effort to understand if and how the pulsed application of the load affects the material ductility, specimens from stainless steel 304 were subjected to uniaxial tension, with the load applied in a pulsed manner. The results of these experiments were compared to the corresponding monotonic cases under the same strain rates. Significant increases in ductility can be noted between the two types of loadings. Subsequently, further experiments described in the paper revealed that the deformation-induced heating of the stainless steel is often responsible for this behavior. However, if the loading is rather slow, the ductility enhancement is still observed, but cannot be attributed to the specimen heating.
Using an Airy Function to Predict Stresses in Wound Metal Strip Having Asymmetric Thickness Profile
Authors: Hinton Jantzen L. , Gross Paul A. , Grandhi Ramana V. , Malik Arif S.
Published: April 2011

This work analyzes the evolution of stresses during the rewinding of flat-rolled steels having asymmetric strip thickness profile (or wedge). When monitoring the stress distribution across the width of the sheet, control systems with strip flatness meters are unable to distinguish between “rolled-in” stresses and the stresses caused by winding. To avoid strip flatness defects, an efficient and accurate method was developed to separate the winding stress contribution from the overall stresses that are measured indirectly by a flatness control system. Commercial finite element software was first applied to determine in-plane evolution of stresses in a strip containing 2.4% wedge for various numbers of mandrel wraps during re-winding. The finite element analysis enabled a trend study that provided insight as to how the in-plane stresses in the rolled sheet evolve during the winding process. Coefficients of a 4th order polynomial Airy Stress Function were then obtained to predict the stresses according to the mandrel wrap number and planar spatial position on the strip. With this approach, only a single function is needed to predict the entire in-plane stress field. This paper illustrates development of the Airy Stress function as characteristics of the in-plane stresses during winding of strip with asymmetric thickness profile.
Ultrasonic Vibration-Assisted Pelleting of Biomass: A Designed Experimental Investigation on Pellet Quality and Sugar Yield
Authors: Zhang Pengfei , Deines Timothy , Nottingham Daniel , Pei Z. J. , Wang Donghai , Wu Xiaorong
Published: April 2011

Increasing demands and concerns for the reliable supply of liquid transportation fuels make it important to find alternative sources to petroleum based fuels. One such alternative is cellulosic biofuels. However, several technical barriers have hindered large-scale, cost-effective manufacturing of cellulosic biofuels, such as the low density of cellulosic feedstocks (causing high transportation and storage costs) and the low efficiency of enzymatic hydrolysis process (causing longer processing time and low sugar yield). Ultrasonic vibration-assisted (UV-A) pelleting can increase the density of cellulosic materials by compressing them into pellets. UV-A pelleting can also increase the sugar yield of cellulosic biomass materials in hydrolysis. At present, the effects of process variables in UV-A pelleting on pellet quality (density, durability, and stability) and sugar yield have not been adequately investigated. This paper reports an experimental investigation on UV-A pelleting of wheat straw. A 24 factorial design is employed to evaluate the effects of process variables (moisture content, particle size, pelleting pressure, and ultrasonic power) on output variables (pellet density, durability, stability, and sugar yield).
Condition Monitoring With Round Ceramic Inserts While Face Milling Using Acceleration Data
Authors: Milner Justin L. , Roth John T.
Published: April 2011

In order to automate machining operations, it is necessary to develop robust tool condition monitoring techniques. In this paper, a tool monitoring strategy for round whisker-reinforced ceramic end milling tools is presented based on the Fourier transform and statistical analysis of the vibrations of the tool during the machining operations. Using a low-cost tri-axial piezoelectric accelerometer, the presented algorithm demonstrates the ability to accurately monitor the condition of the tools as the wear increases during linear milling operations. One benefit of using accelerometer signals to monitor the cutting process is that the sensor does not limit the machines capabilities, as a workpiece mounted dynamometer does. To demonstrate capabilities of the technique for round coated and uncoated ceramic tooling, six tool wear life tests were conducted under various conditions. The indirect method discussed herein successfully tracks the tool’s wear, even with the occurrence of minor chipping, and is shown to be sensitive enough to provide sufficient time to replace the insert prior to damage of the machine tool, cutter, and/or workpiece.
The Development of a Complex Control Methodology for an Intelligent Stamp Forming Die
Authors: Emblom William J. , Weinmann Klaus J.
Published: April 2011

This paper describes the development and implementation of closed-loop control for an oval stamp forming die using Matlab®’s Simulink® and the dSPACE® ControlDesk®. A traditional PID controller was used for the blank holder pressure and an advanced controller utilizing fuzzy logic combining a Linear Quadratic Gauss controller and a Bang-Bang controller. The draw beads were used to control local forces near the draw beads. The blank holder pressures were used to control both wrinkling and local forces during forces. It was demonstrated that a complex, advanced controller could be modeled using Matlab’s Simulink and implemented in dSPACE ControlDesk. The resulting control systems for blank holder pressures and draw beads were used to control simultaneously local punch forces and wrinkling during the forming operation resulting in a complex control strategy that could be used to improve the robustness of stamp forming dies.
Cutting Condition Decision Methodology Based on Data-Mining of Tool Catalog Data
Authors: Kodama Hiroyuki , Hirogaki Toshiki , Aoyama Eiichi , Ogawa Keiji
Published: April 2011

Data-mining methods were used to support decisions about reasonable cutting conditions. The aim of our research was to extract new knowledge by applying data-mining techniques to a tool catalog. We used both hierarchical and non-hierarchical clustering of catalog data and also used applied multiple regression analysis. We focused on the shape element of catalog data and we visually grouped end mills from the viewpoint of tool shape, which here meant the ratio of dimensions, by using the k-means method. We then decreased the number of variables by using hierarchical cluster analysis. We also found an expression for calculating the best cutting conditions, and we compared the calculated values with the catalog values. We did 15 minutes of cutting work using three kinds of cutting conditions: conditions recommended in the catalog, conditions derived by data-mining, and proven cutting conditions for die machining (rough processing).
Development of an Axisymmetric Pressure Application Method for Cylindrical Laminated Device Fabrication
Authors: Vlieg James H. , Paul Brian K. , Peterson Richard B.
Published: April 2011

Microchannel arrays are being developed across a wide spectrum of applications including blood processing, fuel cells and thermal management among many others. Typical arrays are based on a flat laminated architecture produced in a vacuum hot press (VHP) through uniaxial bonding pressure at elevated temperatures. Due to the cylindrical nature of certain microchannel applications, such as chemical processing within chemical facilities and heat rejection within Stirling cycle engines, the packaging of microchannel devices within cylindrical geometries would greatly simplify interconnect. This paper describes the development of a novel technique for axisymmetric diffusion bonding pressure application with the use of a VHP capable of producing cylindrical laminated devices. Uniaxial bonding pressure is converted to axisymmetric pressure through the use of conical wedges. Pressure magnitude and distribution are controlled by the geometry of the pressure delivery platens, the design of which was aided by finite element analysis. Cylindrical test articles were produced by patterning thin metal foils by laser machining a single roll of metal shim stock, which was then coiled within an outer tube shell and axisymmetrically bonded with the VHP to produce a cylindrical laminated workpiece. Preliminary bonding results show quality bond lines with minimal void fractions. This new architecture is shown to be feasible for producing cylindrical laminated devices by microlamination using traditional VHP equipment.
A Variable Search Technique for Multiple Control Valves Used in Melt Modulation During Injection Molding
Authors: Coulter John P. , Tantrapiwat Akapot
Published: April 2011

A variable search technique was investigated for use with a melt modulation system with multiple control valves. The method was developed in order to obtain an optimum solution which determines the positions of all valves. It was shown that not all valve angles in the system had to be determined, as only certain significant valves needed to be fine tuned during the searching process. It was also shown that the valve position and location were greatly dependent on the cavity and runner configurations. Once the valve control variable search method had been established, a series of family mold models was created and analyzed using MoldFlow. Instead of using the default runner from the software, a modification of the 3D models was made in order to embed melt modulation valves. The result showed that within a limited number of trials, an optimum solution can be obtained. The number of searching trials can also be reduced by applying different search gains and changing certain appropriate initial values.
Experimental Investigation of Micro-Milling Accuracy Using On-Machine Measurement System
Authors: Liu Xinyu
Published: April 2011

In this paper, we proposed an error decomposition method, in which some major error components can be experimentally estimated using an on-machine measurement (OMM) system. Unlike the conventional machining, the geometric error of a micro-tool, i.e., the deviation of the effective tool diameter from a nominal value, becomes a dominant factor affecting the machining accuracy. The error stems from both the tool fabrication error and the dynamic runout of the spindle system under high rpm. An on-machine measurement system based on a non-contact confocal laser sensor was developed that can accurately and efficiently acquire the effective tool diameter. To compensate the error due to the tool geometric error, the effective tool diameter was used to replace the nominal tool diameter to generate the tool path. The experimental results showed that the tool geometric error contributes over 50% to the total machining error. After compensation, the machining accuracy was significantly improved. The machine contour error has negligible influence on the dimension error of the machined feature, but it affects the form error, such as circularity of a machined hole. The process induced surface location errors were estimated from both experiments and model simulations, and good match was achieved.