bluuebunny/crossref_metadata_2025 huggingface dataset:
Eulerian Transformation of Vortex Amplifier Static Characteristics
Authors: Boucher R. F. , Kitsios E. E.
Published: July 2009

Tests with ambient air flow through a nominal 300 mm chamber diameter vortex amplifier demonstrate independence of Reynolds number over the test range. This permits data transformations based on constancy of Euler number at any working point. Data taken with constant control-to-outlet pressure drop are shown to produce characteristics for constant supply-to-outlet pressure drop which would be experimentally discontinuous. The independence of Reynolds number also suggests that pressure losses within the vortex chamber are relatively minor.
A Pole-Assignment Controller for an Electrohydraulic Cylinder Drive
Authors: Finney J. M. , de Pennington A. , Bloor M. S. , Gill G. S.
Published: July 2009

This paper is concerned with the practical application of self-tuning control to an electrohydraulic cylinder drive. The experimental drive studied had a dominant natural frequency of 19 Hz and consequently to achieve the fast sampling rate a novel method of controller implementation is required. Estimates of the model parameters are obtained by a square root filter and controller synthesis is achieved by a pole-assignment algorithm. The results presented were generated by an experimental rig under the control of a DEC LSI 11/23 microprocessor.
Bayesian Estimation of Transit Rail Vehicle Parameters
Authors: Fries R. H. , Cooperrider N. K.
Published: July 2009

Bayesian parameter estimation is a powerful and versatile method with good convergence properties. This paper describes the use of the Bayesian method to estimate the parameters of a transit rail vehicle. The paper also addresses several issues of general interest in estimation work: cost function formulation, signal processing methods, parameter linking, and parameter estimability.
Design Criteria for Serial Chain Mechanisms Based on Kinetic Energy Ratios
Authors: Rios Oziel , Tesar Delbert
Published: July 2009

In this article, a description of the kinetic energy partition values (KEPVs) of serial chain mechanisms, as well as their rates of change, is presented. The KEPVs arise from the partitioning of the mechanism’s kinetic energy and correspond to the critical values of the kinetic energy ratios of the actuators and links and are indicators of the kinetic energy distribution within the system while the rates of change in the KEPVs indicate the sensitivity to change in the location of that kinetic energy. A high value for the KEPV rate of change together with a high operational state implies that the amount of kinetic energy flowing in the system is large, further implying a loss of precision in the system due to large inertial torques being generated. The KEPVs and their rates can be used to identify the actuators whose parameters (mass, inertia, and mechanical gain) greatly affect the overall distribution of kinetic energy within the system, thereby allowing the designer to optimize these actuators to improve the performance of the overall mechanism. Two design criteria, one based on the KEPVs and another based on their rates of change, are developed. A two degree-of-freedom (DOF) planar mechanism is used to demonstrate the concepts and to verify the properties of the KEPVs and their rates. Also, a 6DOF spatial manipulator is used to illustrate the solution of a multicriteria design optimization problem where two conflicting criteria are considered: a KEPV criterion and an effective mass criterion. The goal of the design problem is to demonstrate how the inertial parameters of the actuators and the mechanical gains of the actuator transmissions alter the kinetic energy of the system both in terms of its magnitude, which is “measured” via the effective mass criterion, and its distribution, which is measured via the KEPV criterion. It is demonstrated that the mechanical gains in the actuators significantly influence the magnitude of the kinetic energy as well as its distribution within the system due to the inertial amplification. The KEPVs and their rates of change provide a novel new approach to analyzing the dynamic character of serial chain mechanisms.
On the Torque Characteristic of a Crash-Lock Carton Base
Authors: Mullineux Glen
Published: July 2009

An important part of some packaging cartons is the crash-lock base. A recent investigation of the torque required for its erection has made some linearizing assumptions. It is here shown that these can be avoided as the relations connecting the angles between panels can be found. This also indicates that the final increase in the required torque is due to geometric effects rather than frictional ones.
Contact Characteristics of Circular-Arc Curvilinear Tooth Gear Drives
Authors: Wu Yi-Cheng , Chen Kuan-Yu , Tsay Chung-Biau , Ariga Yukinori
Published: July 2009

In this paper, the circular-arc curvilinear tooth gear drive is proposed. The gear and pinion tooth surfaces are generated by two complemented circular-arc rack cutters with curvilinear tooth-traces. According to the theory of gearing, the mathematical model of the proposed gear is developed. The tooth contact analysis technique is utilized to investigate the kinematical errors of circular-arc curvilinear tooth gear drives under different assembly errors. Contact patterns of the circular-arc curvilinear tooth gear drive are simulated by the developed computer-aided tooth contact analysis programs and surface topology method. Numerical examples are presented to show the kinematical errors of the circular-arc curvilinear tooth gear set under different assembly conditions. Relations among the circular-arc tooth profile, curvilinear tooth-trace, contact ratio, contact pattern, and kinematical error are also demonstrated by numerical examples.
Computational Improvements to Estimating Kriging Metamodel Parameters
Authors: Martin Jay D.
Published: July 2009

The details of a method to reduce the computational burden experienced while estimating the optimal model parameters for a Kriging model are presented. A Kriging model is a type of surrogate model that can be used to create a response surface based a set of observations of a computationally expensive system design analysis. This Kriging model can then be used as a computationally efficient surrogate to the original model, providing the opportunity for the rapid exploration of the resulting tradespace. The Kriging model can provide a more complex response surface than the more traditional linear regression response surface through the introduction of a few terms to quantify the spatial correlation of the observations. Implementation details and enhancements to gradient-based methods to estimate the model parameters are presented. It concludes with a comparison of these enhancements to using maximum likelihood estimation to estimate Kriging model parameters and their potential reduction in computational burden. These enhancements include the development of the analytic gradient and Hessian for the log-likelihood equation of a Kriging model that uses a Gaussian spatial correlation function. The suggested algorithm is similar to the SCORING algorithm traditionally used in statistics.
Tracking Controllers for Robot Manipulators: A High Gain Perspective
Authors: Jayasuriya Suhada , Hwang Cheng Neng
Published: July 2009

We propose a controller for the path tracking problem of robotic manipulators. The proposed controller structure is similar to that of the “computed-torque” scheme widely known in the literature. Unlike the computed-torque scheme, this controller is robust with respect to parameter uncertainty and disturbances. The robustness is given by a high gain mechanism that works in conjunction with a nonlinear precompensator in the control loop. The fundamental action of the high gain is to minimize the effective uncertainty that remains, subsequent to any cancellation by the precompensator. Comparison of the performance of this controller with two other schemes reported in the literature suggests that it performs as effectively. An interesting relationship among the high-gain, the control effort and the accuracy of tracking is identified for a special class of path-tracking that is commensurate with zero tracking error. The synthesis of this controller is easily formulated and its performance is dictated primarily by a single high-gain parameter, making it particularly attractive for on-line tuning. Some guidelines are given for the off-line selection of this high-gain parameter.
Dynamic Load Carrying Capacity of Mechanical Manipulators—Part I: Problem Formulation
Authors: Wang L. T. , Ravani B.
Published: July 2009

Two types of problems associated with load carrying capacity of robot manipulators are studied. The first type of problem involves determining the maximum load carrying capacity of a robot manipulator given a dynamic robot trajectory. The second problem involves synthesizing point-to-point dynamic robot motions with optimum load carrying capacities. In this Part I of the paper, the first type problem and the formulation of the second type problem are presented. A computational procedure for obtaining numerical solutions to the second type problem together with the application of the results to advanced trajectory synthesis and classification of multi-degree-of-freedom robot manipulators are given in the companion Part II of the paper.
The Theory of Kinematic Parameter Identification for Industrial Robots
Authors: Everett L. J. , Hsu Tsing-Wong
Published: July 2009

This paper presents the concept of completeness for kinematic identification of robot manipulators. Completeness is defined as the ability to map joint positions into tool positions for all arbitrary manipulators. It is suggested that complete models must contain a certain number of independent parameters. Furthermore it is suggested (and shown by practical examples) that the required number of independent kinematic parameters is easy to determine a-priori. This enables one to check a model for completeness. Although the basic idea behind kinematic identification may have been considered well known, several identification algorithms in the recent literature are incomplete. Two examples are included in this paper. For this reason, this paper presents the topic and includes the conditions for a complete and viable identification algorithm.
Vibrational Control of a Laser Illuminated Thermochemical System
Authors: Bentsman J. , Hvostov H.
Published: July 2009

Vibrational control is a nonclassical open-loop control principle which proposes a utilization of zero mean parametric excitation of a dynamical system for achieving control objectives. In the present paper, excitations introduced into the incident power of a laser beam in a laser illuminated thermochemical reaction are shown to be capable of inducing asymptotically stable operating regimes with averages located at initially unstable steady states. This opens a possibility of alleviating measurement and actuator related difficulties associated with conventional methods in a stabilization of laser-driven systems.
Optimal Control Theory Applied to a Pump With Single-Stage Electrohydraulic Servovalve
Authors: Akers A. , Lin S. J.
Published: July 2009

Optimal control theory is applied to the design of a pressure regulator for an axial piston pump and single-stage electrohydraulic valve combination. The control valve has been modeled and an optimal control law has been formulated. The time response curves due to a step input inflow rate and in current input to the servovalve have been obtained for the open loop and for the optimal control system. Comparison of the results has been made with previous work in which the supply valve to the swashplate actuators was not modeled. It is shown that controlled system modeling of the servovalve significantly improves system performance in terms of response frequency and pressure peaks.
Integrated Communication and Control Systems: Part II—Design Considerations
Authors: Ray Asok , Halevi Yoram
Published: July 2009

Asynchronous time-division multiplexed networks, used in Integrated Communication and Control Systems (ICCS), introduce time-varying and possibly stochastic delays in the feedback control loops. The objective of this on-going research is to develop a comprehensive methodology for the analysis and design of the above class of delayed control systems. In the first part [1] of this two-part paper, we developed a discrete-time, finite-dimensional, time-varying model of the delayed control system; necessary and sufficient conditions for system stability have been established for periodically varying delays. This second part elucidates the significance of the above model relative to the system dynamic performance as well as addresses major criteria for and outlines alternative analytical approaches to ICCS design. Pertinent concepts are illustrated by simulation.
Dynamics of Chain of Flexible Links
Authors: Benati M. , Morro A.
Published: July 2009

A Lagrangian approach is developed for the dynamics of a chain with flexible links. Each link is modeled as a system with a finite number of degrees of freedom, one of them describing the rotation, the other ones the flexibility. While the approach is developed for chains with any numbers of links, the dynamic equations are written explicitly for a chain with two links and a payload.
Optimal Pole Assignment for Discrete Linear Regulator With Deterministic Disturbances
Authors: Lee Tsu-Tian , Lee Shiow-Harn
Published: July 2009

This paper presents the solution of the linear discrete optimal control to achieve poles assigned in a circular region and, meanwhile, accommodate deterministic disturbances. It is shown that by suitable manipulations, the problem can be reduced to a standard discrete quadratic regulator problem that simultaneously ensures: 1) closed-loop-poles all inside a circle centered at (β, 0) with a radius α, where |β| + α ≤ 1, 2) minimizes the cost functional, and 3) accommodates external input disturbance.
Approximation of Irrational Matrix Functions and Its Application to Continuous-Discrete Model Conversion
Authors: Chen Muh-Yang , Hwang Chyi
Published: July 2009

In this paper, an improved method of rational approximation is presented for evaluating the irrational matrix function f(A), where A is a square matrix and f(s) is a scalar irrational function which is analytic on the spectrum of A. The improvement in the accuracy of the approximation off (A) by a rational matrix function is achieved by using the multipoint Pade approximants to f(s). An application example to model conversion involving the evaluations of the matrix exponential exp (AT) and the matrix logarithm ln(F) is provided to illustrate the superiority of the method.
On-Line Identification of Process Models in Closed-Loop Material Testing
Authors: Lee S. R. , Srinivasan K.
Published: July 2009

On-line identification of process models in mechanical material testing situations is considered here. The identification is to be performed under closed loop test conditions and using normally available command signals. Process model forms appropriate for a variety of material testing situations are developed here. The performance of on-line identification schemes is evaluated for some material testing situations, using simulation and experiment. The identification schemes are successful in performing parameter estimation using simple process models.
Evaluation and Time-Scaling of Trajectories for Wheeled Mobile Robots
Authors: Graettinger T. J. , Krogh B. H.
Published: July 2009

A method is presented for evaluating the feasibility of trajectories generated by path-planning systems for wheeled mobile robots (WMRs). Constraints that limit the class of executable trajectories for a given WMR are classified as path constraints, kinematic constraints, and dynamic constraints. Path constraints, which are limits on the path geometry, are a function of the wheelbase configuration and steering mechanism. Limits that involve only functions of velocities and accelerations are termed kinematic constraints. Dynamic constraints refer to limits on force/torque inputs and frictional force constraints which must be satisfied for a trajectory to be feasible. We show that when path constraints are violated the path must be modified to achieve feasibility, while violations of kinematic and dynamic constraints can be eliminated by time scaling so that the same path is followed at a slower speed. The concepts are developed and illustrated in the context of a model for the dynamics of conventionally steered vehicle.
The Optimal Locus Approach With Machining Applications
Authors: Koren Yoram
Published: July 2009

An optimal locus concept is introduced as the basis for an optimization methodology for real-time control subject to time-varying constraints. The optimal locus in the control plane contains all possible optimum points, and the actual point is found at the intersection of the optimal locus with the most limiting constraint. The mathematical basis of the approach is a given set of equations which is less than the number of unknowns, and the addition of real-time measurements to compensate for the missing information. The control system generates the optimal parameters in real time, and uses them as references to the control loops. The optimization methodology and control architecture are structures in a generalized way for application to processes having multiple variables and subject to several constraints. The proposed controller architecture can effectively control many machining processes. The optimal locus approach was applied to a grinding system and the experimental results verify the proposed theory.
Sequential Testing for Fault Detection in Multiply-Redundant Systems
Authors: Ray Asok
Published: July 2009

The paper presents the theory and application of a sequential test procedure for fault detection and isolation (FDI), The test procedure is suited for development of intelligent instrumentation in strategic processes like aircraft and nuclear plants where redundant measurements are usually available for individual critical variables. The algorithm of the test procedure is formulated by use of (1) a generic redundancy management procedure which is essentially independent of the fault detection strategy and measurement noise statistics, and (2) a modified version of sequential probability ratio test (SPRT) algorithm for fault detection and isolation, which functions within the framework of the aforesaid redundancy management procedure. The sequential test procedure is suitable for real-time applications using commercially available microcomputers and its efficacy has been verified by on-line fault detection in an operating nuclear reactor.
Large-Scale Uncertain Systems Under Insufficient Decentralized Controllers
Authors: Chen Y. H.
Published: July 2009

We consider a class of large-scale uncertain dynamical systems under decentralized controllers. The system is composed of N interconnected subsystems which possess uncertainty. Moreover, there are uncertainties in the interconnections. If the subsystems are under sufficient decentralized controllers, the large-scale system is practically stable. As certain controllers fail, study on the conditions for total stability of partial stability to be preserved is made. It can be shown that the stability is only related to bound of uncertainty and the structure of the large-scale system. Moreover, the conditions can be utilized to determine the importance of some controllers for stability.
An Adaptive PI/Sliding Mode Controller for a Speed Drive
Authors: DeSantis R. M.
Published: July 2009

A classical PI speed drive controller modified with the parallel addition of an on-off switching element appears to offer a potential for reasonable improvement over the performance of the original version. This improvement is obtained by combining classical transfer function techniques, sliding mode systems ideas, and self-tuning. While theoretical results, extended simulations, and preliminary experimental tests are encouraging, they do suggest that in actual industrial applications performance improvement may be conditioned by the usage of better performing open loop components.
Robust Control of Robotic Manipulators in the Presence of Dynamic Parameter Uncertainty
Authors: Mills J. K. , Goldenberg A. A.
Published: July 2009

Sufficient conditions are proved for a robotic manipulator controller so that asymptotic tracking/regulation occurs, independent of dynamic parameter uncertainty, for a certain class of input signals. The uncertainty can be quite large, and arise chiefly from the manipulation of payloads with unknown mass/inertia properties. The control is obtained using a robust controller which consists of two separate parts: 1) a compensator which makes the closed-loop robotic system insensitive to parameter uncertainty and generates asymptotic regulation of a certain class of input signals and 2) a stabilizing compensator, whose purpose is to stabilize the closed-loop system. Stability of the closed-loop system is guaranteed by choosing large feedback gains. In addition to the above, it is also shown that the proposed feedback controller provides an arbitrarily small tracking error capability for the particular class of input trajectories.
Knowledge Representation System for Robot-Based Automated Assembly
Authors: Jain Anil , Donath Max
Published: July 2009

The complexity of the man-machine interface and the issues of controlling a robot and ensuring that the robot does indeed complete the task are significant obstacles to the use of robots in the assembly environment. We have developed a knowledge representation model for robots in the assembly environment. The proposed model provides a means of using apriori knowledge and reasoning capabilities for specifying, controlling, and monitoring the tasks performed by robots. This knowledge representation model facilitates robot programming and real time error prevention. We describe the object models for the proposed knowledge presentation system and present the constraint enforcing environment for the modeling of assemblies. This includes the representation of constraints and the rules for simplifying constraints and motion strategies for primitives and assemblies.
Design Optimization Problem Reformulation Using Singular Value Decomposition
Authors: Sarkar Somwrita , Dong Andy , Gero John S.
Published: July 2009

This paper presents a design optimization problem reformulation method based on singular value decomposition, dimensionality reduction, and unsupervised clustering. The method calculates linear approximations of associative patterns of symbol co-occurrences in a design problem representation to induce implicit coupling strengths between variables and constraints. Unsupervised clustering of these approximations is used to heuristically identify useful reformulations. In contrast to knowledge-rich Artificial Intelligence methods, this method derives from a knowledge-lean, unsupervised pattern recognition perspective. We explain the method on an analytically formulated decomposition problem, and apply it to various analytic and nonanalytic problem forms to demonstrate design decomposition and design “case” identification. A single method is used to demonstrate multiple design reformulation tasks. The results show that the method can be used to infer multiple well-formed reformulations starting from a single problem representation in a knowledge-lean manner.
Stability Based Robust Eigenvalue Design for Tolerance
Authors: Lu XinJiang , Li Han-Xiong
Published: July 2009

A novel integrated approach is developed to design systems for stability and robustness. First, design parameters with large variation bounds are chosen to maintain system stability. Then, a robust eigenvalue design problem is considered to make the dynamic response less sensitive to parameter variations. A new complex sensitivity matrix is derived from the system dynamics with the eigenvalue variation approximated into a first-order model by means of the eigenvector orthogonal theory. Through a proper transformation, the complex eigenvalue sensitivity of the Jacobian matrix can still be processed by the traditional robust design approach. By minimizing the eigenvalue sensitivity, design parameters can be obtained for stability as well as robustness. Furthermore, the tolerance space of the selected parameters can be maximized to improve robust performance. A Laval rotor example is used to demonstrate the effectiveness of the proposed robust design method.
Experimental Investigations on Wear Resistance Characteristics of Alternative Die Materials for Stamping of Advanced High Strength Steels (AHSS)
Authors: Cora O¨mer Necati , Koc¸ Muammer
Published: July 2009

Newer sheet alloys (such as Al, Mg, and advanced high strength steels) are considered for automotive body panels and structural parts to achieve lightweight construction. However, in addition to issues with their limited formability and high springback, tribological conditions due to increased surface hardness and higher work hardening effect necessitate the use of improved alternative die materials, coatings, lubricants to minimize the wear-related issues in stamping of such lightweight materials. This study aims to investigate and compare the wear performances of seven (7) different die materials (AISI D2, Vanadis 4, Vancron 40, K340 ISODUR, Caldie, Carmo, 0050A) using a newly developed wear testing method and device. We used DP600 sheets in the tests. Our results showed that almost all of the recently developed specially-alloyed die materials demonstrated higher wear resistance performance when compared with the performance of AISI D2 die material.
Effect of Carbon Nanotube (CNT) Loading on the Thermo-Mechanical Properties and the Machinability of CNT-Reinforced Polymer Composites
Authors: Samuel Johnson , Dikshit Ashutosh , DeVor Richard E. , Kapoor Shiv G. , Hsia K. Jimmy
Published: July 2009

The machinability of carbon nanotube (CNT)-reinforced polymer composites is studied as a function of CNT loading, in light of the trends seen in their material properties. To this end, the thermo-mechanical properties of CNT composites with different loadings of CNTs are characterized. Micro endmilling experiments are also conducted on all the materials under investigation. Chip morphology, burr width, surface roughness and cutting forces are used as the machinability measures to compare the composites. For composites with lower loadings of CNTs (1.75% by weight), the visco-elastic/plastic deformation of the polymer phase plays a significant role during machining, whereas, at loadings ≥ 5% by weight, the CNT distribution and interface effects dictate the machining response of the composite. The ductile-to-brittle transition and reduction in fracture strength that occurs with an increase in CNT loading, results in reduced minimum chip thickness values, burr dimensions and cutting forces in the CNT composite. The increase in thermal conductivity with the increase in CNT loading, results in reduced number of adiabatic shear bands being observed on the chips and reduced thermal softening effects at high cutting velocities. Thus, overall the increase in CNT loading improves the machinability of the composite.
Modeling and Simulation of Focused Ion Beam Based Single Digital Nano Hole Fabrication for DNA and Macromolecule Characterization
Authors: Zhou Jack , Yang Guoliang
Published: July 2009

In this paper we describe a top down nano-fabrication method to make single-digit nanoholes that we aim to use for DNA and RNA characterization. There are three major steps towards the fabrication of a single-digit nanohole. 1) Preparing the freestanding thin film by epitaxial deposition and electrochemical etching. 2) Making sub-micro holes (0.2 μm to 0.02μm) by focused ion beam (FIB), electron beam (EB), atomic force microscope (AFM), or other methods. 3) Reducing the hole to less than 10 nm by epitaxial deposition, FIB or EB induced deposition. One specific aim for this paper is to model, simulate and control the focused ion beam machining process to fabricate holes which can reach single-digit nanometer scale on solid-state thin films. Preliminary work has been done on the thin film (30 nm in thickness) preparation, sub-micron hole fabrication, and ion beam induced deposition, and results are presented.
Disassembly Planning and Timing Through a Petri Net Approach
Authors: Bao Han P. , Lei ChunHsi
Published: July 2009

Disassembly planning and costing is a major task in the achievement of sustainable manufacturing. This paper presents a systematic approach to identify the feasible ways to disassemble a product then to select the most economical one using reliable time data gathered from experimental and practice-oriented sources. The disassembly process is modeled after the Petri Net approach, a technique that has proven to be fairly popular with the research community in the last few decades. The result of our systematic approach is a reliable derivation for a time-effective disassembly plan.
Experimental Study on Shear Fracture of Advanced High Strength Steels
Authors: Shih Hua-Chu , Shi Ming F.
Published: July 2009

Fracturing in a tight radius during stretch bending has become one of the major manufacturing issues in stamping advanced high strength steels (AHSS), particularly for those AHSS with a tensile strength of 780 MPa or higher. Computer simulations often fail to predict this type of fracture, since the predicted strains are usually below the conventional forming limit curve. In this study, a laboratory stretch-forming simulator (SFS) is used to simulate the stretch bending of AHSS in stamping to develop a possible failure criterion for use in computer simulations. The SFS simulates the stamping process when sheet metal is drawn over a die radius with tension applied. Various sizes of die radius are used during the experiment, and the shear fracture phenomenon can be recreated using this test for a given material and gauge. It is found that shear fracture depends not only on the radius-to-thickness ratio but also on the tension/stretch level applied to the sheet. The experimental data show that a critical radius-to-thickness ratio for shear fracture exists for any given material and gauge, but this ratio is not unique and it depends upon the amount of tension imposed during the bending.
Modeling the Flow and Distribution of Nanoparticles in Friction Stir Processed Polymeric Composite Materials
Authors: Gan Yong X.
Published: July 2009

Friction stir processing is an advanced manufacturing process in which a specially designed rotating pin is first inserted into the adjoining edges of the materials to be processed with a proper tool tilt angle and then move all along the adjoining edges. The pin produces frictional and plastic deformation heating in the processing zone. As the tool pin moves, materials are forced to flow around the pin. Material flows to the back of the pin, where it is extruded and forged behind the tool, consolidated and cooled under hydrostatic pressure conditions. The primary research about friction stir processing has been focused on aluminum alloys. In recent years many researchers have been trying to apply this technology for processing other alloys and materials including stainless steels, magnesium, titanium, and copper. In addition, this technology has been used to modify the microstructure of reinforced metal matrix composite materials. However, friction stir processing polymeric based materials are much less studied. Friction stir processing has the advantage of reducing distortion and defects in materials. It has potential to be used in manufacturing nanoparticle-reinforced polymeric composite materials. In this work, modeling the flow pattern and the distribution of nanoparticles in friction stir processed polymeric composite materials was performed. The internal pressure in friction stir processed composite materials was also derived, which may be used to predict the residual stress state in the nanocomposite material joint. It is found that the pressure in the joint is a function of radial position from the tool pin. The magnitude of the pressure is related to the tool geometry and the welding conditions such as tool rotating speed etc.
Chip Stick and Slip Motions of a Machine Tool in the Cutting Process
Authors: Gegg Brandon C. , Suh Steve C. S. , Luo Albert C. J.
Published: July 2009

The two-degree of freedom oscillator is presented to model the dynamics of a machine tool system in the cutting process. The chip dynamics are presented through a discontinuous system with a velocity boundary (frictional force). The closed form solutions are presented for the normalized linear set of ordinary differential equations. The basic mappings are introduced to investigate the stick-slip motion in such a mechanical model. The mapping structures for the periodic motions will be developed. The numerical prediction of the phase trajectory, over a range of the excitation frequency is presented through the discontinuity. The predictions are verified by numerical illustrations of the phase trajectory, velocity and forces time histories. The main contributions are the forces and force product distribution at the switching points for this machine-tool.
Desorption-Limited Mechanism of Release From Polymer Nanofibers
Authors: Srikar R. , Megaridis C. M. , Yarin A. L. , Bazilevsky A. V.
Published: July 2009

This work examines the release of a model water-soluble compound from electrospun polymer nanofiber assemblies. Such release attracts attention in relation with biomedical applications, such as controlled drug delivery. It is also important for stem cell attachment and differentiation on biocompatible electrospun nanofiber scaffolds containing growth factors, which have been encapsulated by means of electrospinning. Typically, the release mechanism has been attributed to solid-state diffusion of the encapsulated compound from the fibers into the surrounding aqueous bath. Under this assumption, a 100% release of the encapsulated compound is expected in a certain (long) time. The present work focuses on certain cases where complete release does not happen, which suggests that solid-state diffusion may not be the primary mechanism at play. We show that in such cases the release rate can be explained by desorption of the embedded compound from nanopores in the fibers, or from the outer surface of the fiber in contact with the water bath. After release, the water-soluble compound rapidly diffuses in water, whereas a release rate is determined by the limiting desorption stage. A model system of Rhodamine 610 fluorescent dye embedded in electrospun monolithic Poly(methylmethacrylate) PMMA or Poly(caprolactone) PCL nanofibers, or in nanofibers electrospun from PMMA/PCL blends, or in core/shell PMMA/PCL nanofibers is studied. Both the experimental results and theory point at the above-mentioned desorption-related mechanism and the predicted characteristic time, release rate, and effective diffusion coefficient agree fairly well with the experimental data. A practically important outcome of this surface release mechanism is that only the compound on the fiber and pore surfaces can be released, whereas the material encapsulated in the bulk cannot be freed within the time scales characteristic of the present experiments (days to months). Consequently, in such cases complete release is impossible. We also demonstrate how the release rate can be manipulated by the polymer content and molecular weight affecting nanoporosity and the desorption enthalpy, as well as by the nanofiber structure (monolithic fibers, fibers from polymer blends and core-shell fibers). In particular, it is shown that by manipulating the above parameters, release times from tens of hours to months can be attained.
Prototyping of Electric Tweezer-Type Soldering Iron Device With Flexible Fingers for SMD
Authors: Ando Hiroki , Murakami Takahiko , Muramatsu Naoki
Published: July 2009

This paper proposes a new tweezer-type soldering iron device. The aim of this device is to make it easier for someone to remove defective small surface mount devices (SMDs) from the high density circuit board. Removal of small SMDs is difficult because of the size and small working space. The proposed device has two flexible fingers to grip small SMDs stably. The opening and closing operation of the two fingers are motorized. Moreover, the two heated metal tips of the tweezer-type soldering iron are divided into the two metal tips unitized into one unit and the one heater, and it is therefore made possible to easily exchange only the metal tips. The proposed electric tweezer-type soldering iron device with flexible fingers is prototyped. From experimental results, the feasibility and effectiveness of the proposed device are verified. In a rework test, a small SMD of 1.2mm × 0.6mm in size has been removed from the circuit board and the operation time has achieved less than 10 seconds.
Machinability of Compacted Graphite Iron in Honing
Authors: Lin Yhu-Tin
Published: July 2009

Compacted graphite iron (CGI) has been viewed as the next generation casting material for diesel engines to further the automotive energy efficiency because of its better mechanical strength for lighter engine designs as compared to gray cast iron. The machinability of CGI is analyzed and tested in honing, a standard engine manufacturing process for cylinder bores. Its comparable stock removal rate and tool life to cast iron honing lessen the concern of the machinability problems normally seen in other machining operations on CGI parts.
Introducing Sustainability Early Into Manufacturing Process Planning
Authors: Mani Mahesh , Lyons Kevin W. , Rachuri Sudarsan , Subrahmanian Eswaran , Ameta Gaurav , Sriram Ram D. , Feng Shaw C.
Published: July 2009

In response to the global trend towards implementing sustainable manufacturing practices, we put forth an exploratory approach that uses energy monitoring as a means to introduce sustainability criteria early into manufacturing process planning. Typically cost, quality and time are the indices for manufacturability assessment in generating manufacturing process plans. In this paper, we propose the idea of introducing sustainability to complement cost, quality and time to arrive at alternative sustainable plans in identified manufacturing processes. To be sustainable, it is pertinent that manufacturing firms understand the energy consumption of different manufacturing equipment used to produce products. This will enable industry to implement energy reduction processes in a more effective manner and pave the way for improved and alternate manufacturing solutions. The paper presents the potential utility of energy usage readings in the interest of continuing dialogue and collaboration.
Some Discussions of Virtual Testing of Cutting Tools
Authors: Fischer Christian E.
Published: July 2009

The drive for ever increasing productivity puts continuously increasing demands on cutting tool performance. With the cost of a single prototype tool design near $10,000, the benefits of virtual development are clear. Computer simulation can provide accurate information on chip form, cutting force, temperature, workpiece surface integrity and other vital performance information. Recent advances in simulation technology, combined with ever increasing available of computational power at low cost, have vastly expanded the range of machining applications which can be studied in practical times. This paper examines finite element solver technology, recent research and test results enabling virtual development and prototyping of cutting tools.
Hot Draw Mechanical Preforming of an Automotive Door Inner Panel
Authors: Luckey S. George , Friedman Peter A.
Published: July 2009

A novel sheet metal forming technology based on aspects of both warm forming and superplastic forming has recently been developed. The new forming process, referred to as hot draw mechanical preforming (HDMP), uses two sequential steps to form a panel within a single tool at elevated temperature. In the first step, the cushion system acts on a binder and upper die to draw the blank over a punch which serves to draw in metal from the perimeter of the blank. In the second step gas pressure is applied to finish the panel details. This two step process of drawing in metal followed by gas forming can result in a significant expansion of the forming envelope for conventional AA5xxx series aluminum sheet alloys commonly used within the automotive industry. Similar to SPF, the HDMP process is performed within a single forming press equipped with heated platens and using gas pressure to shape the component during elevated temperature forming. However, the HDMP process utilizes a blankholder to control the flow of material into the forming cavity during the drawing stage and therefore requires the addition of an integrated cushion system in the bed of the press. HDMP dies are of interest in automotive applications because they maintain the low-investment attributes of SPF tooling while also significantly reducing the forming time as compared to conventional SPF. This work details the CAE based design of an HDMP die to form a one-piece aluminum door inner that can not be formed with conventionally forming processes. Critical aspects addressed in the development of the die include manufacturing targets, part design for manufacturing, and die design for operation at elevated temperature.
A Smart Actuator Design for Multiple Bio-Reagent Mixing in a High Pressure Optical Cell for Bio-Physical Research Applications
Authors: Xie Oliver , Chong Parkson Lee-Gau , Zhou Jack
Published: July 2009

During the past two decades, bio-physicists have had an increasing interest in finding out what happens when two bio-material solutions are mixed under high pressure. Compared to temperature, pressure makes more contributions to our fundamental understanding of the structure-function relationship of biological systems, because pressure produces only volume changes under isothermal conditions, and pressure results can then be interpreted in a more straightforward manner. Window-type High Pressure Optical Cell (HPOC) such as the one designed by Paladini and Weber have provided biophysicists with a powerful tool to understanding the structure-function relationships of biological molecules. However, the conventional HPOC is only good for single solution testing and does not allow for quick mixing and stirring of additional components while the specimen is under pressure. This research is to thoroughly study the feasibility of Shape Memory Alloy (SMA) as an actuator to perform mixing and agitation functions; and five types of SMA actuators were designed, simulated and tested for unplugging and mixing purposes. To conduct this research, SMA helical springs were fabricated in house according to the design requirements. With different combinations of SMA tensile springs, SMA compressive spring and biasing spring, significant ranges of vibration were developed. To further improving mixing process, a unique hybrid design of SMA as an actuator to unplug the stopper and micromotor as a stir device to agitate the solutions was developed. Rapid mixing of 95% of total solution in 10 seconds was achieved under 300 bars. A new HPOC was designed according to the new cuvette with its new unplug and mixing mechanism. Our industrial partner, ISS, further modified our design for easy manufacturing reason and fabricated the HPOC which made SMA actuator mixing test under pressure possible. A complete testing of the new HPOC system to observe bio-reagent mixing and reaction under high pressure was conducted and the results were satisfactory.
Micro Ultrasonic Machining Using Oil Based Abrasive Slurry
Authors: Sundaram Murali M. , Cherku Sreenidhi , Rajurkar K. P.
Published: July 2009

Advanced engineering materials posses excellent properties such as high wear resistance, and inertness to corrosion and chemical reactions. Since these materials are usually hard, brittle, chemically inert, and electrically nonconductive, they pose serious machinability challenges. Micro ultrasonic machining (Micro USM) is an emerging method for the micromachining of hard and brittle materials without any thermal damage. This paper presents the results of micro ultrasonic machining using oil based abrasive slurry. Details of the in-house built experimental setup used to conduct the experiments are explained. The influence of process parameters such as slurry medium, slurry concentration, and abrasive particle size on the performance of micro USM are reported. It was noticed that the evidence of three body material removal mechanism is predominant for micro USM using oil based slurry. In general, the material removal rate increases with the increase in the abrasive particle size for both aqueous abrasive slurry and oil based abrasive slurry. Further, material removal rate is consistently higher for experiments conducted with aqueous abrasive slurry medium. On the other hand, it is noticed that the oil based slurry medium provides better surface finish. It is also noticed that the smaller abrasive grains provide better surface finish for both aqueous, and oil based abrasive slurry mediums. Role of slurry concentration is ambiguous, as no clear trend of its effect of on process performance is evident in the available experimental results.
Improving Chucking Accuracy and Repeatability by Reducing Kinematic Redundancy
Authors: Byun Jeongmin , Liu C. R.
Published: July 2009

In this paper, the effect of kinematic redundancy on chucking, especially, on the positioning accuracy of a cylindrical workpiece was investigated. No previous research on the effect of kinematic redundancy on the positioning accuracy and the repeatability of a workpiece in chucking has been reported, even if kinematic principle has been known for a long time. Starting from the description of the issues, a series of systematic experiments were carried out. It was demonstrated that the non-repeatability and the chucking error proportionally increase as the kinematic redundancy increases. Also, it was shown that kinematic redundancy had a significant effect on the positioning accuracy of chucked workpieces, especially the workpieces with a relatively higher length/diameter ratio. The contact area between the workpiece and the jaws was reduced to the extent which does not hurt the chucking rigidity and safety to reduce kinematic redundancy. It was shown that the concentricity of the workpieces was improved as much as 10 times by just minimizing the kinematic redundancy in the finish hard turning of the rings of a taper roller bearing.
Dry Polishing of Non-Cubic Crystal Wafers
Authors: Sullivan Scott
Published: July 2009

We have investigated polishing non-cubic crystal wafers using a unique dry polishing process. The wafers tested were GaN and SiC. Wafers of both GaN and SiC have surfaces terminated by different materials. Each of these surfaces will react differently when polished. For GaN the Ga (000–1) surface has a higher degree of chemical inertness than the nitrogen terminated surface (0001). To compensate for this difference in chemical inertness complex slurries and long polish times are used in chemo-mechanical polishing (CMP). Dry polishing equaled the surface finish and removal of subsurface damage of CMP in significantly reduced polishing times.
Experimental Study of Sound Signal for Tool Condition Monitoring in Micro Milling Processes
Authors: Yen Chia-Liang , Lu Ming-Chyuan , Lin Ching-Yuan , Chen Tin-Hong
Published: July 2009

The audible sound signals obtained in micro-milling processes are analyzed in the time and frequency domain for the tool wear and breakage monitoring. Micro end-mills of φ 700 μm are implemented in the tool wear test, along with a high speed spindle with speed up to 60000 rpm. The audible sound signals and vibration signals for different tool conditions were collected simultaneously in the cutting. After transferring data from time domain to the frequency domain, as well as the Wavelet coefficients, the capability of audible sound signals in detecting the tool condition for the micro milling process was evaluated.