bluuebunny/crossref_metadata_2025 huggingface dataset:
Nonlinear Dynamic of Functionally Graded Cylindrical Shells Under the Thermalmechanical Loads
Authors: Zhang Wei , Hao Yu-xin
Published: July 2010

An analysis on nonlinear vibrations of a simply supported functionally graded materials (FGM) cylindrical shell at its two ends which subjected to the radial excitation in the uniform thermal environment is presented for the first time. Materials properties of the constituents are graded in the thickness direction according to a power-law distribution. In the framework of the First-order shear deformation shell theory, the nonlinear governing equations of motion for the functionally graded materials cylindrical shell is derived by using the Hamilton’s principle. The Galerkin’s method is utilized to discretize the governing equations of motion to a five-degree-of-freedom nonlinear system under combined thermal and external excitations. By using the numerical method, the five-degree-of-freedom nonlinear system is analyzed to find the nonlinear responses of the FGMs cylindrical shell.
Recent Development of the Fast Multipole Boundary Element Method for Modeling Acoustic Problems
Authors: Liu Yijun , Bapat Milind
Published: July 2010

Some recent development of the fast multipole boundary element method (BEM) for modeling acoustic wave problems in both 2-D and 3-D domains are presented in this paper. First, the fast multipole BEM formulation for 2-D acoustic wave problems based on a dual boundary integral equation (BIE) formulation is presented. Second, some improvements on the adaptive fast multipole BEM for 3-D acoustic wave problems based on the earlier work are introduced. The improvements include adaptive tree structures, error estimates for determining the numbers of expansion terms, refined interaction lists, and others in the fast multipole BEM. Examples involving 2-D and 3-D radiation and scattering problems solved by the developed 2-D and 3-D fast multipole BEM codes, respectively, will be presented. The accuracy and efficiency of the fast multipole BEM results clearly demonstrate the potentials of the fast multipole BEM for solving large-scale acoustic wave problems that are of practical significance.
A Brownian Dynamics Model of Worm-Like-Biomolecule Separation Using Periodic Nanofilter Arrays
Authors: Fayad Ghassan N. , Hadjiconstantinou Nicolas G.
Published: July 2010

We present a Brownian Dynamics model of dsDNA-molecule separation using periodic nanofilter arrays. Particular attention is paid to the model’s ability to capture relevant experimental results. The effect of various device parameters on molecule selectivity is investigated. Moreover, our model is used for validating the theoretical prediction of Li et al. [Anal. Bioanal. Chem., 394, 427–435, 2009] who proposed a separation process featuring an asymmetric device and an electric field of alternating polarity. Good agreement is found between our simulation results and the predictions of the theoretical model of Li et al.
A Case Study on Windage Noise Diagnosis and Reduction in 10,000 HP High Speed Induction Motor
Authors: Singhal Sumit , Nijhuis Alexander , Bauer Christian
Published: July 2010

Noise in large high voltage induction motors (500Hp and above) may be windage or magnetic in nature. Usually large high voltage induction motors induction motors are custom built and tailored to meet customers demand. In large high speed induction motors sometimes it is difficult to isolate windage noise from magnetic noise as the generated frequencies are similar in magnitude; hence reducing noise after motor is manufactured becomes extremely challenging. This paper will present the noise troubleshooting case study of 10,000Hp induction motor that shows overall noise of 100 dB during the factory testing. A variety of tests (e.g unloaded, variable speed, coupled loaded test and also test motor driven as load) were performed to isolate magnetic noise from air borne noise. Noise FFT data was collected to identify peak noise generating frequencies. Sound intensity and sound pressure data were also collected to calculate overall sound power level. After identifying the cause of noise, motor frame design was modified which results in overall noise level of 85 dB.
On Efficient Particle Methods for Solving the Boltzmann Transport Equation in the Relaxation-Time Approximation
Authors: Hadjiconstantinou Nicolas G. , Radtke Gregg A. , Baker Lowell L.
Published: July 2010

We present and discuss a variance-reduced stochastic particle simulation method for solving the relaxation-time model of the Boltzmann transport equation. The variance reduction, achieved by simulating only the deviation from equilibrium, results in a significant computational efficiency advantage compared to traditional stochastic particle methods in the limit of small deviation from equilibrium. More specifically, the proposed method can efficiently simulate arbitrarily small deviations from equilibrium at a computational cost that is independent of the deviation from equilibrium, which is in sharp contrast to traditional particle methods. The proposed method is developed and validated in the context of dilute gases; despite this, it is expected to directly extend to all fields (carriers) for which the relaxation-time approximation is applicable.
Numerical Study on the Interaction of an Inextensible Filament in a Uniform Fluid Flow Using the Immersed Boundary Method
Authors: Maniyeri Ranjith , Suh Yong Kweon , Kang Sangmo
Published: July 2010

Numerical modeling of fluid-structure interaction problems are challenging in the field of computational fluid dynamics because of the complex geometries involved and freely moving boundaries. Flapping of an inextensible filament in a uniform fluid flow is such a problem which mimics the swimming of energy harvesting eel fish. Recently, immersed boundary method has found much attention in simulating fluid-structure interaction problems due to its easiness in grid generation and memory and CPU savings. In the present work, we employed an improved version of immersed boundary method proposed by Shin et al. [1] which combines the feedback forcing scheme of the virtual boundary method with Peskin’s regularized delta function approach. A FORTRAN code is developed for the simulation of flexible filament flapping in a uniform fluid flow. The code is validated for the bench mark problem of two-dimensional flow over a circular cylinder. A single filament hanging under gravitational force is simulated using the developed code which is analogous to a rope pendulum and the results are compared with available analytical results. The results are found to be in good agreement. Finally, the interaction of the flapping filament in the uniform fluid flow is studied for different flow and structure parameters. The production of a series of vortex procession obtained in the case of flapping of filament is in good agreement with the previous available experimental and numerical results.
Mathematical Models for Human Pilot Maneuvers in Aircraft Flight Simulation
Authors: Zhang Yan , McGovern Seamus
Published: July 2010

Mathematical models are presented in this paper to describe human maneuvers for aircraft flight simulation. Input parameters for the human pilot model (HPM), such as the course deviation indicator (CDI) and the heading change, are defined for the model, and are related mathematically to those in the proportional-integral-derivative (PID) controller for automatic control. Similarities are discussed between the parameters in HPM and those in the automatic control for better understanding of the significance of human factors and their effect on aircraft behavior. Examples for the HPM include aircraft instrument landing system (ILS) lateral and vertical control, heading change, and homing. The model is tested by using the high-fidelity flight simulation simulator JSBSim [1].
A Comparison of the Processing Routes on the Properties of Mg Reinforced With Nanosize MgO
Authors: Goh C. S. , Wei J. , Gupta M.
Published: July 2010

Powder metallurgy and liquid metallurgy techniques were used to fabricate Mg reinforced with different volume fraction of nano-size MgO particles. A higher volume fraction of MgO particles could be added into the Mg matrix when the liquid metallurgy technique was used. Microstructural analysis was carried out to examine the distribution of the nanoparticles in the Mg matrix when different processing routes were chosen. Individual particles together with sparsely distributed agglomerations could be discerned in the Mg matrix for both processing routes. Mechanical properties results revealed that a more substantial improvement in macrohardness and tensile properties could be achieved by using the liquid metallurgy route where a higher amount of nano-size MgO particles could be incorporated.
Seismic Reliability Analysis of Structural Systems
Authors: Rekvava Paata
Published: July 2010

A method is presented for the evaluation of the seismic reliability function of realistic structural systems. The method is based on a preliminary simulation involving three-dimensional nonlinear time history analysis of the soil-interface-building system. The design procedure is performed to establish the probabilistic characterization of the demands on the structure, followed by the solution of system reliability problem with correlated demands and capacities. The Structural behavior is evaluated by means of the methodology of Performance-Based Seismic Design (PBSD). This study has taken into account the stochastic nature of the spatial ground motion in Tbilisi region. The method is demonstrated with an application to a 3D RC Buildings subjected to seismic excitation for the specified hazard at the site. The developed method and obtained results can be used in seismic risk study for new buildings of examined type under design, as well as for existing RC buildings of old generation for future seismic activity.
A Multiscale NDT System for Damage Detection in Thermal Barrier Coatings
Authors: Luz A. M. G. , Balint D. , Nikbin K.
Published: July 2010

Progress in aero-engines and land-based gas turbines is continuously linked with a rise of the operating temperature. TBCs are multilayered structures which function together to effectively lower the temperature of its load-bearing superalloy substrate while simultaneously providing oxidation protection against high temperature combustion environments during operation. They typically comprise of a ceramic top coat for thermal insulation and a metallic bond coat that provides oxidation/corrosion resistance and enhances the adhesion of the YSZ to the superalloy substrate. Due to high-temperature oxidation of the bond coat, a thermally grown oxide (TGO) scale of continuous Al2O3 is formed between the ceramic top coat and the bond coat. The formation and growth of the TGO increases the mismatch of thermal expansion coefficients among the multilayered TBC and induce high thermal stresses leading to spallation of the YSZ coat from the underlying metal. Hence, nondestructive diagnostic tools that could reliably probe the subsurface damage state of TBCs are essential to take full advantage of these systems. In this contribution, a new concept of multiscale NDT system is presented. The instrument uses a combination of imaging-based methods with photoluminescence piezospectroscopy, a laser-based method. Imaging-based methods like mid-infrared reflectance, laser optical backscatter and infrared tomography were used to predict the overall lifetime of the coated component. When TBCs approach the end of life, micro-crack nucleation and propagation at the top coat/bond coat interface increases the amount of reflected light. This rise in reflectance was correlated with the lifetime of the component using a neural network that merges the mean and standard deviation value of the gray level. Photoluminescence piezospectroscopy was subsequently used to give information about the structural integrity of the hot spots identified in the image analysis. This laser-based technique measures in-situ the residual stress in the TGO at room temperature. Damage leads to a relaxation of the local stress which is in turn reflected in the luminescence spectrum shape. However, presently there is no agreement on the best spectral parameters that should be used as a measure of the damage accumulation in the coatings. Therefore, the evolution of luminescence spectrum from as-manufactured to critically damaged TBCs was determined using the finite element method. This approach helped to identify the most suitable spectral parameters for damage detection, improving the reliability of photoluminescence piezospectroscopy as a failure assessment tool for TBCs.
A Novel Multifunctional Piezoelectric Microcantilever Sensor
Authors: Heydari P. , Shokuhfar A. , Heydari A. P.
Published: July 2010

In this paper a new theoretical method is developed for finding the amount and position of forces and or mass acting on a piezoelectric microcantilever sensor. In this proposed method, the mechanical parameter of microcantilever and accordingly the response of microcantilever to the forces will be changed by exerting the compression force within microcantilever, via applying different voltage to piezoelectric layers. In addition to some theoretical computations, these results generate an inverse problem to deduce the forces and their positions.
Preconcentration of Cardiac Proteins in a Microfluidic Device
Authors: Jubery Talukder Zaki , Bottenus Danny R. , Dutta Prashanta , Ivory Cornelius F.
Published: July 2010

Preconcentration of cardiac proteins was demonstrated using isotachophoresis (ITP) on a polymethyl methacrylate (PMMA) microchip. PMMA microchip was formed using solvent imprinting and temperature-assisted solvent bonding. ITP experiments were performed on two types of microchip: one containing straight microchannel and the other one with 10X step reducing microchannel. In ITP experiments, Hydrochloric Acid (HCl) was used as leading electrolyte, while Aminocaproic Acid (EACA) was used as terminating electrolyte. Three fluorescent proteins, cTnI Labeled w/ Pacific Blue, Green Fluorescent Protein (GFP) and R-Phycoerythrin (PE), were allowed to separate and concentrate in presence of a constant electric field. Microchip ITP experiments show that the sample proteins were concentrated and stacked into adjacent zones. The final concentration of protein zones were calculated from the microchannel dimensions and initial volume of proteins. In straight microchannel, the concentration factors for PE, GFP, and cTnI proteins were 80, 40, and 30, respectively. The concentration factors were 10 fold higher in the step reducing microchannel.
An Infield Investigation of the Reasons for the Vibration Experienced in the Newly Operated Passenger Coaches by the Iranian Railway Systems
Authors: Ghajar R. , Alizadeh Kaklar J.
Published: July 2010

After the application of the newly purchased passenger coaches by the Iranian railway transportation system, numerous reports showing passengers’ dissatisfaction with the frequent vibrations of these coaches were prepared by the technical agents. To review the reasons of these vibrations and efforts to remove them, bogies, wheelsets, and suspension systems of the coaches were first evaluated. Preliminary studies suggested that wheel hollowing can be the most probable reason of these vibrations. Thus, for a more detailed study of this hypothesis, a field study was prepared. To do so, the wheel profiles of 100 coaches were measured in a controlled manner in a period of 6 months. The results out of these measurements indicate that the criterion and workshop equipment applied for the measurement of wheel hollowing in Iranian railway systems is not able to show the hollowing of these wheels properly and coaches operation with such wheels causes severe vibrations in these types of coaches. To avoid this problem, two solutions were proposed.
Microphone Array Analysis Methods Using Cross-Correlations
Authors: Rhudy Matthew , Bucci Brian , Vipperman Jeffrey , Allanach Jeffrey , Abraham Bruce
Published: July 2010

Due to civilian noise complaints and damage claims, there is a need to establish an accurate record of impulse noise generated at military installations. Current noise monitoring systems are susceptible to false positive detection of impulse events due to wind noise. In order to analyze the characteristics of noise events, multiple channel data methods were investigated. A microphone array was used to collect four channel data of military impulse noise and wind noise. These data were then analyzed using cross-correlation functions to characterize the input waveforms. Four different analyses of microphone array data are presented. A new value, the min peak correlation coefficient, is defined as a measure of the likelihood that a given waveform originated from a correlated noise source. Using a sound source localization technique, the angle of incidence of the noise source can be calculated. A method was also developed to combine the four individual microphone channels into one. This method aimed to preserve the correlated part of the overall signal, while minimizing the effects of uncorrelated noise, such as wind. Lastly, a statistical method called the acoustic likelihood test is presented as a method of determining if a signal is correlated or not.
Atomistic Modeling of Fatigue Crack Growth in Magnesium Single Crystals Under Cyclic Loading
Authors: Tang Tian , Kim Sungho , Groh Sebastien , Horstemeyer Mark F.
Published: July 2010

The fatigue crack propagation behavior of magnesium single crystal was analyzed using molecular dynamics simulation. The inter-atomic potential used in this investigation is Embedded Atom Method (EAM) potentials. The studies of the influences of crystal orientation and strain rate were perfomred using CC (center crack) and EC (edge crack) specimen. For CC specimen, the periodic boundary conditions were assigned in the x and z direction, while for EC specimen, only z direction was allowed periodic boundary conditions. In order to study the orientation dependence of fatigue crack growth mechanism, ten crystal orientations of initial crack, namely, orientation A-(12¯10) [101¯0], orientation B-(101¯0)[12¯10], orientation C-(101¯0)[0001], orientation D-(12¯10)[0001], orientation E-(0001)[101¯0], orientation F-(0001)[12¯10], orientation G (101¯1)[1¯012], orientation H (101¯1)[12¯10], orientation I (101¯2)[101¯1], and orientaton J (101¯2)[12¯10] were analyzed and the simulation results reveal that the fatigue crack growth rate and the crack path vary significantly with the crystallographic orientations of initial crack. The growth rate of orientaton G is the highest and the resistance of fatigue crack growth of orientation B is the highest. A CC specimen was employed to demonstrate the fatigue damage caused by pyramidal slip band under increased maximum strain cyclic loading in the specimen of orientation E. The analysis of the influences of strain rate was carried out on the orientation C, D, F, and G and the results revealed that the growth rate of fatigue crack decreasing with increasig strain rate. Fatigue growth rate can be expressed by da/dN = cΔCTOD, where the constant c was determined by the present atomistic simulations. The values of the constant c are large and vary widely from on orientation to another.
Microstructure-Sensitive Fatigue Design for Notched Components
Authors: Owolabi Gbadebo M. , McDowell David L.
Published: July 2010

The current drive for the discovery and use of advanced materials in safety-critical components necessitates the development of reliable fatigue design tools. However, most of the current tools require a number of approximations based on heuristics and phenomenological data rather than solid theoretical underpinning and still yield unsatisfactory and inconsistent results when applied to complex components under in service loads. Microstructural inhomogeneities in the materials induce notch size effects, but are not explicitly accounted for in phenomenological methods. Accordingly, notch sensitivity remains a highly empirical subject in spite of significant advances in microstructure-sensitive modeling. More robust fatigue design tools should capture the cause and effect relation of microstructure to distribution of slip and driving forces for formation and early growth of small cracks in the notch root field. Recent developments in computational crystal plasticity and microstructure-scale modeling have provided deeper understanding of the complex correlations between properties and structures and further indicate the limitations of conventional fatigue life prediction approaches. These modeling approaches have the potential to substantially reduce the need for costly large scale experimental programs to determine scatter in fatigue, for example. At present, however, there is a lack of simulation-based methodologies for considering interactive effects of stress and strain field gradients at the notch-root and microstructure-scale behavior in predicting notch-root fatigue crack initiation. In this paper results from simulations within a well-defined notch root damage process zone are used along with a probabilistic mesomechanics approach to develop a framework for new microstructure-sensitive fatigue notch factor. In addition, probability distributions of fatigue strength and fatigue life to form small cracks are estimated from simulations, extending notch sensitivity to explicitly incorporate microstructure sensitivity and attendant size effects via probabilistic arguments.
Probabilistic Approach to Conditional Probability of Release of Hazardous Materials From Railroad Tank Cars During Accidents
Authors: Jeong D. Y.
Published: July 2010

This paper describes a probabilistic approach to estimate the conditional probability of release of hazardous materials from railroad tank cars during train accidents. Monte Carlo methods are used in developing a probabilistic model to simulate head impacts. The model is based on the physics of impact in conjunction with assumptions regarding the probability distribution functions of the various factors that affect the loss of lading. These factors include impact velocity, indenter size, tank material, tank diameter, effective collision mass, and tank thickness. Moreover, each factor is treated as a random variable characterized by its assumed distribution function, mean value, and standard deviation (or variance). Reverse engineering is performed to back-calculate the mean values and standard deviations of these random variables that reproduce trends observed in available accident data. The calibrated model is then used to conduct a probabilistic sensitivity analysis to examine the relative effect of these factors on the conditional probability of release. Results from the probabilistic sensitivity analysis indicate that the most significant factors that affect conditional probability of release are impact velocity, effective collision mass, and indenter size.
Evaluation of Fracture Toughness of Human Dentine-Enamel Junction (DEJ) by Finite Element Analysis
Authors: Mishra Dhaneshwar , Yoo Seung-Hyun , Park Chang Yeong , Rak Jeong Ung
Published: July 2010

Human teeth system is one of the most important organs, plays vital role in mastication process. It consist 3 layers, outer hard and brittle cover enamel and porous dentine separated by very thin interfacial region called Dentine Enamel Junction (DEJ) or crown dentine. Dentine and enamel has almost isotropic material property while DEJ has different microstructure near enamel and dentine represented by functionally graded microstructure. Experimental evidences show that the crack initiated in the hard enamel region grows towards the crown dentine, it starts healing after 10–15 micron. Finite element analysis has been carried out and fracture toughness has been evaluated for layered model of human teeth with crack initiated at enamel region grows towards DEJ with its healing capabilities and graded structure. Comparison of the result with experimental value reported in literature shows acceptable matching suggests; FE results can be taken as basis for estimating Fracture toughness of human teeth system especially at interface of Enamel and Dentine, the DEJ.
A Blocking-Free Microfluidic Fluorescence Heterogeneous Immunoassay for Quantitative Detection of Human C-Reactive Protein
Authors: Li Peng , Narayanan Radha , Sherry Alex J. , Cortes Jairo A. , Marchesseault Andrew , Anagnostopoulos Constantine , Faghri Mohammad
Published: July 2010

In this article, a rapid, sensitive, and disposable microfluidic immunosensor is presented for point-of-care testing and clinical diagnostics. For the first time, a heterogeneous immunoassay without blocking process is achieved by using protein A functionalized polydimethylsiloxane microchannels. C-reactive protein (CRP), a biomarker for inflammation and cardiovascular disease risk assessment, is selected as a model analyte to demonstrate the sensitivity of this blocking-free microfluidic heterogeneous immunoassay. A four parameter logistic function is used to model and assess the data. The limit of detection obtained is 0.36 μg/mL, which is lower than the cut-off value for clinical diagnosis. The overall assay is completed in 23 min. The assay procedure can be modified for detection of other disease biomarkers or virulent pathogens by using different capture and detection antibodies.
Intelligent Judgment System for Vehicle-Overtaking by Motion Detection in Subsequent Images
Authors: Shou Yu-Wen
Published: July 2010

We propose an intelligent judgment system to determine the exact timing for overtaking another car in simulated dynamic circumstances by motion detection and feature analysis in subsequent images based on digital image processing in this paper. The strategic methodology in detection of motion vectors extracted from the source video file can effectively evaluate and predict the behavior of surrounding vehicles and at the same time give an appropriate suggestion whether the driver could overtake another car, which is not only different from the traditional methods in computational feature-only analysis for some specific static image but also provides an innovative idea among the related applications of intelligent transportation system (ITS). Our system makes use of the video-typed files recorded from the rear-view mirror in the vehicle that should be obtained from the digital image capturing devices. It also constantly reevaluates the information of motion vectors in surrounding environments to update the useful information between the driver’s vehicle and background. In order to tackle the problem of real-time processing, this paper simplifies the processes of feature selection and analysis for video processing in particular. The crucial features used to give dynamic information, motion vectors, can be obtained from defined consecutive images. We define a variable number of images according to the extent of motion variation in different real-time situations. Our dynamic features are composed of geometrical and statistical characteristics from each processed image in the defined duration. Our scheme can identify the difference between the background and object of interest, which also reveals the dynamic information of the determined number of images extracted from the whole video file. Our experimental results show that the proposed features can give the useful information in a given traffic condition, such as the locations of surrounding vehicles, and the way of vehicles’ moving. The real-time problems of ITS are taken into consideration in this paper and the developed feature series are flexible to the changes of occasions. More useful features in dynamic environments as well as our feature series will be applied in our systematical mechanisms, and the improvement on real-time problems by motion vectors should be progressively made in the near future.
Chaotic Dynamics of a Six-Dimensional Laminated Composite Piezoelectric Rectangular Plate
Authors: Zhang Wei , Gao Mei-juan , Yao Ming-hui , Yao Zhi-gang
Published: July 2010

This paper focuses on the multi-pulse orbits and chaotic dynamics of the six-dimensional nonlinear system for the composite laminated piezoelectric rectangular plate using the theory of normal form and the energy-phase method. Taking into account that the averaged equation has a double zero and two pairs of pure imaginary eigenvalues, we use the theory of normal form to simplify the six-dimensional averaged equation to a simpler normal form. The energy-phase method is to be extended to study the dynamical characteristic of the six-dimensional nonlinear system. The global theory analysis indicates that there exist the homoclinic bifurcation and Shilnikov type multi-pulse jumping chaotic dynamics in the system under the small perturbation. In order to illustrate the theoretical predictions, the Runge-Kutta algorithm is used to perform numerical simulation. The results of numerical simulations also demonstrate that the jumping phenomena of orbits can occur in the composite laminated piezoelectric rectangular plate.
Optimal Sliding Mode Control of AFM Tip Vibration and Position During Manipulation of a Nanoparticle
Authors: Babahosseini Hesam , Khorsand Majid , Meghdari Ali , Alasty Aria
Published: July 2010

This research regards to a two-dimensional lateral pushing nanomanipulation using Atomic Force Microscope (AFM). Yet a reliable control of the AFM tip position during the AFM-based manipulation process is a chief issue since the tip can jump over the target nanoparticle and then the process can fail. However, a detailed Modeling and understanding of the interaction forces on the AFM tip is important for prosperous manipulation control and a nanometer resolution tip positioning. In the proposed model, Lund-Grenoble (LuGre) dynamic friction model is used as friction force on the contact surface between the nanoparticle and the substrate. This model leads to a stick-slip behavior of the nanoparticle that is so similar to the experimental behavior in nanoscale. Derjaguin interaction force is applied between the AFM tip and the nanoparticle which considers both attractive and repulsive interactions. The AFM is modeled by lumped-parameters model. A controller is designed based on the proposed dynamic model in order for positioning the AFM tip during a desired nanomanipulation task. Optimal sliding mode approach is used to design the controller. In this approach sliding surface which is used in the sliding mode approach is selected optimally based on the linear quadratic (LQ) method.
A Magnetic Coulter Counting Device for Wear Debris Detection in Lubrication
Authors: Du Li , Carletta Joan , Veillette Robert , Zhe Jiang
Published: July 2010

A device based on a magnetic Coulter counting principle to detect metal particles in lubrication oil is presented. The device detects the passage of ferrous and non ferrous particles by monitoring inductance change in a coil. First, the sensing principle is demonstrated at the mesoscale using a solenoid. Next, a microscale device is developed using a planar coil. The device is tested using iron and aluminum particles ranging from 100μm to 500μm. The testing results show the device is capable of detecting and distinguishing ferrous and non-ferrous metal particles in lubrication oil. The design concept demonstrated here can be extended to a microfluidic device for online monitoring of ferrous and non-ferrous wear debris particles.
Electrically Tethered DNA Stretching in Nanochannels
Authors: Lee Byung Chul , Kang Chanmin , Kim Jinsik , Kang Ji Yoon , Shin Hyun-Joon , Lee Sang-Youp
Published: July 2010

In present study, stretching dynamics of electrically tethered λ-DNA (48.5kbp) in SiO2 nanochannels has been investigated. At high electrical fields (above 20kV/m), elongations of electrically tethered DNA molecules were observed. At high E-fields, DNAs were tethered in nanochannels and were spontaneously elongated along the nanochannels up to about 90 percent of its contour length. With E-field turned off, the measured relaxation time was about 10 sec from stretching with 20kV/m. In current study, observed behaviors of DNA molecules in nanochannels were explained by field-induced dielectrophoretic DNA trap due to the particular cross-sectional geometry of nanochannels. Also the elongation ratio between 20kV/m and 60kV/m cases and the effect of E-field distribution in the transverse plane on field-induced dielectrophoretic tethering force are discussed based on “worm-like chain” model. The FEM simulation was done to verify induced dielectrophoretic tethering force into the nanohorn.
Dynamics of a Moving Body With the Hole in Its Center and Characteristics of Fluid Flow in a Small Diameter Tube
Authors: Maeda Toru , Sato Akihiro , Otsuka Tatsuya , Yoshizawa Masatsugu
Published: July 2010

A rigid body moving with fluid in a narrow tube is expected to be developed for future engineering applications such as a capsule endoscopy, and it is also applied to some parts of industry. This paper deals with the flow characteristics around a single rigid body with a hole in its center and transient motion of the body when the body is influenced by pressure force from upstream. The model considered the width of the gap between the body and the wall is smaller than a diameter of a tube so that the force on the body can be numerically and analytically estimated as a viscous friction force. It was assumed that the flow is axisymmetric, laminar and taken to be Newtonian and incompressible. It was obtained that, with the hole in its center, the terminal velocity of the body becomes smaller than the average velocity at the inlet. Moreover, because there is a stagnation on the body, the pressure increases behind the body.
Numerical Calculation on Vortex-Induced Vibration of the Circular Cylinder Using Low Reynolds Model in Hybrid Method
Authors: Zhang Xingwei , Zhou Chaoying
Published: July 2010

Fundamental research on interaction between flow and structure is presented for computation the fluid dynamics of different two-dimensional oscillating models. The Navier-Stokes equations are solved using finite volume method. A multigrid mesh method which was applied to the situation of flow past the stagnating or vibrating cylinder is developed to simulate this type of flow. The interactive results between flow and structure rigid cylinders have been present. The computation fluid dynamic codes mainly with low Reynolds RANS solver are used to solve the impressible viscous Navier-Stokes equations. Finite volume method which is coupled with conformal hybrid mesh method is developed to simulate this type of flow. Numerical investigation focused on the response and the fluid forces on the cylinders and also observed the different shedding model in the wake. The numerical results are compared in detail with recent experimental and computational work. Present numerical comparison also showed that solution using different turbulence model will make the result have a little discrepancy and each turbulence model has respective characteristics in numerical solution on the vortex-induced vibration of the cylinder. In addition, the formation of the 2P vortex shedding model through the lock-in region and the beginning of the shedding model transformation in numerical calculation from 2S model to 2P model has been analyzed.
Free Vibration Analysis of Functionally Graded Cylindrical Shells Stiffened by Uniformly and Non-Uniformly Disturbuted Ring Stiffeners
Authors: Moeini S. A. , Rahaeifard M. , Ahmadian M. T. , Movahhedy M. R.
Published: July 2010

Free vibration analysis of a transversely stiffened circular thin hollow cylinder made of functionally graded materials (FGMs) is analytically evaluated. Functionally graded materials are inhomogeneous composites which are usually made from a mixture of metal and ceramic. The gradient compositional variation of the constituents from one surface to the other provides an elegant solution to the problem of high transverse shear stresses induced when two dissimilar materials with large differences in material properties are bonded. In this paper, application of an FGM made of two different materials is investigated by applying Ritz method. While cylinder is assumed to be thin, strain energy evaluation is performed by Sander’s theorem. Stiffeners which are not necessarily in the same uniform shape are treated as discrete elements and can be placed on both sides of the cylinder or concentrate in the middle wall. Bending, stretching and wrapping effects of stiffeners are considered in calculation of strain energy. Evaluation of kinetic energy of stiffeners is performed by taking into account rotary and translational inertia. To apply Ritz method, polynomial functions are used and natural frequencies and mode shapes of ring stiffened thin cylinder are investigated. Results are compared and verified with previous theoretical and experimental studies of stiffened thin cylinders. Comparison indicates a good agreement between results.
Chest Deflection vs. Chest Acceleration as Injury Indicator in Front Impact Simulations Using Full Human Body Finite Element Model
Authors: El-Jawahri Raed E. , Ruan Jesse S. , Rouhana Stephen W. , Barbat Saeed D.
Published: July 2010

The Ford Motor Company Human Body Finite Element Model (FHBM) was validated against rib dynamic tension and 3-point bending tests. The stress-strain and moment-strain data from the tension and bending simulations respectively were compared with human rib specimen test data. The model used represented a 50th percentile adult male. It was used to compare chest deflection and chest acceleration as thoracic injury indicator in blunt impact and belted occupants in front sled impact simulations. A 150 mm diameter of 23.4 kg impactor was used in the blunt impact simulations with impact speeds of 2, 4, and 8 m/s. In the Front sled impact simulations, single-step acceleration pulses with peaks of 10, 20, and 30 g were used. The occupants were restrained by 3-point belt system, however neither pretensioner nor shoulder belt force limiter were used. The external force, head acceleration, chest deflection, chest acceleration, and the maximum values of Von Mises stress and plastic strain were the model outputs. The results showed that the external contact force, head acceleration, chest deflection, and chest acceleration in the blunt impact simulations varied between 1.5–7 kN, 5–28 g, 18–80 mm, and 8–40 g respectively. The same responses varied between 7–24 kN, 13–40 g, 15–50 mm, and 16–46 g respectively in the front sled impact simulations. The maximum Von Mises stress and plastic strain were 50–127 MPa, and 0.04–2% respectively in the blunt impact simulations and 72–134 MPa, and 0.13–3% respectively in the sled impact simulations.
Experimental Study on Cytoplasmic Calcium Oscillation in MG-63 Cells Induced by Pressure-Driven Fluid Flow
Authors: Jeon Jong Heon , Kim Tae Kyung , Park So Hee , Shin Jung Wook , Jeong Ok Chan
Published: July 2010

This paper determined the optimal periodic mechanical stimulation of live bone cells from the intracellular calcium oscillation induced by shear stress. The shear stress-induced intracellular calcium responses of cells on a micro-cell chip were measured to study the mechanotransduction of bone cells. From the measured static and dynamic characteristics of the internal cellular signaling in cells, the optimum duration of the mechanical stimulation is determined.
Temperature Investigations in Tire/Road Contact
Authors: Wangenheim Matthias , Ripka Stefan
Published: July 2010

The mechanical properties of rubber materials are strongly dependent on temperature. This also affects the friction properties of rubber elements like tires or sealings. Therefore, the temperature distribution in a friction contact of rubber is investigated more closely in this publication. At first the steady-state temperature distribution in a sliding contact is examined experimentally and theoretically. These steady-state considerations are extended by transient processes like a step in the sliding velocity and a step in the normal load or a non-uniform surface pressure distribution. The temperature distribution in the rolling friction contact of a rubber wheel is investigated for a variation of the normal load, angular velocity and slippage. This is also performed experimentally and theoretically.
Parameter Sensitivities to Damage Progression in Structures
Authors: Bordonaro Giancarlo G. , Hajj Muhammad R.
Published: July 2010

Variations in the natural frequency and damping coefficients with cyclic fatigue testing in steel and composite beams carrying a lumped mass are assessed. The identification of these parameters is performed by exploiting the nonlinear behavior of the beam-mass system and matching an approximate solution of the representative model with quantities obtained from spectral analysis of measured vibrations. Percentage variations of the identified parameters during the tests and up to the point where cracks were observed are determined. The results show that the damping is more sensitive to damage progression than the natural frequency.
Snap-Through Instability of Graphene Morphology on Substrates
Authors: Zhang Zhao , Li Teng
Published: July 2010

We determine the graphene morphology regulated by substrates with herringbone surface corrugation. As the graphene/substrate interfacial bonding energy and the substrate surface roughness vary, the graphene morphology snaps between two distinct states: 1) closely conforming to the substrate and 2) remaining nearly flat on the substrate. Such a snap-through instability of graphene can potentially lead to desirable electronic properties to enable graphene-based devices.
Effect of a Graded Layer on the Dissipated Energy During Fatigue Crack Growth on Plastically Mismatched Interfaces Under Mixed-Mode Loading
Authors: Baudendistel Craig M. , Klingbeil Nathan W.
Published: July 2010

Recent work has proposed a dissipated energy theory of fatigue crack growth under mode I loading for homogenous materials and has since been extended to a bimaterial interface geometry under mixed-mode loading. An inherent assumption of this prior work is that a perfect crack exists along the interface joining the top and bottom layers. The current work extends the approach of previous studies to incorporate a grading of plastic properties between the two layers. The plastic dissipation is extracted from 2D parametric finite element models with ABAQUS. Results have shown that incorporation of a graded layer increass the overall amount of plastic dissipation between modes I and II, but is still bounded by the two cases where a minimum and maximum amount of plastic dissipation is accumulated. While the graded layer has a measurable effect, plastic dissipation is still dominated by the mode of loading.
Microfluidic Emulsion Generation and Trapping Enabling Droplet-Interfaced Bilayer Lipid Membrane Arrays
Authors: Shao C. , DeVoe D. L.
Published: July 2010

Freestanding bilayer lipid membranes provide an exceptional platform for measurements of lipid/protein interactions and ion translocation events at the single molecule level. For drug screening applications, large arrays of individual bilayer supports are required. However, an effective method for generating, stabilizing, and monitoring arrays of lipid bilayers remains elusive. Here we investigate a novel approach towards the facile generation of bilayer arrays for high throughput screening. The approach takes advantage of fundamental microfluidic capabilities by combining an emulsion generator with droplet-interfaced membrane formation, allowing for fully-automated production of membrane arrays whose density is, in principle, unlimited.
Response of Random Chopped Fiber Reinforced Composite to Uniaxial Tensile Load
Authors: Pan Yi , Pelegri Assimina A.
Published: July 2010

Recent interests of application of random chopped fiber reinforced composites in manufacturing lightweight components in the automotive industry motivate active research on the material behaviors of this kind of materials. A representative volume element is generated numerically based on microscopic observation on the realistic samples. It captures the complex meso-structure of random chopped fiber composites. A finite element model is developed for the RVE of random chopped fiber composite. The elastic stiffness properties of the composite material thus can be derived with homogenization scheme. The representative volume element was verified by Young’s modulus obtained from experimental measurements and analytical calculation of the modulus by other methods. Furthermore, damages deboning of fiber/matrix interface is simulated using the representative volume element.
Application of Multifunctional Materials for Machine Tool Structures
Authors: Aggogeri Francesco , Merlo Angelo , Mazzola Marco , Pellegrini Nicola
Published: July 2010

The competition on the international markets pushes manufacturers towards shorter design cycles and decreasing manufacturing times and costs for their products. This trend generates a demand for smart, flexible and faster machining systems, easy to set up and configure, which are able to drastically reduce machining time and improve the final accuracy. This paper rises from these considerations evaluating the possible application of multifunction materials in machine tool (MT) design and building. These solutions can provide a fundamental impact on functionality and reliability of a manufacturing system. In particular, use of innovative materials in today’s technology continues to grow steadily. Numerous reasons for this growth include light weight, superior insulating abilities, energy absorbing performance, excellent strength/weight ratio and low cost. This paper aims to investigate a possible application of multifunction materials in realisation of structure components for Machine Tools. There are many aspects that affect the machining accuracy and the cutting conditions of a high performance MT. The most important issues are related to the static, dynamic, mechatronic and thermal behavior of the machines. In particular, a strict requirement that a machine tool has to fulfill in order to drastically reduce operating time while improving the final accuracy is the thermal stability. This paper shows a complete study and testing validation on prototypes (plates and beam) based on sandwiches with core made of metal foam (open and closed cells) materials impregnated by a PCM (Phase Material Change) wax. Metal foams represent a class of materials with low density and novel physical, mechanical, thermal, electrical and acoustic proprieties. They offer potential for lightweight structures, for energy absorption and thermal management. PCMs are latent heat storage materials that absorb heat keeping constant the temperature of a machine component in a defined time range. The authors have designed, realized and tested the prototypes developing thermal trials, and then evaluating the comparison between experimental data and simulative analysis (FEM). The trials consisted to process the prototypes at a variation of temperature in order to assess the PCM proprieties to absorb heat and maintain thermal stability in a defined time range. The paper shows also a simulative study on PCM material behavior and their application in MT design supported by experimental trials and data analysis. The significant advantages and perspectives that can be obtained in applying of these MT structures complete the developed study.