bluuebunny/crossref_metadata_2025 huggingface dataset:
An Optimal Matching Algorithm Based on Rough Localization and Exact Adjustment
Authors: Sun Y.W. , Xu J.T.
Published: March 2009

Aiming at the problems on estimate of the initial transformation, matching precision and global optimization in matching, this paper presents a matching method, which is based on rough localization and exact adjustment. By means of rotation, translation and coincidence of the minimum bounding boxes of surface and measured points, rough localization is realized, which produces a good estimate for the follow-up iterative algorithm. The closest points that were calculated via the normal projection of the sample points then establish the correspondence between two objects. An iterative process is used in the exact adjustment to ensure the global optimization of match. For reducing the effect of bad points or local distortion, a maximum distance criterion is adopted to refine the transformation between objects. A computer simulation is given to demonstrate that the algorithm is steady and effective.
Considerations for Practical Neural Network Application to a Damage Detection Problem
Authors: Pierce Gareth , Worden Keith , Manson Graeme
Published: March 2009

The application of a multilayer perceptron (MLP) neural network to a damage location problem on a GNAT aircraft wing is considered. The problems associated with effective network training and evaluation are discussed, focussing on ensuring good generalisation performance of the network to the classification of new data. Both conventional Maximum Likelihood and Bayesian Evidence based training techniques are considered and a simple thresholding technique is presented to aid in the rejection of poorly regularised network structures. Examples are presented for an artificial simple 2 class problem (drawn from a Gaussian distribution) and a real 9 class problem on the GNAT aircraft wing.
Applications of Spectral Kurtosis in Machine Diagnostics and Prognostics
Authors: Randall R.B.
Published: March 2009

Many machine faults, such as local defects in bearings and gears, manifest themselves in vibration signals as a series of impulsive events. Kurtosis is a measure of the impulsiveness of a signal, and spectral kurtosis (SK) gives an indication of how the kurtosis (of a bandpass filtered signal) varies with frequency. This not only gives an indication of the frequency bands to be processed, but can also be used to generate a filter to extract the most impulsive part of a signal. The first step in calculating SK is to perform a time/frequency decomposition of the signal, and then calculate the kurtosis for each frequency line. The paper compares the original STFT (short time Fourier transform) with wavelet analysis for the time/frequency decomposition, and for determining the optimum combination of centre frequency and bandwidth for maximizing the SK. The paper also describes how the SK can be enhanced by “prewhitening” the signal using an autoregressive (AR) model, this sometimes revealing an incipient fault at a much earlier stage.
Damage Analysis of Internal Surface Flaws Using Thermoelastic Stress Analysis
Authors: Sathon N. , Dulieu-Barton Janice M.
Published: March 2009

Thermoelastic Stress Analysis (TSA) has been used to detect and evaluate the severity of damage on a flat metallic plate. The damage takes the form of a semi-circular notch that represents a surface flaw. Thermoelastic data was gathered from the undamaged side of the plate. The experimental results show that shallow surface flaws can be detected by using phase information from thermoelastic data. This information can then be used to indicate the flaw severity in terms of the notch depth. It is shown that the phase data is dependent on the heat conduction effects around the notch, which enable an assessment of the damage. This is modelled using a simple finite element simulation of the effects of heat conduction on the thermoelastic response. A discussion on the potential of using phase variation across damaged regions to analyse damage severity is provided.
Vibration-Based Structural Health Monitoring – Concepts and Applications
Authors: Fritzen Claus Peter
Published: March 2009

This paper gives an overview on the current status of vibration-based methods for Structural Health Monitoring. All these methods have in common that a structural change due to a damage results in a more or less pronounced change of the dynamic behavior. The use of modal information is discussed, as well as the direct use of forced and ambient vibrations. From this information, different strategies can be deduced which depend on the type of measurement data (time/frequency domain) but also on the frequency spectrum. The incorporation of actuation and sensing devices into the structure leads to modern concepts of Smart Structural Health Monitoring. Examples from civil and aerospace engineering show the applicability of these methods.
Wireless Structural Health Monitoring Using MEMS
Authors: Krüger Markus , Grosse Christian U. , Marrón Pedro José
Published: March 2009

So far, the inspection of building structures and especially of bridges is mainly done visually. Therefore, the condition of the structure is examined from the surface and the interpretation and assessment is based on the experience of the expert. However, the main purpose of monitoring civil structures is not to substitute visual inspection. Continuous structural health monitoring should provide data from the inside of a structure to better understand its structural performance and to predict its durability and remaining life time. Monitoring should render objective data and observable alterations in the structure continuously, which cannot be done by visual inspection. More detailed information is needed with respect to different exposure due to dynamic and static loads and also temperature and moisture. Today mainly wired monitoring systems are used to monitor structures, which are relatively expensive and time consuming to install. In this paper the basic principle of a wireless monitoring system equipped with MEMS sensors is presented, which can be easily installed at different structures. Microelectromechanical systems (MEMS) are small integrated devices or systems that combine electrical and mechanical components. A wireless monitoring sensor network equipped with such MEMS could be produced with a very low budget and becomes very efficient. This permits a wide area of applications not only in civil engineering. With respect to different applications relevant properties of a wireless monitoring system are described. In detail network configuration, power consumption, data acquisition and data aggregation, signal analysis and data reduction as well as reliability and robustness are discussed.
Instantaneous Identification of Polynomial Nonlinearity Based on Volterra Series Representation
Authors: Demarie Giacomo V. , Ceravolo Rosario , de Stefano Alessandro
Published: March 2009

In structural engineering applications a sufficient quantity of experimental data to be able to achieve a consistent estimate of nonlinear quantities is seldom available: this applies in particular when the structures are to be tested in situ. This report discusses the definition of instantaneous estimators to be used in the dynamic identification of invariant nonlinear systems on the basis of Short-Time Fourier Transform representation of excitation and system’s response and within the framework of a Volterra series representation of the input/output relationship. An estimation of the parameters of a dynamic system can be worked out from the evolution of such instantaneous estimators.
Prediction of the Influence of Vibration on Structural Integrity of Elevator Suspension Ropes
Authors: Kaczmarczyk Stefan
Published: March 2009

Traction drive elevator installations employ ropes of variable length as a mean of car and counterweight suspension. The inertial and elastic characteristics of elevator suspension systems depend on the rope construction and vary slowly during the elevator travel. The system suffers from vibrations caused by various sources of excitation. This paper presents the analysis of the dynamic response of the suspension system employing traditional steel wire ropes as well as ropes constructed of aramid fibers. The equations describing the lateral response of the system subjected to a boundary periodic excitation are solved numerically. The results show that the entire rope is subjected to repetitive low frequency transient resonances. Consequently, the structural integrity of the suspension ropes is compromised. The issue of active vibration control and the feasibility of the integration of shape memory alloy elements within the suspension rope design are discussed.
A Biological Sensor for Detecting Foreign Bodies Using a Balloon Probe
Authors: Shimizu Hideki , Kiyono S. , Gao Wei , Shoji H.
Published: March 2009

For effective medical treatment, sensors that can find foreign bodies such as tumors in early stage are required. This paper describes a new sensor for foreign body detection utilizing the fact that the property hardness of foreign bodies differs from that of normal tissues. It consists of a balloon probe, which is constructed with a thin rubber membrane inflated with compressed air, and an optical deformation analyzing system. Experiments are carried out using samples in which single hard balls are embedded to model single tumor in soft tissue. It was confirmed that this sensor can detect the existence of the hard ball and can also distinguish the inequality of size and hardness of the ball. Furthermore, experimental results detecting multi-objects showed that this sensor has the ability to detect the existence of multi objects and their relative positions simultaneously. By measuring the consistence of the arm and the abdomen of human body, it is proved that the sensor is also suitable for consistence measurement of human anatomy.
Development and Verification of a Confocal Fabry-Perot Interferometer for Broad Band Ultrasound Detection
Authors: Shaw Jiunn Haur , Lee J.Y. , Chow L.H. , Shih Hseuh Ching
Published: March 2009

This paper describes the development of a confocal Fabry-Perot interferometer (CFPI) for non-contact and non-destructive detection of broadband ultrasound generated by a pulsed laser. The operation theory of CFPI is introduced. The transmission and reflection modes of operation were investigated theoretically and verified experimentally. For the present study, a CFPI cavity of 50cm with 95.4% reflectivity spherical mirrors was constructed with associated resonant cavity control and signal detection electronics. The design is capable of providing detection frequency bandwidth from 140kHz to 50MHz. For the first step of verification, the input signal simulated by an electro-optical modulator (EOM) was used for verifying the feasibility of surface wave measurement. Signals obtained from an avalanche detector were compared with the results through theoretical analysis of the CFPI transfer function in a transmission mode. The results show a favorable agreement between the two. Furthermore, transmitted ultrasound signals from a 5MHz contact ultrasound transducer were detected and compared between the CFPI system and a Michaelson interferometer. Patterns of ultrasound arrival and reflection were clearly detected by both. Because an intrinsic transfer function is embedded in the operation of CFPI, the output signal will be distorted when measuring surface displacement. A digital filtering process was considered for compensation for the surface displacement signal. From the comparative results, it was further concluded that the present CFPI design has a displacement resolution of 0.05nm. Future studies will be focused on the reflection mode operation for fully utilization of non-contact laser ultrasound generation and detection.
Advances in Micro and Nano-Scale Surface Metrology
Authors: Blunt L. , Jiang X. , Scott P.J.
Published: March 2009

This paper provides an overview of advances in the surface metrology field, concerning surface creation, measurement need, instrumentation, characterisation methods and standard development. It indicates industry requirements and further developments for micro and nano scalar surface metrology.
A Two-Dimensional Surface Profile Imaging Technique Based on Heterodyne Interferometer
Authors: Wang K.W. , Cai Z.J. , Zeng Li Jiang
Published: March 2009

A two-dimensional surface profile imaging technique based on heterodyne interferometer is proposed. A piezo translator vibrated grating is used to generate a heterodyne signal. A high speed CCD camera is used to extract the interference signal using a five step method. The uncertainty in the displacement measurement is approximately 0.035 µm within a measurement range of 1.7 µm, confirming the two dimensional heterodyne interferometer is valid for measuring the surface profile. The method is also available for low coherence heterodyne interferometer due to the optical frequency shifts caused by the vibration of grating independent on the wavelength.
Intelligence and Metrological Reliability of Measuring Transducers Built in Equipment
Authors: Taymanov Roald E. , Sapozhnikova Ksenia
Published: March 2009

It has been proved that artificial intelligence leaned on self-checking is an efficient factor for increasing metrological reliability of measuring instruments. The possibility to create intelligent measuring instruments based upon redundancy of measurement information and informational redundancy of a measuring transducer is presented. Practical examples are provided.
Implementation of a Mesoscopic Mechanical Model for the Shear Fracture Process Analysis of Masonry
Authors: Wang Shu Hong , Tang Chun An , Zhang Juan Xia , Zhu Wan Cheng
Published: March 2009

This short paper will present a two-dimensional (2D) model of masonry material. This mesoscopic mechanical model is suitable to simulate the behavior of masonry. Considering the heterogeneity of masonry material, based on the damage mechanics and elastic-brittle theory, the new developed Material Failure Process Analysis (MFPA2D) system was brought out to simulate the cracking process of masonry, which was considered as a three-phase composite of the block phase,
the mortar phase and the block-mortar interfaces. The crack propagation processes simulated with this model shows good agreement with those of experimental observations. It has been found that the shear fracture of masonry observed at the macroscopic level is predominantly caused by tensile damage at the mesoscopic level. Some brittle materials are so weak in tension relative to shear that tensile rather than shear fractures are generated in pure shear loading.
Thermomechanical Fatigue Behavior of the Ferritic Stainless Steel
Authors: Lee Keum Oh , Hong Seong Gu , Yoon Sam Son , Lee Soon Bok
Published: March 2009

A thermomechanical fatigue (TMF) life prediction model for ferritic stainless steel, used in exhaust manifold of automobile, was developed based on Tomkins’ two-dimensional crack propagation model. Low-cycle fatigue (LCF) and TMF tests were carried out in a wide temperature range from 200 to 650°C. New concept of plastic strain range on TMF was proposed. Effective stress concept was introduced to get a reasonable stress range in TMF hysteresis loop. The proposed model predicted TMF life within 2X scatter band. The experimental results reveal that TMF life is about 10% of isothermal fatigue life.
Analysis of Underground Pipelines Subjected to Frost Heaving Forces
Authors: Song Weon Keun , Rhee Jong Woo
Published: March 2009

This paper examined the fundamental problem of an interaction between a soil medium that experiences frost heave in a closed system and an underground pipeline. The coupled thermal transfer and structural analysis, considering the material nonlinearity of freezing soil, for an underground pipeline subjected to the low cyclic load was focused on the development of computational scheme by introducing the effective heat capacity concept and the effective thermal expansion
coefficient into the study. The effective heat capacity model in the thermal transfer analysis took into consideration the phase-change effect in the frozen fringe of a soil medium. The comparative analyses between the theory and the actual performances were valuable in establishing a level of confidence in the application of introduced theory to the field. The numerical results in the paper illustrated the influence for the frost heave of a soil medium on the temperature-dependent development of stress fields on metallic underground pipe walls in South Korea.
Fatigue Crack Growth Behavior of Corner Cracks under LBH Loading
Authors: Oh Chung Seog , Park Philip , Huh Yong Hak , Ko Soon Gyu , Hwang Don Young , An Hyeon Mo
Published: March 2009

This investigation aims at doing some durability and damage tolerant (DaDT) tests with 2124-T851 aluminum specimens having corner cracks under a random history, correlating with the simulation results from AFGROW and then drawing some conclusions from those comparisons. Two hydraulic actuators and a homemade Wood’s alloy grip are employed to do the test. The surface crack
lengths are measured by a traveling microscope and used as a reference for the later fractography. The crack penetration and the total lives are about 17 and 27 blocks, respectively. The crack length and depth are evaluated by the fractography after completing each test and used to grasp the shape change. The Forman equation is used to simulate the fatigue crack growth behavior according to a bearing stress ratio extensively. The crack penetration life is decreased as the bearing stress ratio increases. The crack aspect ratio is very dependent on the bearing stress ratio. The LBH loading accelerates the fatigue crack growth in the crack depth direction but decelerates that in the length direction until crack penetration.
Finite Element Analysis of Brain Damage due to Impact Force with a Three Dimensional Head Model
Authors: Suh Chang Min , Kim Sung Ho , Hwang Byung Won
Published: March 2009

Brain damage by the impact force was evaluated by the numerical analysis with a three dimensional Finite Element (FE) model. The FE model was constructed from the MRI data of a subject, and visco-elastic behavior for constitutive equation was applied to the brain tissue. From the FE simulation, brain damage and deformation of the frontal head impacted by a steel impactor were analyzed. The variations of head acceleration and Intra-Cranial Pressure (ICP) during the impact were analyzed in order to evaluate Traumatic Brain Injury (TBI). In addition, relative displacement
between the skull and the brain due to head impact was investigated. And, pathological severity was evaluated according to Head Injury Criterion (HIC) from the FE simulation. The analytic results of brain damage showed a good agreement with those of the cadaver test performed by Nahum et al. (1977) and other medical reports. And then, the variation of the HIC value was evaluated according to various impact conditions. This study would provide useful data and methodology in the field of biomechanics for analyzing the brain damage by head impact.
Energy Absorption Characteristics on Aluminum Beams Strengthened with CFRP Laminates under Impact Loading
Authors: Jang Seung Min , Kawai Yuuki , Sato Chiaki
Published: March 2009

In this paper, the energy absorption characteristics on extruded aluminum box-section strengthened with carbon-fiber-reinforced plastics (CFRP) laminates and/or foam material were investigated under impact loading. Impact tests using a pneumatic impact tester were conducted with the specimens in three-point bending flexure with consideration given to the side-door impact beams in vehicles. The absorbed energy to the specimen during the impact was determined from the loaddisplacement curve, which was obtained from the strain gauge attached to the impactor and the laser displacement transducer. From the results, it was found that the strengthening by externally bonding with CFRP laminates improved the impact-induced energy absorption. Also, the effect of the improvement was clearly seen in the case of the use of filling form material in the aluminum extrusion together with attaching CFRP laminates.
Analysis Technology on the Thick Plate Free Drop Impact of the Cask for Radioactive Material Transport
Authors: Lee Young Shin , Kim Hyun Soo , Kim Yong Jae
Published: March 2009

The package used to transport radioactive materials, which is called by cask, must maintain the structural integrity for the requirements of hypothetical accident conditions, 9m free drop of the thick plate impact. These requirements for the cask design should be verified through test or finite element analysis to confirm the regulatory guide. In this paper, three dimensional impact analysis using ABAQUS/Explicit code under 9m free drop of the thick plate impact condition for the KSC-4 cask is performed. As the results, maximum stress intensity on each part of the cask and deformation shape of the cask is calculated and the structural intensity of the cask is evaluated by NRC Regulatory Guides.
Fracture Toughness of Liquid Phase Sintered SiC by Using Indentation Fracture Method
Authors: Jung Hun Chae , Yoon Han Ki , Kim Bu Ahn , Park Joon Soo , Kohyama Akira
Published: March 2009

SiC materials have excellent high temperature strength, low coefficient of thermal
expansion, good resistance to oxidation and good thermal and chemical stability etc. However, the brittle characteristics of SiC such as low fracture toughness and low strain-to fracture still impose a severe limitation on practical applications of SiC materials. Therefore, in the interests of safety, we are required to measure fracture toughness of materials. In the present work, monolithic Liquid Phase Sintered SiC (LPS-SiC) was fabricated by hot pressing method under 20MPa using sintering
additives at different temperature such as 1760oC, 1780oC, 1800oC and 1820oC. The starting powder was high purity β-SiC nano-powder with an average particle size of 30nm. Compositions of sintering additives were Al2O3 / Y2O3 = 0.7 and 1.5 (wt. %). Monolithic LPS-SiC was evaluated in terms of sintering density, hardness and fracture toughness through indentation fracture method by the Vickers hardness tester. Sintered density, hardness and fracture toughness of fabricated LPS-SiC increased with the increase of sintering temperature. They are higher than those of fabricated SiC by the chemical vapor deposition method.
Effective Thermal Conductivity of Functionally Graded Composite with Arbitrary Geometry of Particulate
Authors: Zhang Mei , Zhai Peng Cheng , Zhang Qing Jie
Published: March 2009

In this paper, a new micromechanical method, the Weighted Residual Self-consistent
Scheme (WRSCS), is developed for the prediction of the effective thermal conductivity of particulate composites with arbitrary configurations. The method is based on the concept of the traditional Self-consistent Scheme (SCS). For some special configurations of inclusions, such as spherical or ellipsoidal, the effective conductivity of the composite can be solved without much difficulty using SCS. But for the composite with inclusion of arbitrary geometry, such as polygon or other irregular configurations, it is difficult to get an analytic solution. In the WRSCS, the arbitrary inclusion configuration is modeled by applying collocation points at interface. Based on SCS micromechanical model, the local fields inside the inclusion can be evaluated by using the solution of a single inclusion in an infinite matrix and inclusion interaction is taken into account through the yet unknown average equivalent medium. The solution for calculating the potential field inside the inclusion is obtained by means of Weighted Residual Method (WRM). Using the WRSCS, the effective thermal conductivities for composites with different inclusion’s geometry are calculated. For the case of spherical inclusion, the results from the WRSCS show good agreements with the one from traditional SCS [7, 8]. Examining results corresponding to different inclusion’s geometry, it shows that the effective thermal conductivity depends not only on the volume fractions and the properties of components, but also on the inclusion’s configuration.
Behavior of Fatigue Crack around a Hole under Biaxial Loading: Effect of Biaxial Static Load
Authors: Huh Yong Hak , Park Philip , Kim Dong Jin
Published: March 2009

Fatigue crack initiation and propagation behavior around a hole subjected to various biaxial fatigue loading modes has been investigated considering the effect of the biaxial static stress. Two different biaxial loading systems, i.e. cyclic tensile loading with static torsional load and cyclic torsional loading with static tensile load, were employed to thin-walled tubular specimens with a circular notch. Variation of the initiaiton and propagation directions of the crack around a hole under these loading ssytems was examined. The initiation directions were observed using replication technique and the crack propagation was measured by two crack gages mounted near the notch. It was found that the biaxial static stress superimposed on the cyclic tensile or torsional loading tests has no influence on the initiation and propagation directions of the cracks around a hole. The fatigue crack initiation and propagation direction under cyclic loading with biaxial static load can be very well explained by the maximum of tangential stress range, Dsqq,max. Furthermore, it was shown that the fatigue crack growth rates under biaixial faigue loading becomes higher with increment of biaxial static load.
Analysis Technology on the Temperature and Thermal Stress of the Cask for Radioactive Material Transport
Authors: Lee Young Shin , Choi Young Jin , Soo Kim Hyun , Chung Sung Hwan
Published: March 2009

The cask is used to transport the radioactive materials. It is required to withstand for the thirty minute under the hypothetical fire accident condition of the 800ı. According to development of the computer simulation, finite element analysis is applied to the calculation widely. But finite element method for the hypothetical accident conditions is not established in domestic regulations. In this study, the temperature and thermal stress analysis of KSC-4 cask under 800ı fire condition is
conducted using by ANSYS 7.0 code. In order to analyze finite elements, two-dimensional model of KSC-4 cask is used. Symmetric boundary, convection, and radiation condition are applied in the analysis. As the results, maximum temperature and thermal stress of the KSC-4 cask is evaluated.
Determination of the Key Microstructural Parameter for the Cleavage Fracture Toughness of Reactor Pressure Vessel Steels in the Transition Region
Authors: Kim Min Chul , Lee Bong Sang , Yang Won Jon , Hong Jun Hwa
Published: March 2009

The effects of the microstructural parameters, such as the prior austenite grain size and carbide size, on the cleavage fracture toughness were investigated in the transition region of Mn-Mo-Ni bainitic low alloy steels. Cleavage fracture toughness was evaluated by the ASTM standard E 1921 Master curve method. In order to clarify the effects of each microstructure, the grain size and carbide size of the test materials were independently controlled by modifying the heat treatment process. Firstly, the grain sizes were changed from 25㎛ to 110㎛ without any significant
changes in the carbide size and shape. Secondly, the average carbide sizes were changed from 0.20 ㎛ to 0.29㎛ but maintaining the initial grain sizes. As a result, the fracture toughness in the transition region did not show any significant dependency on the austenite grain size, while the carbide size showed a close relation to the fracture toughness. Fracture toughness was decreased with an increase of the average carbide size. From the microscopic observation of the fractured surface, the cleavage initiation distance (CID) from the original crack tip showed no direct relationship to the prior austenite grain sizes but a strong relationship to the carbide sizes. However, the measured cleavage fracture toughness was strongly related to the distance from the crack tip to the cleavage initiation site. From the viewpoint of the weakest link theory, the particle size and their distribution in front of the crack tip is probably more important than the grain size in the transition temperature range where the fracture was controlled by the cleavage crack initiation.
The Mechanical Property of TiN Film Deposited on N+-Implanted Aluminum by Magnetron Sputtering
Authors: Cai Xun , Liu Youming , Li Liuhe , Chen Qiu Long , Hu Ya Wei
Published: March 2009

The effect of a AlN gradient interlayer on the surface mechanical properties was
investigated by nano-indentation for the TiN film on N+-implanted Al substrate. The AlN interlayer, 80nm thick measured by Auger Electron Spectrometer (AES), was formed by high energy N+-implantation prior to magnetron sputtering the TiN film in our custom designed multifunctional ion implanter. The nanohardness of N+-implanted aluminum was 450HV at extremely small depth, but quickly decreased to a constant value (65HV). The hardness and Young’s modulus of the TiN film on two different substrates, one with and the other without N+-implantation, kept almost constant up to a small depth of 200nm, and then decreased to the values of the Al substrate with increasing indentation depth, but with a lower decreasing rate for the N+-implanted system. It was found from the load-displacement curves that the interfaces cracked when the indentation load was 38mN for the N+-implanted system, while 18mN for the unimplanted system. Therefore the N+- implantation
improved the surface mechanical properties significantly.
Reliability Analysis of ACF Interconnection Assembly Process Using FEM
Authors: Koguchi Hideo , Attaporn Wisessint , Nishida Kazuto
Published: March 2009

Anisotropic conductive film (ACF) is commonly used as underfill for flip chip assembly. The present study focuses on elastic recovery and stress distribution along the interfaces of particle-pads and underfill-pads associated with heat or a mechanical loading. In the same manner as the experimental process for ACF assemblies, ACF interconnection is simulated using FEM. Firstly, the properties of the nickel were determined by fitting FEM to the experimental results. After that, the
nickel properties are used for ACF interconnection analysis. We found that delamination may also occur at a three-joint interface of a particle, a pad and an underfill at the lowest temperature during a heat cycle.
Reliability Optimum Design of NWG-Type Oil-Submerged Planetary Gear Reducer
Authors: Wang Shi Jie , Lv Jianhua
Published: March 2009

Progressing cavity pumping technology will be extensively applied for oil exploitation because of its advantages such as lower cost, higher adaptability for oil viscosity, sand-content and oil-gas ratio. This pumping system consists of motor, reducer, coupling, progressing cavity pump, variable frequency converter and protector. Among them, oil-submerged planetary gear reducer is one of the most important transmission components, which transmits torque and adjusts the rotational speed between motor and pump. Because the reducer is required to work successively under the harsh down-hole condition of high temperature and pressure for long span, the reliability design and fatigue life become the key technical problems for research. Based on reliability theory and optimum design method, the mathematical model for reliability optimization of NWG-type gear reducer is built up and optimum geometrical parameters are found in this paper. It is testified that, with such parameters, the diameter of the reducer can be reduced, daily oil-output can be increased and life span of the pumping system can be thus lengthened.
Nondestructive Evaluation in Materials Using Time-Frequency Analysis Methods
Authors: Nam Ki Woo , Ahn Seok Hwan , Kim Jin Wook
Published: March 2009

Application of signal processing techniques to nondestructive evaluation (NDE) in general has become a standard tool in determining the frequency characteristics of the signals and relating these characteristics to the integrity of the structure under consideration. The joint time-frequency analysis techniques are applied to analyze ultrasonic signals in degraded austenite stainless 316 steel, to study the evaluation of damage in this material. It is demonstrated that the nonstationary characteristics of ultrasonic signals could be analyzed effectively by these methods. WVD was found to be more effective for analyzing the attenuation and frequency characteristics of degraded materials through ultrasonic. It is indicated that the time-frequency analysis methods should also be useful in evaluating various damages and defects in structural members.
Boundary Element Analysis of Viscoelastic Fracture
Authors: Lee Sang Soon , Kim Noh Yu
Published: March 2009

In this paper, the boundary element analysis of viscoelastic strain energy release rate ) (t G for the cracked linear viscoelastic solids has been attempted. The ) (t G has been defined as the derivative of the viscoelastic potential energy ) (t P with respect to crack length a . Numerical results show the applicability of the proposed method to the analysis of the cracked linear viscoelastic structures.
A Study on the Relationship of Frequency and Deformation for Viscoelastic Material
Authors: Lee Seong Beom , Cho Youn Ho
Published: March 2009

Viscoelastic materials are used in automobiles and other products. However, because of theoretical complexity, it has not been easy to put all the energy exhausted into the automotive viscoelastic materials. Since time is the most important factor in the study of viscoelastic material, creep and stress relaxation functions are very important. In this study, a bushing was selected for special viscoelastic material. A bushing is a device used in automotive suspension systems to cushion the force transmitted from the wheel to the frame of the vehicle. A bushing is essentially a hollow cylinder which is bonded to a solid metal shaft at its inner surface and a metal sleeve at its outer surface. The shaft is connected to the suspension and the sleeve is connected to the frame. The cylinder provides the cushion when it deforms due to relative motion between the shaft and sleeve. The relation between the force applied to the shaft or sleeve and their deformation is nonlinear and exhibits features of viscoelasticity. A force-displacement relation for a bushing is important for multi-body dynamics numerical simulations. Hence, an explicit force-displacement relation has been introduced. The relation is expressed in terms of a force relaxation function. With Pipkin-Rogers model, the direct relation of force and displacement that has been derived from experiment and numerical simulation, the sinusoidal displacement was chosen and the relation of frequency and deformation for the viscoelastic material was studied.
AGV System with Dual Motor Drive by Distributed Control
Authors: Cho Yon Sang , Jun Sung Jae , Park Heung Sik
Published: March 2009

With the recent progress in flexible manufacturing systems (FMS) in industry, increasing attention has been given to Automatic Guided Vehicle (AGV) systems. An AGV is a self-powered unit for transporting materials between stations without needing to be controlled by an operator. Such a system has several sensors to recognize the external state, and it is designed to travel between stations without external assistance. To manage each device quickly and independently it requires a
distributed controller with a main computer as the host, as well as a number of micro-controllers. In this study, an AGV system with dual motor drive was constructed. A Pentium 4 personal computer was set up as the main host for the distributed control, and this communicated with other micro-controllers in the management of the motor. The speed of each motor was also controlled by a micro-controller.
The Mechanism of Postural Balance Control of High-Heeled Women
Authors: Cho Won Hak , Choi Hyeon Ki
Published: March 2009

High-heeled women have been identified with balance control problems. The purposes of this study were to objectively quantify the displacements and velocities of center-of-pressure (COP) of body during waist pulling and to compare the differences between barefooted and high-heeled situations. We used a waist pulling system which has three different magnitudes to sway the subjects. We found that the kinematic information of barefooted and high-heeled women’s COP is very
important in understanding the mechanism of postural balance control of women in every-day life. In the high-heeled’s case, the displacement of COP increases by 9% (1kg), 33% (2kg), 44% (3kg) as against bare footed. Also the velocity of COP grows two times than that of the bare footed. COP analysis in postural balance study of high-heeled women is considered useful in development of the
safety systems that prevent high-heeled women from falling.
Shape Memory Thin Film for Blood Vessel Holding Actuator of Thrombus Detector
Authors: Mineta Takashi , Hirota Ken-ichi , Makino Eiji , Sugawara Takashi , Toh Satoshi , Shibata Takayuki
Published: March 2009

For the purpose of an application for a blood vessel holding actuator of thrombus detector, evaporation technique and film properties of TiNiCu ternary shape memory alloy (SMA) thin film was studied. The SMA thin film was formed on a sacrificial Cu substrate by using a flash evaporation technique, with which very small TiNiCu alloy pellets were evaporated repeatedly. With this evaporation technique, phase transformation temperature of the deposited thin film can be controlled by deposition timing after the each pellet starts to vaporize. When the interval time before the deposition was 0s, the deposited thin film became a super elastic alloy (SEA), which starts to deform below the human body temperature of 37°C. On the other hand, when the interval time was 1s or longer, the deposited thin film shows a shape recovery temperature of about 60°C. Fracture strength of the thin film was obtained at least 170MPa, that corresponds to a fracture force of 570mN for holding actuator
of 0.6mm in width and 6µm in thickness. Although the SEA film was fragile, the SMA film at the interval time of 5s was flexible enough to be bendable to small radius of 0.15mm.
Experimental Investigation on the Proper Fatigue Parameter of Cyclically Non-Stabilized Materials
Authors: Hong Seong Gu , Lee Keum Oh , Lim Jae Yong , Lee Soon Bok
Published: March 2009

Low-cycle fatigue tests were carried out in air in a wide temperature range from room
temperature to 650oC to investigate the role of temperature on the low-cycle fatigue behavior of two types of stainless steels, cold-worked (CW) 316L austenitic stainless steel and 429 EM ferritic stainless steel. CW 316L stainless steel underwent additional hardening at room temperature and in 250-600oC: plasticity-induced martensite transformation at room temperature and dynamic strain aging in 250-600oC. As for 429 EM stainless steel, it underwent remarkable hardening in 200-400oC due to dynamic strain aging, resulting in a continuous increase in cyclic peak stress until failure. Three fatigue parameters, such as stress amplitude, plastic strain amplitude and plastic strain energy density, were evaluated. The results revealed that plastic strain energy density is nearly invariant through a whole life and, thus, recommended as a proper fatigue parameter for cyclically non-stabilized
materials.
Effect of Cyclic Loading on Crack Propagation of X-70 Pipeline Steel in Near-Neutral pH Solution
Authors: Guo Hao , Li Guang Fu , Cai Xun , Bai Jiasheng , Yang Wu
Published: March 2009

Crack propagation of X-70 pipeline steel in near-neutral pH solution was studied under different modes of cyclic loading. A revised equation of crack growth rate vs. Δ K was obtained. Average crack growth rate increased with cycles under conditions of different R values. Linear shape notch specimen made cracks much easier to initiate and propagate than V-shaped notch specimen did. For different R values, the curves of crack growth rate with cycles were similar, but the platform
propagation period and quick propagation period were different obviously. Crack growth rate at both periods increased and thus failure time decreased markedly with decrease of R value. The propagation directions of cracks were different under different cyclic loading conditions. Under mode I (single tensile stress) cyclic loading, cracks were straight and perpendicular to the tensile stress axis, while under mixed-mode I/III (tensile/shear stress) cyclic loading, cracks were sinuous
and did not propagate in the direction perpendicular to the main tensile stress axis.
Mechanical Improvement of Multi-Walled Carbon Nanotube/Poly (Methyl Methacrylate) Composites
Authors: Kim Hyun Chul , Lee Sang Eui , Kim Chun Gon , Lee Jung Ju
Published: March 2009

Multi-walled carbon nanotube (MWNT)/poly (methyl methacrylate) composites were fabricated with the variation of the concentration rate of nanotubes by the solution casting. SEM images showed that the nanotubes were dispersed well throughout PMMA. Assuming that MWNTs in MWNT/PMMA composites were randomly oriented, the Tsai-Pagano equation, which can give the moduli of short fiber reinforced composites, was used to evaluate that of the MWNT/PMMA composite. For investigating mechanical properties of the MWNT/PMMA composite, tensile loading tests were performed, varying the concentration rate of the MWNTs. For each concentration rate of the MWNTs, at least 5 specimens of MWNT/PMMA composites were made and tested. As the concentration rate of the MWNTs increased from 0 to 0.15wt%, tensile strength and modulus of the MWNT/PMMA composites were improved by about 20% and 32%, respectively. However, the experimental results were not in agreement with what we estimated. Here are two reasons supposed. First, the MWNTs used in this research were not stretched straightly but entangled. It means that MWNTs cannot be assumed to be short fibers. Second, the concentration rate of the MWNTs is too small to be considered as short fiber composites.
Avalanche Behaviour in Microfracturing Process of 3-D Brittle Disordered Material
Authors: Zhao De Shen , Xu Tao , Tang Chun An , Zhang Hou Quan , Liang Zheng Zhao
Published: March 2009

Using a newly-developed Material Failure Process Analysis code (MFPA3D), the
micro-fracturing process and the avalanche behavior characterization of brittle disordered materials such as rock or concrete is numerically studied under uniaxial compression and tension. It is found that, due to the heterogeneity of the disordered material, there is an avalanche behavior in the microcrack coalescence process. Meanwhile, a hierarchy of avalanche events also numerically observed though a study of numerically obtained acoustic emissions or seismic events. Numerical simulations indicate that macro-crack nucleation starts well before the peak stress is reached and the crack propagation and coalescence can be traced, which can be taken as a precursory to predict the macro-fracture of the brittle disordered materials. In addition, the numerically obtained results also reveal the presence of residual strength in the post-peak region and the resemblance in the stress-strain
curves between uniaxial compression and tension.
Mechanical Properties of CaB6 Sintered Body
Authors: Min Guang Hui , Yang Li Xia , Yu Hua Shun , Han Jiande
Published: March 2009

In this paper, CaB6 sintered body was fabricated by hot-pressed sintering with/without nickel as a sintering aid. The microstructure and fracture morphology were observed by means of SEM. CaB6 polycrystalline hot-pressed at 2123K showed insufficient densification. Fracture surface revealed that the existence of pores and the poor grain boundaries made the occurrence of intergranular fracture. When 28wt% nickel was added, nearly full density was obtained, although the sintering temperature is 200K lower. Hardness, Bending strength and fracture toughness of polycrystalline CaB6 were measured. By adding the Ni in CaB6 matrix, the flexural strength and the fracture toughness were enhanced, and the ratio of transgranular to intergranular fracture type was increased notably. The fracture surface showed a transgranular fracture. The crack bridging, micro-cracking and crack deflecting were deemed as the contribution to the improved fracture toughness.
Force-Calibrated AFM for Mechanical Test of Freestanding Thin Films
Authors: Lee Hak Joo , Cho Ki Ho , Kim Jae Hyun , Han Seung Woo , Choi Byung Ik , Baek Chang Wook , Kim Jong Man , Choa Sung Hoon
Published: March 2009

Atomic force microscope (AFM) is a powerful tool for exploring a nano-scale world. It can measure a nano-scale surface topography with very high resolution and detect a very small force. In this paper, we propose a novel AFM cantilever and its calibration scheme to utilize AFM as a mechanical testing machine. We call this AFM with a new cantilever as a force-calibrated AFM. The feasibility of the AFM cantilever is validated through measurement of mechanical properties of freestanding Au thin films.
Effect of Nanoscale SiC Particles on Strength Distribution of Joined Si3N4 to Inconel Alloy
Authors: Seo Do Won , Chi Chang Heon
Published: March 2009

Two-layered Si3N4/SiC nano-composites with 50vol.% SiC have been fabricated by
two-step sintering of a powder mixture of a-Si3N4 and carbon powder with a mean size of 13nm, and 5wt.% Y2O3. Nano-sized SiC particles were formed through reactions: carbon and surface SiO2 on the Si3N4 particles, and carbon and Si3N4 particles. To combine the specific advantages of nanoscale ceramics with that of metals, they are often used together within one composite component. In this study, the fabrication and mechanical properties of a nanoscale SiC layer brazed with an Inconel alloy were investigated. It was shown that, with a variation of strain rate, the joints have a bending strength of 330-380MPa, and the deflection of the interlayer increases with increasing strain rate. The fracture types are classified into three groups; cracks grow into the metal-brazing filler layer, the ceramicbrazing filler layer or inside the ceramic.
Effects of Sea Water Immersion and Temperature on the Strength of Spot-Welded Steel Plates
Authors: Choi Jun Yong , Kim Hyo Jin , Lim Jae Kyoo
Published: March 2009

The spot welded structure operates in diverse climatic situations because of temperature, humidity and precipitation. In addition, factors of environmental pollution such as acid rain, that causes corrosion, have the tendency to increase. But spot welded structure strength is affected by dampness and environment temperature. Therefore, it is important to evaluate the effect of temperature of the spot welded part. In this study, the strength distribution of spot welded plates is evaluated for the environmental temperature of zinc coated steel plates and the test is conducted with
the welded part immersed in distilled and synthetic sea water. Specimens are immersed into water for 10, 100, 500 and 1000hours to evaluate the effects of water immersion time on tensile-shear strength under the conditions of -40, 0, 20 and 50°C. Strength is evaluated by using the tensile-shear test. The conditions of spot welding are 240kgf electrode force, 10kA welding current with 0 and 5mm clearance. In this study, spot welded specimens with clearance have lower tensile-shear strength in the distilled water or synthetic sea water compared with spot welded specimens without clearance. And they have lower tensile-shear strength under -40°C and over 50°C.