bluuebunny/crossref_metadata_2025 huggingface dataset:
Research of the Technological Parameters Influencing on the Surface Quality of Micro Complex Surface
Authors: Chen Ming Jun , Liang Ying Chun , Sun Ya Zhou , Guo W.X. , Zong Wen Jun
Published: March 2009

In order to machine complex free surface parts, a micro NC (numerical control)
three-dimensional machine tool is developed, integrated the PMAC control. Based on this NC machine tool, the influencing of the technological and tool’s parameters on machining accuracy of micro complex surface parts are analyzed, and the cause to lead to the machining errors is explained. Therefore, the cutting parameters and tool geometry parameters to machine micro complex surface, such as the human’s face, can be selected optimally. Finally, the micro complex human’s face is machined on this developed micro machine tool under optimal parameters. The experimental results show that the machined surface is smooth and continuous. The machined quality is satisfied.
Simplified Methods for Prediction of Elastic-Plastic Behaviour of Complex Structures with Repeated Structural Units
Authors: Leen Sean B. , Hyde Thomas H. , Sabesan R. , Pan W.
Published: March 2009

This paper reviews a range of simplified and approximate techniques developed and implemented by the authors in the context of elastic-plastic, elastic-creep and elastic-plastic-creep, monotonic loading of both simple components and complex structures. The primary motivation for the work is to provide more rapid methods for estimating failure variables for damage assessment of structures. The context of the work has included both aerospace structures and tubular frameworks, such as offshore jacket-type structures, both of which belong to a class of structures, which contain repeated units where localised plastic damage may be concentrated.
Internet/Intranet Based Remote Condition Monitoring and Fault Diagnosis Scheme and System for Steam Turboset
Authors: He Yong Yong , Lu Wen Xiu , Chu Fu Lei
Published: March 2009

The steam turboset is the key equipment of the electric power system. Thus, it is very important and necessary to monitor and diagnose the running condition and the faults of the steam turboset for the safe and normal running of the electric power system. In this paper, the Internet/Intranet based remote condition monitoring and fault diagnosis scheme is proposed. The corresponding technique and methods are discussed in detail. And a real application system is developed for the 300MW steam turboset. In this scheme, the system is built on the Internet/Intranet and the Client/Server construction and Web/Server model are adopted. The proposed scheme can guarantee real-time data acquisition and on-line condition analysis simultaneously. And especially, the remote condition monitoring and fault diagnosis can be implemented effectively. The developed system has been installed in a power plant of China. And the plant has obtained great economic benefits from it.
Magnetic Bearings for Non-Destructive Health Monitoring of Rotating Machinery Supported in Conventional Bearings
Authors: Kasarda M. , Quinn D.D. , Bash T. , Mani G. , Inman Daniel J. , Kirk R.G. , Sawicki Jerzy T.
Published: March 2009

This paper describes initial results from a project expanding the field of rotor health monitoring by using Active Magnetic Bearings (AMBs) as actuators for applying a variety of known force inputs to a spinning rotor in order to monitor and evaluate response signals resulting from these inputs on-line. Similar to modal analysis and other nondestructive evaluation (NDE) techniques which apply input signals to static structures in order to monitor responses; this approach allows for the measurement of both input and output response in a rotating system for evaluation. However, unlike these techniques, the new procedure allows for multiple forms of force input signals to be applied to a rotating structure. This technique is being developed for use on rotating equipment supported in conventional bearings where an AMB actuator is added to a system for improved health monitoring. This paper presents initial results from this project including a demonstration of the system identification capability of the procedure during the commissioning of a test rig, and a summary of a technique developed for identifying breathing-cracks in rotors using the new technique.
Bush Skewness Defect in Journal Bearing as an Example of Knowledge Base Development
Authors: Luczak Marcin
Published: March 2009

In the paper presented are course and results of investigations of the influence of slide bearing bush and shaft mutual skewness on the dynamic properties of the 200 MW 13K215 turboset. The defect was simulated by means of numerical model of the turboset. Simulation was performed for each bearing individually in both, horizontal and vertical planes. Maximum values of the skewness angle were calculated for each bearing at both planes. The influence of the defect on dynamic properties of turboset was presented. Basing on the results of the simulation multiple defect-symptom diagnostic relations were built. Diagnostic relations were used as learning and testing data sets for a knowledge base of an expert system based on the inverse diagnostic model. This expert system is implemented at the unit 7 at the Kozienice Power Station as a first domestic diagnostic system.
Multi-Fault Classifier Based on Support Vector Machine and Its Application
Authors: Zhang Zhou Suo , Shen Minghui , Lv Wenzhi , He Zheng Jia
Published: March 2009

Aiming at problem on limiting development of machinery fault intelligent diagnosis due
to needing many fault data samples, this paper improves a multi-classification algorithm of support vector machine, and a multi-fault classifier based on the algorithm is constructed. Training the multi-fault classifier only needs a small quantity of fault data samples in time domain, and does not need signal preprocessing of extracting signal features. The multi-fault classifier has been applied to fault diagnosis of steam turbine generator, and the results show that it has such simple algorithm, online fault classification and excellent capability of fault classification as advantages.
A Mobile Shearography System for Non-Destructive Testing of Industrial and Artwork Components
Authors: Kalms M. , Jueptner W.
Published: March 2009

By reason of their sensitivity, accuracy and non-contact as well as non-destructive
characteristics, modern optical methods such as digital speckle shearography have found an increasing interest for NDT applications on factory floors. With new carbon fiber technologies and other lightweight constructions in aircraft and automotive manufacturing, adapted examination designs and especially developed testing methods are necessary. Shearography as a coherent optical method has been widely accepted as a useful NDT tool. It is a robust interferometric method to determine locations with maximum stress on various material structures. However, limitations of this technique can be found in the bulky equipment components, the interpretation of complex shearographic result images and at the work with non-cooperative surfaces such as dark absorber and bright shining reflectors. We report a mobile shearography system that was especially designed for investigations at aircraft and automotive construction sites. It is also useful to find out the current conditions of artworks.
Automatic Laser Monitoring for Dam Safety
Authors: Yue K.D. , Zhou X. , Gao J.
Published: March 2009

Many monitoring methods for dam safety have been proposed in recent years but it is difficult to monitor the arch dam automatically. A novel inspecting method for arch dam safety monitoring is described in this paper. This measurement system is based on the principle of transmitting the comparative displacement one by one. The error and accuracy of the system is analyzed. By this method, a large arch dam can be measured automatically. Long distance data transmission system using CAN bus and Internet is established. It is convenient to monitor the safety of dams from long distances.
An Application of the Kalman Filter in a Laser Tracking Measurement System
Authors: Chen X.R. , Cai P. , Shi Wen Ku
Published: March 2009

Flexible coordinate measuring system based on laser tracking measurement system (LTS) is an effective method to detect 3D coordinates of moving target. However, the system suffers from various interferences resulting in low accuracy. This paper extends the application of a Kalman filtering algorithm in LTS to solve the problem. The laser tracking system is introduced. The state model of the laser tracking measurement system is developed and the linearization method of the model is analyzed. A Kalman filtering algorithm is used for the system. The result of the simulation shows that the proposed Kalman filter method works well for the improvement of accuracy of LTS.
Measurement of the Straightness of a Leadscrew-Driven Precision Stage
Authors: Arai Yoshikazu , Gao Wei , Kiyono S. , Kuriyagawa Tsunemoto
Published: March 2009

This paper describes a multi-probe method for measuring the straightness error of a leadscrew-driven stage. Two displacement probes are employed to scan a flat artifact mounted on the stage. The surface profile error of the flat artifact is separated from the straightness error of the stage in a differential output of the probes. The straightness error can thus be obtained accurately from an integration operation of the differential output without the influence of the surface profile error. An improved technique of data processing is adopted for measurement of straightness error components with periodicity shorter than the probe spacing. The influence of the angular error of the stage is compensated for by using the result measured by an autocollimator. Experiments of straightness measurement of a leadscrew-driven stage with a lead of 1 mm were carried out by using two flat artifacts with different degrees of precision. The successful detection of the short-periodicity component of the straightness error with a periodicity equal to the lead indicated the feasibility of the multi-probe method.
A Thermovision Method for Studying Deformation Kinetics of Materials and Structure Elements
Authors: Lukin Evgeny S. , Ivanov Alexander M.
Published: March 2009

A method of the thermovision study for solving the problems of the experimental mechanics is presented. The method of the experimental study of deformation and fracture is based on the registration and interpretation of the infrared radiation pattern of a sample, which is caused by plastic deformations and material fracture. The thermofilm shows the kinetics of the sample deformation. Thermograms allow estimation of the plastic deformation zones. The characteristic changes in the temperature of a sample correspond to the limiting states of the material. Examples of studying the deformation and fracture of constructional steels under the conditions of the homogeneous and heterogeneous limiting states with the use of the thermovision method are given.
High Resolution Ultrasonic Distance Measurement Systems Using Pulse Compression and Their Applications
Authors: Schweinzer Herbert F. , Elmer H.
Published: March 2009

Ultrasonic distance measurement in air is broadly used for industrial and commercial low cost applications with medium or small resolution. Configurations for the applications are usually restricted to passive reflection and A-B measurement. This paper gives a survey of the ultrasonic distance measurement method with high resolution based on pulse compression. Improvements resulting from this method include good noise suppression, possibility to operate several systems in parallel without disturbing influence of cross talk, and high measurement rate. Modified configurations and the available high resolution lead to new applications which are summarized.
Determination of the Jetting Force of a Jet Actuator
Authors: Zhao L. , Yang Shu Xiang , Ren H.
Published: March 2009

This paper is resulted from a jetting force measurement experiment. The principle and the mathematical model of a jetting force measurement system are introduced. The characteristics of the measured data and the algorithm of extracting the jetting force are examined. The experimental results verify the algorithm and the theoretical results by use of system identification techniques.
A New Sensing System for Dynamic Pressure Measurement under Severe Conditions
Authors: Wu Z.T. , Wang Q.S. , Jiang Zhuang De
Published: March 2009

It is hard to ensure the survival of sensors for jet flow pressure measurement for several hundred microseconds to approximately 20 milliseconds under a severe radiation condition with a dose rate at 1013 rad (Si)/s and a strong explosion shock. A novel method is proposed to effectively solve the problem. The method is based on the plastic deformation principle of metal material and is based on the use of a pressure threshold. The method is particularly useful for large scale chemical explosion tests.
Evaluation of Thrust Force and Positioning Accuracy of a New Linear Motor
Authors: Chen Xin , Takamasu Kiyoshi , Nikaidou M.
Published: March 2009

A new linear motor based on the Sawyer principle is firstly introduced. Some important features of the linear actuator are discussed for better understanding of its performances and functions with absolute positioning. We investigated the static characteristics of the linear motor such as the relationship between the current and the maximum thrust force (I-F curve), the relationship between the displacement and the thrust force (D-F curve), and the positioning accuracy. The measuring methods for these characteristics are explained in detail. We analyzed the experimental data and evaluated the characteristics. We obtained that the suitable working current is 1A and the maximum thrust force is 15N for the linear motor. The positioning accuracy is ±12µm.
Evaluation of Dynamic Parameters for Underdamped Grinding Machines
Authors: Gao Y. , Tse S.
Published: March 2009

Evaluation of the dynamic parameters of a modulator based grinding machine system, which is underdamped, is presented. The modulator is one of a displacement-frequency type for dynamic manipulation of the stepping motor of a tool feed system which is part of a composite grinding system for a wide bandwidth control involving both low and high frequency signals. To obtain the parameters of the underdamped system, a method of multiple uses of the transient displacement responses to step commands is proposed to reduce assessment errors. The parameters to be obtained include damping ratio, undamped natural frequency, time constant, and settling time. The evaluation results were obtained based on the minimum of a composite error index using a second order dynamic system model for reference. The parameters will be useful for further development of the composite control for the precision machining process.
Verification of Mechanical Properties of A V-4Cr-4Ti Alloy Using Finite Element Method
Authors: Lee Choon Yeol , Donahue E.G. , Odette G.R.
Published: March 2009

Vanadium alloys in the composition range around V-4Cr-4Ti have been proposed as
candidate materials for fusion reactor applications and structures. These applications will require detailed characterization of constitutive and fracture properties. This study is aimed at understanding the basic constitutive and fracture mechanisms in vanadium alloys. Understanding of the basic constitutive and fracture mechanisms is achieved through a series of mechanical tests. These test results are combined with quantitative models of the underlying macro- and micromechanics. In addition to these experimental studies, finite element analysis (FEA) techniques are used to determine stress and strain fields to verify the constitutive law used in the fracture specimens.
Computational Evaluation of Micro- to Macroscopic Mechanical Characteristics of Low-Carbon TRIP Steel under Different Conditions
Authors: Saito K. , Ikeda Shushi , Makii Koichi , Akamizu H. , Tomita Yoshihiro
Published: March 2009

Low carbon TRIP steel shows quite complicated deformation behavior. The main purpose of this study is to clarify the deformation mechanism of low carbon TRIP steel by using a numerical simulation method. According to research works in the past, continuous transformation of retained austenitic phase is essential in order that TRIP steel may show favorable ductility, which implies that appropriate control of martensitic transformation is most important for improvement of ductility. Therefore, we built models for deformation-induced martensitic transformation and performed FEM analysis using homogenization method accounting for the chemical composition, temperature, and crystal orientation. As a result, the effects of chemical composition, temperature, and crystal orientation on the deformation and transformation behavior of low carbon TRIP steel were clarified quantitatively and the conditions to realize improved ductility in TRIP steel were suggested.
Numerical Studies on Damage Evolution of Notched Round-Bar with Welding Mechanical Heterogeneity
Authors: Zhang Jian Xun , Li Ji Hong
Published: March 2009

The effects of the welding mechanical heterogeneity on the damage evolution of notched round-bar tensile specimens were investigated numerically using a fully coupled elastic-plastic damage finite element method. Some parameters reflecting the welding mechanical heterogeneity such as strength mismatching, rupture strain and weld metal width were taken into account to study their effects on the damage evolution of the weld metal. The calculation results show that the damage evolution of the weld metal is affected strongly by the welding mechanical heterogeneity. The damage evolution of the weld metal becomes larger with the decrease of both the rupture strain and yielding stress of the base metal. The effects of the mechanical properties of the base metal on the damage evolution of the weld metal decreases with the increase of the weld metal width.
Mechanisms of Fatigue Crack Growth in WC-Co Cemented Carbides
Authors: Boo Myung Hwan , Park Chi Yong
Published: March 2009

In order to study the influence of stress ratio and WC grain size, the characteristics of fatigue crack growth were investigated in WC-Co cemented carbides with two different grain sizes of 3 and 6 µm. Fatigue crack growth tests were carried out over a wide range of fatigue crack growth rates covering the threshold stress intensity factor range DKth. It was found that crack growth rate da/dN against stress intensity factor range DK depended on stress ratio R. The crack growth rate plotted in terms of effective stress intensity factor range DKeff still exhibited the effect of microstructure. Fractographic examination revealed brittle fracture at R=0.1 and ductile fracture at R=0.5 in Co binder phase. The amount of Co phase transformation for stress ratio was closely related to fatigue crack growth characteristics.
Applied Research of Fracture for Brass in Extra-Low Cycle Rotating Bending Fatigue
Authors: Li You Tang , Ma Ping , Wei Yao Bing
Published: March 2009

The application of regular blanking for brass under extra-low cycle rotating bending fatigue was studied. The experiments of rotating bending fatigue have been made in special equipment designed by us. Several problems, the relations of the cycle times of fracture, the strain amplitude near the tip of notch and fracture toughness of fatigue to the presetting deflection, the effects of depth and tip radius of notch to the cycle times of fracture, were discussed through the experiments. The formulae of stress amplitude at the tip of notch and fracture toughness of brass to presetting deflection were obtained. The suitable parameters of fracture in rotating bending fatigue for blanking of brass under extra-low cycle times have been proposed.
In Situ Observation of Fracture of Aluminium Foam Using Synchrotron X-Ray Microtomography
Authors: Toda Hiroyuki , Ohgaki Tomomi , Uesugi Kentaro , Makii Koichi , Aruga Yasuhiro , Akahori Toshikazu , Niinomi Mitsuo , Kobayashi Toshiro
Published: March 2009

Synchrotron X-ray microtomography has been utilized for the 3D characterisation of
microstructure in the cell materials of aluminium foams. Tomographs, consisting of about 109 isotropic voxels with a maximum of 1.0µm edge, were collected at the SPring-8 in Japan. A combination of high-resolution phase contrast imaging technique and several state-of–the-art application techniques has enabled the quantitative image analyses of micro-pore, intermetallic particles and grain boundary as well as the assessment of their effects on compressive deformation and fracture behaviours in two kinds of aluminium foams.
Micro Behavior Study of Non-Metallic Inclusion in High Strength Shaft Steel
Authors: Zeng Yan Ping , Xu Chun Mei , Dong Jian Xin , Zhang Mai Cang , Xie Xi Shan
Published: March 2009

The composition, shape, size and distribution of non-metallic inclusions in a kind of high strength shaft steel enriched CoNi have been investigated. In situ tensile tests in special designed SEM have been conducted to trace the whole process of crack initiation and propagation till to fracture at inclusion. The experimental results show that the non-metallic inclusions in the high strength shaft steel are primarily AlN. Their average size is about 3.6µm. Sometimes, a string of inclusions distributes along the rolling direction. Non-metallic inclusion can induce crack to be initiated by inclusion debonding. When the inclusion size is larger than the critical size, the crack can propagate as the main crack that induces the specimen to fracture.
Mechanism of Delamination and Its Effects on Fracture of Surface Crack Bodies in Ductile Pipeline Steel
Authors: Dong Hui Ru , Guo Wanlin , Yang Zheng
Published: March 2009

The effects of three-dimensional crack configurations and delaminations on fracture
mechanism and fracture toughness Jc of pipeline steel were investigated experimentally by use of tensile specimens having surface cracks of different depth to length ratio. Comparison with test results of through-thickness cracks and mechanism analyses are made as well. When 3D stress constraint is larger than the strength in the thickness direction the delamination forms. As no delamination occurs in the interior of a surface crack, the constraint is higher and the fracture toughness is lower than that of the through-thickness cracks. Therefore, the nominal fracture toughness obtained from through-thickness cracked specimens is not a real material constancy, and not suitable for safety assessment of pipelines.
A Study on Low Velocity Impact of Woven Glass/Phenolic Composite Laminates Considering Environmental Effects
Authors: Kim Jae Hoon , Kim Duck Hoi , Kim Hu Shik , Park Byoung Jun
Published: March 2009

The objectives of this study are to evaluate the internal damage and compressive residual strength of composite laminate by impact loading. To investigate the environmental effects, as-received and accelerated-aged glass/phenolic laminates are used. UT C-Scan is used to determine the impact damage characteristics and CAI tests are carried out to evaluate quantitatively the reduction of compressive strength by impact loading. The damage modes of the woven glass/phenolic laminates are evaluated. In the case of the accelerated-aged laminates, as aging time increases, initial failure energy and residual compressive strength decrease.
Analysis of the Failure of Turbocharger Shaft Bearing in Diesel Engines
Authors: Xu Xiao Jing , Kim Seock Sam , Chen Kang Min , Luo Q.F.
Published: March 2009

A sudden failure of the bearing of the turbocharger shaft in a diesel engine, with the power of 11520KW and the total running time of 2,417h, is investigated in this paper. Based on an examination of the disassembled turbocharger and a residue analysis, it was found that the failure of the turbocharger originated from a fatigue fracture of an aluminum-alloy bearing retainer (cage) on its compressor side. The axial load was a chief cause of the fatigue fracture and the looseness defects in the aluminum alloy retainer deteriorated its fatigue strength which in turn accelerated the development of fatigue cracks. After the retainer broke, the off-centered rotation of the turbocharger shaft triggered a severe impact and led to deformation, wear and a fracture of the bearing parts, ultimately resulting in the failure of the turbocharger.
A Fundamental Study of the Tribological Characteristics of Sheave Steel against a Wire Rope
Authors: Ryu Jung Buk , Chae Young Hun , Kim Seock Sam
Published: March 2009

In contact conditions of crane sheave steel materials against a wire rope, the contact surface of the sheave generally exhibits scuff damage. In the present study, sliding wear tests using annealed-low carbon cast steel were carried out under three kinds of normal loads calculated from the actual model conditions in a pin-on-disk grease lubrication test. The sliding speed was fixed at 220mm/s. Therefore, the wear behavior and wear mechanism and the residual stress distribution of the substrate surface were examined. The results of this study indicate that the wear rate of annealedlow carbon cast steel depends on the diameter of the wires. The wear mechanism of annealed-low carbon cast steel is characterized by fatigue and abrasive wear, but the wire shows partial adhesion
due to micro abrasive wear by fatigue crack propagation. The contact distribution of residual stress is independent of sliding distance. Therefore, there are constant values on the contact surface.
Development of Wear Test System for Steam Generator Tubes in Nuclear Power Plants
Authors: Park Chi Yong , Lee Yong Sung , Boo Myung Hwan
Published: March 2009

In steam generators of nuclear power plants, flow-induced vibration (FIV) can lead to tube damage by fretting-wear occurred due to impact and sliding movement between the tubes and their supports. There have been many studies and test results on wear damage of steam generator tubes but they were not reflected the mechanical and chemical conditions accurately. KEPRI nuclear power laboratory developed a wear test system, which is able to control the motion of impact and sliding simultaneously in the pressurized high temperature water-chemistry conditions. Some wear tests were performed to verify the stable operation for the wear test. This wear test system with new concepts was described briefly, and some data for verifying its performance have been shown in the cases of the selected some test results. In the test, Alloy 690 was used for tube materials and 409 stainless steel for support plates. A little data deviation was obtained and stability of system operation was investigated.
Effect of Film Thickness on Fatigue Strength of TiAl Alloy Coated with TiAlN Film at Elevated Temperature
Authors: Kasuya Takeshi , Suzuki Hideto
Published: March 2009

The fatigue strength of TiAl intermetallic alloy coated with TiAlN film was studied in
vacuum at 1073K using a SEM-servo testing machine. In addition, three kinds of TiAlN films were given by physical vapor deposition (1, 3, and 10μ m). The fatigue strength of 3μ m was highest. Also, the fatigue strength of 1μ m was lowest. From this result, existence of optimum film thickness was suggested because the difference of fatigue strength arose in each film thickness. The justification for existence of optimum film thickness is competition of 45-degree crack and 90-degree crack. The 45-degree crack is phenomenon seen in the thin film (1μ m), and is caused by plastic deformation of TiAl substrate. The 45-degree crack is the factor of the fatigue strength fall by the side of thin film. In contrast, the 90-degree crack is phenomenon in the thick film (10μ m), and is caused as result of reaction against load to film. The 90-degree crack is the factor of the fatigue strength fall by the side of thick film. In conclusion, the optimum film thickness can perform meso fracture control, and improves fatigue strength.
Comparison of Creep Behavior of 2.25Cr-1.6W/Mod. 9Cr-1Mo Dissimilar Weld Joint with Each Matching Filler Metal
Authors: Park Jong Jin , Zhang Xinghong , Kim Jeong Tae , Yu Hyu Sun
Published: March 2009

This paper describes the evaluation of the creep behavior with two types of matching filler metals for 2.25Cr-1.6W(T23)/Mod. 9Cr-1Mo(T91) dissimilar weld joint. Through the welding procedure qualification tests prior to the creep tests, optimum PWHT holding times at 745±5oC were determined as 30minutes for T23 matching filler metal and 60minutes for T91 matching filler metal. It was also confirmed that carbon migration across the weld interfaces and the softened area at HAZ occurred during PWHT. Creep rupture tests were carried out at 575-650oC and 70-220MPa for two dissimilar metal welds manufactured by an optimum PWHT condition. From the comparison of creep rupture strength, it was shown that the creep strength of the welded joint including T23 matching filler metal was similar to that of T23 base material and somewhat higher than that of the welded joint including T91 matching filler metal. From metallurgical study on the crept specimen, the creep
damage of T23/T91 dissimilar weld joints could occur at T23 side IC HAZ and near the T23/T91 weld interface simultaneously. However, the final failure locations seemed to depend on the filler metal and the cause of this phenomenon might be regarded as the additional effect of carbon migration across the weld interfaces. It is thought that the dissimilar weld including T91 filler metal which failures at T23 side CG HAZ subject to both metallurgical notch and carbon migration become more susceptible to creep damage than that including T23 filler metal in which the carbon depletion occurs at the T23 filler metal with higher creep strength than T23 HAZ. T23 filler metal can therefore be proposed for matching filler metal of T23/T91 dissimilar weld joints
Elevated Temperature Mechanical Properties of a Directionally Solidified NiAl/Cr(Mo)-Hf Alloy
Authors: Xu Chun Mei , Guo Jian Ting , Xie Xi Shan
Published: March 2009

The microstructure of directionally solidified (DS) NiAl-28Cr-5Mo-1Hf eutectic alloy was investigated by SEM and TEM. The eutectic alloy is composed of NiAl matrix , Cr (Mo) phase and a small amount of Heusler phase. Tensile testing of this alloy was performed from room temperature to 1373K. The brittle-to-ductile transition temperature (BDTT) is dependent on strain rate, with two orders of increase on strain rate resulting in a100K increase in transition temperature. The observation of fracture surface showed that at temperature above BDTT, the fractograph changes from NiAl cleavage and debonding along NiAl/Cr(Mo) interface boundary to ductile in nature.
An Elastic-Plastic Fracture Behavior of the Interface Using the Property Gradient in MMC
Authors: Kang Ji Woong , Kwon Oh Heon
Published: March 2009

The strong continuous fiber reinforced metal matrix composites (MMCs) are recently used in aerospace and transportation applications as an advanced material due to its high strength and light weight. However, MMC is significantly affected by the interface under the transverse loading. Furthermore, the crack at the interface induces weakness of the characteristics of the overall mechanical response and strength of the MMCs. In order to be able to utilize these MMCs effectively and with safety, it must be determined their elastic plastic fracture behaviors at the interface. The influence of different regular fiber arrangement as like square and hexagonal arrangement on the strength of transversely loaded fiber reinforced matrix is analyzed. And the interface of fiber and matrix is modeled as thin multi layers with properties linearly gradient to distinguish the interface from the fiber and matrix. Different fiber arrangement of square and hexagon type is studied. And fiber volume fraction is changed for several kinds (5%-60%).
Characterization of High Temperature Thermomechanical Fatigue Properties for Particle Reinforced Composites
Authors: Shi Hui Ji , Zheng Ya-Xiong , Guo Ran , Mesmacque Gerard
Published: March 2009

Voronoi cell finite element method (VCFEM) is introduced in this paper to describe the elastic-plastic-creep behavior of particle reinforced composites. The interfacial damage is simulated by partly debonding between Matrix and inclusion. A validation of the nonlinear behavior of the cell element has been carry out by comparing VCFEM results with those calculated by the general finite element package MARC and ABAQUS, and good agreements are found. A microstructure with five inclusions is taken as an example to describe the cyclic stress-strain behavior under different particulate orientation condition, and it shows the influence of the topological microstructure of inclusions. Thermomechanical fatigue properties are also investigated and the loops of stress-strain show the great differences of fatigue behavior between the in-phase case and out-of-case.
Strength Characteristics and Deformation Behavior of Aluminum Honeycomb Sandwich Plates under Three-Point Bending Loads
Authors: Kim Hyoung Gu , Choi Nak Sam
Published: March 2009

The strength characteristics as well as local deformation behaviors of honeycomb sandwich composite (HSC) structures under three-point bending loads were investigated in consideration of various failure modes such as skin layer yielding, interface-delamination as well as shear deformation and local buckling in the core layer. Various types of aluminum honeycomb core and skin layer were used for this study. Their finite-element simulation was performed to analyze stresses and deformation behaviors of honeycomb sandwich plates. The results were very comparable to the experimental ones. Consequently, thicker skin layer, smaller cell size of honeycomb core and less delamiantion had dominant effects on the improvement in strength and deformation behaviors of honeycomb sandwich plates.
Influences of Isotropic and Anisotropic Material Properties on Stress Intensity Factors of the Crack Tip under Biaxial Stress
Authors: Shimomura Taku , Shimamoto Akira , Nemoto T. , Yoneyama Satoru
Published: March 2009

In order to clarify the effect of anisotropy on local deformation and the stress intensity factors in the vicinity of the crack tip under complicated stress states, biaxial loading tests were carried out on isotropic (Photoelastic sheet: PSM-1, Measurements Group, Inc) and anisotropic (LEXAN 9030, General Electric Company) polycarbonate materials. The biaxial dynamic loading device, which was developed by the authors, was fully utilized in the experiments. We carried out the experiments using isotropic and anisotropic specimens with a pre-processed 0°, 15°, 30°, 45°, 60°, 75° or 90° crack angle. We applied the equal biaxial stress, that is, the loads for both the Y- and X-axis as 0N : 0N-3920N : 3920N (1 : 1). We determined the stress intensity factors of specimens using both photoelasticity and caustics method. The results of the experiments were compared. As a result, when the materials with anisotropic property are used as machine or structural members, it is important to consider the extrusion direction of the material in their design.
Fatigue Life Prediction of the Vulcanized Natural Rubber
Authors: Woo Chang Su , Kim Wan Doo , Kwon Jae Do , Kim Wan Soo
Published: March 2009

Fatigue lifetime prediction methodology of the vulcanized natural rubber was proposed by incorporating the finite element analysis and fatigue damage parameter determined from fatigue test. Finite element analysis of 3D dumbbell specimen of natural rubber was performed based on a hyper-elastic material model determined from the tension, compression and shear tests. Stroke controlled fatigue tests were conducted using fatigue specimens at different levels of mean strain. The Green-Lagrange strain at the critical location determined from the FEM was used for
evaluating the fatigue damaged parameter of the natural rubber. It was shown that the maximum Green-Lagrange strain was proper damage parameter, taking the mean strain effects into account. Fatigue lives of the natural rubber are predicted by using the fatigue damage parameters at the critical location. Predicted fatigue lives of the natural rubber agreed fairly well the experimental fatigue lives a factor of two.
Effect of Mode Mixty on Interfacial Fracture Toughness of Si/Organic Polymer
Authors: Yamazaki Hirofumi , Enoki Manabu
Published: March 2009

Recently, the organic polymer films attract attention as promising dielectric films which reduce environmental burdens and inhibit RC-delays. It is very important to understand its mechanical properties. In the previous studies, we could evaluate its reliability by measuring the interfacial energy release rates during the peeling under various conditions. So in this study, we applied this method to several types of specimens. Then, the phase angle effect on interfacial toughness and its contributions were considered by analyzing the results. In addition, we derived fracture criterion in order to feed back to manufacturing process. SiLK (trademark of the Dow Chemical Company) was selected as dielectric material. We prepared two types of specimens. One consists of spin-coated SiLK layer sandwiched between Si substrates using adhesion bond (adhesion bond specimen). The
other is made by the following process; at first, two Si substrates with spin-coated SiLK were swelled in solvent. Then, their SiLK faces were pressured and heat cured in oven (thermal pressure bond specimen). Four points bending and DCB tests were performed. Crack path was identified using SEM observation and ESCA analysis in addition to the mechanical test. From the results under different mode mixty condition, the existence of phase angle effect on facial fracture toughness was studied out. Its primary factors were due to bridging of SiLK layer and plastic deformation of SiLK layer and/or adhesion bond layer. Moreover, we evaluated the fracture criteria under several conditions using an ellipse approximation.
Evaluation of Nuclear Piping Failure Frequency in Korean Pressurized Water Reactors
Authors: Choi Sun Yeong , Choi Young Hwan
Published: March 2009

The purpose of this paper is to evaluate the piping failure frequency based on the piping failure events in Korean pressurized water reactors (PWRs) until the end of 2003. Two types of the piping failure frequencies including the piping damage frequency and the piping rupture frequency are considered in this study. The piping damage frequency for the failed piping system was estimated by using the piping population data such as the weld count or the base metal count. The piping rupture
frequency related to the initiating event in a probabilistic safety assessment (PSA) was evaluated by using both the Bayesian approach (Method 1) and the conditional rupture probability approach (Method 2). In the Bayesian approach, two methods using Jeffreys noninformative prior (Method 1-1) and prior distributions based on the results in NUREG/CR-5750 (Method 1-2) were considered. Thirty piping failure events in ASME safety class pipings of Korean PWRs were identified and analyzed in this study. The results showed that the piping damage frequency for the events ranged from 5.42E-3/cr.yr to 2.77E-5/cr.yr. Three kinds of initiating events including the very small LOCA, the feedwater line break, and the flood are evaluated for Korean PWRs. The results for the piping rupture frequency in Korean PWRs were as follows: 1) The mean piping rupture frequency of the very small LOCA event ranged from 3.6E-3/cr.yr to 1.2E-2/cr.yr, the feedwater line break event from 3.6E-3/cr.yr to 2.5E-2/cr.yr, and the flood event from 7.8E-4/cr.yr to 3.6E-3/cr.yr. The mean piping rupture frequencies of the very small LOCA and feedwater line break events were higher than that of the flood event by one order of a magnitude. 2) Method 2 gave conservative results in the very small LOCA and feedwater line break events compared to Method 1-1 or Method 1-2, while Method 1-1 gave conservative results in the flood event. 3) The order of magnitudes in the mean piping rupture frequencies of the very small LOCA, the feedwater line break, and the flood in Korean PWRs were similar to those in the U.S. PWRs.
Alternative Fatigue Evaluation of Nuclear Piping Designed by ANSI B31.1 Code
Authors: Park Young Jae , Chang Yoon Suk , Choi Jae Boong , Kim Young Jin
Published: March 2009

Class 1 piping components of a certain old vintage nuclear power plant were designed by ANSI B31.1 code without a detailed fatigue evaluation such as the one required by recent ASME Section III code. These components may undergo fatigue damage when considering the continued operation beyond the design life whilst the inherent fatigue resistances of those may satisfy the corresponding implicit limits. In this paper, the alternative fatigue evaluation has been carried out explicitly for Class 1 piping of old nuclear power plant. At first, four representative nuclear piping systems were selected to check the operational adequacy. After characterization of conservative loading conditions based on design features, a series of finite element analyses have been performed and the cumulative usage factors were calculated to guarantee if the components at each system sustain adequate fatigue resistance. Finally, comparisons were drawn between the implicit fatigue design specifications and alternative explicit fatigue analysis results. Even though there were some exceptions, it was demonstrated that most components satisfied the current explicit fatigue criterion.
Surface Crack Behavior in Socket Weld of Nuclear Piping under Fatigue Loading Condition
Authors: Choi Young Hwan , Choi Sun Yeong , Kim Jin Su
Published: March 2009

The ASME B & PV Code Sec. allows the socket weld for the nuclear piping in spite of the weakness on the weld integrity. Recently, the integrity of the socket weld is regarded as a safety concern in nuclear power plants because many failures and leaks have been reported in the socket weld. OPDE (OECD Piping Failure Data Exchange) database lists 108 socket weld failures among 2,399 nuclear piping failure cases during 1970 to 2001. Eleven failures in the socket weld were also reported in Korean NPPs. Many failure cases showed that the root cause of the failure is the fatigue and the gap requirement for the socket weld given in ASME Code was not satisfied. The purpose of this paper is to evaluate the fatigue crack behavior of a surface crack in the socket weld under fatigue loading condition considering the gap effect. Three-dimensional finite element analysis was performed to estimate the fatigue crack behavior of the surface crack. Three types of loading
conditions such as the deflection due to vibration, the pressure transient ranging from P=0 to 15.51MPa, and the thermal transient ranging from T=25oC to 288oC were considered. The results are as follows; 1) The socket weld is susceptible to the vibration where the vibration levels exceed the requirement in the ASME Operation and Maintenance (OM) Code. 2) The effect of pressure or Temperature transient load on the socket weld integrity is not significant. 3) No-gap condition gives very high possibility of the crack initiation at the socket weld under vibration loading condition. 4) For the specific systems having the vibration condition to exceed the requirement in the ASME Code OM and/or the transient loading condition from P=0 and T=25oC to P=15.51MPa and T=288oC, radiographic examination to examine the gap during the construction stage is recommended.
Analysis of Cracking and Delamination of Sputtered Thin Films during Wear Process
Authors: Nakasa Keijiro , Setyanto Taufiq Arif , Zhang Bo , Zheng Jin Hua , Kato Masahiko
Published: March 2009

Pure titanium substrate specimen was sputter-coated with SiC or CoCrNi-oxide thin film and the wear test was carried out by using a “ball-on-disk” type testing machine. The semi-circular parallel cracks appeared on the film surface with angles of 45 degree to the sliding direction of the SiC ball and the delamination of film quickly occurred after the cracking. With the aid of finite element methods, stress distribution before and after cracking in the film was obtained. The maximum tensile
stress existing in the film at the back-contact edge of ball is the reason for the initiation of semi-circular parallel cracks. After the film is cracked, the tensile stress normal to interface as well as the shear stress along interface appear at crack tip. The combination of these two stresses is the main reason for the delamination after the film is cracked.
Compression Characteristics of Paper and Coated Paper
Authors: Hwang Jae Jung , Adachi Tadaharu , Araki Wakako , Yamaji Akihiko
Published: March 2009

We experimentally investigated compressive behaviors of a paper and a paper coated by polyethylene resin. The initial thickness of sheets of paper measured under a compressive stress of 4.5kPa was widely distributed in comparison with the basis weight, although the results based on the ISO 534 standard (under compressive stress of 100kPa) had relatively little dispersion. For compressive deformation, the thickness immediately decreased under low compressive stress,
because the gap between fibers in the paper collapsed. After that, the variation of the thickness under higher compression was small due to the compression of fibers. We found that although the resin-coat layers did not have an insignificant effect on compressive compliance above 250kPa, the compliance of the coated paper was larger than that of uncoated paper.
A Study on Automatic Belt Tensioner Life Evaluation in Accessory Belt System
Authors: Jung Do Hyun , Bae Sung In , Phark Joung Woo
Published: March 2009

It is well-known that the noise and vibration from the torque change of the engine and the inertia change of its accessories (alternator and water pump) have severe effects on both the quality and the life expectancy of the engine belt system. An automatic belt tensioner is generally used not only to reduce the noise and vibration of such belt system, but also to enhance the life cycle. In the present research, measurement of the user running conditions and the data analyses were performed to try to derive an evaluation method of life cycle of such an automatic belt tensioner system. As a part of results, a running condition for the evaluation was suggested from the study of conditions loaded on an automatic belt tensioner. This running condition was divided into two parts, the Structure part and the Pulley one, and suggested separately for the accelerated life-test of the system. As the other part of the results, an accelerated life-test condition was derived using Palmgen-Miner rule for structure part. And a modified accelerated life-test condition, which uses temperature as an acceleration factor, was suggested for pulley part.
Reliability Evaluation of Hinges Used in Electronic Communication Devices
Authors: Lee Tae Hun , Jhang Kyung Young
Published: March 2009

The hinge, which is used in various folders of electronic communication devices, damages easily due to the repeated impact-like stress that occurs when the folder is opened. The hinge damage not only affects the lifetime of devices, but it may cause to lose the reputation of the brand name of the company. In this paper, the total process for the life evaluation and failure analysis of this part is proposed. For this, the mechanism of the hinge motion was analyzed first to calculate the force acting on the hinge. Also an automatic durability test system was developed to repeatedly open and shut the folder. Then the change in deformation around the hinge was monitored using an Electronic Speckle Pattern Interferometer (ESPI) method, as the repetition number increased for the opening of the folder. ESPI results showed that the deformation was concentrated at the hinge and it increased
according to the increase of repetition number of folder opening. Finally, we evaluated the life of the hinge through an accelerated life test (ALT). ALT results showed that the life of hinge was dependent on the force acting on the hinge