bluuebunny/crossref_metadata_2025 huggingface dataset:
The Evolution of Contact Stress and Surface Profile in Press-Fitted Shaft under Partial Slip Conditions
Authors: Lee Dong Hyung , Kwon Seok Jin , Lee Chan Woo , Choi Jae Boong , Kim Young Jin
Published: March 2009

In this paper the fretting wear of press-fitted specimens under partial slip conditions was simulated using finite element method and numerical analysis based on Archard's equation. An elasto-plastic analysis of contact stresses in a press-fitted shaft in contact with a boss was conducted with finite element method and the amount of microslip and contact pressure due to bending load was estimated. The predicted wear profile of press-fitted specimens at the contact edge was compared with the experimental results. It is found that the depth of fretting wear by repeated slip between shaft and boss reaches the maximum value at the contact edge. The initial surface profile is continuously changed by the wear at the contact edge, and then the corresponding contact stresses and strain are redistributed.
Statistical Analysis of Casting Defects in Microstructure for Understanding the Effect on Fatigue Property of 17-4PH Stainless Steel
Authors: Kim Jong Yup , Lee Joon Hyun , Nahm Seung Hoon
Published: March 2009

High strength materials have been used for critical components in order to ensure the reliability of aircraft gas turbine engine. But it usually costs high to maintain their premium quality. Therefore, the optimum quality level of materials should be defined under operating condition by material property estimation technique in order to meet the requirement of reliability and economical efficiency. Most cast rotating parts of gas turbine engine have casting defects caused during the casting process. The casting defects less than certain acceptable limit can be permissible for usage. So, it is very important to understand material defect shape and distribution, and its effect on mechanical properties exactly. In this study, 17-4PH stainless steel specimens with variable internal casting defects were prepared to investigate the fatigue property characteristics. The defect fraction and condition were estimated in microstructure by statistical analysis. The correlation between estimated defect condition and fatigue property was discussed.
Dynamic Analysis and Fatigue Life Prediction of a Very Flexible Component in Multibody System
Authors: Yoon Ji Won , Jun Kab Jin , Park Tae Won
Published: March 2009

Recently, the finite element absolute nodal coordinate formulation(ANCF) was developed
for large deformation analysis of flexible bodies in multi-body dynamics. This formulation is based
on finite element procedures and the general continuum mechanics theory to represent elastic forces.
In this paper, a computational method, which predicts the dynamic and structural properties of a very
flexible beam in a multibody system, is presented based on Euler-Bernoulli beam theory and ANCF.
In order to consider the dynamic interaction between a continuous large deformable beam and a rigid
multibody system, a combined system equations of motion was derived by adopting absolute nodal
coordinates and rigid body coordinates. The efficiency and reliability of the computational results are
verified by comparison with a commercial program. These methods can be applied for predicting the
dynamic stress and fatigue life of the wire harness used in a robot system. The process of predicting
the fatigue life using the proposed method in this paper may be applied to continuous mechanical
parts of various dynamic systems.
Optical Emission Spectra Related to Microstructures of Diamond Film Deposited by Plasma Enhanced Chemical Vapor Deposition
Authors: Noda Mikio , Umeno Masayoshi , Kim Hee Joon
Published: March 2009

Optical emission spectra from plasma during deposition of diamond film were investigated
by an optic multi-channel spectrometer using a CCD array sensor. The diamond film was deposited by
DC plasma enhanced (PE) chemical vapor deposition (CVD) using hydrogen and methane gas
mixture, where substrate was located at near the plasma and the discharge was performed by
intermittent discharge. When Pg during the deposition was increased from 50 to 250 Torr, the optical
emissions of hydrogen (Hα and Hβ) and C2 were increased, and corresponding to these increases,
deposition rate of the diamond film was increased and crystalline quality became superior. When Cm
was changed from 1 to 3 %, the emission from C2 was increased, and whereas, the emission from
hydrogen was decreased. Corresponding to these changes of the emission, the deposition rate of the
film was increased and amorphous component in the deposited film was also increased. These results
show that the increase of C2 results in the increase of the deposition rate, and increase of hydrogen is
effective to eliminate amorphous component, and therefore, monitoring of the optical emission from
hydrogen and C2 is useful for the deposition process of the diamond film.
Monitoring of a Steel Plate Girder Railroad Bridge with Fiber Bragg Grating Sensors
Authors: Chung Won Seok , Kang Dong Hoon , Choi Eun Soo , Kim Hyun Min
Published: March 2009

This study investigates an existing steel plate girder railroad bridge in order to monitor
static and dynamic responses using fiber Bragg grating (FBG) sensors. This paper also presents an
experimental technique to estimate the vertical deflection of the bridge using FBG sensors. Seven
FBG sensors are multiplexed in a single optical fiber and installed in parallel pairs along the length of
the bridge, with one set on the top flange and the other on the bottom flange. The train passes over the
bridge at different speeds, ranging from 10 km/h to 90 km/h, so as to monitor the dynamic response of
the bridge. The results show that the proposed instrumentation technique is capable of estimating the
deflection of the bridge for various loading conditions, which is crucial in structural monitoring.
A Model to Predict Phased Array Ultrasonic Testing Signals from a Flat-Bottomed Hole in Two Medium
Authors: Song Sung Jin , Park Joon Soo , Kim Hak Joon , Seong Un Hak , Kang Suk Chull , Choi Young Hwan
Published: March 2009

In this study, the expanded multi-Gaussian beam model is adopted to develop a model to
calculate the ultrasonic beam fields radiated from an ultrasonic phased array transducer. Combining
this beam model with three other components including time delays, a far-field scattering model and a
system efficiency factor, we develop a complete ultrasonic measurement model for predicting the
phased array ultrasonic signals that can be captured from a flat-bottom hole in a steel specimen in a
pulse-echo set-up using an array transducer mounted in a solid wedge. This paper describes the
complete model developed with its key ingredients.
Simultaneous Measurement of Longitudinal and Transverse Waves Velocities Employing Spherically Focused Acoustic Transducer
Authors: Kim Noh Yu , Lee Cheol Kyou
Published: March 2009

Scanning acoustic microscopy (SAM) has been applied successfully to measure leaky
surface wave(LSAW) velocity from V(z) curve for material characterization. Besides LSAW, SAM
produces a variety of wave modes in the material propagating with different phase speeds and features,
one of which is the mode-converted ultrasound. In this paper, a novel method for simultaneous
measurement of longitudinal and transverse acoustic wave velocities using the mode-converted
ultrasound is developed and studied at SAM. Each ultrasound arriving at the acoustic lens with
different speed and phase (or time-of-flight (TOF)) is measured by the defocused transducer to
calculate longitudinal and transverse wave velocities. Simple mathematical ray analysis for the mode
conversion is conducted to determine the relationship of acoustic velocities with TOF of the waves in
plate. Experimental results for metals and glass show that the longitudinal and transverse wave
velocities measured by the proposed method are as accurate as maximum 3% in error.
Evaluation of Corrosion Fatigue Characteristics of Artificially Sensitized Austenitic Stainless Steel Using the DCPD Method
Authors: Bae Dong Ho , Choi Byung Bok , Lee Gyu Young
Published: March 2009

Austenitic stainless steel has a large problem to decrease its corrosion resistance and
mechanical properties by sensitization in the welding process. Thus, in this paper, corrosion fatigue
characteristics of artificially sensitized STS304 were investigated. According as heat treatment
period for sensitization increases, the Cr-carbide deposition in the grain boundary and degree of
sensitization (Ia/Ir) increased. From the results, corrosion fatigue strength of sensitized STS304 was
remarkably reduced compare to non-sensitized ones.
Tribological Performance of Multi-Walled Carbon Nanotubes in Mineral Oils under Boundary Lubricated Sliding
Authors: Baik Seung Hyun , Lee Kyu Sun , Yoon Do Kyung , Lee Young Ze
Published: March 2009

The tribological performance of multi-walled carbon nanotubes (MWNT) in mineral oils is investigated at ambient temperature. The frictional forces, wear amounts and cycles to scuffing of the oils with nanotubes and without those were measured using the ball-on-disk tester. It was found that there were little differences in the frictional forces and wear amounts of two oils. However, the scuffing times of oils with nanotubes were much longer than those of oils without nanotubes in sliding tests. The nanotubes were very effective on maintaining the oil gap and protecting the surfaces in boundary lubricated sliding.
Plastic Limit Loads for Through-Wall Cracked Pipes Using Finite Element Limit Analysis
Authors: Huh Nam Su , Chang Yoon Suk , Kim Young Jin
Published: March 2009

The present paper provides plastic limit load solutions for axial and circumferential
through-wall cracked pipes based on detailed three-dimensional (3-D) finite element (FE) limit analysis
using elastic-perfectly plastic behavior. As a loading condition, both single and combined loadings are
considered. Being based on detailed 3-D FE limit analysis, the present solutions are believed to be
valuable information for structural integrity assessment of cracked pipes.
Degradation Depth Measurement of Polycarbonate Used by Castfilm Method
Authors: Nemoto Tetsuya , Matsuura Hiroyuki , Nakano Masahiro , Shimamoto Akira
Published: March 2009

The effect of hydrolysis of polycarbonate on tensile behavior were investigated.
The specimens were exposed in a chamber at constant room temperature and water for 300 hours,
and measurements were made on the variation of weight and tensile properties. In addition,
the increase and decrease of the carbonate part was measured with an ultraviolet spectroscopy.
The results are as follows: It was confirmed that it was effective to the examination of the influence of
the diffusion of water with an overlay castfilm. It has been understood to the diffusion of water from
the surface layer has diffused at the same time by about 6μm, and it has diffused gradually
when it is deeper than 6μm. The change in the tensile behavior by the hydrolysis
was able to be confirmed by observing the carbonate part of the polycarbonate. It became clear,
the break strain has decreased because the carbonate part is taken apart by the hydrolysis.
Afterwards, the break strain steadies by constructing a bridge, and the yield stress increases.
Analysis of Thermal Distribution for LCD-TV Using Infrared Camera
Authors: Oh Seok June , Chung Du Hwan , Ko Han Seo
Published: March 2009

Demand of a LCD-TV is remarkably increasing with development of the LCD technology
in these days. However, there are thermal problems to improve efficiency for the LCD-TV. Thus, the
thermal problems such as convection and conduction heat transfer characteristics have been analyzed
for the LCD-TV using an IR (Infrared) camera. Measured temperatures in an outer side of the front
panel have been compared with results of an inner side of the front panel using the IR camera and
T-type thermocouples, respectively. Equations have been derived for the temperature distribution of
the inner side of the LCD panel by developed multiple regression methods including variables for
ambient temperatures and measured outer temperatures of the front panel of the LCD-TV.
Impact Characteristics and Damage Detection of Woven Carbon/Epoxy Laminates for Car Body Structures of a Tilting Train
Authors: Lee Jae Heon , Cheong Seong Kyun , Kim Jung Seok , Eum K.Y.
Published: March 2009

Recently, the use of composite material to railway vehicles is gradually increasing due to its light weight. The concept of light weight design will be very helpful for the tilting train to travel around a curve at a faster speed because the light weight car body makes the center of gravity lower. The impact characteristics of composite materials should be investigated because the impact property of composites is very important for the design and repair of a tilting train. This paper investigates the low-velocity impact and damage characteristics conducted on woven carbon/epoxy laminates for a tilting train. Low-velocity impact tests were carried out at different energy levels on woven type of laminates using a drop-weight apparatus. The impact-induced delaminations are examined by ultrasonic technique such as C-Scan. Those delaminations are also examined by laser technique such as ESPI (Electronic Speckle Pattern Interferometry). Experimental results show that the type of damage is dependent on the impact energy level and the delamination area becomes larger as the impact energy increases.
The Stress Concentration Factor (Kt) and Fatigue Crack Behavior on the Relative Defect Location in Monolithic Aluminum versus GLARE
Authors: Kim Cheol Woong , Kim Kwang Lae , Lee Won Pyung , Lee Sung Hyuk , Heo Seok
Published: March 2009

To analyze the stress distribution and the crack initiation due to the location of the defects,
artificial defects were made on the different locations of the high strength monolithic Al and GLAss
fiber REinforced laminate (GLARE). Experimental study shows that the defect location in the
vicinity of the circular hole was changed from ° = 90 4 θ to ° = 0 1 θ , the stress concentration was
increased. The stress concentration of GLARE was about 15% higher than that of the monolithic Al.
When the defect was at ° = 30 2 θ , Multi Site Damage (MSD) crack was found in the monolithic Al but
not in GLARE. Instead of MSD crack, a delamination was made in GLARE and that it resulted in the
prevention against the second crack initiation.
A Numerical Study and Design of Turbine Blade under High Temperature and Rotational Speed Using FEM
Authors: Lee Jang Hyun , Lee Kyung Ho , Kim Kyung Su
Published: March 2009

The turbine wheels of a turbocharger are operated at high revolution speed in high temperature inlet gas. Alloy 713LC blades of the turbine wheel broke in an hour the during a model test. Two failures and several cracks were found in the turbine blades. Failures in blades are suspected to occur as a result of thermal mechanical stresses or fatigue load and other cause such as creep-rupture and resonant vibration. The present study investigates the possible causes of the failure of these blades. FEM (Finite Element Method) was used to calculate the thermal centrifugal stresses and natural frequency to find the cause of failures. LCF (Low Cycle Fatigue) life of blades was roughly estimated by using the stress and strain level calculated by FEM. The investigation indicates that the failures were associated with resonant forces and HCF (High Cycle Fatigue).
Experimental and Numerical Study on the Melting Acceleration of Phase Change Material by Ultrasonic Vibrations
Authors: Oh Yool Kwon , Yang Ho Dong
Published: March 2009

The present study was investigated on the melting phenomena and the accelerative factors
of phase change material (PCM) by acoustic streaming induced ultrasonic vibrations. To investigate
the melting phenomena and accelerative factors, the experimental study was measured the liquid
temperature and melting time of PCM and was observed the velocity vectors and thermal fluid flow
induced acoustic streaming to investigate the heat transfer using particle image velocimetry (PIV) and
infrared thermo vision camera, respectively. Also, the numerical study based on a coupled finite
element-boundary element method (Coupled FE-BEM) was performed to investigate the analysis of
pressure field in the PCM. The results of experimental works revealed that acoustic streaming
observed by PIV and infrared thermo vision camera is one of the prime effects accelerating phase
change heat transfer. And, the final temperature of PCM is lower and melting speed is 2.6 times faster
than that without ultrasonic vibrations when ultrasonic vibrations are applied. The results of
numerical work presented that acoustic pressure is higher near the ultrasonic transducer than other
points where no ultrasonic transducer was installed and develops more intensive flow such as acoustic
streaming, destroying the flow instability. Moreover, the profile of acoustic pressure variation is
consistent with that of enhancement of heat transfer.
On the Progressive Buckling Behaviour of Power Screw Actuators
Authors: Cricca Gianluca , Molari Pier Gabriele , Morelli Piero
Published: March 2009

This paper presents the results of an experimental investigation on the failure behaviour of power screw linear actuators subjected to very high compressive loads. Quasi-static tests performed in laboratory have shown the presence of primary and secondary buckling failure modes. On the one hand the primary buckling is characterized by plane deflection of the inner screw, on the other hand the secondary buckling involves either spatial buckling, forcing the screw to assume a helical shape, or plane buckling of the external arm, in relation to the actual slenderness and the position of the actuator. Non linearities of the axial stiffness have been observed during the proportional phase of loading, as a consequence of the superposition of primary buckling and the lateral constraint effect opposed by the cylindrical case of the actuator to the bending deformation of the screw. Maximum deflections and longitudinal deformations have been measured as a function of the applied compressive load, whose axial and bending components have been calculated. A mathematical model of the elastic loss of stability has been developed, in order to calculate the critical load as a function of the actuator geometry.
Influence of Residual Stresses on Threshold Values for Crack Propagation Through an Interface Between Two Materials
Authors: Náhlík Luboš , Hutař Pavel , Knésl Zdeněk
Published: March 2009

The article deals with the behaviour of a fatigue crack propagating across a bi-material
interface. A stability criterion for the crack touching the bi-material interface, taking into account the
residual stresses closing the crack faces is formulated. The linear elastic fracture mechanics is
assumed to apply and the finite element method is used in the calculations. The criterion proposed is
applied to determine the fatigue threshold stress for crack propagation across the interface. It is shown
that the threshold values for crack propagation are influenced by the residual stresses closing the crack
and by the specific combination of the elastic constants of the materials used. The results contribute to
a better understanding of the failure of structures with bi-material interfaces (protective layers,
composite materials, etc.).
Percolation-Relaxation Model with Critical Damage for Describing the Dynamic Tensile Spall of Ductile Metals
Authors: Wang Yong Gang , He Hong Liang , Wang Li Li , Jing Fu Qian
Published: March 2009

In the framework of percolation theory, a simple void-coalescence model combined with
the constitutive relations for describing the stress relaxation and material softening during the
void-coalescence process, name as the percolation-relaxation (P-R) model, is proposed to describe
the dynamic tensile spallation of ductile metals. A critical damage is introduced and coupled into the
model to identify the onset of the void coalescence. Mesoscopically, the critical damage
corresponds to the critical intervoid ligament distance (ILD), indicating the start of transition from
the void-growth to the void-coalescence.
Fatigue Strength Evaluation of the Load-Carrying Cruciform Fillet Welded Joints Using Hot-Spot Stress
Authors: Noh Byeong Wook , Song Jung I. , Bae Sung In
Published: March 2009

In this study, fatigue strength of load-carrying cruciform fillet welded joints were evaluated
using a new method proposed by Yamada, for geometric or structural stress in welded joint, that is,
one-millimeter stress below the surface in the direction corresponding to the expected crack path.
Validity of the method is verified by analyzing fatigue test results for load-carrying cruciform welded
specimens has different size of weld toe radius, leg length and plate thickness reported in
literature. Structural stress concentration factor for 1mm below the surface was calculated by finite
element analysis for each specimen respectively. When compared to the basic fatigue resistance curve
offered by BS7608, the one-millimeter stress method shows conservative evaluation for load-carrying
cruciform fillet welded joints.
Fracture Analysis on the Interface Crack of Concrete Gravity Dam
Authors: Chen Zhong Hui , Feng Jing Jing , Li Li , Xie He Ping
Published: March 2009

Some numerical parameters-sensitivity analysis has been conducted to evaluate the
stability and propagation of the interface cracks at heel of concrete gravity dam. In this paper,
utilizing the software ANSYS to simulate the stress and displacement fields of the tip of the
interface cracks between concrete gravity dam and foundation, the stress intensity factor (SIF) of
the interface crack is analyzed using facture mechanics. Three impacting factors have been
discussed, such as the crack length, the angle of crack, and the water height. Critical length and
loads of interface crack propagation are obtained using composite fracture criteria. The results
indicate that the coarse interface retards the propagation of interface crack, and redounds to stability
of gravity dam. It is found that the interface crack often propagates alone the interface between dam
and foundation, simultaneously the branch crack kinks to foundation at the specific condition.
Finite Element Analysis for the Fatigue Behavior of Steel Plates Strengthened with CFRP Plates
Authors: Yun Zheng , Ye Lie Ping , Lu Xin Zheng , Yue Qing Rui
Published: March 2009

The experimental research on six steel plates strengthened with CFRP plates, loaded in
tension, shows that their fatigue lives can be greatly increased compared with un-strengthened
specimens. Linear elastic fracture mechanics (LEFM) is adopted to explain the mechanism of CFRP
plates strengthening. The stress intensity factors of the steel plates are calculated with finite element
method (FEM), and Paris law on crack propagation is used to predict the fatigue life of strengthened
specimens. The comparison between experimental results and numerical predictions shows good
agreements on the fatigue crack propagation.
Failure Modes and FEM Analysis of Microelectronic Packaging
Authors: Lu Guo Yun , Hu Da Yong
Published: March 2009

Based on the theory of thermo-elasticity mechanics, the finite element numerical simulation models have been established for the package bulging process. The mechanism of the interfacial void evolution is postulated. By taking the interface strength as function of process (moisture and temperature), it shows that the critical stress that results in the unstable void growth and delamination at the interface is significantly reduced and becomes comparable to the magnitude of the vapor pressure. The simulation result can make us understand the mechanism of the void-growth at the interface framework and provide data base for improving reliability of package and optimum design
Influence of Microstructure on the Fracture Mechanism and Mechanical Behavior in 7010 and 7150 Alloys
Authors: Fan Xi Gang , Jiang Da Ming , Wang Chang Li , Guo Yong Liang , Liu Xing Qiu
Published: March 2009

The effect of ageing treatment and coarse intermetallic particles on the compromise between the toughness and the yield strength of 7010 and 7150 aluminum alloys (Al-Zn-Mg-Cu alloys) are investigated. Plane-strain fracture toughness tests were performed on the compact-tension specimens of L-T orientation. The fracture toughness of 7010 alloy was higher than that of 7150 alloy at the same ageing treatment. The 7150 alloy contain a greater amount of coarse Cu-bearing particles, which deteriorate the fracture behavior and decrease the ageing hardening ability of the alloy. The toughness of the both alloys increased greatly for the overaged condition as compared to that for the T6 condition. Two dominant mechanisms of failure occur: microvoid-induced transgranular fracture and intergranular fracture modes, and the former becomes more important in the overaged ageing conditions.
The Study of Fatigue Life of the Crack of Weld Bead
Authors: Li Dong Xia , Mei Ying , Jia Fang , Jia Bao Chun
Published: March 2009

The effects of multiple repairing-weld and TIG-dressing on the fatigue property of high
strength steel weld joints used in platform have been investigated. Through the fatigue tests on high
strength steel welded joint samples, the life estimating formula is obtained after each time of
repairing weld and TIG-dressing. The S-N curve and the equation after repairing weld and
TIG-dressing are given. The work in this paper offers an important basis for the multiple
repairing-weld of platforms.
Effects of Polypropylene Fiber on Plastic Shrinkage Crack and Mechanical Properties of Concrete
Authors: Li Xue Ying , Zhao Jing , Wang Wei Zhe , Jiang Alan
Published: March 2009

This paper reports on the mechanical properties and plastic shrinkage crack of concrete
containing modified polypropylene fibera kind of new porous polypropylene fiber. Results of
crack properties tests show that after adding modified polypropylene fiber, crack area, maximum
crack width and average crack width of concrete decreased markedly. Results of mechanical
properties show that flexural and splitting tensile strength of concrete with 1.0‰ modified
polypropylene fiber volume fraction at 28 days increased 24% and 28% respectively compared to
the reference concrete; Reticulate polypropylene fiber has less effects than modified polypropylene
fiber on flexural and splitting tensile strength. Compressive strength of fiber reinforced concrete
changed slightly, but flexural strength and splitting tensile strength increased, and the ratio of
splitting tensile strength to compressive strength decreased.
Damage Mechanisms in Polymer Matrix Composites in Extreme Environments
Authors: Kumosa Maciej S.
Published: March 2009

In this work, potential problems with the application of polymer matrix composites
(PMC) in extreme environments [1] is discussed. Then, two specific examples of the applications of
PMCs in high voltage [2-7] and high temperature [8-15] situations are evaluated. The first example
deals with damage evolution in high voltage composite insulators [2-7] with PMC rods subjected to
a combined action of extreme mechanical, electrical and environmental stresses. These insulators
are widely used in transmission line and substation applications around the world. Subsequently,
advanced high temperature graphite/polyimide composites [8-15] are evaluated for aerospace
applications. The composite investigated in this project were used to manufacture and successfully
test a Rocket Based Combined Cycle (RBCC) third-generation, reusable liquid propellant rocket
engine, which is one possible engine for a future single-stage-to-orbit vehicle [8].
Dynamic Damage and Microscopic Analysis of Frozen Aeolian Soil in the West of Liaoning Province
Authors: Zhang Shu Guang , Zhang Xian Dong
Published: March 2009

In order to study the dynamics property and damage evolution of frozen aeolian soil in the
west of Liaoning Province, laboratory test have been done by using the DDS-70 dynamic triaxial test
machine. The damage evolution formula of frozen soil is established, and the dynamic evolution
curve between damage variable and strain is sketched. The research results show that the process on
damage of frozen soil can be divided into three stages, and the increase of damage variable is
non-linear. The speed of damage growth is fast in plasticity damage stage, but the damage growth is
relatively flat and smooth in micro-crack damage stage. Aiming at initial stages of damage in frozen
soil, its microstructure is observed by using scanning electronic microscope (SEM). The occurrence
of interior micro-cracks begins with the middle of sample. From the middle to ends in the sample, the
micro-cracks are in circular growth. Through transfixion and collection of cracks, the inclined cracks
come into being and enlarge step by step.
Bond Strength and Damage of Long Rebar Anchored in HPC under Static and Fatigue Loading
Authors: Xiao Jian Zhuang , Zhang Chuan Zeng , Falkner Horst
Published: March 2009

This paper presents an experimental study on the anchorage behaviour of long
high-strength steel rebars embedded in high-performance concrete (HPC) under both static loading
and fatigue loading. The HPC was designed as C60 with its cube compressive strength larger than 60
MPa, and the high-strength steel bar was adopted as HRB500 with its characteristic yield strength
equals 500 MPa. Under 3×106 fatigue loading cycles and then followed by a monotonous static
loading, the strain and the stress state of the reinforcement bar, and the bond stress between the
concrete and the 700 mm-long bar were investigated. Based on the test results and the ANSYS finite
element analysis, the bond behaviour between HPC and long high-strength steel bars is discussed.
Evaluation of Low-Cycle Fatigue in Simulated PWR Environment
Authors: Jeong Ill Seok , Kim Sang Jai , Song Taek Ho , Hong Sung Yull
Published: March 2009

For developing fatigue design curve of cast stainless steel that is used in piping material
of nuclear power plants, a low-cycle fatigue test rig was built. It is capable of performing tests in
pressurized high temperature water environment of PWR. Cylindrical solid fatigue specimens of
CF8M were used for the strain-controlled environmental fatigue tests. Fatigue life was measured in
terms of the number of cycles with the variation of strain amplitude at 0.04%/s strain rates. The
disparity between target length and measured length of specimens was corrected by using finite
element method. The corrected test results showed similar fatigue life trend with other previous
results.
A Study on the Relationship between Fatigue Crack Growth Behavior and Cyclic Crack Tip Opening Displacement
Authors: Choi Hyeon Chang , Choi Hyeon Ki
Published: March 2009

The relationship between fatigue crack growth behavior and cyclic crack tip opening
displacement is studied. An elastic-plastic finite element analysis (FEA) is performed to examine
the growth behavior of fatigue crack, where the contact elements are used in the mesh of the crack
tip area. We investigate the relationship between the reversed plastic zone size and the changes of
the cyclic crack tip opening displacement along the crack growth. The cyclic crack tip opening
displacement is related to fatigue crack opening behavior.
An Experimental Study on the Corrosion and Fatigue of Structural Steels
Authors: Goo Byeong Choon
Published: March 2009

In general, structural integrity of rolling stock structures should last more than 25 years.
During the lifetime corrosive degradation occurs. For structural design and diagnosis, quantitative
relationship between corrosive degradation and variation of mechanical properties such as tensile
strength and fatigue strength is needed. In this study, electrochemical corrosion tests, atmospheric
corrosion tests and fatigue tests of corroded specimens were carried out. The electrochemical
characteristics of SS400, SM490A, SUS205L and SUS304 were examined. At regular intervals
tensile and fatigue tests were carried out by using specimens of SM490A and SS400 on the
atmospheric corrosion test bed. The fatigue strength decreases as the atmospheric corrosion period
increases. In addition, the effect of heat treatment on the tensile and fatigue behavior was studied.
Experimental Verification of the Structural Damage Identification Method Developed for Beam Structures
Authors: Youn Deokki , Lee Usik , Kwon Oh Yang
Published: March 2009

In this paper, an experimental verification has been conducted for a frequency response
function (FRF)-based structural damage identification method (SDIM) proposed in the previous
study [1]. The FRF-based SDIM requires the natural frequencies and mode shapes measured in the
intact state and the FRF-data measured in the damaged state. Experiments are conducted for the
cantilevered beam specimens with one and three slots. It is shown that the proposed FRF-based
SDIM provides damage identification results that agree quite well with true damage state.
Damage Evolution Inspection of Rock Using Digital Speckle Correlation Method (DSCM)
Authors: Ma Shao Peng , Wang Lai Gui , Jin Guan Chang
Published: March 2009

In order to evaluate the damage evolution of rock under external loading, the surface
deformation field of a rectangle marble specimen is inspected and analyzed using digital speckle
correlation method (DSCM). Experimental results show that the damage evolution of rock
undergoes 3 stages: they are uniformly distributed damage, localized damage and catastrophic
failure stage. A statistic indicator, standard deviation of the strain field, can be used to quantitatively
express the damage localization level.
The Thermal Cyclic Behavior of the VPS and HVOF-Sprayed MCrAlY Coatings
Authors: Jung Jine Sung , Yoo Keun Bong , Kim Eui Hyun , Jeon Chae Hong , Kim Do Hyang
Published: March 2009

Rotating components used in the hot sections of land-based gas turbine are exposed to
severe environment of several ten thousands operating hours above 1100. To protect such
components against high temperature oxidation an intermediate bond coat is applied, typical of a
MCrAlY-type metal alloy. Various processing methods have been studied for bond coat deposition.
This study is concerned with the cyclic oxidation behavior of CoNiCrAlY coatings. Coatings
were deposited by a vacuum plasma spray and high-velocity oxygen fuel method on a nickel-based
superalloy (GTD-111). Cyclic thermal oxidation test condition is at 1100 in ambient air for
various periods of time. Tests were used to evaluate the oxidation resistance of the spray-coated
specimens. The microstructure and morphology of as-sprayed and of tested specimens were
characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD).
The oxide phases formed on the coating surface are NiO, CoCr2O4, and Al2O3. The nickel oxide
of them was to be dominant with increasing cycles. The differences in microstructure and phase
composition in the interface with coating layer are reported. The influence of coating process
methods on coating characteristics and degradation mechanisms is discussed. The HVOF coating
with the splats was more resistant on the high temperature oxidation than the VPS coating.
Experimental and Numerical Study on Enhanced Heat Transfer of Solid-Liquid PCM by Ultrasonic Wave
Authors: Yang Ho Dong , Oh Yool Kwon
Published: March 2009

The present study is investigated the causes of enhanced heat transfer during the melting
process of solid-liquid PCM (Phase Change Material) using an ultrasonic vibration. Paraffin (noctadecane)
was selected as a PCM and experimental studies were performed as following. Heat
transfer coefficient and enhancement ratio of heat transfer was measured, acoustic streaming
induced by ultrasonic waves observed using a PIV (Particle Image Velocimetry) and thermally
oscillating flow phenomenon observed using an infrared thermal camera during the melting process.
For the numerical study, a coupled FE-BEM (Finite Element-Boundary Element Method) was
applied to investigate acoustic pressure occurred by acoustic streaming in a medium. And then, the
profiles of pressure variation compared with the enhancement ratio of heat transfer. The results of
this study revealed that ultrasonic vibrations accompanied the effects like acoustic streaming and
thermally oscillating flow. Such effects are a prime mechanism in the overall melting process when
ultrasonic vibrations are applied. Also, as the acoustic pressure occurred by acoustic streaming
increases, the higher enhancement ratio of heat transfer is obtained.
Development of Industrial SFF System Using a New Selective Dual-Laser Sintering Process
Authors: Lee Won Hee , Kim Dong Soo , Ahn Young Jin , Choi Byung Oh , Choi Kyung Hyun
Published: March 2009

In order to develop more elaborate and speedy system for large objects than existing
selective laser sintering (SLS), this study applies a new selective dual-laser sintering process. It
contains a 3-axis dynamic focusing scanner system for scanning large area instead of the existing fθ
lens. As sintering parameters, the sintering temperature, the laser beam power and the layer
thickness have a great influence on sintering of the polymer and metal powder. This paper will
address the development of a solid freeform fabrication (SFF) system employing the dual laser
system. Experiments were performed to evaluate the effect of a scanning path and to fabricate the
large-sized object.
Wear Scar Progression of Impact-Fretting at Elevated Temperature for Steam Generator Tubes in Nuclear Power Plants
Authors: Park Chi Yong , Lee Jeong Keun
Published: March 2009

Fretting wear generated by flow induced vibration is one of the important degradation
mechanisms of steam generator tubes in the nuclear power plants. Understanding of tube wear
characteristics is very important to keep the integrity of the steam generator tubes to secure the
safety of the nuclear power plants. Experimental examination has been performed for the purpose of
investigating the impact fretting. Test material is alloy 690 tube and 409 stainless steel tube
supports. From the results of experiments, wear scar progression is investigated in the case of
impact-fretting wear test of steam generator tubes under plant operating conditions such as pressure
of 15MPa, high temperature of 290C and low dissolved oxygen. Hammer imprint that is actual
damaged wear pattern, has been observed on the worn surface. From investigation of wear scar
pattern, wear mechanism was initially the delamination wear due to cracking the hard oxide film
and finally transferred to the stable impact-fretting pattern.
Local Heat Transfer Measurements and Numerical Analysis in the Cooling Passage of the Ventilated Disc Brake with Semi-Cylindrically Grooved Surface
Authors: Lee Dae Hee , Lim Chang Yul , Yoon Kyoung Ill , Kim Man Sig , Kim Moon Kyoung , Park Sung Bong , Lee Kwan Soo
Published: March 2009

The local heat transfer measurements in the cooling flow passage having both flat surface
and semi-cylindrically grooved surface geometries inside the automobile disc brake were made. A
uniform wall heat flux boundary condition on both surface geometries was created using gold film
Intrex. Liquid crystal was used to measure the surface temperature. The experiments were made at
Reynolds number (based on the hydraulic diameter of the rectangular duct) of Re=23,000, groove
pitch-to-width (P/D) from 3 to 7, and groove depth-to-width (H/D) from 0.15 to 0.2. The results
show that the magnitudes in the average Nusselt number on the grooved surface are maximum
92.8% higher than those on the flat surface without groove. A computer program utilizing the
coupled FEM numerical technique that can predict the temperature distributions on the disc brake to
analyze the thermal deformation has been developed.
Experimental Performance Verifications for Compound CVT with Differential Gear
Authors: Kim Yeon Su , Park Jae Min
Published: March 2009

For the designed and manufactured compound CVT that can improve the characteristics
of efficiencies and power ratios, realize backward and forward motion including geared neutral
without an auxiliary device, various experimental studies have been performed to verify their design
validation and theoretical performance analysis. Various comparisons between the theoretical and
the experimental results have verified that they can improve the efficiency and speed ratio when
compared with the case power circulation mode mechanism and power split mechanism mode are
used individually.
ASME Code Evaluation on Stress Analysis of Snubber
Authors: Huh Sunchul , Chung Han Shik , Jeong Hyo Min , Choi Byeong Keun
Published: March 2009

Small snubber of hydrogen compressor do duty as buffer pulsation of compressed
hydrogen. Snubber is a kind of internal pressure vessel and design optimum of snubber very
important problem. In this paper, we will estimation results of elastic finite element structural
analysis using the commercial program such as ANSYS for comparison to the limits in ASME
Code Sec. Ⅷ that are related to membrane and bending stresses. In case of membrane stress in a
circular cylindrical due to internal pressure or to distributed live loads. Bending stress in the central
portion of flat head due to pressure. In addition, We will propose optimum design value of snubber
for hydrogen compressor.
Displacement Smoothing and Strain Estimation Using Savitaky-Golay Filters in Digital Image Correlation
Authors: Pan Bing , Xie Hui Min , Hua Tao , Wang Wei Ning , Fang Yan
Published: March 2009

Recently, many research works were concentrated on how to improve the accuracy of
displacement fields in digital image correlation (DIC). However, the original displacement fields
calculated at discrete locations using DIC are unavoidably contaminated by noises. If the strain
fields are directly computed by differentiating the original displacement fields, the noises will be
amplified even at a higher level and the resulting strain fields are untrustworthy. To acquire reliably
estimation of strain fields, in this paper, Savitaky-Golay (SG) filters are introduced to obtain
smoothed displacement fields and reasonable strain estimation. The principle of two-dimensional
SG filters is described in detail first. Then images of uniaxial tensile and three-point bending
experiments were used to verify the proposed approach. The resulting smoothed displacement fields
and strain fields clearly show that the proposed method is simple and effective.
The Application of Fiber Optic Sensor to the Study of Engineering Structure
Authors: Zhu Qi Rong , Fang Ru Hua , Yang Guo Biao , Zeng Wei Ming
Published: March 2009

The fiber optic sensor measuring system based on the Mech-Zehnder interferometry is
developed in the paper. The system can be used for the strain and vibration measurement of
engineering structure, and has the advantages: convenient adjusting, stable performance and strong
ability of anti-interference, etc. Therefore the fiber optic sensor has been widely used in the
engineering field.
First the system is introduced into measuring the frequency and amplitude of the vibration
subjected to force of the FRP-concrete beam. The fiber optic sensor measuring system and the
electronic measuring system are synchronous used for the measurement. The analysis results of
fiber optic sensor measurement approximate to the results of electronic strain gauge. Then the
system is introduced into experimental stress analysis on the gas pipe, good results is obtained too.
The paper provides new technical equipment for the experimental testing of various engineering
structure using fiber optic sensor, also establishes the technical foundation of the research of smart
structure.
A Study on the Materials Properties of Piezoelectric Ceramics Used in Jetting Apparatus
Authors: Yang Juh Wan , Park Chang Sung , Sim Won Chul , Kim Young Jae , Kim Soon Young , Yang Chung Mo , Park Sung Jun , Yoo Young Seuck , Joung Jae Woo
Published: March 2009

In this study, specially used in fluidic jetting apparatus, the electrical properties of piezoelectric ceramics were investigated by the resonance method and from its vibratory motion point of view. The piezoelectric ceramics were a rectangular bar type bulk and estimated by their piezoelectric constants, for example, electromechanical coupling factor, piezoelectric strain constant and so on. The measured values were compared with the displacement by the Laser Doppler Vibrometer analysis and with the droplet properties.
Temperature Compensation in Deformation Testing for Smart Concrete Structures
Authors: Song Xian Hui , Zheng Li Xia , Li Zhuo Qiu
Published: March 2009

Carbon fiber reinforced concrete (CFRC) structures exhibit both strain sensibility and
temperature sensibility, which are coupled with each other when used in traffic or health monitoring
for concrete structures. This coupling property results in inaccurateness of measured deformation.
In this paper Four-probe Difference Method is used to detach the above two effects according to
loaded conditions of structures and different characteristics of the two effects. The theoretical and
experimental results indicate that the method is feasible and effective.
Piezoelectric Effect of Electro-Active Paper Materials
Authors: Kim Heung Soo , Kim Jae Hwan , Zhao Li Jie , Jang Sang Dong , Yun Kyu Young , Lee Sun Kon
Published: March 2009

The application of electroactive polymer devices requires the availability of their
properties at various operating conditions. This in turn necessitates a structure-property relationship
based on an in-depth understanding of the underlying mechanism responsible for their strain-field
response. Cellulose-based Electro-Active Paper (EAPap) has been studied as an attractive Electro
Active Polymer (EAP) material for artificial muscles. The feasibility of EAPap material as an
actuator/sensor application is greatly dependant on piezoelectric effect. In this paper, converse and
di rect piezoelectric ef fect s of Electro-Active Paper materials are studied to characterize
piezoelectric effects of EAPap. All experiments were conducted in an environmental chamber that
can control temperature and humidity.
Preparation of Polydivinylbenzene/Au Core-Shell Beads
Authors: Phan K.Xuyen , Cho Mi Suk , Nam Jae Do , Choi Hyouk Ryeol , Koo Ja Choon , Lee Young Kwan
Published: March 2009

A novel core-shell material composed of closely packed gold shells on poly (divinylbenzene)
(PDVB) cores was fabricated via the reduction of a gold complex. PDVB beads (2-5 +m) were synthesized by
precipitation polymerization. The surface of the PDVB beads was modified by three different methods, viz.
sulfonation, chloromethylation, and thiolation. The modification of the surface of the PDVB beads was
designed to allow the facile attachment of the gold layer onto the PDVB cores. The gold seeding layer was
initially formed on the modified PDVB cores by the chemical reduction of a gold-phenanthroline complex.
The subsequent growing reactions of NH2OH and HAuCl4 increased the gold coverage to more than 90%. The
structure of the PDVB/Au core-shell material was characterized by SEM, XPS, and FT-IR.
Analysis of Pile-Soil Interaction by Computer Simulation
Authors: Zhang Guang , Pan Dong Zi , Chen Jing Xi , Zhou Ai Fang
Published: March 2009

In this paper, a numerical model to simulate the interaction of pile-soil based on the
one-dimension stress wave theory is established, which can provide the propagating process and
reflection characteristics of stress wave under impulsed load in concrete piles. The simulation is
carried on about the stress wave in integrated pile and defective pile, which provide all kinds of the
propagating characteristics. It can enhance the accuracy of dynamic test. The validity of this
approach is verified through the comparison of the measured curve and the simulated curve.