bluuebunny/crossref_metadata_2025 huggingface dataset:
Numerical Study on Elastic-Plastic Stress Field Near the Cooling Holes of Nickel-Based Single Crystal Air-Cooled Blades
Authors: Yu Qing Min , Yue Zhu Feng , Liu Yong Shou
Published: March 2009

In this paper, a plate containing a central hole was used to simulate gas turbine blade with cooling hole. Numerical calculations based on crystal plasticity theory have been performed to study the elastic-plastic stress field near the hole under tension. Two crystallographic orientations [001] and [111] were considered. The distributions of resolved shear stresses and strains of the octahedral slip systems {110}<112> were calculated. The results show that the crystallographic orientation has remarkable influence on both von Mises stress and resolved shear stress distributions. The resolved shear stress distributions around the hole are different between the two orientations, which lead to the different activated slip systems. So the deformed shape of the hole in [001] orientation differs from that in [111] orientation.
Effect of Plastic Deformation on Torsional Fatigue Properties of a Low Carbon Steel
Authors: Nishida Shinichi , Hattori Nobusuke , Zhou Cong Ling , Uchisako Akihiro
Published: March 2009

This paper is aimed to investigate the effect of roller working on the torsional fatigue properties of a typical low carbon steel referring by the resutls of FEM analysis. Three types of specimens had been prepared with plastic deformation value of 0, 0.5 and 1.0mm, respectively. The main results obtained in this study are as follows: (1) The torsional fatigue strength of roller-worked specimen with 1.0mm plastic deformation is increased more than twice of that of non-rollerworked specimens. (2) Surface hardness of roller worked specimen is much higher than that of the non-roller worked one, and compressed and elongated structure is formed at the notch bottom of the specimen. (3) Crack length along the axial direction of roller worked specimens is longer than that of the non-roller worked specimen, and plural cracks initiated and propagated in the roller worked specimens. (4) The residual stress distribution at the specimen’s notch bottom was analysed using FEM analysis and it is verified the same tendency as the experimental results.
The Thermal Cyclic Behavior of the TBCs with the MCrAlY Coating Method
Authors: Jung Jine Sung , Yoo Keun Bong , Kim Eui Hyun , Jeon Chae Hong , Kim Do Hyang
Published: March 2009

The rotating components in the hot sections of land-based gas turbine are exposed to severe environment during several tens thousand hours at above 1100則 operating temperature. To protect such components from 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 thermal cyclic behavior of thermal barrier coatings. The MCrAlY bond coatings are deposited by a vacuum plasma, low vacuum plasma and highvelocity oxygen fuel spray on a nickel-based superalloy (GTD-111). Thermal cyclic tests at 1100則 in still air for various periods of time were used to evaluate the thermal cyclic resistance of the TBC coating with the various processing sprayed bond coating layer. The microstructure and morphology of as-sprayed and of thermal cycled coatings were characterized by scanning electron microscopy (SEM) equipped with energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD). The order of thermal cyclic resistance was YSZ-VPS bond coat, YSZ-LVPS and YSZHVOF. The influence of bond coat spray methods on durability of TBCs is discussed.
Analysis of Cracking Phenomenon Occurring during Cold Forging of ML25Mn Steel
Authors: Li Zhuang , Wu Di , Liu Jian Xun
Published: March 2009

Cold forging has various advantages compared to other forming processing. Cracking
phenomenon was taken place during cold forging of ML25Mn steel. In this study, microstructural
analyses were made on the cracked regions of the steel. The reason of cracking phenomenon
occurring during cold forging for ML25Mn steel was investigated based on SEM observation in
detail. The results have shown that ML25Mn steel presents lower strength and toughness. A larger
amount of inclusions which are composed of MnS and complex oxides containing Mg, Al, Mn, Fe,
S, Ca and O are found, and the complex inclusion might be brought during the deoxidation and the
solidification in smelting and casting. Non-metallic inclusions result in significant stress
concentration, which cause cracking phenomenon occurring during cold forging of ML25Mn steel.
Simulation of Welding Deformations of Ship Structures
Authors: Li Hong , Ren Hui Long
Published: March 2009

Welding deformations of real structures are complicated and the accurate prediction of welding deformations has been a difficult problem. The equivalent load method is presented in this paper. The method uses the FE method combining the inherent strain theory and the experimental results for accurate and efficient analysis. A simplified elastic plastic analysis model, bar-spring model is used. It is showed that the highest temperature and the degree of restraint change the distributions of the inherent strains in the welded region. Applying the equivalent loads induced by the inherent strain on the structure, the final deformations are calculated by FE analysis. The results in this paper have been supported by the results of C.H.LEE and the experimental data.
The Reliability Analysis for Piezoelectric Truss Structure in Consideration of Electroelastic Damage
Authors: Wang Bin Sheng , An Wei Guang , Yang Duo He
Published: March 2009

In the piezoelectric truss structure with many random parameters under incipient defect,
taking into consideration the mechanical-electric coupling effect under electric load and mechanical
load, the formula of safety margins of bar have been proposed by the fracture intensity, bar section
area and loads as random variables. On the base of above research, stochastic finite element method
is adopted to attempt to analyze reliability of the piezoelectric truss structure. In the end, the
example is given to demonstrate the influence of voltage and of damage on reliability index of the
piezoelectric truss system.
Fatigue Test on a Full Scale Panel
Authors: Apicella A. , Armentani Enrico , Esposito Renato
Published: March 2009

Fatigue test on a full scale panel with complex loading and geometry has been carried out
by using a tri-axial test machine located in the laboratory of the University of Naples. The
aeronautical test panel was designed and manufactured by Alenia. The demonstrator is made up of
two parts which are linked by a transversal joint that is parallel to the stringer direction. A fatigue load
was applied in the normal direction to the longitudinal joint, while a constant load was applied in the
joint direction. The full scale panel was equipped with strain gauges for deformation state
measurements. Preliminary static load tests were performed in order to provide deformation
measurements for numerical correlation. The outcomes confirmed that the applied load level is
consistent with a linear elastic material behaviour. Three intermediate failures occurred before the
final one: the first two under a clip, while in the third case a panel frame failed. Finally after about
177,000 cycles the demonstrator broke down. A non linear finite element analysis was also carried out
in order to correlate failure events that occurred during the demonstrator testing.
Hot Spot Stress Fatigue Evaluation to Duplex Stainless Steel Welded Joints
Authors: Jia Fa Yong , Huo Li Xing , Chen Gang , Zhong Qun Peng
Published: March 2009

Fatigue strength of duplex stainless steel welded joints with longitudinal fillet welded
guess and with longitudinal flat side guess welded on plate was evaluated by hot spot stress, hot
spot stress S-N curves were produced and compared with normal stress S-N curves. The results
show that the hot spot stress fatigue strength of the two kinds welded joints should be expressed by
only single S-N curve while nominal stress S-N curves can only be regressed respectively. The test
data are greatly above the S-N curves with slope m=3, recommended by IIW, which indicates that
the slope m=3(IIW) has great safety factor in practical engineering application. But there is no
appreciable difference in fatigue strength between duplex stainless steel and common structural
steel with similar welded joints when fixed the test data to slope m=3.
Unified Solution of Expansion of Cylindrical Cavity of Elastic-Brittle-Plastic Strain-Softening Materials with Different Elastic Modulus in Tensile and Compression
Authors: Xia Jian Zhong , Luo Zhan You , Wang Wei Tang , Liu Wei
Published: March 2009

For strain-softening materials with different elastic modulus of tensile compression, two
controlling parameters were introduced to take into account the different modulus and strainsoftening
properties. By means of twin shear unified strength theory, unified solutions calculating
stress and displacement fields of expansion of cylindrical cavity were derived. The effects caused
by different elastic modulus in tensile and compression, different models and strain-softening rates
on stress and displacement fields, development of plastic zone were analyzed. The results show the
ultimate expansion pressure, stress and displacement fields and development of plastic zone vary
with the changes of different elastic modular, different models and strain-softening properties.
A Study on Measurement of Welding Residual Stress Using ESPI System
Authors: Kim Kyung Su , Choi Seung Bok , Lee Jang Hyun , Park Seong Mo , Kim Beom Il , Lee Nak Hoon , Lee Chang Hyun , Woo Min
Published: March 2009

In this study, an experimental method has been studied to measure the residual stresses
on a specimen with I-groove weldment. The specimens were extracted from I-groove weldment
which was joined by SAW (Submerged Arc Welding) with CO2 shield gas. A FEA (Finite Element
Analysis) model was developed for the estimation of the residual stresses for the specimen.
Measurements were carried out using ESPI(Electronic Speckle Pattern Interferometry) system
which can measure the strain distribution on the surface of specimen. The residual stresses were
estimated by the value of strain measured by ESPI system. Strain gages were added to evaluate the
accuracy of ESPI system. In addition, a three-dimensional FE model was used to estimate the
residual stresses generated by the welding procedure. A thermal elasto-plastic analysis was
performed by the FEA. The stresses measured by the experiments were compared with the results of
FEA. Also, discussed are the difference and agreement between the stresses obtained by
experiments and FEA, respectively.
Analysis of the Surface Cracks of Long Range Storage Solid Motor Grain
Authors: Yuan Duan Cai , Tang Guo Jin , Lei Yong Jun , Meng Shang Yang
Published: March 2009

The surface cracks are easy to occur in the solid missile motor grain. The solid missile
motor grain with cracks is very dangerous when it is lunched, because the surface cracks might be
propagation unstable when the internal pressure enters the surface cracks cavity. In order to analyze
the surface crack of solid motor grain, with accelerated aging test, the variation law of mechanics
properties of propellant in the storage period is obtained. Under internal pressure and axial
acceleration loading, the three-dimension finite element models of the motor grain are established,
three-dimension singular crack elements at the tips of surface cracks are established to simulate the
cracks propagation. Along with the surface crack propagation, the stress intensity factors of the
crack tips in different storage period are calculated to prejudge its stability respectively. The method
and conclusions are available for using solid missile motor grain with surface cracks.
Prediction Approach for Corrosion Fatigue Life of Aircraft Structure Based on Probabilistic Fracture Mechanics
Authors: Tan Xiao Ming , Chen Yue Liang , Jin Ping
Published: March 2009

The corrosion, corrosion fatigue and fracture failure process of aircraft structure is
directly concerned with combined effect of many factors, such as load, material characteristics,
corrosive environment and so on. The process is very complicated, and there is typical randomness.
Based on probabilistic fracture mechanics, with consideration of the limitation of the conventional
probabilistic approaches for prediction of corrosion fatigue life of aircraft structure at present, and a
new reliability approach under loading spectrum was proposed, in which corrosion damage and
fatigue crack damage was united as a same damage parameter. Short crack and long crack growth
behavior was separately discussed, and influence of short crack aspect ratio on structure life was
discussed. The Advanced First-Order Reliability Method, Importance Sampling Method and
iteratively advanced Second-Order Reliability Method were used to compute the fracture failure
probability. The results show that the model is feasible. By sensitivity analysis of random parameter,
the important parameter was obtained, which helped to monitor the structure fatigue life.
Numerical Simulation of Short Cracks in Fiber-Reinforced Ceramics
Authors: Wang Da Guo , Yang Ju Ying , Li Li Chong , Jiang Wei
Published: March 2009

In this paper, a numerical code, Realistic Failure Process Analysis code (RFPA), was
used to perform a microscopic analysis of a crack in a fiber-reinforced ceramic, when the crack
length is the same order of magnitude as the fiber spacing. The numerical results performed in the
paper shown the failure process of fiber-reinforced ceramic subjected to tension loading, which
indicate that the reinforcing fibers in a ceramic composite have a significant effect in inhibiting
crack propagation even during the stages of the development of crack. Moreover, the fiber evidently
increased the load-carrying capacity.
Modelling of Rolling Contact Fatigue of Rails
Authors: Fajdiga Gorazd , Šraml Matjaž , Kramar Janez
Published: March 2009

Rail dark spot defect, also termed as squat failure or shelling, is a rolling contact fatigue
failure which occurs frequently on the high speed traffic railway rails. The main goal of this study is to
develop a computational model for simulation of the squat phenomena on rails in rail-wheel contact.
The proposed computational model consists of two parts: (i) Contact Fatigue Crack Initiation (CFCI)
and (ii) Contact Fatigue Crack Propagation (CFCP). The results of proposed unified model enable a
computational prediction of a probable number of loading cycles that a wheel-rail system can sustain
before development of the initial crack in the rail, as well as the number of loading cycles required for
a crack to propagate from initial to critical length, when the final fatigue failure (squat) can be
expected to occur.
Nano and Micro Mechanical Measurement of Interaction Forces Between Solid Surfaces
Authors: Kim Kyung Suk
Published: March 2009

Two different types of experimental methods have beeen developed for measuring lateral
interaction forces between two solid surfaces for nano- and micro-meter scale contacts. One is the
type of direct measurement methods which typically utilize AFM instrumentations. In the direct
lateral force measurements some size-scale effects are commonly observed due to the effects of
adhesion and surface roughness. A recent development of a fine AFM lateral force calibration
method, a diamagnetic lateral force calibrator, has made it possible to study such size-scale effects
systematically. The other type is the field projection method which requires a high resolution
measurement of a deformation field near the edge of a contact. For such measurements a
comprehensive map of deformation measurement techniques is introduced in a domain of spatial
and strain resolutions. This technique provides a way of assessing the non-uniform distribution of
the surface interaction forces for nano and micro-meter scale contacts.
Experimental Simulation of Complex Thermo-Mechanical Fatigue
Authors: Bardenheier Reinhard , Rogers Graham
Published: March 2009

Fatigue damage plays an increasingly important role in the design of various safety critical
components that are exposed simultaneously to thermal and mechanical loads. Non-isothermal
conditions, as these are to be found in turbine components, rocket engines, but also in high-speed
machining tools makes the understanding even more complex. As the nature of those loading histories
is mostly multiaxial, design engineers are interested in material models, which take into account
the complexity of stress state and temperature history as well. The experimental validations of those
models require specially designed test set-ups. The basic concepts of experimental techniques to
perform non-isothermal, uniaxial fatigue tests will be described in general. Test systems, capable to
simulate non-isothermal multiaxial stress states are presented. A new miniaturised electrothermalmechanical
test rig, which allows testing of small specimens under complex thermomechanical
loading conditions, will be discussed.
An Evaluation of Low-Cycle Fatigue Property for Sn-3.5Ag and Sn-0.7Cu Lead-Free Solders Using Surface Deformation
Authors: Takahashi Takehiko , Hioki Susumu , Shohji Ikuo , Kamiya Osamu
Published: March 2009

The low-cycle fatigue behavior and the relationship between the surface features in the
low-cycle fatigue testing and the fatigue life of Sn-3.5Ag and Sn-0.7Cu lead-free solders were
investigated at strain rate of 0.1%/s at room temperature, 80 and 120oC. In addition, the fatigue life
was estimated by using the surface deformation of the solders, and image processing. And also, it
was compared with Coffin-Manson type of fatigue behavior. The fatigue life of Sn-3.5Ag solder
was superior to that of Sn-0.7Cu solder at temperatures, 80 and 120oC. The fatigue life determined
by surface deformation indicated a close behavior to Coffin-Manson type fatigue behavior in those
solders. Therefore the low-cycle fatigue life of solders could be estimated by the surface
deformation.
3-Dimensional Finite Element Analysis of the Residual Stress by Cold Expansion Method and Interference Fit
Authors: Jang Jae Soon , Cho Myoung Rae , Yang Won Ho
Published: March 2009

Cold expansion method and interference fit of fastener hole have been used for over 40
years by the aircraft industry to improve the fatigue life of structures because they induce
compressive residual stresses around holes. Especially, interference fits are very widely applied in
the industry, because of their simple manufacturing process. There have been only few studies on
the difference in the effect between cold expansion method and interference fit. The purpose of this
study is to compare the effect between cold expansion method and interference fit according to
plate thickness. Furthermore, residual stress distribution according to real clamping force is also
investigated.
A Study on the Fatigue Characteristics of Al6061-T651 by Shot Peening Velocity
Authors: Park Won Jo , Huh Sunchul , Park Sung Ho
Published: March 2009

Small steel ball is utilized in Shot peening process. Called “shot ball” are shot in high
speed on the surface of metal. When the shot ball hit the surface, it makes plastic deformation and
bounce off, that increase the fatigue life by compressive residual stress on surface. In this study, the
results of observation on the tensile strength, hardness, surface roughness, compressive residual
stress and fatigue life of a shot peened Al6061-T651 were obtained. Experimental results show that
arc height increase tremendously by shot velocity. Also, it shows that surface roughness, hardness,
compressive residual stress and fatigue life increase as shot velocity increase.
The Improved Johnson-Cook’s Strength Model Taking Account of the Rate-Dependent Micro-Damage Evolution for C30 Concrete
Authors: Shih Shao Chiu , Wang Yong Zhong , Wang Li Li
Published: March 2009

The dynamic mechanical behavior of C30 concrete under a wide range of strain rates
from 10-4s-1 up to 102s-1 is studied. According to Johnson-Cook’s strength model, the strain rate
coefficients and related material constants of C30 concrete subjected to large strains, high strain
rates and high pressures are determined experimentally: C=0.34*10-1, A=1.05, B=1.65, N=0.76, TC
=3.162MPa, fc’=39.2MPa. The damage evolution for C30 concrete is a rate-dependent process,
which can be formulated to a rate-dependent damage evolution law in a simple form for engineering
application. When ε > ε
th, ( ) 1
D th D = K ε&α − ε −ε . The corresponding dynamic coefficients of C30
concrete are also obtained from impact experimental results: KD=530.2, a=0.83. Due to a<1, the
damage evolution corresponds to an impact toughening process that coincide well with the dynamic
experimental results for C30 concrete.
Effect of Initial Static Load on the Rate-Sensitive Behavior of Concrete in Compression
Authors: Yan Dong Ming , Lin Gao
Published: March 2009

Before concrete structures are subjected to dynamic loadings such as earthquake, usually
they have already withstood static loads. Accordingly, the study on the strain-rate sensitivity of
concrete should also be closely related to the initial static loads that concrete structures experience.
But majority of the available documents concerning the dynamic properties of concrete do not take
initial static load into consideration. In this study, experiments were carried out to investigate the
effect of initial static load on the dynamic strength and deformation characteristics of concrete in
compression. A load was initially applied on the specimen at a very low speed to a specified value
and then the dynamic load was applied at a high strain rate up to the failure of the specimen. From
the test results it was revealed that the initial static load had significant influence on the dynamic
strength. The dynamic strength tended to decrease as initial static load increased. An exponential
function was proposed to formulate the relationship between the initial static load and the dynamic
strength.
Fabrication of Superfine Electron Moiré Grid
Authors: Xing Yong Ming , Kishimoto Satoshi
Published: March 2009

The electron moiré method uses a high frequency grating to measure microscopic
deformation. Finer and finer gratings are being pursued to meet higher and higher resolution
requirements in microscopic stress analysis. In this study, the techniques of fabricating electron grid
by means of a scanning electron microscope are improved. The use of a low accelerating voltage
shows a better effect than the high accelerating voltage in fabricating a superfine grid. A new group
of parameters is suggested based on this consideration. A cross-line grid with a frequency of 10,000
lines/mm and a parallel grating with a frequency of 13,000 lines /mm have been successfully
fabricated.
Experimental and Theoretical Study of Frequency and Temperature Dependence on Seismic Attenuation of Saturated Rocks
Authors: Liu Xiao Yan , Zhang Cheng Yuan , Xi Dao Ying , Liu Quan Sheng
Published: March 2009

Most rocks are saturated or partly saturated with different fluids under different depth,
temperature and pressure conditions. It is generally acknowledged that fluids have the most
important effect on the attenuation and dispersion of seismic waves. There exists a relation between
frequency- and temperature- dependence on rock’s seismic properties. It is not yet clear in literature
whether there exist other equally important attenuation mechanisms as that in Biot’s model, since
there are other sources of dissipation, also related to fluids, that are not considered in Biot theory
but that may also contribute to the overall dissipation of seismic energy. Identifying the precise
relaxation mechanisms is still the subject of experimental and theoretical research. In this article, a
series of experiments are conducted on dry and saturated rocks (sandstone, marble, granite) at
different temperatures and frequencies to find the attenuation mechanism of interaction between
rock skeleton and pore-fluid. Fluid viscosity generally depends on temperature, so the effect of pore
fluid on attenuation is confirmed in terms of apparent viscosity variation of rock caused by the
change of pore-fluid conditions (such as frequency or temperature). Based on our experimental
data, we develop a new model of macroscopic apparent viscosity in saturated rock which is
consistent with the nonlinear relaxation law. It helps to derive the analytical expressions to compute
velocity dispersion and attenuation as functions of frequency and temperature.
Microfabrication of Polymers Using KrF Excimer Laser Beam
Authors: Shin Dong Sig , Lee Jae Hoon , Suh Jeong
Published: March 2009

Pulsed UV laser beams, which are widely used in the processing of polymers, offer many
advantages in the field of polymer production, primarily because their photon energy is higher than
the binding energy of the polymer. In particular, the fabrication of polymers with an excimer laser
process is faster and more convenient than with other processes. Nevertheless, some problems occur
in the precision microprocessing of polymers, including the formation and deposition of surface
debris, which is produced from the breakdown of either polymer chains or radical bonds. In the
present work, a process for eliminating carbonized surface debris contamination generated by the
laser ablation of a polymer was developed. The proposed approach for removing surface debris
utilizes an erasable ink pasted on the polymer. The surface debris ejected from the polymer is then
combined with the ink layer on the polymer. Finally, both the surface debris and the ink layer can
be removed using adhesive tape.
The Effect of Temperature and Sizes on Deformation of Cantilever Rectangular Plate with Double Layer
Authors: Lin Meng Ju , Chou Yun Ju
Published: March 2009

As depositing layers with different thermal expansion coefficients, the residual gradient stress will cause the structure deformed. The deformation of structure in the free ending, middle section, and clamped end are detail investigated. It is found the clamped end often has complex deformation shape. The warpage due to buckling is found. The results show if the thickness of structure is much larger than above deposing layer, warpage will hardly happen and the free ending will have more flat region. As the thickness of structure layer being not much larger than above deposing layer, the warpage happens and the free ending is parabolic shape. In the clamped end, the complex deformation even is concave shape in the center part but protruding shape in the side region. The larger temperature difference will be more easily warpage and be no more flat. The results also show that as the ratio of length to width decreasing, seriously warpage and complex deformation happens. The free ending may be a little protruding shape. However, if the ratio of length to width is larger, the free ending will have concave shape.
Experimental Study on the Film Cooling Performance at the Leading Edge of Turbine Blade Using Infrared Thermography
Authors: Kim Kwang Su , Kim Youn Jea
Published: March 2009

In order to protect turbine blades from high temperature, film cooling can be applied to
gas turbine engine system since it can prevent corrosion and facture of material. To enhance the
film cooling performance in the vicinity of the turbine blade leading edge, flow characteristics of
the film-cooled turbine blade have been investigated using a cylindrical body model. Mainstream
Reynolds number based on the cylinder diameter was 1.01×105 and the mainstream turbulence
intensities were about 0.2%. CO2 was used as coolant to simulate the effect of coolant-tomainstream
density ratio. The effect of coolant flow rates was studied for various blowing ratios of
0.5, 0.8, 1.1 and 1.4, respectively. Results show that the blowing ratio has a strong effect on film
cooling effectiveness and the coolant trajectory is sensitive to the blowing ratio.
Characteristic Analysis and Experimental Evaluation of Fluidic Muscle Cylinder
Authors: Kim Dong Soo , Bae Sang Kyu , Choi Kyung Hyun
Published: March 2009

The fluidic muscle cylinder consists of an air bellows tube, flanges and lock nuts. Its
features are softness of material and motion, simplicity of structure, low production cost and high
power efficiency. Recently, unlike the pneumatic cylinder, the fluidic muscle cylinder without air
leakage, stick slip, friction or seals was developed as a new concept actuator. It has characteristics
such as light weight, low price, high response, durable design, long life, high power and high
contraction. In this study, we carried out finite element modeling and analysis on the main design
variables such as contraction ratio and force, and diameter increment of the fluidic muscle cylinder.
On the basis of finite element analysis, the prototype fluidic muscle cylinder was fabricated and
tested. Finally, we compared the test results with the finite element analysis.
The Geometry Characteristics of Rock Mass of Multi-Fields Coupling Action
Authors: Zhang Guang , Tang Guang Hua , Chen Jing Xi , Zhou Ai Fang
Published: March 2009

This paper introduces the method that determines rock bridge intensity based on rock
discontinuity and connectivity ratio in the multi-fields coupling action. First, the method is used to
study the smallest anti-shear way of rock mass in the microscopic discontinuity and integrated rock.
Then the smallest anti-shear stress is computed in the way. The connectivity ratio of discontinuity is
taken as the weighting coefficient, and the synthetical anti-shear intensity is obtained with summing
the indexes of the discontinuity parameters and connectivity ratio coefficient.
An Improved Hybrid Full-Field Stress Analysis of Circularly Perforated Plate by Photoelasticity and Finite Element Analysis
Authors: Baek Tae Hyun , Koh Seung Kee , Park Tae Geun
Published: March 2009

hybrid experimental-numerical method is presented for determining the stresses around a
circular hole in a finite-width, tensile loaded plate. Calculated fringes obtained by FEA provided the
information about the external boundary of the hybrid element, and those fringes on straight lines
were used for hybrid analysis. In order to see the effects of varying stress field, different numbers of
terms in a power-series representation of the complex type stress function were tested. Actual and
reconstructed fringes were compared. The hybrid results were highly comparable with those predicted
by FEA. The result showed that this approach is effective and promising because isochromatic data
along the straight lines in photoelasticity can be conveniently measured by use of phase shifting
photoelasticity.
Process Parameter Optimization for Machining SiCp/Al-MMC Using RSM and GA
Authors: Kwak Jae Seob , Chi Long Zhu , Koo Yang , Jeong Yeong Deug , Ha Man Kyung
Published: March 2009

This study aimed to achieve optimization of grinding parameters for aluminum-based
metal matrix composites using response surface model and genetic algorithm. Experiments were
conducted in accordance with a preplanned orthogonal array. The effect of grinding parameters on
surface roughness and grinding forces was evaluated and second-order response surface models
were developed for predicting grinding outcomes. Optimal grinding parameters were determined
from the genetic algorithm and the response surface models.
Development of Dynamic Photoelastic Experimental Hybrid Method for Orthotropic Material
Authors: Nam Jeong Hwan , Hawong Jai Sug , Lee Ouk Sub , Shin Dong Chul
Published: March 2009

In this paper, transparent dynamic photoelastic experimental hybrid method for
propagating cracks in orthotropic material was developed. Using transparent dynamic photoelastic
experimental hybrid method, we can obtain stress intensity factor and separate the stress
components from only isochromatic fringe patterns without using isoclinics. When crack is
propagated with constant velocity, the contours of stresses components in the vicinity of crack tip in
orthotropic material are similar to those of isotropic material or orthotropic material with stationary
crack under the static load. Dynamic stress intensity factors are decreased as crack growth. It was
certified that the dynamic photoelastic experimental hybrid method was very useful for the analysis
of the dynamic fracture mechanics.
Cure Kinetic Behavior of 191# Unsaturated Polyester Resin Used in Advanced Composites
Authors: Yang Mei , Yan Shi Lin , Liu Mei
Published: March 2009

The cure kinetic properties of 191# resin was studied by means of the differential
scanning calorimeter (DSC) data. Dynamic DSC scanning at four different heating rates (5, 10, 15
and 20/min) are employed to investigate the cure kinetics. DSC curves show that there are two
exothermal peaks. Kissinger’s method is applied to processing the data. The activation energy E
and pre-exponential factor A were gained by linear regress and the cure kinetics model was
developed. Based on T − β method, the temperatures of cure reaction beginning, maximum
reaction rate and reaction ending were obtained. These will help to process designing of unsaturated
polyester resin used in advanced composite materials.
Local Heat Transfer Measurements Using Liquid Crystal Thermography Technique
Authors: Lee Dae Hee , Lim Chang Yul , Jeon Min Hyon , Kim Moon Kyoung , Park Sung Bong , Lee Kwan Soo
Published: March 2009

The micro-encapsulated thermochromic liquid crystal has been used for the surface
temperature measurement using its color change with heat. There are exciting new opportunities to
apply this liquid crystal to the investigation of important and interesting heat transfer/fluid flow
problems. The various techniques of using liquid crystal for the measurement of the local Nusselt
numbers in very complex geometries are presented in this paper.
Application of Photocatalytic Metal Membrane System for Water Purification
Authors: Kim Jong Oh , Jung Jong Tae , Choi Won Youl
Published: March 2009

This study was conducted to evaluate the applicability of photocatalytic metal membrane
system for the treatment of humic acid and heavy metals in aqueous solution. The catalysts, TiO2
powder P25 Degussa and metal membrane with 0.5 μm nominal pore size were used for
experiments. Removal efficiency of humic acid and heavy metals increased with the increase of
TiO2 dosage, however decreased over 0.3 g/L of TiO2 dosage. The addition of H2O2 as an oxidation
reagent had a positive effect for the removal rate of humic acid and heavy metals. Metal membrane
with stainless steel seemed to be quite stable to UV light with oxidation reagent in long-term
operational periods over 6 months. Moreover, TiO2 particles can be effectively separated from the
treated water by membrane rejection and the permeation flux was also enhanced by the combination
of photocatalytic reaction.
Electronic Transport Properties of Chemical Gas Sensor Using Conducting Polymer PAni
Authors: Lee Jae Jong , Park Soo Yeon , Lee Seung Woo , Jeon In Deok
Published: March 2009

The conducting polymer PAni is coated on Au electrode sample by spin coater on
500rpm and 3000rpm for 5sec and 30sec. Then, it was drying 10min at 180C. The layer thickness
was 140~200nm. The electrodes were fabricated the resist pattern by electron beam writing
machine which was performed on a Raith75 e-Line on the PMMA 950K, thickness 100nm. The
electrodes were written at an electron does of 200uAs/cm2 and developed for 40sec in a 1:3 MIBK
(methyl-isobutyl-ketone): IPA (isopropyl alcohol) solution. Metal lift-off of the PMMA in acetone
was preceded by an e-beam evaporation consisting of 50Å Cr and 250Å Au.
Electrical measurements were performed on low-noise commercial probe stations equipped. We
measured distance between the electrodes ranges from a few tens of nanometer to hundreds
nanometer by AFM (Atomic Force Microscopy) which was done with silicon tips in non-contact
mode on a PSIA, XE-100.
An Electrical Signal Detection System for a Microbiochip with Gold Nanoparticles
Authors: Park Jae Jun , Kim Dae Jin , Ahn Byoung Woon , Lee Seoung Hwan , Ahn Yoo Min , Hwang Seung Yong , Cho Nahm Gyoo
Published: March 2009

In this paper, an electrical signal detection system for microbiochips is proposed to
overcome the limitations of conventional optical systems such as bulky system size and high
manufacturing cost. An electrical detection system with interdigitated microelectrodes is fabricated
using MEMS technology. High conductive nano size gold particles were selected for the system to
detect biological reactions between bio materials in the microbiochip. Experiments were performed
with variations of particle densities and electrode gaps. In addition, a simulation to predict the
electrical resistance of the microbiochip was developed. Both the simulation and experimental data
show that the conductivity increases as the gap becomes narrower and the particle density higher.
A Study on the Actuating Performance of Unimorph Piezoelectric Actuators with a Center Load
Authors: Nguyen Ngoc Trung , Yoon Kwang Joon
Published: March 2009

Research on piezoelectric unimorph actuators has been intensively increased during the
past decade due to the wide applications of this actuator type in aerospace, vibration control,
biomimetic robots, artificial muscles… Most analyses focused on the design performance with
load-free actuating condition. Loading performance has not been considered adequately yet though
in real application the actuators always work under certain carrying load. This paper introduces the
measuring system, the experimental setup and presents the observed loading performance of the
actuators with center load. Two typical kinds of piezoelectric unimorph actuator, LIPCA-C3 and
THUNDER, are investigated. The numerical analyses are also conducted to illustrate the loading
behavior of these devices. Some remarks and suggestions for future research activities are drawn.
Impact Strength Assessment of LNG Carrier Insulation System
Authors: Lee Jae Myung , Kim Myung Hyun
Published: March 2009

The aim of present paper is to experimentally investigate the dynamic strength
characteristics of LNG cargo containment system under impact loads. A series of impact tests for
full-scale MARK III insulation system is undertaken using a custom-built drop test facility as
varying height and weight of the drop object. Based on a series of repeated drop tests, displacement
recovery was measured for the assessment of damping characteristic of insulation system. Crack
initiation was also measured during the cyclic drop test. The quantitative relationship between
impact load and crack initiation as well as the crack propagation with respect to drop number are
derived.
Numerical Simulation of SHPB Experiment on Dynamic Behaviour of Ceramic Particle Reinforced MMCs
Authors: Liu Li Sheng , Cao Dong Feng , Zhang Jiang Tao , Zhang Qing Jie
Published: March 2009

The dynamic behaviour of ceramic particle reinforced metal matrix composites (MMCs)
is a key to its application. In this paper, the computational micro-mechanics method (CMM) is used
to simulate SHPB experiment of MMCs. The numerical SHPB’s specimen of MMCs is firstly
generated by CMM. Then, for verifying the correction of numerical experiment, the Al2O3/6061-
T6Al composite is used to carry out numerical experiment, and the Johnson-Holmquist (JH-2)
damage model is used to describe the ceramic mechanics behaviour, and a comparison between this
numerical method and Unit Cell analytical model is carried out. Lastly, the dynamic behaviour of
T6061Al/Al2O3 is investigated by this method.
Investigation of the Impact Analysis of Microscale Thin-Walled Structures Manufactured by High-Speed Machining
Authors: Shin Bo Sung
Published: March 2009

High-speed machining (HSM) is very useful method as one of the most effective
manufacturing processes because it has excellent quality and dimensional accuracy for precision
machining. Recently micromachining technologies of various functional materials with very thin
walls are needed in the field of electronics, mobile telecommunication and semiconductors.
However, HSM is not suitable for microscale thin-walled structures because of the lack of their
structure stiffness to resist high-speed cutting force. A microscale thin wall machined by HSM
shows the characteristics of the impact behavior because the high-speed cutting force works very
shortly on the machined surface. We propose impact analysis model in order to predict the limit
thickness of a very thin-wall and investigate its limit thickness of thin-wall manufactured by HSM
using finite element method. Also, in order to verify the usefulness of this method, we will compare
finite element analyses with experimental results and demonstrate some applications.
Experimental Studies on the Impact Buckling of Bars and the Effect of Stress Wave
Authors: Wang Rui , Han Zhi Jun , Zhang Shan Yuan
Published: March 2009

The experimental studies on the dynamic buckling of the perfect bars with three
kinds of lengths under impulsive axial compression were completed and the boundary
condition of clamped-fixed was realized firstly in present studies. The time-history curves of
axial strain of bars under different impact velocity were recorded. According to the magnitudes
of the axial strain and bifurcate time, the quantitative relation of dynamic buckling load and
critical bifurcate length are achieved; according to the curves recorded, the lateral velocity of
bars are computed also. The experimental results show that the dynamic buckling load of the
bar is distinctly greater than the static one, the front of stress wave can be regarded as fixed
and the effect of the axial stress wave in the dynamic buckling of bar must be considered.
Experimental Determination of Non-Ideal Structural Boundary Conditions Based on Spectral Element Model
Authors: Cho Joo Yong , Lee Usik
Published: March 2009

In this paper, experiments are conducted to determine the non-ideal boundary conditions
(BCs) of example beam structures. The spectral element (SE)-model is used for the beam structures,
and the non-ideal BCs are represented by the frequency-dependent effective boundary springs. The
boundary spring constants are then determined from the measured FRF-data. It is shown that the
vibration responses analytically predicted by using experimentally identified BCs are very close to
the measurements.
An Experimental Study on the Flow Structure inside a Display Cooler Using PIV Techniques
Authors: Park Cheol Woo , Baek In Je , Yoon Jong Hwan
Published: March 2009

In the present study, the flow structure inside the refrigerating compartment of a scaleddown
display cooler model was investigated experimentally using the particle image velocimetry
(PIV) method, which is a reliable velocity field measurement technique. In addition, we also carried
out flow visualization and computer simulations regarding the movements of thermo-fluid inside a
display cooler. As a result, the velocity field measurement shows a large scale vortical flow
structure inside the refrigerating compartment due to the entrained flow, thus penetrating a base
plate through the open inlet gap.
Damage Identification by Embedded Piezoceramic Sensors in the Composite Plate
Authors: Chun Heoung Jae , Yi Choong Hee , Byun Joon Hyung
Published: March 2009

The embedded structural health monitoring system is envisioned to be an important
factor of future structural systems. One of the many attractions of in situ health monitoring system
is its capability to inspect the structural systems in less intrusive way over many other visual
inspections which require disassembly of built up structures when some indications have appeared
that damages have occurred in the structural systems The vacuum assisted resin transfer molding
(VARTM) process is used to fabricate woven-glass/phenol composite specimens which have the
PZT sensor array embedded in them. The embedded piezoceramic (PZT) sensors are used as both
transmitters and receivers. A damage identification approach is developed for a woven-glass/phenol
composite laminates with known localized defects. Propagation of the Lamb waves in laminates and
their interactions with the defects are examined. Lamb waves are generated by the high power
ultrasonic analyzer. A real time active diagnosis system is therefore established. The results
obtained show that satisfactory detection accuracy could be achieved by proposed method.
Seismic Performance of Bridge Pier with FRP Wrapping
Authors: Joo Hyung Joong , Lee Seung Sik , Yoon Soon Jong , Park Joo Kyung , Cho Sun Kyu
Published: March 2009

This paper presents the results of an experimental study on the seismic performance of
reinforced concrete (RC) bridge piers wrapped with FRP at the lap-spliced region. It is well known
that the FRP wrapping on the surface of concrete bridge pier can prevent concrete cover from
spalling and it can reduce the slip displacement of lap-spliced longitudinal re-bars due to
confinement. In order to develop the effective way of strengthening the concrete bridge pier with
poor lap-spliced longitudinal re-bars, which is not designed under seismic design consideration, a
series of pier test under seismic loading condition is conducted. As a result, FRP wrapped bridge
pier under seismic loading exhibits ductile behavior with plastic deformation at lap-spliced region.
Half-scaled six circular and nine square pier specimens were tested under uniform concentric axial
compression and quasi-static lateral loading at the top of the pier. For the purpose of comparison,
two piers without lap-splice and two piers with lap-splice were not wrapped with FRP and tested
under same loading condition. Other experimental parameters were the height of FRP wrapping and
the reinforcing method. The experimental results showed that the FRP wrapping could significantly
increase ductility of piers with lap-spliced longitudinal re-bars at the potential plastic hinge region.
Preparation and Characterization of Polyimide/BaTiO3 Nanocomposite Films with Lower Infrared Emissivity
Authors: Lin Bao Ping , Liu Hong Jian , Sun Yue Ming , Yuan Chun Wei
Published: March 2009

The silicon-containing polyimide/BaTiO3 nanocomposite films were prepared by mixing
the silicon-containing poly(amic acid) based on bis(3,4-dicarboxyphenyl)dimethylsilane
dianhydride and 4,4'-Oxydianiline with BaTiO3 nanoparticles, followed by thermal imidization.
Structure and properties of the nanocomposite films were measured with FTIR, SEM, XPS and
DMTA. The results indicated that the interfacial interaction between BaTiO3 nanoparticles and the
silicon-containing polyimide was conspicuous, and that BaTiO3 nanoparticles appeared to be better
dispersed in the polyimide matrix at a higher BaTiO3 concentration than at a lower one. The siliconcontaining
polyimide/BaTiO3 nanocomposite films exhibited higher storage modulus and glass
transition temperature than the original polyimide. It was also found that the infrared emissivity of
the nanocomposite films varied with the content of BaTiO3 in the nanocomposites, and the
nanocomposite films exhibited lower infrared emissivity value than the corresponding polyimide by
measure of infrared emissivity.