bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of Aging Treatment Conditions on the Microstructure and Strength of Fe-36Ni Based Invar Alloy
Authors: Ha Tae Kwon , Lee Kyu Dong , Song Jin Hwa , Jeong Hyo Tae
Published: March 2009

Strengthening method for the Fe-36Ni based Invar alloy for power transmission wire was
investigated in this study. High strength of 1300 MPa could be obtained in this alloy through solution
hardening, precipitation hardening and strain hardening by cold working. Phase equilibrium of the
Invar alloy was calculated using FactSage®, revealing that thermodynamically stable phases are
Mo2C, MoC, M23C6-type FeCrMo carbide, and M6C-type FeMo carbides. Aging treatments were
carried out at temperatures ranging from 400 to 900oC for time intervals from 3 min to 30 hrs. Peak
aging condition was obtained as 400oC and 1 hr. With temperature increased, peak hardness was
decreased abruptly. Microstructure observation was conducted by optical microscopy, scanning
electron microscopy, and transmission electron microscopy. By using the result from aging treatment,
high strength above 1300MPa was obtained in the cold rolled Invar alloy plate.
Processing and Mechanical Properties of Solid Core and Porous Surface Ti-6Al-4V Implants Fabricated by Powder-Metallurgy
Authors: Dewidar Montasser , Lim Jae Kyoo
Published: March 2009

Porous-surfaced with solid core Ti-6Al-4V implant compacts were fabricated by
traditional powder metallurgy. Powder metallurgy technique was used to produce three different
porous surfaced implant compacts 30, 50, and 70% in vacuum atmosphere. The solid core formed in
the center of the compact shows similar microstructure of near full density of Ti-6Al-4V. The
compressive yield strength was up to 270 MPa and significantly depended on the surface porosity,
core size, and temperature of sintering. Selected porous-surfaced Ti-6Al-4V implant compacts with
a solid core have much higher compressive strengths compared to the human teeth and sintered
fully porous Ti-6Al-4V joint replacements. The ingrowth of bone tissue into the outer porous
surface layer results in part fixation, while the solid inner core region provides the necessary
mechanical strength for a device used for the replacement of heavy load bearing joint regions such
as the hip and knee. The microstructure of sintered samples was investigated.
Deformation of Dental Abutment Screw after Tightening and Loosening
Authors: Kim Hee Jung , Choe Han Cheol , Chung Chae Heon , Brantley William A.
Published: March 2009

To evaluate the mechanical deformation phenomena of dental abutment screw after
tightening and loosening, five species of abutments were selected (3i-three, Avana- two) respectively
by two pieces. The abutment screws were repeatedly tightened and removed 20 times with a digital
controller. Field emission scanning electron microscope (FE-SEM) was used to observe changes of
each part caused by repeatedly tightening and loosening experiment. As the number of tightening and
loosening was increased, the wear or distortion of hexed or squared slot that contacted with the driver
tip was more severely progressed. Wear or distortion of hexed slot was more severe than that of
squared slot and it was more remarkable in the titanium screw than in the gold screw. All the tested
screws showed that the width in the crest of their screw thread decreased gradually as the test was
proceeded.
A Gear Chain Fault Detection Method Using an Adaptive Interference Canceling
Authors: Bae Bum Won , Kang In Pil , Choi Yeon Sun
Published: March 2009

A fault diagnosis method based on wavelet and adaptive interference canceling is presented
for the identification of a damaged gear tooth. A damaged tooth of a certain gear chain generates
impulsive signals that could be informative to fault detections. Many publications are available not
only for the impulsive vibration signal analysis but the application of signal processing techniques to
the impulsive signal detections. However, most of the studies about the gear fault detection using the
impulsive vibration signals of a driving gear chain are limited to the verification of damage existence
on a gear pair. Requirements for more advanced method locating damaged tooth in a driving gear
chain should be a motivation of further studies. In this work an adaptive interference canceling
combined with wavelet method is used for a successful identification of the damaged tooth location.
An application of the wavelet technique provides a superior resolution for the damage detection to the
traditional frequency spectrum based methods. An analysis and experiment with three pair gear chain
show the feasibility of this study yielding a precise location of the damaged gear tooth.
Evaluation of Linear and Nonlinear Ultrasonic Response of Contacting Surfaces
Authors: Biwa Shiro , Hiraiwa Shunsuke , Matsumoto Eiji
Published: March 2009

Linear and nonlinear ultrasonic responses of contacting surfaces were studied based on
the contact-pressure dependence of the interfacial stiffnesses. To this purpose, the reflection
coefficients of longitudinal and transverse waves were measured for the contacting interface
between polished aluminum blocks. The normal and tangential stiffnesses of the interface were then
obtained as function of the contact pressure. The reflection coefficients were found to decrease,
while the interfacial stiffnesses were found to increase, with the contact pressure. It was also found
that the ratio of the tangential to normal stiffness as well as the nonlinearity parameters (ratio of the
second harmonic to the squared fundamental amplitudes) could be used as a parameter to
characterize the contact condition.
Characterisation of Composite Material Properties by an Inverse Technique
Authors: Barkanov Evgeny , Chate Andris , Ručevskis Sandris , Skukis Eduards
Published: March 2009

An inverse technique based on vibration tests to characterise isotropic, orthotropic and
viscoelastic material properties of advanced composites is developed. An optimisation using the
planning of experiments and response surface technique to minimise the error functional is applied
to decrease considerably computational expenses. The inverse technique developed is tested on
aluminium plates and applied to characterise orthotropic material properties of laminated
composites and viscoelastic core material properties of sandwich composites.
A Study on the Equipotent Switching Direct Current Potential Drop Method for the Monitoring of Piping Thinning
Authors: Ryu Kyung Ha , Lee Na Young , Hwang Il Soon
Published: March 2009

Flow Accelerated Corrosion (FAC) has become a hot issue because of aging of passive
components. Ultrasonic Technique (UT) has been adopted to inspect the secondary piping. UT,
however, covers only narrow region, which results in numerous detecting points and thus takes
time. In this paper, we suggested a Wide Range Monitoring (WiRM) concept with Equipotent
Switching Direct Current Potential Drop (S-DCPD) method to monitor the thickness of piping.
Since the DCPD method covers area, not a point, it needs less monitoring points. We use the SDCPD
method to screen the candidate area to monitor. Based on the monitoring results, we can
determine the inspection area. To improve the applicability to the piping system, we suggested the
Equipotent concept, which eliminates the leakage current. Finite element analysis results and
developed resistance model are presented for the simple analysis to describe the wall thinning by
DCPD signals. And also validation test results are presented, from which we can identify the
consistency of the model and the experiment.
Plastic Limit Loads for Piping Branch Junctions
Authors: Kim Yun Jae , Lee Kuk Hee , Park Chi Yong
Published: March 2009

The present work presents plastic limit load solutions for branch junctions under internal
pressure and in-plane bending, based on detailed three-dimensional (3-D) FE limit analyses using
elastic-perfectly plastic materials. The proposed solutions are valid for a wide range of branch
junction geometries; ratios of the branch-to-run pipe radius and thickness from 0.0 to 1.0, and the
mean radius-to-thickness ratio of the run pipe from 5.0 to 20.0.
The Time Dependent Reliability Analysis for the Deteriorated Reinforced Concrete Columns Using the Monte Carlo Simulation
Authors: Kim Hee Kyu , Hong Young Kyun , Park Jung Hyun
Published: March 2009

his study was prosecuted to analyze a structural resistance degradation model for the
existing column in the 3-story building to be remodeled. The probabilistic random variables in this
study were dealt with an initial member strength, current maximum crack width, current density and
diameter of reinforcement with elapsed time and corrosion initiation time, TDRA has been performed
to calculate the reliability index, the failure probability, the degradation level according to the member
strength loss in reinforced concrete columns due to corrosion of steel reinforcement.
Reliability Evaluation of Hydrothermal Crystallization on Plasma-Sprayed HA Coatings by the Weibull Model
Authors: Yang Chung Wei , Lui Truan Sheng
Published: March 2009

Plasma-sprayed HA coatings (HACs) on Ti-6Al-4V substrates with post-heat treatments
were employed to improve the microstructural homogeneity, bonding strength and reliability of the
HACs. A defect-healing effect can be recognized to diminish coating defects with the hydrothermal
treatment, and 150°C hydrothermally-treated HACs shows a significant improved bonding strength
than 600°C vacuum heating HACs because of its dense structure from the defect-healing effect.
Low-temperature hydrothermal treatment demonstrates a more superior crystallization effect than
vacuum heat treatment. Based on the statistical calculation by the Weibull distribution function,
hydrothermally-treated HACs show a wear-out failure with a higher Weibull modulus than vacuum
heating HACs. Hydrothermally-treated HACs possessed better reliability can be attributed to the
suppression of defect content (about 2.6-3.2 volume %) and its smaller strength data fluctuation.
Delamination Analysis of Low-Temperature Processed SU-8 Photoresist for MEMS Device Fabrication
Authors: Kim Gwang Beom , Park Chong Dae , Seo Dong Sun , Hong Sang Jeen
Published: March 2009

Negative SU-8 photoresist processed at several levels of lower temperature than
conventional approach was investigated, and its low-temperature processing has been characterized
in terms of delamination. According to two phases of statistical design of experiment (DOE), initially
statistically significant variables of SU-8 photoresist processing were selected, and the selected
variables were further investigated to find their effects on delamination of SU-8 microstructure. A
three leveled factorial designed experiments were performed followed by a 2(6-1)
fractional factorial
designed as a screening experiment. Characterizing low-temperature SU-8 photoresist process, 27
samples were fabricated and the degree of delamination was measured. In addition, nine additional
samples were fabricated for the purpose of verification. Employing a neural network modeling
technique, a process model is established, and response surfaces are generated to investigate the
degree of delamination associated with three process parameters: post exposure bake (PEB)
temperature, PEB time, and exposure energy. From the response surfaces generated, two significant
parameters associated with delamination are identified, and their effects on delamination were
analyzed. The higher the post exposure bake (PEB) temperature at a fixed PEB time and the more
delamination occurred. In addition, the higher the dose of exposure energy, the lower the temperature
at which the delamination begins and the larger the degree of delamination. The results identified
acceptable ranges of the three process variables to avoid the delamination of SU-8 film, which in turn
might lead to potential defects in MEMS device fabrication.
Strength Behaviour of Rockmass Containing Coplanar Close Intermittent Joints under Direct Shear Condition
Authors: Ren Wei Zhong , Wang Yong Gang , Feng Yong , Chen Hao , Chen Jing Qin , Ho John
Published: March 2009

Based on the results of model tests, the deformation and facture mechanisms of brittle
rockmass containing coplanar close intermittent joints under direct shear condition were analysed ,
then the incipient crack strength and communicating destruction criterion of such rockmass were
proposed in this paper. It was shown that the computing results suited the real measuring values well
by comparing them, which indicated the criterions was reasonable ,reliable and has both the theory
and construction significances.
Development of Dissimilar Inertia Welding Process of Large Superalloy Spindle
Authors: Jeong H.S. , Cho J.R. , Park H.C.
Published: March 2009

Considering the exhaust valve spindle consists of a valve head and a stem comprising the
body, the use of different materials, that is, Nimonic 80A for the head and SNCrW for the stem, can
reduce the manufacturing cost dramatically. The inertia welding was conducted to make the large
exhaust valve for low speed marine diesel engines, superalloy Nimonic 80A for valve head of 540mm
diameter and high alloy SNCrW for valve stem of 115mm diameter. Due to different properties of
material like thermal conductivity and flow stress on the two sides of the weld interface, modeling is
crucial in determining the optimal weld geometry and parameters. FE simulation was performed by
the commercial code DEFORM-2D. A Good agreement between the predicted and actual welded
shape was observed. It was expected that simulation will significantly reduce the number of
experimental trials needed to determine the weld parameters, especially for welds of very expensive
materials or large shaft. A variety of tests, including microstructure observation, tensile, hardness and
fatigue test, are conducted to evaluate the quality of welded joints.
Strength and Modal Analysis on Welded Bracket of the Large-Scale Agitator
Authors: Qu Li Gang , Wu Da Wei
Published: March 2009

The welded bracket is an important supporting component with the structural complexity
and crucial functional roles in a large-scale agitator. Strength and modal analysis on it are carried
out with the finite element analysis software COSMOS/DesignStar according to the equipment’s
working behaviours in presence of rational FEA model of the welded bracket being created with 3D
CAD software SolidWorks. The conclusion is made from analysis results that the strength criterion
is satisfied with operating requirement of the equipment, and the risk area of the tensile stress is
explored, moreover, the dangerous natural frequencies are 41Hz and 95Hz which are worked out
respectively through modal analysis results. This analysis process is significant for the agitator
design. The technique foundation and method are not only set up effectively, but also the utilized
data is provided for the product design and successive manufacturing. The lead time of the agitator
will be shortened, and the product quality will be improved.
Numerical Analysis of Mechanical Test Methods for Evaluating Shear Strength of Joint by Using Interface Element
Authors: Serizawa Hisashi , Katayama Kazuaki , Lewinsohn Charles , Singh Mrityunjay , Murakawa Hidekazu
Published: March 2009

As examples of the most typical methods to determine the shear strength of SiC/SiC composite joints, the tensile test of lap joined composite and the asymmetrical four point bending test of butt joined composite were analyzed by using finite element method with the interface element. From the calculation results, it was revealed that the strength in the tensile test was strongly influenced by the residual stress as the increase of the joint layer thickness. In the case of asymmetrical bending test, it was found that the crack initiation point would move due to the residual stress and the strength was also affected by the joint layer thickness.
Comparative Studies of Tensile Strength on Polyester Resin Matrix Composites with Planar and Random Orientation Fibers
Authors: Suherman Hendra , Martiana Wenny , Satria Iman , Saputra Aria
Published: March 2009

Composites have become the chosen material for new engineering materials specially in
the areas of aerospace applications, military weapon and automotive components, due to its unique
mechanical properties, like: high strength weigh ratio, extreme thermal shock resistance, low
coefficient of thermal expansion, oxidation and wear resistance
Polyester resin matrix composites reinforced with coconut fibers are being utilized as replacement
synthetic fiber in fiberglass products. The high price of synthetic fiber, which is use as fiber
reinforcement on fiberglass products, makes its products price become expensive. One alternative to
reduce its prices is by replace fiber synthetic with other fiber, which have similar mechanical
properties but cheaper and still not abandon regional potency. Coconut fiber are regional potency
that still not used optimally, moreover they often considered as waste that doesn’t have economic
values.
These research use experimental methods with control variables are percentage of coconut fiber and
polyester resin by Planar and Random orientation fiber. Specimen testing makes by hand lay up
fabrication.
The research result shows that the optimum composition is on 40% fiber: 60% polyester resin, with
value of tensile strength is 20.75 N/mm2 and value of strain is 0,7 % by planar orientation fibers,
while optimum composition on random orientation is on 30% fiber: 70% polyester resin, with value
of tensile strength is 30.73 N/mm2 and value of strain is 1.4%.
Morphology and Viscoelasticity of Organic/Inorganic Hybrid Nanocomposite
Authors: Araki Wakako , Adachi Tadaharu
Published: March 2009

Two different processes were used to manufacture epoxy/silica hybrid materials.
Observations by AFM, TEM, and Raman spectroscopy demonstrated different silica structures,
depending on the hybrid process. DMTA results indicated that the “sequentially” hybridised sample
had a new glass transition at higher temperatures, which could be attributed to the physical
interaction between the silica chain and the epoxy resin. The dynamic modulus was significantly
improved and depended only on the silica content, not on the silica structure nor the aging.
Sliding Wear Characteristics and Fabrication of LPS-SIC Ceramic by Sintering Additives
Authors: Yoon Han Ki , Park Sung Ho , Park Won Jo
Published: March 2009

Silicon carbide (SiC) materials have been extensively studied for high-temperature
components in fusion blanket system and gas turbines, because they have excellent a hightemperature
mechanical properties, high thermal conductivity and wear resistance. However, the
brittle characteristics of SiC such as low strain-to fracture still impose a severe limitation on the
practical application of SiC materials. Therefore, a study of the sliding wear characteristics and
fabrication of SiC ceramic by sintering temperature and additives are need. As the result of abrasion,
the friction coefficient of the monolithic SiC sintered at 1800°C was the lowest, and the friction
coefficient of that sintered at 1760°C was the highest. The monolithic SiC manufactured at 1800°C
showed the highest hardness and the lowest friction coefficient. The friction coefficient of the
monolithic SiC sintered by the SiO2 contents of 2wt% was the lowest, and the friction coefficient
that sintered by the SiO2 contents of 5wt% was the highest. 1800°C of sintering temperature and
2wt% of SiO2 contents ware shown high hardness, low friction coefficient and wear loss compare
with other temperatures and SiO2 contents.
The Multi-Channels Measurement of Strain Generated Potentials in Osseointegrated Implant-Bone Composite
Authors: Hong Jung Hwa , Ko Sang Ok , Lee Soon Hyuck
Published: March 2009

"Osseo" refers to bone and "integration" refers to how a prosthesis can be integrated with
the bone in residual limbs both arms and legs. Osseointegration(OI) was originally defined as a
direct structural and functional connection between ordered living bone and the surface of a loadcarrying
implant. OI could be described as the modality for stable fixation of titanium implant to
bone structure. The OI has become a realized phenomenon of importance in the dental and
rehabilitation sciences since recently developed dentures and artificial limbs are directly attached to
human skeleton by using osseointegrated implants. Previously, a study showed that bone strain
generated potential (SGP) that is an electrical potential and considered to be generated by fluid flow
in bone could be used as a parameter to examine the amount of OI on bone-implant interface. Since
no study was performed to understand according to the point on behavior of SGP for the boneimplant
composite. In this study, we used a multi-channel measurement system and investigated
SGP according to the point. Four white New Zealand rabbits underwent pure titanium implant
insertion surgery to tibia after amputation. After checking full OI at the end of the 5 weeks,
experimental animals were euthanized and the amputated tibia-implants were harvested. Holes of
0.5mm in diameter were made on the tissue of the tibia and electrodes of 0.16mm in diameter were
inserted to the holes. Then, the instrumented bone-implant composites were placed to a servo
material testing machine to apply axial compressive displacement loadings. During the compression
tests, SGPs were also measured. Magnitude of SGP was found to be significantly increased near
bone and implant interface for the osseointegrated bone-implant composite.
Web-Based Material Database for Material Selection and its Application Programming Interface (API) for CAD
Authors: Chun Doo Man , Kim Hyung Jung , Lee Jae Chul , Ahn Sung Hoon
Published: March 2009

Material selection became one of the important activities for engineers in design and
manufacturing processes. A selected material at the beginning of design stage affects functionality of
the designed part as well as manufacturability and cost of the final product. Unfortunately there are
not many accessible material databases that can be properly used for design. In this research, a
web-based material database was constructed. In order to assist designers to compare different
materials, two-dimensional and three-dimensional graphs for comparison of material properties were
provided via the web browser. Using these graphical tools, multi-dimensional comparison was
available in more intuitive manner. In addition, this web site is open to the public, and one may add
new material properties to the database in order to compare the data with existing materials. To
provide the database in a commercial CAD (Computer Aided Design) environment, API (Application
Programming Interface) modules were developed using Web services. The web-based material
database can be accessible from http://fab.snu.ac.kr/matdb.
Fabrication of Diamond Dispersed Nickel Composite Coating by Electroplating Method to Enhance the Mechanical Property of Coating
Authors: Moon Yun Sung , Lee Jae Ho , Oh Tae Sung , Byun Ji Young
Published: March 2009

The codeposition behavior of submicron sized diamond with nickel from nickel
electrolytes has been investigated. Electroplating of diamond dispersed nickel composites was
carried out on a rotating disk electrode (RDE). The effects of current type and current density on
the electrodeposited Ni-diamond composite coating were investigated. The effects of pH and
surfactants on the composite coating were also investigated. The hardness of coating was
measured with varying electroplating conditions. As diamond was incorporated into the coating,
the hardness of coating as well as the wear resistance was improved. The surface morphologies of
the Ni-diamond composite coatings were observed using FESEM.
Creep Resistance of Thermoplastic Nanocomposites
Authors: Schlarb Alois K. , Yang Jing Lei , Zhang Zhong
Published: March 2009

Relatively poor creep resistance is considered as a deficiency of thermoplastic materials
in general. In order to comprehensively and deeply study the effect of nanoparticles incorporated
into a polyamide matrix a systematic investigation on various kinds of nanofillers under differed
temperatures and stress levels have been performed. It was found that the creep resistance of
polyamide 66 can be significantly enhanced due to the incorporation of nanofillers and the behavior
of the composites can be easily described by the model of Findley.
The Effect of Mn/S Ratio on Hot Ductility of Bi Bearing Free Cutting Steels
Authors: Kim Min Soo , Lee Hyong Jik , Chang Young Won
Published: March 2009

The effect of Mn/S ratio on hot ductility of Bi bearing steels has been investigated at the
temperatures ranging from 950 to 1250. The hot ductility, measured as the reduction ratio of
area, was found to depend on the Mn/S ratio and test temperature to provide the largest hot ductility
at the ratio of 3.903 at 1200 . The hot workability of Bi bearing free cutting steels seems to
depend greatly on the size, volume fraction, and type and distribution of inclusions. In addition, hot
deformation behavior of Bi bearing free cutting steel has also been characterized by constructing a
processing map developed on the basis of the dynamic material model. A series of hot compression
tests has been carried out at the temperatures ranging from 950 to 1250 under the strain rate
ranging from 10-3 /s to 102 /s.
Effect of Peel Rate on Interfacial Strength
Authors: Masuda Ryota , Omiya Masaki , Inoue Hirotsugu , Kishimoto Kikuo
Published: March 2009

Adhesives are widely used in industrial world. However, it is difficult to characterize
their mechanical properties because those strongly depend on environmental and mechanical
conditions such as temperature, humidity or strain rate. In this paper, we focus on the strain rate
dependence of the interfacial strength and investigate the interfacial strength by peel tests under
several peel rates. The results show that, in low rate case (under 10-2 mm/s), the interfacial strength
was constant and, in middle rate case (10-2 to 103 mm/s), the interfacial strength increased with the
peel rate. Over 103 mm/s case, the interfacial strength became lower than those in middle rate cases.
From the observation of peeling front by a high speed video camera, the deformation behavior of
adhesives changed with the peel rate.
In-Situ Atomic Force Microscopy and Crystallo Graphic Orientation Analysis of Small Fatigue Crack Deflection Behavior
Authors: Sugeta Atsushi , Uematsu Yoshihiko
Published: March 2009

Successive observation of transgranular small fatigue crack growth behavior of
alpha-brass was performed by means of an atomic force microscope (AFM) equipped with
small in-plane bending fatigue testing machine. The fatigue crack deflection behavior, which
was observed frequently in the low growth rate region, was investigated by the
crystallographic orientation analysis based on the Electron Back Scatter Diffraction (EBSD)
technique. The slip factor considering the slip system and singular stress field at the crack
tip was introduced in order to evaluate the easiness of slip deformation instead of Schmid
factor. The direction of crack deflection was found to be explained well by the slip factor
and the geometric relative location between the preferential slip plane and crack front.
Fatigue Strength of Formable Ultra High-Strength TRIP-Aided Steels with Bainitic Ferrite Matrix
Authors: Sugimoto Koh Ichi , Tsuruta Junji , Song Sung Moo
Published: March 2009

Formable ultra high-strength TRIP-aided steel with bainitic ferrite matrix structure (TBF
steel) contributes to a drastic weight reduction and an improvement of crash safety of automobile.
In this study, fatigue strength of 0.2%C-1.5%Si-1.5%Mn TBF steels was investigated. High fatigue
limit was achieved in TBF steels austempered at 400-450oC, containing a large amount of stable
retained austenite. The fatigue limit was linearly related with mobile dislocation density, as well as
TRIP effect of retained austenite. When compared to conventional martensitic steel, the TBF steel
exhibited lower notch-sensitivity or higher notched fatigue performance. Complex additions of
0.5%Al, 0.05%Nb and 0.2%Mo considerably improved the notched fatigue performance, as well as
the smooth fatigue strength. This was associated with the stabilized retained austenite and refined
microstructure which suppress fatigue crack initiation and/or propagation.
Elevated-Temperature Creep-Fatigue Crack-Growth Behavior of HAYNES®188 Superalloy
Authors: Lee S.Y. , Lu Y.L. , Liaw Peter K. , Choo Hahn , Thompson Scott A. , Blust James W. , Browning Paul F. , Bhattacharya Arun K. , Aurrecoechea Jose M. , Klarstrom Dwaine L.
Published: March 2009

The creep-fatigue crack-growth behavior of HAYNES® 188, a cobalt-based superalloy, was studied at the temperatures of 649, 816, and 927 oC under isothermal conditions. Various hold times at the maximum load were introduced to study the effects of hold time and temperature on the crack-growth behavior. The experiments were conducted under constant stress-intensity-factorrange control modes. Crack lengths were measured by a direct current potential method. The introduction of hold times led to an increase in the cyclic crack-growth rate. As the temperature increases, the time-dependent crack-growth behavior was dominant.
Effect of Semi Austempering Treatment on the Fatigue Properties of Ductile Cast Iron
Authors: Lim Bokkyu , Choi Young Woo
Published: March 2009

Single phase bainite structure which is obtained by the conventional austempering
treatment reduces the ductility of ductile cast iron. Because of the reduction of ductility it is possible
to worsen the fatigue properties. Therefore, semi austempered ductile iron which is treated from +ϒ
is prepared to investigate the static strength and fatigue properties in comparison with fully
austempered ductile iron (is treated from ϒ). In spite of semi austempered ductile iron shows the 86%
increase of ductility. Also, semi austempered ductile iron shows the higher fatigue limit and lower
fatigue crack growth rate as compared with fully austempered ductile iron. By the fractographical
analysis, it is revealed that the ferrite obtained by semi austempering process brings about the plastic
deformation(ductile striation) of crack tip and gives the prior path of crack propagation. The
relatively low crack growth rate in semi austempered specimen is caused by above fractographical
reasons
Fatigue Crack Growth Behavior in Girth Weld of Natural Gas Transmission Pipelines
Authors: Kim Young Pyo , Kim Cheol Man , Kim Woo Sik , Shin Kwang Seon
Published: March 2009

A clear understanding of fatigue properties for the pipeline steel and its weld is important
to provide information for pipeline design during pipeline construction and predict pipeline fatigue
life during pipeline operation. The materials used in this study are API 5L X65 pipeline steel
generally used for natural gas transmission. This pipeline was welded by gas tungsten arc welding
(GTAW) and shielded metal arc welding (SMAW) with V-groove configuration. The fatigue crack
growth behaviors of pipeline steel and its girth weld according to crack growth directions and stress
ratios were investigated over a wide range of stress intensities in laboratory air.
Fatigue Strength Evaluation for Gas Welded Joint of Similar and Dissimilar Materials
Authors: Bae Dong Ho , Kim Yeong Sin , Lee Gyu Young , Park Kwang Jin
Published: March 2009

In order to establish a reasonable and integrated fatigue design criterion for the long life
design of the gas welded body structure, stress distribution around the gas welded joints subjected
to tensile load was numerically analyzed. And also, the P-Nf curves were obtained by fatigue tests.
By using these results, P-Nf curves were rearranged in the σ-Nf relation with the hot spot stress at
the welded joint. And a guideline for fatigue design of gas welded joints was proposed.
Crack Propagation as a Free Boundary Problem
Authors: Spatschek Robert , Brener Efim A. , Pilipenko Denis
Published: March 2009

We present a continuum theory which predicts the steady state propagation of cracks. The
theory overcomes the usual problem of a finite time cusp singularity of the Grinfeld instability by the
inclusion of elastodynamic effects which restore selection of the steady state tip radius and velocity.
We developed a sharp interface method and a phase field approach to investigate the model. The
simulations confirm analytical predictions for fast crack propagation.
Dynamic Analysis of a Piezoelectric Material with an Impermeable Penny-Shaped Crack under Pure Torsional Wave
Authors: Chen Zeng Tao
Published: March 2009

A torsional transient wave was assumed acting at infinity on the piezoelectric body
with an embedded penny-shaped crack. Appropriate governing equations and boundary conditions
have been built within the three-dimensional electroelasticity. The total displacement field was
simply considered as the combination of two parts, one related to incident waves inducing an
oscillating motion, and another with the scattered waves. An electric impermeable crack was
assumed to simplify the mathematical analysis. The problem was formulated in terms of integral
transforms techniques. Hankel transform were applied to obtain the dual integral equations, which
were then expressed to Fredholm integral equations of the second kind.
Failure Stress Estimation of Table Liner for Vertical Roller Mill
Authors: Lee Dong Woo , Cho Seok Swoo , Joo Won Sik
Published: March 2009

A roller mill is composed of several rollers, rotational table liners, hydraulic cylinders and
raw materials are ground between the rollers and the table with the assistance with a shearing and
compressive force. It has been reported that an unexpected fatigue failure occurred in a table liner in
the course of grinding portland cement. It is subjected to the cyclic bending stress by the rollers load
and the centrifugal force by the table rotation and fractures at the edge of grinding path of outer roller.
It demands design life 4×107 cycles but has fatigue life 4×106 ~ 8×106 cycles. The purpose of this
study is to reveal the failure mechanism of the table liner occurring in the grinding operation of roller
mill and to show the structural design guidelines for reducing the fatigue failure.
Embrittlement Behavior of Isothermally Heat-Treated T/P92 Steel at 350°C
Authors: Koo Ja Min , Kim Sung Yong , Shin Kee Sam , Jung Yeon-Gil , Hur Sung Kang
Published: March 2009

P92 steels as well as P91 are widely used as boiler tube materials of ultra super critical
(USC) power plants these days. And thus embrittlement is very important for structural integrity of
the USC plants. The embrittlement was observed when P92 (Modified 9Cr-1.8W-0.5Mo-V-Nb)
steels were quenched to and held at the temperature of 320 to 350°C, which were the temperatures
intermediate between Ms and Mf, and then air-cooled. Nearly same kind of the embrittlement had
been observed with the T/P91 steels and a theory had been proposed to explain the mechanism of
the embrittlement by us. From the theory, the embrittlement might be caused by the brittle
martensite which is freshly formed during air-cooling. We tried to apply the theory for the
embrittlement of the T/P92 steel. The behaviors of the embrittled T/P92 steel were explained well
by the theory.
Strain Rate Dependent Micro- to Macroscopic Deformation Behavior of Carbon-Black Filled Rubber under Monotonic and Cyclic Straining
Authors: Tomita Yoshihiro , Azuma K. , Naito M.
Published: March 2009

A constitutive equation of rubber is derived by employing a nonaffine molecular chain network
model for an elastic deformation behavior and the reptation theory for a viscoelastic deformation behavior.
The results reveal the roles of the individual springs and dashpot, and the strain rate dependence of
materials in the monotonic and cyclic deformation behaviors, particularly softening and hysteresis loss, that
is, the Mullins effect, occurring in stress-stretch curves under cyclic deformation processes of carbon black
filled rubber..
Microstructure and Tensile Creep Behavior of Mg-Nd-RE-Ca Casting Alloys
Authors: Jun Joong Hwan , Park Bong Koo , Kim Jeong Min , Kim Ki Tae , Jung Woon Jae
Published: March 2009

Influences of Ca addition on microstructures and mechanical properties at room and elevated
temperatures have been investigated for Mg-1.5%Nd-1.0%RE-0.5%Zn-(0~1.0)%Ca casting alloys, on
basis of experimental results from X-ray diffractometry (XRD), scanning electron microscopy (SEM)
with energy dispersive X-ray spectroscopy (EDS), tensile and creep tests. Microstructures of the alloys
are characterized by dendritic α-(Mg) grains surrounded by Mg12Nd-Zn-(Ca) eutectic network phase.
The average size of α grains decreases gradually with an increase in Ca content. At room temperature,
yield strength (YS) is enhanced with increasing Ca content with a decrease in ultimate tensile strength
(UTS) and elongation to fracture, whereas the Ca addition leads to greater YS and UTS at 175oC. The
tensile creep strain and secondary creep rate, measured at 150 and 200oC under 100MPa for 100hrs,
become lower with the increase in Ca content. The obtained tensile properties at elevated temperature
demonstrate that the addition of Ca plays a role in improving high temperature mechanical properties
including creep resistance for the Mg-Nd-RE-Zn-(Ca) alloys. In view of microstructural evolution, this
would be attributed to the refined primary α grains and higher thermal stability of the Mg12Nd-Zn-Ca
eutectic strengthening phase.
Effect of Powder Particle Sizes on the Development of Ultra Hard Surface through Superplastic Boronizing of Duplex Stainless Steel
Authors: Yusof H.A. Mohd , Jauhari Iswadi , Rozali Shaifulazuar , Hiroyuki O.
Published: March 2009

In this work, a further study on boronizing using compression method called superplastic
boronizing (SPB) was conducted. This process was conducted on duplex stainless steel (DSS) that
exhibited superplasticity. Efforts were being put in obtaining ultra hard surface through SPB by
focusing on the boron powder particle size. The microstructure, hardness, and layer thickness of the
boronized materials were investigated. Comparison using as-received DSS with coarse
microstructure also was performed. The overall results from the study showed that the SPB process
can produced a very hard surface of close to 4000 HV and significantly improved the surface
properties of the DSS.
Slope Stability Analysis by Strength Reduction Elasto-Plastic FEM
Authors: Chen Jing Xi , Ke Peng Zhen , Zhang Guang
Published: March 2009

An strength reduction technique combined with elasto-plastic Finite Element Method
(FEM)is applied in the analysis of slope stability in this paper .The authors present a well-defined
total equivalent plastic strain (TEPS) zone as the failure criterion when it running through the
bottom to the top of a slope. Based on non-linear FEM and computed displacement technique, the
result of elasto-plastic FEM analysis could be displayed, which makes the conception of slope
failure more clear. Moreover, according to TEPS zone , the position of sliding face and the safety
coefficient also can be obtained . The calculated result of the example proves the presented method
is more effective in analyzing the stability of slope, which offers a new thinking for the analysis of
slope stability, and can be wildly applied to slope engineering practices.
Prediction of Defects in Nano-Imprint Lithography Using FEM Simulation
Authors: Son Ji Won , Song Nam Ho , Rhim Sung Han , Oh Soo Ik
Published: March 2009

In nano-imprint lithography (NIL) process, which has shown to be a good method to
fabricate polymeric patterns, several kinds of pattern defects due to thermal effects during polymer
flow and mold release operation have been reported. A typical defect in NIL process with high aspect
ratio and low resist thickness pattern is a resist fracture during the mold release operation. It seems
due to interfacial adhesion between polymer and mold. In the present investigation, FEM simulation
of NIL process was carried out to predict the defects of the polymer pattern and to optimize the
process by FEA. To achieve the above mentioned purpose, FEM simulation technique based on
constitutive modeling of polymer with experiments was firstly investigated [1]. Secondly, the
embossing operation in NIL process was investigated in detail by FEM. From the analytical results, it
was found that the non-uniform flow-pattern of polymer and the applied pressure in the embossing
operation induce the cavity and the drastic lateral-strain at the edge of pattern. It was also shown that
the low polymer-thickness result in the delamination of polymer from the substrate. It seems that the
above phenomena cause the defects of the final polymer pattern.
Micromechanics of Rupture in Combined Tension and Shear
Authors: Barsoum Imad , Faleskog Jonas
Published: March 2009

A micromechanics model based on the theoretical framework of plastic localization
into a band introduced by Rice [1] is developed. The model employed consists of a planar band with
a square array of equally sized cells, with a spherical void located in the centre of each cell. The
micromechanics model is applied to analyze the rupture mechanisms associated with mixed mode
ductile fracture. The stress state is characterized by the stress triaxiality T and the Lode parameter μ,
which adequately describe the stress state ahead of a crack tip under mixed mode loading of an
isotropic elasto-plastic material. The main focus is the influence of μ on void growth and
coalescence behavior. It is shown that the Lode parameter exerts a strong influence upon this
behavior.
Strain Rate Effect on Out of Plane Shear Strength of Fiber Composites
Authors: Tsai Jia Lin , Kuo Jui Ching
Published: March 2009

This research aims to investigate strain rate effect on the out of plane shear strength of
unidirectional fiber composites. Both glass/epoxy and graphite/epoxy composites were considered in
this study. To demonstrate strain rate effect, composite brick specimens were fabricated and tested to
failure in the transverse direction at strain ranges from 10-4/s to 700/s. Experimental observations
reveal that the main failure mechanism of the specimens is the out of plane shear failure taking place
on the plane oriented around 30 to 35 degree to the loading direction. The corresponding out-of-plane
shear strength was obtained from the uniaxial failure stress through Mohr-Coulomb strength analysis.
In addition, the associated shear strain rate on the failure plane was calculated through the coordinate
transformation law. Results show that the out-plane shear strength increases with the increment of the
shear train rates. A semi-logarithmic function expressed in terms of the normalized shear strain rate
was employed to describe the rate dependence of the out-plane shear strength.
Fabrication of Pt-IrOx and Au-V2O5 Thin Films
Authors: Vinci Richard P. , Bannuru T. , Hyun Seung Min , Brown Walter L.
Published: March 2009

Pt-IrOx and Au-V2O5 thin films were created by magnetron co-sputtering from multiple
targets in an Ar-O2 mixture. Successful Pt-IrOx production required high O2 partial pressure and
slow deposition rate followed by post-annealing in pure O2. In contrast, deposition of Au-V2O5
films required relatively low O2 partial pressure, and did not need any post-anneal. These different
strategies for forming oxide dispersion strengthened films in a multi-target reactive sputtering
configuration are directly related to the thermodynamic characteristics of the two materials systems.
The most important characteristics are the low equilibrium oxygen solubility in Pt and Au, and the
different degrees of oxygen affinity by Ir and V.
Effect of TRIP on the Damping Capacity and Strength in Fe-Al-Mn Alloy
Authors: Kang Chang Yong , Son Don Wook , Sung Jang Hyun , Nam Ki Woo
Published: March 2009

The damping capacity and strength of Fe-6Al-25/34Mn alloys have been studied for the
development of new materials with high strength and damping capacity. Particularly, the effect of
α’(including α) and ε martensite phases, which constitute the microstructure of cold rolled Fe-Al-Mn alloys,
has been investigated in terms of the strength and damping capacity of the alloys. The damping capacity rises
with increasing the degree of cold rolling and reveals the maximum value at 32% reduction. The damping
capacity is strongly affected by the volume fraction of ε martensite. The phases such as α’ and austenite(γ)

on damping capacity. Considering that tensile strength increases and elongation decreases
with increasing the volume fraction of α’-martensite, it is proved that tensile strength is mainly affected by
the amount of α’martensite.
Nanoindentation by Multiple Loads Methodology: A Pile Up Correction Procedure
Authors: Garrido-Maneiro Miguel Ángel , Rodríguez Jesus
Published: March 2009

Young’s modulus and hardness data obtained from nanoindentation are
commonly affected by phenomena like pile up or sink in, when elastic-plastic materials
are tested. In this work, a finite element model was used to evaluate the pile up effect on
the determination of mechanical properties from spherical indentation in a wide range of
elastic-plastic materials. A new procedure, based on a combination of results obtained
from tests performed at multiple maximum loads, is suggested.
Stresses at the Interface between the Functionally Graded Coating and the Elastic Half-Space Caused by Spherical Indentation
Authors: Aizikovich S.M. , Krenev L.I. , Trubchik I.S.
Published: March 2009

Recent advances in nanotechnology have revealed numerous new methods of manufacturing
functionally graded coatings and materials, but progress in this field is limited by the lack of
knowledge about the mechanical behavior of such structures. Existing models of the mechanics of
layered structures are not generally adequate for this purpose, since functionally graded structures
can exhibit both qualitative and quantitative behavioral differences in comparison with
homogeneous or layered structures, particularly if there is a significant gradient of elastic properties
in the coating.
In applications, interest is focused mainly on the deformation fields and stresses inside the
inhomogeneous material caused by the contact tractions. Stresses at the interface between the
functionally graded coating and the elastic half-space are of particular interest because of their
influence on the propagation of cracks and other defects on this interface. Shear stresses at this
interface associated with rapid variation in elastic properties with depth are particularly dangerous
because of potential delaminations.
In their work the authors:
• develop a precise mathematical model and of the computational methods which makes it
possible to achieve stable numerical results while analyzing the mechanical properties of
functionally graded coatings;
• study the variation effect in elastic properties on the maximum stresses in the surface layers
of materials with functionally graded coatings caused by indentation.
Texture Evolution during Hot Rolling Deformation in Al-5wt%Mg Alloy
Authors: Choi Shi Hoon , Song Y.S. , Kim Jong Kweon , Kim Hyoung Wook , Kang Suk Bong
Published: March 2009

Evolution of crystallographic texture by hot rolling deformation at the temperature of
200°C was investigated by hot rolling tests on as-cast Al-5wt%Mg alloy fabricated by a new strip
cast technology. Texture variation through the thickness direction in the Al-5wt%Mg alloy was
examined experimentally. Macrotexture and microtexture measurements were conducted using
X-ray diffractometer and electron backscatter diffraction (EBSD), respectively. Experimental
investigation reveals that the evolution of texture and microstructure is strongly dependent on a
distance from center of the Al-5wt%Mg alloy sheet. It was found that the shear texture components
tend to be increased at the surface region of the hot-rolled specimen.