bluuebunny/crossref_metadata_2025 huggingface dataset:
Release Profile of BSA or BDNF from Temperature Sensitive Hydrogels
Authors: Cho Mi Hee , Hyun Hoon , Shin Yu Na , Lee Jung Won , Lee Min Suk , Ahn Hyun Hee , Kim Moon Suk , Lee Bong , Ghang Gil Son , Lee Hai Bang
Published: March 2009

Methoxy poly(ethylene glycol) (MPEG)-b-poly(ε-caprolactone) (PCL) diblock
copolymer was synthesized by ring-opening of ε-caprolactone (ε-CL) in the presence of a monomer
activator with the terminal alcohol of MPEG as an initiator. The temperature sensitive behavior of
the prepared MPEG-PCL diblock copolymer solution was examined. The polymer solution formed
translucent sol at the room temperature. As the temperature increased from room temperature, the
sol became gel, indicating that the diblock copolymer solution at room temperature can form gel at
body temperature. Brain-derived neurotrophic factor (BDNF) loaded MPEG-PCL diblock
copolymer solution and Pluronic solution for comparison were prepared to examine the release
behavior of BDNF. Pluronic gel exhibited nearly complete release of BDNF even at 2 day, while
the release of BDNF in MPEG-PCL gel showed the prolonged release profile for 21 days. In this
study, we confirmed that thermosensitive MPEG-PCL diblock copolymer in this work could utilize
as a potential carrier of BDNF.
Improving Blood Compatibility of Cardiovascular Devices by Surface Modification
Authors: Huang Nan , Yang Ping , Leng Yong Xiang , Chen Jun Ying , Wang Jin , Wan Guo Jiang , Sun Hong , Wu X. , Zhao An Sha
Published: March 2009

This paper presents recent activities on the surface modification of blood contacting
biomaterials and devices in the author’s laboratory. Surface coating of inorganic films on materials
for artificial heart valves, ventricular pumps and coronary stents, such as titanium, stainless steel
and low temperature isotropic pryolitc carbon, etc, shows a significant improvement in the
anticoagulation behavior. Further, the formation of functional groups such as hydroxyl or amino
groups and the binding of biomolecules as well as seeding of endothelial cell shows the promise of
biomimetic surface formation. Plasma grafting on materials for artificial heart valve sewing cuff,
extracorporeal circulation tube, etc, such as PET, PU, PVC polymers, revealed a significant
improvement of anti-platelet adhesion as well as anti-bacterial properties.
Punching Force Reduction with Wave-Formed Tools
Authors: Karjalainen Jussi A. , Mäntyjärvi Kari , Juuso Martti
Published: March 2009

Flat-end tools are the most general types used in sheet metal punching and nibbling. They
are geometrically simple and easy to sharpen but, on other hand, their cutting forces are relatively
large, and hence the cutting process is frequently noisy. In order to reduce both cutting force and
noise tools with one-way or two-way shearing have been utilised. The major drawbacks of these
tools are the asymmetry of cutting easily causing non-circular holes with round tools, lateral forces
with one-way shearing, excessive forming during cutting and more complex tool geometry to
maintain.
Here a new geometry for a punch is employed. The shearing edge is a sinus curve with several
peaks making the cutting edge circularly symmetric and the phenomenon totally balanced. This
means smaller forming forces, particularly in cases when also the radial form is concave. The
geometry is without doubt more complex compared to the flat-end tool but rather easy to produce
by multi-axis milling and electro-discharge machining.
In the current work a set of experimental punches has been designed, manufactured and tested. A
simple analytical theory for cutting force has also been derived and compared with the test results.
The results show that the new geometry produces very precise hole geometry with a lower cutting
force compared to conventional flat-end tools. Of course, more theoretical and experimental work is
required to optimise the tool geometry including the tool clearance for each pair of material strength
and thickness.
Effects of High Temperature Gas Environments(H2, Pure Air, Ar, Vacuum) on Slow Strain Rate Tensile Properties at 700°C of TiAl Alloy
Authors: Iino Y. , Itoh M. , Omote M. , Yamaguchi Y. , Ban T.
Published: March 2009

Tensile test of TiAl alloy was carried out in 700oC gas environment(H2, pure air, Ar,
vacuum) at three strain rates, 2.8x10-4, 2.8x10-5, and 2.8x10-6s-1. With decreasing strain rate, the
ultimate tensile strength decreased in all environments similarly. However, elongation to fracture
differed from each environment. With decreasing strain rate, the elongation to fracture in vacuum
and Ar increased slightly, that in H2 increased much and that in pure air significantly. The reasons
of such behaviour are not known. One of the reasons for high elongation to fracture would be
formation of multiple microcracks in H2 and pure air on the gauge surface of the specimen during
tensile deformation.
Formability Evaluation of both Monolithic and Multiphase Zr-Based Bulk Metallic Glasses
Authors: Lee K.S. , Jun H.J. , Kim Choong Nyun Paul , Eckert Jürgen , Chang Young Won
Published: March 2009

The formability of several Zr-based bulk metallic glasses in the supercooled liquid region has been
estimated. Using the data obtained from compression tests, normalized processing maps based on a dynamic
materials model (DMM) have been constructed to evaluate feasible forming conditions. Laboratory-scale hot
extrusion of the Zr44Ti11Cu9.8Ni10.2Be25 BMG has also been carried out to clarify the effectiveness of the
normalized processing maps established in this study. The influence of thermal properties and
microstructural differences on the formability of BMGs is interpreted in terms of a normalized temperature
within the supercooled liquid region.
Experimental Study on Degradation of 1Cr5Mo Steel Tubes in the Coking Furnace at Super Temperature
Authors: Fang De Ming , Li Ying , Lou Bai Yang
Published: March 2009

Microstructure, hardness and mechanical properties of the 1Cr5Mo steel tubes for the
coking furnace at super temperature were investigated in this paper. It revealed that under
super-temperature, oxidation corrosion for the furnace tubes was strengthened, wall thickness was
evident thinner, pearlite in microstructure was spheroidised mostly, strength would be decreased
and marked degradation in material occurred.
Overview on Nanoimprint Technology - Process, Tools, Applications and Technical Issues for Industrialization
Authors: Goto Hiroshi
Published: March 2009

Nanoimprint process is a simple and a low cost micro/nano fabrication method based on
mold replication principle. Various kinds of applications such as optical devices for flat panel
displays or electronic papers, patterned medias, bio-medical devices and electronics devices using
nanoimprint process are expected. In the past a decade, many researches and developments on the
process, the tool, the application relating to nanoimprint were carried out and partly
commercialized. In this paper, overview on nanoimprint technology including recent progress is
described. And important issues to be solved and solution idea for industrialization of nanoimprint
process are pointed out. Also, our recent R&D activities on nanoimprint tool and process, which are
UV/thermal nanoimorint tool and process, roll to roll type imprint system are introduced.
An Adaptive Loading Test on Collapse Mechanism Formation of Multi-Story Steel Frames Subjected to Uncertain Lateral Load Pattern
Authors: Ohi Kenichi , Choi Jae Hyouk
Published: March 2009

An adaptive loading system is developed to examine a design point of multi-story steel
test frames subjected to uncertain load pattern. Lateral loads are given as a random combination of
basic load patterns, and the system drives a test frame to the most likely failure situation. Two-story
steel moment resisting frames are tested considering a failure mechanism formation of plastic
collapse as a tentative limit state. A random 2-dof lateral force is given by a random combination of
two basic load patterns, which are arranged to represent elastic earthquake load effects. Hybrid
design point search or adaptive loading tests on the 2-story frame are performed, and the detected
likely failure mechanisms are compared with the results of pseudo-dynamic response tests to
deterministic excitations.
Evaluation of Mechanical Properties of Graphite Layers on a Nuclear Fuel Particle by Kinetic Nano-Indentation Technique
Authors: Choi K.S. , Choi Y. , Kim Bong Goo , Lee Y.W.
Published: March 2009

Small specimen with simple geometry has advantage for irradiation tests because the
tests have limits for experiments and nuclear wastes after irradiation tests. In this study, a kinetic
indentation technique is applied to evaluate mechanical properties of coated layers of a particle fuel
of a high temperature gas cooled reactor. Hardness of buffer, IPyC and OPyC are 0.55, 0.874 and
2.726 GPa, respectively. The density, strength and friction coefficient estimated by kinetic
indentation method are 1.08, 1.15 and 1.81 g/cm3, and 174, 291 and 606 MPa, and 0.51, 0.45 and
0.4, respectively.
Casting and Modeling of Titanium Matrix Composites
Authors: Sung Si Young , Choi Bong Jae , Kim Young Jig
Published: March 2009

The aim of this study is to establish the net-shape forming of titanium matrix composites
(TMCs) shot sleeve for Al alloys die-casting using a casting route. In-situ synthesis and casting of
TMCs were carried out in a vacuum induction melting furnace. The synthesized (TiC+TiB) TMCs
were examined using an scanning electron microscopy and electron probe micro-analyzer. The
thermo-physical variables estimated by casting process were applied to the modeling of TMCs
shot-sleeve casting using the Magmasoft®. The results of the investment casting and modeling of
TMCs confirm that the casting route can be an effective approach for the economic net-shape forming
of TMCs shot sleeve.
Mechanical Properties of Carbon Nanofiber Reinforced Polylactic Acid
Authors: Shimamura Yoshinobu , Yamamoku Atushi , Tohgo Keiichiro , Tasaka Shigeru , Araki Hiroyasu
Published: March 2009

Carbon nanofiller reinforced PLA was fabricated, and the mechanical properties and heat
resistivity were measured. Vapor grown carbon fiber (VGCF) produced by Showa Denko K.K. was
used for reinforcement, which has 150 nm in diameter and 10 μm in length. No surface treatment of
VGCF was conducted. VGCF and PLA were compounded by using a twin screw extrusion machine
and then pelletized. The weight fraction of VGCF ranged from 1wt% to 10wt%. Three point bending
specimens were fabricated by using injection molding. At first, three point bending tests were carried
out at room temperature. The bending stiffness increased from 3GPa to as high as 5GPa, but the
bending strength slightly decreased. SEM observation of the fracture surfaces indicated pull-out of
VGCFs over the fracture surfaces. These results imply that adhesion between VGCF and matrix was
imperfect. Then, the heat deflection temperatures and glass transition temperatures of the specimens
were measured. The addition of VGCF did not increase the glass transition temperature but slightly
increased the heat deflection temperature.
A Simple and Direct Method for Local Temperature Measurement and its Applications to Materials Evaluations
Authors: Hasegawa Takashi , Kohara Toru , Saka Masumi
Published: March 2009

General thermometers pose difficulty in measuring the actual surface temperature of a
micro-area, especially in electronic devices. In the present study, an approach to direct measurement
of surface temperature is described, which utilizes the potential of melting point of different chemical
reagents. The present technique exhibits a temperature resolution of about 5○C and the measurable
maximum temperature of about 200○C. A short comment on the application of the technique to
determine the actual surface temperature of small areas in some engineering applications is also
stated.
Structural Integrity Evaluation of API 5L X65 Pipe Subjected to Pre-Strain up to Tensile Strain Using the API 579 Procedure
Authors: Baek Jong Hyun , Kim Cheol Man , Kim Young Pyo , Seok Chang Sung
Published: March 2009

Mechanical properties of the pre-strained material are different with those of virgin
material without pre-strain. Buried pipelines for natural gas transmission may be deformed by
outside force such as ground subsidence, ground liquefaction, cold bending and mechanical
damage. Plastic deformation affects the tensile properties and fracture toughness. The effects of prestrain
on the mechanical properties of API 5L X65 pipe were diversely investigated through the
tensile test, crack tip opening displacement test and Charpy impact test. Axial tensile pre-strain of
1.5, 5 and 10% was applied to plate-type tensile specimens cut from the pipe body prior to
mechanical testing. Tensile test revealed that yield strength and tensile strength were increased with
increasing tensile pre-strain. However, Fracture toughness for crack initiation decreased with
increasing tensile pre-strain. Structural integrity evaluation of the API 5L X65 pipe with crack-like
flaws was assessed by using the level 2 in the API 579 code.
Limit Loads for Circumferential Cracks in the Steam Generator Tube under Combined Pressure and Bending Loads
Authors: Kim Hyun Su , Jin Tae Eun , Kim Hong Deok , Chung Han Sub , Chang Yoon Suk , Kim Young Jin
Published: March 2009

Steam generator in a nuclear power plant is huge heat exchanger that transfers heat from
reactor to make steam to drive turbine-generator. Failure of the steam generator tubes can result in the
release of fission products to the secondary side. Therefore, accurate integrity assessment of the
cracked steam generator tubes is of great importance for maintaining the safety of the nuclear power
plant. This paper provides limit loads for circumferential through-wall cracks in steam generator
tubes under combined internal pressure and bending loads. Such limit loads are developed on the
basis of three dimensional finite element analyses assuming elastic-perfectly plastic material
behavior. As for the crack location, both the top of the tubesheet and U-bend regions are considered.
The analysis results can be directly applied to the practical integrity assessment of cracked steam
generator tubes, because the comparison between experimental data and FE results shows a very good
agreement.
Mechanical Joint of Abutment/Fixture Screw Interface in the Internal Dental Implant System
Authors: Chung Chae Heon , Choe Han Cheol , Kim Hee Jung , Kim Jin Sup , Brantley William A.
Published: March 2009

To investigate mechanical fitness of abutment/fixture screw interface in the internal dental implant
system, internal connection type implants from AVANA(Osstem®), Bioplant(Cowell-Medi®), Dio(DIO®),
Neoplant(Neobiotech®), systems were used in this study. Each group was acquired 2 fixtures at random. Two
piece type abutment and one piece type abutment for use with each implant system were acquired. Screw was
respectively used to hold a two piece type abutment to a implant fixture. All samples were cross-sectioned
with grinder-polisher unit and all specimens were analyzed the interface phenomena between implant
fixture/abutment/screw contact interfaces by using field emission scanning electron microscope(FE-SEM).
Implant fixture/abutment/screw connection interfaces of internal connection systems made in Korea were in
good condition. The results of the above study showed that materials and mechanical properties and quality of
milling differed depending on their manufacturing companies.
Numerical Simulation of Friction Stir Welding of AA6111-T4 Sheets
Authors: Kim Ji Hoon , Kim Don Gun , Chung Kwan Soo
Published: March 2009

In an effort to develop the numerical modeling method to optimize the friction stir welding
process for quality products, the plastic deformation and thermal histories of friction stir welded
AA6111-T4 sheets were numerically simulated. Material and heat flow during friction stir welding
were calculated considering the momentum and energy balance equations under the steady state
condition. The results agreed well with the temperature measurements, suggesting that the method
can be applicable to optimize the friction stir welding process, if proper mechanical and thermal
properties of materials are available.
Evaluation of Plastic Behaviors in FCC Polycrystal Sheet Metal
Authors: Sakamoto Hidetoshi , Nakamachi Eiji , Jong Lee Soo
Published: March 2009

The stress-strain characteristics and plastic behavior of aluminum alloy were examined
by tensile test and infrared thermo-viewer. This thermo viewer is a device for converting a thermal
radiation pattern from an object into visible images. Al-Mg alloy plates with different crystal grain
size subjected to a uni-axial tensile load were measured continuously by this thermo viewer. The
strain concentration pattern was analyzed by the differential thermal image and the macroscopic
estimation method by the thermal image processing was proposed and the propriety of FE
simulation based on polycrystalline plasticity model was shown.
Mechanical Properties of Nano/Micro-Silica Particles Bidispersed Epoxy Composites
Authors: Kwon Soon Chul , Adachi Tadaharu , Araki Wakako , Yamaji Akihiko
Published: March 2009

Mechanical properties of nano/micro-silica particles bidispersed epoxy composites were
investigated based on experimental results. The composite specimens varied with different compositions of
nano and micro-silica particles (240 nm and 1.56$m) were prepared with the constant volume fraction, 0.30.
The thermo-viscoelastic properties for the composites and the neat epoxy measured in the temperature ranges
from 123 K to 523 K and compared to theoretical results according to Lewis and Nielsen’s law with the
maximum particle packing given by Ouchiyama and Tanaka’s model. In addition, fragility derived from the
thermo-viscoelasticity measurements was used to characterize the strength and fracture toughness of the
composites. From results, we found that the thermo-viscoelasticity of the composite was dependent on nano
and micro-particles packing, and its strength and fracture toughness were effectively evaluated by fragility.
Optical Properties of Aspheric Glass Lens Using DLC Coating Mold
Authors: Kim Hyun Uk , Jeong Sang Hwa , Kim Hye Jeong , Kim Jeong Ho
Published: March 2009

In this research, the optimal grinding condition has been obtained by design of
experiment(DOE) for the development of aspheric lens for the 3 Mega Pixel, 2.5x optical zoom
camera-phone module. Also, the WC mold was processed by the method of ultra precision grinding
under this optimal grinding condition. The influence of DLC coating on form accuracy (PV) and
surface roughness(Ra) of the mold was evaluated through measurements after DCL coating using
ion plating on the ground mold. Also, aspheric glass lens was molded by before and after the use of
the mold of DLC coating, respectively. The optical characteristics of each sample, which were
molded by the different mold, were compared with each other.
Novel Rheometer for Superposed Constant and Oscillatory Shear Rate
Authors: Dinser Sandro , Haeusler Klaus , Dual Jürg
Published: March 2009

A newly developed resonator in combination with a UDS 200 rheometer allows
performing different kinds of measurements. The characteristics of the resonator are its resonant
frequency slightly above conventional rheometers, the high sensitivity allowing measurement of
fluids with viscosities as low as that of water and the very small oscillation amplitudes. The nonlinear
behavior of viscoelastic liquids can be analyzed using parallel superposition of shear. It is
known that the parallel complex shear modulus differs from the complex modulus of a fluid at rest.
First measurements have shown the ability of the instrument to quantify this effect. At the same
time, normal force, shear rate viscosity and complex viscosity can be measured on a sample.
Stress Analysis during Crack-Crazing Patterns Interactions: A Mathematical Approach
Authors: Chabaat M. , Seddiki H.
Published: March 2009

In this study, interactions between a main crack and a surrounding layer of crazing patterns are
considered. Analysis of the stress field distribution induced during these interactions is based on the
resolution of some differential equations along with appropriate boundary conditions and the use of
a numerical approach. These equations are established according to Mohr’s criteria since the craze
growth occurs along directions parallel to the minor principal stress axis. Because this damage can
constitute an important toughening mechanism, the mode I stress intensity factor (SIF) is employed
to quantify the effects on a crack of the damage consisting of crazing patterns. It is proven, herein,
that crazes closer to the main crack dominate the resulting interaction effect and reflect an antishielding
of the damage while a reduction constitutes a material toughness.
Effects of Laser Peening on Fatigue Crack Behaviors in Pre-Cracked Cast Aluminum Alloy
Authors: Ochi Yasuo , Masaki Kiyotaka , Matsumura Takashi , Sano Yuji , Akita Koichi , Kajiwara Kentaro
Published: March 2009

In order to investigate effects of low energy laser peening (LP) without protective
coating on surface fatigue crack growth behavior, rotating bending fatigue tests were carried out on
cast Al-Si-Mg aluminum alloy with a pre-cracked round bar type specimens. As the results, the
fatigue crack growth was restrained by the compressive residual stress induced by laser peening
treatment. And also, the three dimensional (3D) image of surface fatigue cracks was reconstructed
by using a micro computed tomography (μCT) with phase contrast technique. It was also shown
that the surface crack growth was restrained for the laser peened materials.
Low Cycle Fatigue Properties of 316LN Stainless Steel Welded by GTAW in Nitrogen Added Environment
Authors: Kim Dae Whan , Han Chang Hee , Ryu Woo Seog
Published: March 2009

Tensile and fatigue properties were evaluated for base and welded type 316LN stainless
steel. Welding methods were GTAW (308L, Ar environment) and GTAWN (316L, Ar + N2
environment). Yield strength of weld joint was higher than that of base metal but elongation of weld
joint was lower than that of base metal. UTS of weld joint was slightly lower than that of base metal.
Yield strength and elongation with welding method were almost same. Fatigue life of weld joint
was lower than that of base metal but fatigue strength of weld joint was higher than that of base
metal. Ferrite content was increased with welding. Fatigue life welded by GTAWN was better than
that of GTAW at RT and 600°C. This fatigue life behavior was consistent with the behavior of
ferrite content.
Effects of Heating Rate and Temperature Holding Time on Mechanical Behaviors of Aluminum Alloy
Authors: Huang Chen Guang , Chen Si Ying , Wang Chunkui
Published: March 2009

In this paper, the mechanical properties of several aluminum alloys are obtained
experimentally at different temperatures, from room temperature to about 4000C by using the
Gleeble 1500 thermomechanical system. Besides, the thermal softening characteristics, effects of
heating rate and temperature holding time are discussed in details. It is found that the strength of
LF6, a kind of antirust aluminum alloy, is not sensitive to the heating rate (0.1-1000K/s) and
temperature holding time (0-1h). However, the mechanical behaviors of other alloys depend on
these factors very obviously. At last, these phenomena are discussed in the viewpoint of the
microstructures and techniques of ageing strengthening of these alloys.
Fatigue Fracture Behavior Depending on Stacking Sequences in Quasi-Isotropic CFRP Laminates after Lateral Impact
Authors: Shimizu Toshihiro , Nakajima Masaki
Published: March 2009

A series of fatigue tests has been conducted to estimate the fracture behavior depending
on stacking sequences in quasi-isotropic CFRP laminates. Strips of laminate with four different
directions were cut out from the same CFRP plate to prepare the specimens with the four kinds of
stacking sequences. Prior to fatigue test, the specimens were impacted with lateral load in order to
simulate the damage induced by the fallen tools. During the fatigue tests, the damage developed in
the specimen was detected by non-destructive techniques using a scanning acoustic microscope
(SAM) and a replicating method.
Stacking sequences exerted an influence on fracture behavior of laminate specimens, i.e. the
stacking position of the zero degree layers, in which fiber direction was parallel to the loading axis,
played an important role in the fracture process. When the zero degree layers are located at the
specimen surface, no remarkable damage propagation was observed from the surface. On the other
hand, when the zero degree layers are located in the middle of laminates, the damage in the surface
layer was found in the fatigue process. Not only the degradation of the equivalent elastic modulus
was seen in all specimens, but also the degradation curve varied with the stacking sequences.
On the Fatigue Crack Growth Behavior of a Nitrided and Shot Peened Steel
Authors: Guagliano Mario , Vergani Laura
Published: March 2009

In this paper the fatigue crack growth properties of a nitrided shot-peened steel is dealt
with: different peening intensities were considered and the resulting residual stresses measured by
means of an X-ray diffractometer. Rotating bending fatigue tests were executed on specimens with
a blind micro-hole, acting as a pre-existent crack. The results allowed determining the threshold of
propagation of the nitrided and of nitrided and shot peened material. It was also possible to relate
the crack initiation point with the applied and the residual stresses.
Thermomechanical Processing Controlling the Austenite Transformation in Si – Mn TRIP Steel
Authors: Zrník Jozef , Muránsky Ondrej , Stejskal Ondrej , Horňak Peter
Published: March 2009

The paper deals with the deformation and transformation behaviour of
thermomechanically (TM) treated low alloyed Si-Mn TRIP steel. The aim of this work was to
investigate the contribution of the factors governing the deformation and transformation process of
conditioned austenite. Variation in strain and temperature parameters of TM treatment of TRIP steel
samples resulted in formation of different complex microstructures. The deformation behaviour of
TRIP specimens of different multiphase structures was tested in incremental neutron diffraction in
situ tensile testing. It was proved that neutron diffraction technique is very convenient method for
retained austenite (RA) transformation of the retained austenite with respect to monitoring of
transformation quantification of retained austenite and rising internal stress in structural phases.
Deformation Behaviour and Ultrafine Grained Structure Development in Steels with Different Carbon Content Subjected to Severe Plastic Deformation
Authors: Zrník Jozef , Dobatkin Sergey V. , Stejskal Ondrej
Published: March 2009

The article focuses on the results from recent experimental of severe plastic deformation
of low carbon (LC) steel and medium carbon (MC) steel performed at increased temperatures. The
grain refinement of ferrite respectively ferrite-pearlite structure is described. While LC steel was
deformed by ECAP die (ε = 3) with a channel angle φ = 90° the ECAP severe deformation of MC
steel was conducted with die channel angle of 120° (ε = 2.6 - 4). The high straining in LC steel
resulted in extensively elongated ferrite grains with dense dislocation network and randomly
recovered and polygonized structure was observed. The small period of work hardening appeared at
tensile deformation. On the other side, the warm ECAP deformation of MC steel in dependence of
increased effective strain resulted in more progressive recovery process. In interior of the elongated
ferrite grains the subgrain structure prevails with dislocation network. As straining increases the
dynamic polygonization and recrystallization became active to form mixture of polygonized
subgrain and submicrocrystalline structure. The straining and moderate ECAP temperature caused
the cementite lamellae fragmentation and spheroidzation as number of passes increased. The tensile
behaviour of the both steels was characterized by strength increase however the absence of strain
hardening was found at low carbon steel. The favourable effect of ferrite-pearlite structure
modification due straining was reason for extended work hardening period observed at MC steel.
Fatigue Crack Growth Behavior of a Gas Pressure Welded Part of Rail Steel under Mixed Mode Loading
Authors: Kim Chul Su , Kim Jung Kyu
Published: March 2009

The transverse crack, which is the most dangerous damage among the various types of rail
defects, is developed from shelling near the rail running face, and grows perpendicular to the rail
surface. Therefore, to assure the safety of rolling stocks, it is necessary to investigate the fatigue crack
growth behavior of a gas pressure welded part of rail steel under mode I and mixed mode loadings. In
this study, the fatigue crack growth behavior under the mixed mode was discussed by using
comparative stress intensity factor ranges proposed by Richard. In addition, to evaluate the effect of
the crack closure quantitatively, the crack opening load was determined a using clip-on gauge and
computerized image processing system. As a result of this, a mixed mode crack growth rate regardless
of the stress ratio could be correlated with the effective comparative stress intensity factor ranges
derived from the crack opening loading.
Effects of Notch Tip Geometry on the Cleavage Fracture of RPV Steel
Authors: Lee Bong Sang , Yang Won Jon , Kim Min Chul , Hong Jun Hwa
Published: March 2009

A series of fracture tests and elastic-plastic FEM analysis were carried out for three-point
bend specimens with different notch root radius in the cleavage temperature region of a RPV low
alloy steel. The cleavage initiation distance (CID) from the notch tip was measured by SEM
photographs on the fracture surface of each specimen. The local cleavage fracture stress σf
* was
defined as the stress σyy at the cleavage initiation site. The σf
* increased with decreasing notch root
radius. The CID’s were larger in specimens with bigger root radius. This implies that a larger
volume of material and possibly bigger microcracks should be involved in the cleavage fracture
process of those specimens. The σf
* is considered to have a certain relationship with the level of
stress-strain concentration in different geometry specimens.
Connection among the Characteristics of the Low Cycle Fatigue, High Cycle Fatigue and Fatigue Crack Growth
Authors: Nagy Gyula , Lukács János
Published: March 2009

The material quality, the deformation rate, the temperature and the stress state influence
mechanical behaviour and properties of different materials. Due to this great variety of the influencing
factors we do not have one model of general validity describing the behaviour of materials, but we
have to use a great number of material constants in order to characterize the properties. The exponents
of the Manson-Coffin, the Basquin and the Paris-Erdogan laws were applied for the verification of the
connection among the fatigue fracture types. Own measured values and test results can be found in the
literature were used for the illustration of the connections. “Fracture surface”-s were determined for
characterizing of different steel grades and their welded joints. It can be concluded that “fracture
surface”-s are suitable for the describing of the fracture behaviour and the conversion of different
fracture parameters of steels.
Prediction of Breakdown Transition of Creep Strength in Advanced High Cr Ferritic Steels by Hardness Measurement of Aged Structures at High Temperature
Authors: Armaki Hassan Ghassemi , Maruyama Kouichi , Yoshizawa Mitsuru , Igarashi Masaaki
Published: March 2009

Recent researches have shown the premature breakdown of creep rupture strength in
long term creep region of advanced high Cr ferritic steels. As safe operation of power plants
becomes a serious problem we should be able to detect and predict the breakdown transition of
creep rupture strength. Some methods for detecting the breakdown transition have been presented
till now like the measurement of reduction of area after creep rupture and particle size of laves
phase. However it will be more economic if we make use of non-destructive tests, for example,
hardness testing. In this paper 3 types of ferritic steels with different Cr concentration have been
studied. The results suggest that the hardness of aged structures is constant independently of
exposure time in short term region, whereas the hardness breaks down in long term region. The
boundary of breakdown in hardness coincides with that of breakdown in creep rupture strength.
Analysis of Creep Deformation Due to Grain-Boundary Diffusion/Sliding
Authors: Kim Byung Nam , Hiraga Keijiro , Morita Koji , Yoshida Hidehiro
Published: March 2009

For steady-state deformation caused by grain-boundary diffusion and viscous
grain-boundary sliding, the creep rate of regular polyhedral grains is analyzed by the
energy-balance method. For the microstructure, the grain-grain interaction increases the degree of
symmetry of diffusional field, resulting in a decrease of the effective diffusion distance. Meanwhile,
the viscous grain-boundary sliding is found to decrease the creep rate. The present analysis reveals
that the grain-size exponent is dependent on the grain size and the grain-boundary viscosity: the
exponent becomes unity for small grain sizes and/or high viscosity, while it is three for large grain
sizes and/or low viscosity.
A study of Carbon and Nitrogen Free New Alloys with Superior Creep Properties More over 700°C
Authors: Muneki Seiichi , Okubo Hiroshi , Abe Fujio
Published: March 2009

In order to improve the creep strength of the heat resistant steels at elevated
temperatures over 700°C, a new attempt has been demonstrated using carbon and
nitrogen free Fe-Ni martensitic and austenitic alloys strengthened by Laves phase
such as Fe2W and Fe2Mo. It is important that these alloys are independent of any
carbides and any carbo-nitrides as strengthening factors. The high temperature
creep tests over 700°C exceed 36,000 hours and the test is continued. Creep
behavior of alloys is found to be completely different from that of the conventional
high-Cr ferritic steels. The alloys exhibit gradual change in the creep rate with
strain both in the transient and acceleration creep regions, and give a larger strain for
the minimum creep rate. Effect of Cr on the Fe-12Ni-9Co-10W alloys on the creep
properties more over 700°C was investigated. It became clear that the value for
100,000 hours was exceeded at 700°C and 100MPa calculated from the
Larson-Miller parameter at C=20. And surface appearance of crept specimen was
investigated in detail.
Fracture Resistance in Multiphase Alloys
Authors: Chan Kwai S.
Published: March 2009

The fracture behavior of Nb-based in-situ composites is reviewed to elucidate the effects of
alloy additions on the fracture process in multiphase alloys. The overview paper summarizes the current
understanding of the processes by which alloying addition and microstructure alter the near-tip
deformation and fracture mechanism, and presents a methodology for predicting the fracture toughness
of the constituent phases and the composite. The alloying effects observed in Nb-based in-situ
composites can be attributed to changes in dislocation mobility in the metallic solid solution matrix that
provides ductile phase toughening in the composites. The size, volume fraction, and the continuity of
the intermetallic phases dictate the fracture path and impact significantly the facture toughness of the
in-situ composites.
Dynamic Deformation and Fracture Behavior of Zr-Based Bulk Metallic Glasses
Authors: Lee Dong Geun , Kim Yang Gon , Hwang Byoung Chul , Lee Sung Hak , Kim Nack
Published: March 2009

Dynamic deformation and fracture behavior of Zr-based bulk metallic glass (BMG) and
BMG composite containing dendritic β phases was investigated in this study. Dynamic compressive
test results indicated that both maximum compressive stress and total strain of the BMG and BMG
composite decreased with increasing test temperature because shear bands could propagate rapidly
as the adiabatic heating effect was added at high temperatures. Above the glass transition
temperature, total strain decreased more abruptly due to crystallization of amorphous phases.
Maximum compressive stress and total strain of the BMG composite were higher than those of the
BMG because β phases played a role in forming multiple shear bands. The BMG composite having
more excellent dynamic properties than the BMG can be more reliably applied to the structures or
parts requiring dynamic properties.
Effects of Annealing Temperature and Si Content on Mechanical Properties of Cold Drawn Pearlitic Steel Wires
Authors: Park Dae Bum , Nam Won Jong
Published: March 2009

The effects of annealing temperature and silicon content on mechanical properties on cold
drawn pearlitic steel wires were investigated. Cold drawn steel wires, containing Si, 0.99 ~ 1.4%,
were annealed at the temperature of 200 ~ 450°C with different annealing time. The variation of
microstructural evolution with annealing temperature was not affected by silicon content. For steels
containing high silicon content above 1.0%, the increase of silicon content did not cause the changes
of peak temperature showing age hardening and age softening, except for the increase of tensile
strength due to solid solution hardening.
A Study on the Safety Assessment of Car-Body Structure for Urban EMU
Authors: Chung Jong Duk , Pyun Jang Sik
Published: March 2009

Engineering safety diagnosis of crashed subway electric multiple units (EMUs) was
conducted for safety assessment. Several advanced engineering analysis techniques including
nondestructive evaluation (NDE) techniques and stress and structural analyses programs, were
performed for better understandings and exploration of failure analysis and safety concerns. Moreover,
stress and structural analyses using commercial I-DEAS software provided important information on
stress distribution and load transfer mechanisms as well as the amount of damages during the crash.
One-dimensional crashworthiness was conducted to estimate the speed at the time of the accident by
investigating the permanent deformation of the train. The estimated speed was used as the input value
of a three-dimensional crashworthiness analysis. A good agreement has been found between
structural analysis results and the results of actual damages in EMUs during crash. In this
investigation, various advanced engineering analysis techniques for the safety analysis of subway
EMUs have been introduced and the analysis results have been used to provide the critical
information for the safety assessment of crashed EMUs.
The Effect of Nitrogen on High Temperature Deformation Behaviors in Type 316L Stainless Steel
Authors: Liu F. , Jung J.G. , Nam Soo Woo
Published: March 2009

Both tensile and strain controlled low cycle fatigue (LCF) tests were conducted for 316L
and 316LN at 550oC and 600oC to investigate the nitrogen effect on the deformation behavior of
type 316L stainless. The waveform of LCF was a symmetrical triangle with a constant strain rate of
4×10-3/s was employed for most tests. It shows that the addition of nitrogen in the alloy results in an
increase in tensile strength but a decrease in ductility. Both the alloys exhibited cell structure after
severe tensile deformation. However, after low cycle fatigue, only planar slip band is observed in
316LN, whereas cell structure is still the main feather of microstructure in 316L. This is due to the
strong interstitial-substitutional Mo-N pairs and various stress strain conditions.
A Novel Capacitance Bulge Apparatus and Measurements of the Mechanical Properties of Al Thin Films Using It
Authors: Hyun Seung Min , Brown Walter L. , Vinci Richard P.
Published: March 2009

Thin metal films often play an important role as structural elements or reflective surfaces
in MEMS applications. Mechanical properties of the films are important due to their influence on
the performance of MEMS devices that involve bending or stretching metal parts. In order to gain a
better understanding of the mechanical behavior of thin metal films, we have developed a novel
bulge system and measured mechanical properties of aluminum thin films. The thin films were
prepared by e-beam evaporation of high purity Al onto 2 or 3mm ×12 mm rectangular silicon
nitride membrane windows in silicon frames. N2 gas was used to pressurize and thus bulge the
membranes. The bulge height was measured based on changes of capacitance between the
membrane and a fixed, closely spaced electrode. This apparatus provides resolution of
approximately 50 nm in bulge height at a data acquisition rate of 100/sec and provides strain rates
in the membrane up to 10-5/sec. The stability of the apparatus allows stress relaxation measurements
to be made to times of many hours. Time dependent elastic modulus changes of 1 m Al films were
measured over periods of times under constant stress.
Performance Evaluation of a Valveless Micropump Considering Electro-Structural-Fluid Interaction
Authors: Lee Kwang Chul , Goo Nam Seo
Published: March 2009

In this paper, the pumping performance of a piezoelectric micropump is simulated with
commercial finite element analysis (FEA) software COMSOL Multiphysics 3.2a. The micropump is
composed of a 4-layer piezo-composite actuator (LIPCA), a polydimethylsiloxane (PDMS) pump
chamber, and two diffusers. The piezoelectric domain, structural domain and fluid domain are
coupled in the simulation. Water flow rates are numerically predicted for geometric parameters of
the micropump. Based on this study, the micropump is optimally designed to obtain its better
pumping performance.
Implicit Formulation of Homogenization Method for Periodic Elastic-Viscoplastic Solids
Authors: Asada Takashi , Ohno Nobutada
Published: March 2009

In this study, to determine incremental, perturbed displacement fields in periodic
elastic-viscoplastic solids, an incremental homogenization problem is fully implicitly formulated
using a linearized constitutive relation, a micro/macro-kinematic relation, and a stress balance
equation. It is shown that the homogenization problem can be iteratively solved with quadratic
convergences by successively updating strain increments in unit cells, and that the present
formulation allows versatility in the initial setting of strain increments in contrast to Terada-Kikuchi
(2001) and Miehe (2002). This homogenization algorithm is then examined by analyzing a holed
plate, with an elastic-viscoplastic micro-structure, subjected to tensile loading. It is thus
demonstrated that the convergence in iteratively solving the homogenization problem strongly
depends on the initial setting of strain increments in unit cells, and that quick convergences can be
attained if the initial setting of strain increments is appropriate.
Hybrid Full-Field Stress Analysis Around Holes in Tensile-Loaded Plates by Phase-Shifting Photoelasticity
Authors: Baek Tae Hyun , Panganiban Henry , Lee Choon Tae , Chung Tae Jin
Published: March 2009

A hybrid stress determination around circular and elliptical holes utilizing photoelastic
phase-shifting and nonlinear least-squares methods is presented. The method was demonstrated by
calculating fringe orders of distant points along straight lines using 8-step phase-shifting method.
The data was used to evaluate the coefficients in the complex stress functions for hybrid analysis.
Tangential stresses around the boundary of the holes were obtained using conformal mapping
technique. Different number of terms in a power-series representation of the complex type stress
function was tested to qualitatively observe the effects of varying stress field. Actual fringes were
related with the reconstructed and sharpened fringes along with the change in the number of terms,
m. Good agreement was obtained when m in stress functions was equal to nine. At high stress
concentration, the result obtained from the hybrid method agrees with FEM by two and five percent
for circular and elliptical hole, respectively. The results show that the established numericalexperimental
method for stress analysis is considerably reliable.
Shape Optimization of a Knuckle using the Design of Experiments
Authors: Park Young Chul , Kang Jung Ho , Lee Dong Hwa , Oh Seung Hwan , Ko Won Deg , Lee Kwon Hee
Published: March 2009

DOE (design of experiments) was applied to the design of a knuckle as a part of a
suspension system. Specifically, knuckle made of aluminum alloy was optimized considering the
strength. On the other hand, design variables were set as shape variables. During structural
optimization using DOE, an orthogonal array strategy was developed to determine the optimum
design. The relevant discrete variables were treated as levels. Since the conventional orthogonal
array did not consider the constraint, however, the characteristic function was defined to include the
effect of constraint feasibility. The general DOE was expanded to include problems with constraints
related to the new characteristic function.
Computational Study on Mechanical Behavior of Steel-Concrete Composite by using Interface Elements
Authors: Shin Dae Seock , Lee Heung Shik , Cho Chong Du
Published: March 2009

Although steel-concrete interface has significant influence on bonding strength and shear
strength, the composite structure with the consideration of the interface fracture has been rarely
conducted. In this study, sensitivity analyses are performed to find out steel-concrete interface
characteristics by using interface finite elements, defined as elastic-plastic behavior. In order to verify
computational accuracy, the analyzed interface properties are compared with experimental results.
Generally, interface in steel-concrete composite structure plays a critical role of controlling bonding
strength as well as transferring loads between steel and concrete. The composite interface should be
avoided to reach to an interface fracture condition; otherwise composite structure may deviate from
intended behavior even under low stress state. It is then led to catastrophic fracture or collapse of the
structure. This study shows that interface properties of steel-concrete can be analyzed by using the
interface element, and the results provide more reliable prediction for the steel-concrete composite
behavior.
Modeling of Maximum Spread Variation of Workpiece under High Speed Deformation in Rod Rolling Process
Authors: Lee Young Seog
Published: March 2009

A maximum spread model dependent on rolling speed is proposed for rod rolling process
following the analysis of deformation behavior of steel under compression and four-pass continuous
high speed rod rolling test. Results reveal that amount of spread depends on a region which
restricts plastic flow of workpiece during deformation. Increasing rolling speed (strain rate) leads to
decrement of friction coefficient and, in turn, enlarge deformation-restricted region in the workpiece
and consequently reduce amount of spread during deformation. Hence, the rolling speed dependent
spread model could be expressed in terms of flow stress, which is a function of strain, strain rate
and temperature and finally the model is proposed in a concise form.