bluuebunny/crossref_metadata_2025 huggingface dataset:
Interface Properties of Copper/Aluminum/Stainless Steel Clad Materials
Authors: Bae Dong Su , Kim Soon Kook , Lee Sang Ll , Shibayama Tamaki , Bae Dong Hyun
Published: March 2009

Copper/aluminum/stainless steel (Cu/Al/STS) clad materials were made by rolling and
heat treatment process. These specimens were evaluated the formability and bonding strength of
Cu/Al/STS clad materials. Thin disc specimens for TEM observation were prepared from the
interfaces of Cu/Al and Al/STS by using the Focused Ion Beam (FIB) utility. Brittle oxide film
formed on copper surface during heat treatment at 673K~773K. Diffusion bonding was observed at
the interface of Cu/Al. Reacted region was formed in the interface of Al/STS with width about
10nm, while in the case of Cu/Al was formed about 1,600nm width. It was also observed nanosized
crevice in reacted region of Al/STS interfaces.
Effects of the Additives and Current Density on the Electrodeposition Behavior and Mechanical Properties of the Ni-SiC Composite Coatings
Authors: Oh Teck Su , Lee Jae Ho , Byun Ji Young , Oh Tae Sung
Published: March 2009

In Ni-SiC composite coating, the SiC content is dependent on the surface properties of
SiC particles. As sulfuric acid has a strong dehydration force, addition of sulfuric acid in the Ni
sulfamate bath changed the surface properties of SiC particles, affecting the codeposition behavior
of SiC particles. Also the additives such as SDS affect the electrodeposition behavior of the Ni-SiC
composite coating. In this study, effects of the HSO4
‾ and the current density on the
electrodeposition behavior of the Ni-SiC composite coating have been investigated. The Ni-SiC
composite coatings were electrodeposited at current densities of 50~200mA/cm2. The surface and
cross-sectional morphologies of the Ni-SiC composite coatings were observed using SEM, and their
mechanical properties were characterized with micro-Vikers hardness.
Serrated Flow Behavior in 2090 Al-Li Alloy
Authors: Shen Yin Zhong , Oh Kyu Hwan , Lee Dong Nyung
Published: March 2009

Flow behavior of the surface and center layers of solution-treated, peak-aged, or
reversion-treated 2090 Al-Li alloy specimens has been reviewed and discussed in terms of
microstructures and textures.
Electromagnetic Wave Shielding Properties of ITO/PET Thin Film by Film Thickness
Authors: Kim Do Hyoung , Yoon Han Ki , Shin Do Hoon , Murakami Riichi
Published: March 2009

The thin films of indium tin oxide (ITO) are used for a variety of electronic devices such as
solar cells, touch panels, liquid crystal displays (LCDs). However, these electronic devices are not
strong enough against heavy impact since their ITO thin films are deposited on glass substrates.
Therefore, ITO thin films were prepared by the inclination opposite target type DC magnetron
sputtering equipment onto the Polyethylene Terephthalate (PET) substrate at room temperature using
oxidized ITO with In2O3 and SnO2 in a weight ratio of 9:1. In this study, the transmittance, resistivity
and electromagnetic wave shielding effectiveness of the ITO thin films prepared at various sputtering
time (20~80min namely film thickness; 130~500nm) are measured. The results show that
transmittance of the ITO thin films could show about 70% in the range of a visible ray by the variation
of film thickness. It also can be seen that a minimum exists in the resistivity of ITO thin films for the
variation of film thickness. Electromagnetic wave shielding effectiveness was increased as film
thickness increased.
Effect of Cr2N Precipitation on Deformed Microstructure in High Nitrogen Austenitic Stainless Steel
Authors: Lee Tae Ho , Kim Sung Tae , Bang Hae Jung , Oh Chang Seok , Kim Sung Joon , Takaki Setsuo
Published: March 2009

The effect of Cr2N precipitation on deformed microstructure in high nitrogen austenitic
Fe-18Cr-18Mn-2Mo-0.9N steel was investigated with a particular emphasis on deformation
twinning. Based on the crystallographic analysis in the stereographic projection, the orientation
relationship between austenite (γ) matrix and Cr2N was determined to be Cr2N
[110]γ //[1100] and
Cr2N
(111) γ //(0001) . The deformation twinning had {111} < 112 > crystallographic component similar to
that of cellular Cr2N. The cellular Cr2N precipitates caused a different orientation dependence of
deformation twinning: only one twinning system in the <111 > grain was activated almost parallel
to the growth direction of Cr2N.
Mechanical Properties and Metallurgical Qualities of Magnesium Alloy Sheets Manufactured by Twin-Roll Casting
Authors: Watari Hisaki , Nakamura Ryoji , Paisern R. , Koga Nobuhio , Davey Keith
Published: March 2009

This paper is concerned with a manufacturing process and technology to facilitate the
economical manufacture of high-quality magnesium alloy sheets. Magnesium alloys AZ31, AZ61,
AM60 and AZ91 were used to investigate the appropriate anufacturing conditions for use in twin-roll
strip casting. Temperatures of the molten materials and roll speeds were varied to find the appropriate
manufacturing conditions. The effects of manufacturing conditions on possible forming were
clarified in terms of roll speeds and roll gaps between upper and lower rolls. In addition, microscopic
observation of the microstructure of the finished casting was performed. It was clarified that a
magnesium sheet of 2.5 to 4.5mm thickness could be produced at a speed of 20 m/min by a horizontal
copper roll caster. It was also found that the cast magnesium sheet of AZ31, AZ61, AM60 and AZ91
manufactured by roll strip casting could be used for plastic forming if the appropriate magnesium
sheets were produced after the roll casting process. By a warm deep drawing test, it also demonstrated
that a limiting drawing ratio of 2.4 was possible in the case of AZ91 sheet that was difficult to be
manufactured by conventional extrusion process or DC casting and hot-rolling process for magesium
alloy sheets with high aluminium contents.
Achieving Both Powder Consolidation and Grain Refinement for Bulk Nanostructured Materials by Equal-Channel Angular Pressing
Authors: Yoon Seung Chae , Nghiep Do Minh , Hong Sun Ig , Horita Z. , Kim Hyoung Seop
Published: March 2009

Manufacturing bulk nanostructured materials with least grain growth from initial powders
is challenging because of the bottle neck of bottom-up methods using the conventional powder
metallurgy of compaction and sintering. In this study, bottom-up type powder metallurgy processing
and top-down type SPD (Severe Plastic Deformation) approaches were combined in order to achieve
both full density and grain refinement of metallic powders. ECAP (Equal-Channel Angular Pressing),
one of the most promising processes in SPD, was used for the powder consolidation method. For
understanding the ECAP process, investigating the powder density as well as internal stress, strain
and strain rate distribution is crucial. We investigated the consolidation and plastic deformation of the
metallic powders during ECAP using the finite element simulations. Almost independent behavior of
powder densification in the entry channel and shear deformation in the main deformation zone was
found by the finite element method in conjunction with a pressure dependent material yield model.
Effects of processing parameters on densification and density distributions were investigated.
Approximation of Thermal Deformation Behaviour of a Machine Tool to Improve its Process Precision
Authors: Tachiya Hiroshi , Kaneko Yoshiyuki , Aramoto Teppei , Shinjo Hirotsugu , Miyazaki Yusuke
Published: March 2009

This paper presents a stochastic method to approximate the thermal deformation of a
machine tool, by using the temperature changes of the body. The method examines the relationship
between the thermal deformations and temperature changes of plural positions on a machine tool, and
determines the appropriate temperature measuring points. In addition, the approximate equation of
the thermal deformation is drawn by t-test, which uses those influential temperature changes as
parameters. This study shows that the approximation equation of the thermal deformations can be
expressed in a simple form with few parameters, and remarkably improve cutting processing.
Work Hardening Behavior of Low Carbon Martensitic Steel
Authors: Nakashima Koichi , Fujimura Y. , Tsuchiyama Toshihiro , Takaki Setsuo
Published: March 2009

The work hardening behavior by cold rolling was investigated in ultralow carbon and low
carbon martensitic steels containing 12%Cr or 18%Ni, and then the effect of carbon on the work
hardening behavior was discussed in terms of the change in dislocation density and the microstructure
development during deformation. In the ultralow carbon steel, the hardness is almost constant
irrespective of the reduction ratio. On the other hand, the low carbon steel exhibits marked work
hardening. The dislocation density of these specimens was confirmed to be never increased by cold
rolling. It was also found that cold rolling gives no significant influence on the morphology of
martensite packet and block structure. TEM images of the cold-rolled steels revealed that the
martensite laths in the ultralow carbon steel are partially vanished, while those in the carbon bearing
steel are stably remained. These results indicate that the solute carbon retards the movement of
dislocations, which results in the high work hardening rate through the formation of fine dislocation
substructure within laths.
Microstructure Control of High Nitrogen Alpha + Beta Type Titanium Alloy
Authors: Ando Tomohiro , Nakashima Koichi , Tsuchiyama Toshihiro , Takaki Setsuo
Published: March 2009

Solution nitriding and aging treatment were applied to Ti-4mass%Cr alloy in order to
fabricate a ductile high-nitrogen titanium alloy with fine (α + β) structure. The solution-nitrided
specimen withα’ martensitic structure was significantly hardened by solid solution strengthening by
the absorbed nitrogen. During the aging treatment, fine β grains with a size of 1 microns in thickness
precipitated along the martensite-plate boundaries. Although the specimen was softened to some
extent after the aging treatment, the hardness is kept much higher than that of the aged Ti-4mass%Cr
alloy without solution nitriding. This indicates that the nitrogen is still in solid solution of α phase
even after the aging treatment, and contributes to strengthening of the fine-structured
Ti-4mass%Cr-N alloy.
New Insights into Plasticity-Induced Crack Tip Shielding via Mathematical Modelling and Full Field Photoelasticity
Authors: Tee K.F. , Christopher Colin J. , James M. Neil , Patterson Eann A
Published: March 2009

The topic of plasticity-induced closure and its role in shielding a crack tip from the full
range of applied stress intensity factor has provoked considerable controversy over several decades.
We are now in an era when full field measurement techniques, e.g. thermoelasticity and
photoelasticity, offer a means of directly obtaining the stress field around a crack tip and hence the
effective stress intensity factor. Nonetheless, without a clear understanding of the manner in which
the development of plasticity around a growing crack affects the applied stress field, it will remain
difficult to make crack growth rate predictions except through the use of an often highly conservative
upper bound growth rate curve where closure is absent, or through semi-empirical approaches. This
paper presents new evidence for an interpretation of plasticity-induced crack tip shielding as arising
from two separate effects; a compatibility-induced interfacial shear stress at the elastic-plastic
interface along the plastic wake of the crack, and a crack surface contact stress which will vary
considerably as a function of stress state, load and material properties.
Multiaxial Fatigue--A Perspective
Authors: Ellyin Fernand
Published: March 2009

Research on the fatigue resistance of mechanical components/structures has been
proceeding for nearly a century and a half. Yet, there is no universally agreed upon theory that can
predict most aspects of fatigue failure. The reason is the complexity of phenomenon and its
dependence on the microstructure. Here, we present a strain energy based damage parameter which
has an underlying microscopic basis. A master life curve is subsequently defined which correlates
very well with experimental data.
Formability of Mg-Zn-Zr Based Alloy Sheets at Elevated Temperatures
Authors: Kim Jeong Min , Park Bong Koo , Jun Joong Hwan , Kim Ki Tae , Jung Woon Jae
Published: March 2009

Mg-3%Zn-0.2%Zr based alloy sheets with various alloying elements additions were
fabricated through thermo-mechanical process, and their microstructure and mechanical properties
were investigated at room and elevated temperatures. CCV(conical cup value) and V-bend tests
were also carried out to evaluate the formability of the fabricated alloy sheets. The experimental
results showed that small amounts of Sn or Sr additions could improve the elongation at elevated
temperatures, even though the room temperature tensile properties were slightly deteriorated by the
Sr addition.
Analysis of Biaxial Fatigue Crack Growth in Microstructure Modeled by Voronoi-Polygon
Authors: Hoshide Toshihiko , Sata Yasunori
Published: March 2009

Cracking behavior in low cycle fatigue regime depends on the level and the multiaxiality
of the applied stress and also on the microstructure. Such a complex cracking behavior affects
failure life significantly. More realistic assessments of failure life and integrity require a new
appropriate procedure to analyze the crack growth process in multiaxial fatigue. A model of the
fatigue process has been proposed to describe the cracking behavior in biaxial stress state. There is,
however, no adequate model to present features of material microstructure. In this work,
simulations of crack initiation and propagation based on a previous model were carried out in
microstructure modeled by using Voronoi-polygon. In a crack initiation analysis, slip-band crack
was modeled for the slip system given randomly in each grain composing the modeled
microstructure. In modeling crack growth, a competition model between the coalescence growth
and the propagation as a single crack was applied. Simulated cracking morphology and failure life
were compared with experimental results observed in biaxial fatigue using circumferentially
notched specimens of a pure copper, and the applicability of the proposed model was discussed.
The Mechanism of Fatigue Crack Propagation
Authors: Furukawa Katsuaki
Published: March 2009

As a retardation of fatigue crack propagation occur under two step loading such as high to low
loading, it is difficult to predictt the fatigue life in variable loading conditions. Therefore, the mechanism of
retardation was investigated by changing the ratio of two step-loading in some materials in this paper. It is
found in this study that when the ratio of low loading to high loading is less than 50 %, crack arrest occur in
agreement with Elber’s formula about crack closure. We believe that crack closure phenomenon is the main
problem in considering mechanism of crack propagation in the second stage. In this paper it is estimated that
crack closure phenomenon arises because tensile plastic zone at crack tip is compressed by surrounding
elastic zone. On the basis of the crack closure phenomenon, the mechanism of crack propagation in the
second stage is proposed.
Microstructural Effects on Low Cycle Fatigue of Sn-3.8Ag-0.7Cu Pb-Free Solder
Authors: Zeng Qiu Lian , Wang Zhong Guang , Shang J.K.
Published: March 2009

Low cycle fatigue behavior of Sn-3.8Ag-0.7Cu solder was investigated under fully
reversed cyclic loading, with particular emphasis on microstructural effects. The LCF behavior of
the solder with equiaxed microstructure was found to differ greatly from that of the solder with a
dendrite microstructure. At a given total strain amplitude, the dendrite microstructure exhibited a
much longer fatigue life than the equiaxed microstructure. Such a strong microstructural effect on
fatigue life arose from the difference in cyclic deformation and fracture mechanisms between the
two microstructures. A large number of microcracks along grain boundaries of the equiaxed
structure solder developed with increasing cycling, while for the dendrite structure solder, cyclic
deformation took place along the direction of the maximal shear stress during fatigue tests and
microcracks initiated and propagated along shear deformation bands. Besides, the fatigue behavior
of the dendritic microstructure was very sensitive to cyclic frequency whereas the fatigue behavior
of the equiaxed microstructure showed less sensitivity to cyclic frequency.
Notched Fatigue of Zr-Based Bulk Metallic Glass
Authors: Nakai Yoshikazu , Sei Naoki , Kim Bok Key
Published: March 2009

In the present study, fatigue tests of sharp-notched Zr-based bulk metallic glass (BGM),
were conducted under fully reversed cyclic bending, and the fatigue crack initiation mechanisms
were clarified by using AFM. The fracture surface was also observed to examine the crack
propagation mechanism. The fatigue notch factor was 2.0, while the elastic stress concentration
factor is 2.7. From the macroscopic observations of fractured specimen, either tension mode or
shear mode fracture morphologies were observed. Either in smooth specimens or notched
specimens, no prodigious sign of crack initiation were observed, i.e., fatigue cracks were initiated
from shear bands those were formed just before the crack initiation.
Low Cycle Fatigue Behavior of Zirconium Tube under the Cyclic Pressurization
Authors: Kim Jun Hwan , Lee Myoung Ho , Choi Byoung Kwon , Jeong Yong Hwan
Published: March 2009

Study was attempted to produce stress-life curve of the zirconium tube under the cyclic
pressurization and to analyze its behavior. The internal pressurization machine was devised and the
low cycle fatigue test at the zirconium cladding tube was carried out. The result showed that the
O’Donnell and Langer relationship can be fitted to the fatigue behavior of the zirconium cladding
under the cyclic pressurization, where the fatigue limit of the Zircaloy-4 at 350oC was shown at
341.6MPa. From the analysis of the diametral changes and the fractographic observation, a
combined creep-fatigue interaction rather than a pure fatigue had an influence on the failure of the
zirconium cladding under the cyclic pressurization at 350oC.
A Study on Fatigue Characteristic of Connecting Rod Materials for Automobile
Authors: Kim Tae Gyu , Kim Hyun Soo , Park In Duck , Kim Hye Sung
Published: March 2009

In this study, we investigated the fatigue characteristics of SMA40 materials as a
potential application in connecting rod material for an automobile. Average fatigue life of
168,700 cycles and fatigue limit of 437 MPa was determined from SMA40 specimens. However,
when tested under fretting condition, decrease in fatigue lifetime was 20% and fatigue limit was
reduced to 350 MPa.
Sub-Grain Size and Hall-Petch Relation in Pure Copper Single Crystals
Authors: Miura Sei , Nishimura Yoshito , Ono Nagato
Published: March 2009

The effect of sub-grain on the yield stress of pure copper single crystals with the [253]
orientation was investigated by using the etch pit technique. The single crystal plates were
successfully prepared from the seed crystals, which were produced at the melting temperature of 1473
K by the Bridgeman method. The present investigation confirmed the Hall-Petch relation concerning
the effect of sub-grain boundaries on the macroscopic yielding of pure copper. The result derived
from the extrapolation of the relationship of critical resolved shear stress (CRSS) and the initial
dislocation density and sub-grain size is in good agreement with the evaluation in high purity copper
single crystals of low dislocation density.
Fatigue Life Prediction of High-Strength Bolt Subjecting to Torque
Authors: Choi Young Woo , Lim Bokkyu , Bae Sung In
Published: March 2009

The effect of axial loading resulting from torque on the fatigue life of bolts has been
investigated. It was found that the fatigue limit of bolts increased by an amount proportional to the
increase in torque. There was a linear relationship between torque and fatigue limit. Using the Shigley
method, the prediction of fatigue limit from calculated stress concentration factors was also
examined. A good correlation was found between the experimental and predicted fatigue limit. The
Shigley method was appropriate for the prediction of fatigue life of bolts.
Life Estimation of SUS304 Steel Subjected to Nonproportionally Combined Push-Pull and Cyclic Torsion at 973K
Authors: Tokimasa Katsuyuki
Published: March 2009

The present paper summarizes the fully reversed strain-controlled creep-fatigue tests
conducted on thin-walled tubular specimens of SUS304 austenitic stainless steel at 973K in air
under push-pull, cyclic torsion, in-phase straining and 90deg out-of-phase straining of push-pull and
cyclic torsion. It is shown that, as the results of analysis of the experimental data by the strain-range
partitioning methodand the critical plane model parameter, a new inelastic-strain based parameter
was proposed for life estimation of SUS304 subject to nonproportionally combined push-pull and
cyclic torsion by the strain-range partitioning method.
A Study on the Micro Property Testing of Micro Embossing Patterned Metallic Thin Foil
Authors: Lee Hye Jin , Lee Nak Kyu , Lee Hyoung Wook
Published: March 2009

In this paper, Experimental results on the measurement of mechanical properties of fine
patterns in the MEMS structure are described. The mechanical properties of embossing patterns on
metallic thin foil is measured using the nano indentation system, that is developed by Korea Institute
of Industrial Technology(KITECH). These micro embossing patterns are fabricated using CIP(Cold
Isostatic Press) process on micro metallic thin foils(Al-1100) that are made by rolling process. These
embossing patterned metallic thin foils(Al-1100) are used in the reflecting plate of BLU(Back Light
Unit) and electrical/mechanical MEMS components. If these mechanical properties of fine patterns
are utilized in a design procedure, the optimal design can be achieved in aspects of reliability as well
as economy.
Beneficial Effects Induced by High Temperature Cycling in Aged Duplex Stainless Steel
Authors: Armas A.F. , Degallaix Suzanne , Degallaix Gérard , Hereñú S. , Marinelli C. , Alvarez-Armas I.
Published: March 2009

The cyclic behavior of type DIN 1.4460 duplex stainless steels in as-received and aged
conditions was investigated at room temperature and at 500°C. At room temperature, the aged
samples showed embrittlement effects such as loss of toughness and reduction of fatigue life. At
500°C, beneficial effects of the synergy between temperature and strain cycling were observed. It is
proposed that at high temperature in the ferrite the strain cycling can decompose the chemical
composition fluctuations, promoting a demodulation of the spinodal decomposition formed by
aging.
Definition of Damage Parameter in Low-Cycle Fatigue of Gray Cast Iron
Authors: Lee Keum Oh , Lee Soon Bok
Published: March 2009

Gray cast iron shows large asymmetrical features by the graphite flake when tensile and
compressive stresses are applied. The plastic strain rage which is used in low-cycle fatigue life
prediction by many researchers is hardly defined and gives very different values by the Standards in
this case. From the results of this study, it is not reliable to use the plastic strain range as a low-cycle
fatigue damage parameter. Therefore, the plastic strain energy density which is uniquely defined was
suggested as a damage parameter and it showed good correlation in low-cycle fatigue in gray cast
iron.
Fatigue Crack Initiation in Crystalline Materials – Experimental Evidence and Models
Authors: Polák Jaroslav , Man Jiří , Vystavěl Tomáš , Zouhar Lukáš
Published: March 2009

Recent observations relevant to the early stages of the fatigue damage of crystalline
materials are reviewed. Experimental evidence on the localization of the cyclic plastic strain and on
the surface relief formation in cyclic loading of 316L austenitic stainless steel is presented. The
focused ion beam is used for exposing three-dimensional evidence of persistent slip markings
(PSMs). PSMs consist of extrusions and parallel or alternating intrusions which develop during
cyclic loading. Monte Carlo simulations of vacancy generation within persistent slip band (PSB)
and their migration to the matrix where they annihilate on the edge dislocations are used to simulate
the growth of extrusions and intrusions. The results of the simulations are compared with
experimental data and discussed in terms vacancy models of fatigue crack initiation.
Application of Notch Strain Approach to Evaluate Fatigue Life of Construction Equipment
Authors: Han Seung Ho , Han Jeong Woo , Shin Byung Chun , Kwak Sung Kyu , Kim Jou Sik
Published: March 2009

The technical development of construction equipment such as wheel loader leads to an
increase of not only amount of workload per hour, but also magnitude of allowable stress range.
Since welded structures of the wheel loader occupy approximately 40-60% of its total weight and
are subjected to incessant fatigue loads, fatal fatigue failures occur occasionally around the welded
zone during its practical operation in the field. To reasonably evaluate the fatigue life, the effect of
these geometries and welding residual stress on the fatigue life should be taken into account. In this
paper, the modified notch strain approach developed previously by the authors is applied practically
to assess the fatigue life of welded joints in boom and front frame structures of the wheel loader.
Alignment and Combination Rules on Multiple Flaws in Fitness-for-Service Procedures
Authors: Hasegawa Kunio , Miyazaki Katsumasa
Published: March 2009

If multiple discrete flaws are detected, alignment and combination rules are used to
determine whether the flaws should be treated as non-aligned or as coplanar, and independent or
combined flaws. Alignment and combination rules for multiple flaws are provided in
Fitness-for-Service (FFS) procedures of many codes and standards in the world. However, these
alignment and combination rules defined in the FFS are different. This paper aims to give overview
of alignment and combination rules for multiple flaws in FFS procedures. In addition, experimental
data on flat plates with parallel planar flaws are compared with the alignment rules of these FFS
procedures.
Initiation and Propagation of Impact-Induced Damage in CFRP Laminates
Authors: Jang Seung Min , Adachi Tadaharu , Yamaji Akihiko
Published: March 2009

This paper investigated the initiation and propagation characteristics of impact-induced
damage in carbon-fiber-reinforced-plastic (CFRP) laminates with different stacking sequences and
thicknesses under low-velocity impact. Impact force histories were measured with a drop-weight
impact tester. A strain gauge was attached on the back face of CFRP laminates to measure exactly
when a matrix crack on its back face was initiated. It was found from fractographic observation that
impact-induced damage in CFRP laminates was initiated at the matrix crack on the back face of
CFRP laminates due to bending deformation during impact. Finite element analysis was conducted
using the impact forces derived from the experimental results of the impact test. Its results clarified
that the tensile stress normal to the fiber on the back face of the specimen was the criterion to
initiate impact damage in CFRP laminates.
Finite Geometrically Similar Element Method for Dynamic Fracture Problem
Authors: Li You Tang , Ma Ping
Published: March 2009

A finite geometrically similar element method is proposed to determine the dynamic
stress intensity factor. A group of geometrically similar elements is automatically generated layer
by layer around the point of singularity. The large number of degrees of freedom around the tip of
singularity is transformed to a small set of generalized coordinates by means of the series expansion
formulas of the displacement field. By taking advantage of the same stiffness and similar mass of
similarly shaped elements, the combined stiffness matrix of super-element is obtained directly. The
small set of generalized coordinates can be obtained through solving the equation, and then the
dynamic stress intensity factor of V-notch (crack) will be obtained. There are some advantages for
this method such as good adaptability, high precision and good convenience.
Development and Application of Slow Crack Propagation of Polyethylene Based on Crack Layer Theory
Authors: Choi Byoung Ho , Chudnovsky Alexander
Published: March 2009

For explaining the SCG behavior of polyethylene, the crack layer theory is applied based on
the description of two driving forces: crack and PZ. The relations between the speed of SCG, crack
length and elapsed time are the most important characteristics of polyethylene resistance to crack
propagation, or long-term brittle fracture. The crack layer model of slow crack growth in polyethylene
is designed in such a way that it qualitatively reproduces the main features of the process indicated
above and makes it possible to quantitatively match any pattern of step-wise crack growth. In this
paper, the behavior of SCG of polyethylene is developed for numerical simulation based on the crack
layer theory. Some parametric study and applications are addressed based on the developed
simulation program.
Quantitative Evaluation of Dislocation Structure Induced by Cyclic Plasticity
Authors: Mayama Tsuyoshi , Sasakir Katsuhiko , Narita Yoshihiro
Published: March 2009

In the present study, a new approach is conducted to evaluate dislocation structure induced
by cyclic plasticity. First, cyclic plastic loading tests are carried out up to 100 cycles with three
different small strain amplitudes on SUS316L stainless steel at room temperature. The test result
presents the dependence of the strain amplitude on cyclic hardening and softening behaviors.
Specifically, it is found that the cyclic loading test with strain amplitude of 0.25% shows both cyclic
hardening and cyclic softening, while the cyclic loading tests with strain amplitudes of 0.75% and
1.0% show no cyclic softening. Secondly, the dislocation structures of the specimens after cyclic
loading are observed by using a transmission electron microscope (TEM), and this observation
reveals that the dislocation structure after cyclic loading test depends on the strain amplitude. Finally,
a quantitative evaluation method of the dislocation structure is also proposed. The TEM images are
converted into binary images and the resolution dependence of the generated binary image is used to
visualize the characteristics of the dislocation structure. The relationship between strain amplitudes of
cyclic plasticity and dislocation structure organization is clarified by the evaluation method. Finally,
the heterogeneity of the dislocation structure is discussed.
Development of Toughness Scale Diagram Considering Temperature Dependency
Authors: Ko Han Ok , Kang Sun Jung , Chang Yoon Suk , Choi Jae Boong , Kim Young Jin , Kim Min Chul , Lee Bong Sang
Published: March 2009

Fracture toughness data from the cleavage resistance test of structural steels often show a
large scatter. Geometry dependency as well as the scatter makes it difficult to evaluate appropriate
fracture integrity of cracked components. To address these restrictions, several stochastic models
have been proposed by Beremin group, Mudry and other researchers while each of them employs
specific estimation scheme and micro-mechanical parameters. The purpose of this paper is to
investigate applicability of the Weibull stress model in transition temperature regime and to quantify
constraint effect among different-sized CT and PCVN specimens. The constituting parameters m and
σu are determined at three temperatures by maximum likelihood estimate (MLE) technique in use of
FE analysis results and experimental data of PCVN specimens. Also, failure probabilities of PCVN
and CT specimens are calculated from the Weibull parameters, which are used for derivation of a
prototype of toughness scale diagram. The diagram provides a technical basis to resolve
transferability issue in the same material under different temperatures and constraint conditions.
Effect of Temperature and Specimen Thickness on Toughness of Nickel Alloy 22
Authors: Grubb John F. , Manahan Sr. Michael P.
Published: March 2009

Nickel Alloy 22, UNS N06022, is being evaluated for use as the material of construction in
permanent containers for spent nuclear fuel in Yucca Mountain, NV. To meet nuclear design criteria,
Charpy impact data were required for the N06022 plate material, but conventional full-size specimens
exceed the energy capacity of typical 400 J impact test machines, which results in stopping the
pendulum during the test. Half-size specimens break with about 40% of the machine energy capacity,
but their use raises questions concerning energy scaling to full size equivalent data. To address this, a
range of subsize specimens were tested at room temperature using a standard 400 J impact test
machine, and full-size, 3/4-size, and 2/3-size specimens were tested on a high energy capacity, 950J
machine. Additional tests were performed at temperatures ranging from -196 to +200°C. Impact
energy and lateral expansion measurements for the various test conditions are presented, their
implications are examined, and a new model for absorbed energy correlation between subsize
specimens and full size conventional Charpy specimens is proposed.
Super Plastic Flow and Cosmic Micromechanics
Authors: Muñoz-Andrade Juan Daniel
Published: March 2009

A unified interpretation of super plastic flow (SPF) and cosmic micromechanics in
spatially extended single and polycrystalline systems (SESPS) allows determined that the nature of
the hyperbolic granular flow in SESPS is assisted by the movement of dislocations as the pattern of
the inner dimension flow. Consequently in this work a mathematical model related with relativistic
cosmology and quantum mechanics is used in order to obtain the activation energy for super plastic
flow in SESPS. This correspondence law between SPF and cosmic micromechanics is important in
the light of recent cosmological theories of the existence of dark matter and dark energy in the
cosmic structure, because in this new interpretation of the universe the planets, stars, galaxies,
clusters of galaxies, etc., are considered as precipitates on dislocations in the cosmic structure,
which is formed in a nature way by the dark matter and dark energy, in a similar form of
precipitates on dislocations in a SESPS of metals. Physically in this context the expansion process
of the universe is highly dependent upon the volume fraction, size and distribution of precipitates on
dislocations in the cosmic structure. Therefore, in this work the main results obtained in cosmic
micromechanics and cosmic macromechanics are related with the Max Planck’s scale (MPE) and
Edwin Hubble’s scale (EHS) respectively.
Creep Rupture of Sn-Ag-Cu Pb-Free Solder Alloy
Authors: Zhang L. , Wang Zhong Guang , Shang J.K.
Published: March 2009

The eutectic Sn3.8Ag0.7Cu alloy is widely considered a leading Pb-free replacement
for the eutectic Pb-Sn solder alloy in electronic packaging where creep deformation and rupture is a
major concern. In this study, creep rupture behavior of Sn-Ag-Cu solder alloy was investigated
under the isothermal condition. Creep tests were conducted under a range of stresses and
temperatures. Creep lifetime data were analyzed by the combined time-temperature equations
following the Sherby, Larsen-Miller, and Manson-Haferd approaches. From these analyses, a series
of material parameters were obtained from the experimental data. The results showed that the
Manson-Hanferd method provided a better correlation with the creep rupture data. The mechanisms
of creep deformation and rupture at different time-temperature combinations are discussed.
Creep Curve Modeling of Hastelloy-X Alloy by Using the Nonlinear Regression Method in the Kachanov-Rabotnov Creep Model
Authors: Kim Woo Gon , Yin Song Nan , Ryu Woo Seog , Kim Yong Wan , Yi Won
Published: March 2009

To design HTGR components for up to 1000oC, their creep curves are necessary during a
design process. In this study, the full creep curves were modeled by the nonlinear least square fitting
method using the Kachanov-Rabotnov (K-R) creep model. A series of creep data was obtained
experimentally under various stress levels for Hastelloy-X at 950oC, and the data was used to model
the creep curves. The K-R model gave a poor description of modeling creep curves, but the modified
K-R one, which has another variable, K in the K-R model, was in better agreement than the K-R one. It
was found that the λ parameter in the K-R model was constant regardless of the stress variations. The
λ value was about 3.9 for the K-R model and about 5.8 for the modified one.
Texture and Mechanical Properties of ECA-Pressed Ti
Authors: Yu Seng Ho , Shin Dong Hyuk , Hwang Sun Keun
Published: March 2009

To study the effect of grain size on texture and tensile properties of equal channel angular
pressed commercially pure Ti, specimens were made to have the grain size ranging from 4 m to 60
m with the severe plastic deformation followed by recrystallization annealing. In this initial
condition all the specimens exhibited a strong bimodal split basal texture. During subsequent repressing
at 350°C, the texture pattern became randomized through crystal rotations, the
phenomenon being more pronounced in coarse-grained specimens. The microstructure of deformed
specimens, as examined by electron back scattered diffraction, showed formation of mechanical
twins and microstructural inhomogeneity in the coarse-grained specimens. The room temperature
tensile properties of the re-pressed specimens showed that the yield strength was remarkably
enhanced regardless of the grain size whereas the elongation was reduced as compared to the initial
condition, particularly in coarse-grained specimen. It was concluded that microstructural refinement
during the severe plastic deformation was the main cause of the improved yield strength while the
twinning and microstructural inhomogeneity were responsible for the texture randomization and the
impaired ductility.
The State-of-the-Art of Controlling Intergranular Fracture and Brittleness by Grain Boundary Engineering
Authors: Watanabe T. , Tsurekawa Sadahiro , Kobayashi S. , Zhao X. , Zuo L.
Published: March 2009

In last two decades it has been extensively studied whether the grain boundary engineering
can be effectively applied to controlling intergranular fracture and brittleness of different kinds of
brittle materials. Grain boundary engineering has been well established. A new processing method
based on magnetic field application has reached a new stage of grain boundary engineering.
Fracture Toughness and Fracture Mechanisms of Cast A356 Aluminum Alloys
Authors: Kwon Yong Nam , Lee Kyu Hong , Lee Sung Hak
Published: March 2009

The present study aims at investigating the effects of microstructure on fracture
toughness of two A356 Al alloys. These A356 alloys were fabricated by casting processes such as
rheo-casting and casting-forging, and their mechanical properties and fracture toughness were
analyzed in relation with microfracture mechanisms. All the cast A356 alloys contained eutectic Si
particles mainly segregated along solidification cells, and the distribution of Si particles was
modified by the casting-forging process. Microfracture observation results revealed that eutectic Si
particles segregated along cells were cracked first, but that Al matrix played a role in blocking crack
propagation. Tensile properties and fracture toughness of the cast-forged alloys having
homogeneous distribution of eutectic Si particles were superior to those of the rheo-cast alloy.
Improvement of Hardness and Wear Resistance of Steel-Based Surface Composites Fabricated by High-Energy Electron Beam Irradiation
Authors: Nam Duk Hyun , Lee Kyu Hong , Lee Sung Hak
Published: March 2009

The present study is concerned with the improvement of hardness and wear resistance in
(Cr3C2,CrB)/carbon steel surface composites fabricated by high-energy electron beam irradiation.
Two kinds of powder mixtures, 50Cr3C2-50STS304 and 50CrB-50STS304 (wt.%), were placed on a
plain carbon steel substrate, which was then irradiated with electron beam. The surface composite
layer of 1.0~1.3 mm in thickness was successfully formed without defects, and contained a large
amount (up to 58 vol.%) of Cr7C3 or Cr1.65Fe0.35B0.9 particles in the austenite or martensite matrix.
The hardness and wear resistance of the surface composites were 2~3 times higher than those of the
steel substrate according to hard particles. Particularly, the surface composite fabricated with CrB
powders showed excellent wear resistance because selective wear of the matrix was considerably
reduced.
Wear Resistance of Plasma-Sprayed Al2O3-TiO2 Nanocoatings
Authors: Ahn Jee Hoon , Song Eun Pil , Lee Sung Hak , Kim Nack
Published: March 2009

Wear resistance of Al2O3-8wt.%TiO2 coatings plasma-sprayed using nanopowders was
investigated. Four types of nanostructured Al2O3-8wt.%TiO2 powders were plasma-sprayed on a
low-carbon steel substrate by using different critical plasma spray parameters (CPSP). The coatings
consisted of completely melted and partially melted regions. The hardness of the coatings increased
with increasing CPSP, while the wear resistance was the highest for the coating sprayed with the
lowest CPSP. The main wear mechanism was a delamination mode in the coating sprayed with the
high CPSP, but was changed to an abrasive mode in the coating sprayed with the low CPSP.
According to this change in the wear mechanism, the wear resistance was the best in the coating
sprayed with lowest CPSP, while its hardness was lowest.
Microstructure and Mechanical Properties of Mg-Al-Ca-Sm Alloys at High Temperature
Authors: Son Hyeon Taek , Lee Jae Seol , Hong Ji Min , Oh Ik Hyun , Yoshimi Kyosuke , Maruyama Kouichi
Published: March 2009

The aims of this research are to investigate the effect of Sm addition in Mg-Al-Ca alloys on
microstructure and mechanical properties. Sm addition to Mg-5Al-3Ca based alloys results in the
change from dendritic to equiaxed grain morphorlogy and formation of Al-Sm rich itermetallic
compounds at grain boundary and α-Mg matrix. And these Al-Sm rich intermetallic compounds were
dispersed homogeously and stabilized at high temperature. And maximum yield and ultimate strength
value was obtained at Mg-5Al-3Ca-2Sm alloys at elevated temperature because of homogeneous
dispersion of stable Al-Sm rich intermetallic compound at high temperature.
The Effect of Fiber Winding Angles on the Bending Strength of Fiber-Reinforced Plastic Rods
Authors: Park Hoy Yul , Na Moon Kyong , Ahn Myeong Sang , Yoon Seog Young , Park Seong Soo
Published: March 2009

Fiber-reinforced plastics consist of fibers of high strength and modulus embedded in, or
bonded to a matrix with distinct interfaces between them. Because fiber configuration plays a key role
in determining mechanical strength of fiber-reinforced plastic rods, especially bending strength of
fiber-reinforced plastic rods was measured and simulated numerically in variation with winding
angles. Also, stress distribution in fiber-reinforced plastic rods was simulated numerically under the
condition of constant bending load to fiber-reinforced plastic rods. The measured bending strength of
fiber-reinforced plastic rods in variation with winding angles was different from that of simulated.
The difference between measured and simulated results was due to the effect of shear stresses on the
strength of fiber-reinforced plastic rods.
Failure Mechanism and Analysis of Reinforced Concrete Members with Fiber-Steel Laminate Composites
Authors: Yoon Jeong Bae , Choi Ji Hye , Hong Young Gyun , Ahn Sang Ho , Park Jung Hyun
Published: March 2009

The new composite method combined by fiber laminates and steel plate composites was
applied for reinforced concrete members. The experimental investigation for the applicability of this
method was presented for flexural member. Two different fiber materials such as carbon and
fiberglass with steel plate were used. All specimen using fiber material and steel plate were divided by
two different groups such as control group without strengthening, innovated fiber-steel laminate
composites group. Failure modes and load-deflection curves were presented for flexural members by
fiber-steel laminate composites. Numerical analysis for tested beam was investigated.
Calibration and Validation of an Elasto-Viscoplastic Material Model for a Hot Work Tool Steel Used in Pressure Casting Dies
Authors: Ecker Werner , Antretter Thomas , Ebner R.
Published: March 2009

Pressure casting dies are subjected to a large number of thermal as well as mechanical load
cycles, which are leading to a characteristic thermally induced crack network on the die surface. As a
typical representative for a die material the cyclic thermo-mechanical behavior of the hot work tool
steel grade 1.2343 (X38CrMoV5-1) is investigated both experimentally as well as numerically. On
the one hand the information from isothermal compression-tension tests is used in a subsequent
analysis to calibrate a constitutive model that takes into account the characteristic combined
isotropic-kinematic hardening/softening of the material. On the other hand the non-isothermal
mechanical response of the material to thermal cycles is characterized by means of a periodic laser
pulse applied to a small plate-like specimen which is cooled on the back. The residual stresses
developing at the surface of the irradiated region of the specimen are determined ex-situ by means of
X-ray diffraction. The obtained values agree well with the results of an accompanying finite-element
study. This information is used to verify the calibrated constitutive model. The material law is finally
used for the prediction of stresses and strains in a die.
Fatigue Crack Growth of Glass Fiber Reinforced Aluminum Alloy Laminate (Al/GFRP) According to the Micro Hole Location
Authors: Kim Cheol Woong , Oh Dong Joon , Kim Kee Joo , Kang Ki Weon
Published: March 2009

The diverse studies on Al/GFRP laminates with the circular holes, therefore, have been
carried out recently. The recent studies just focused on the behavior of the fatigue crack
propagation and the delamination when the shape and the size of the notches were changed.
Therefore, this study evaluated the location effect of the defects in the vicinity of the circular notch
of the high strength monolithic aluminum and Al/GFRP laminates on the initiation life (Ni) of the
fatigue cracks, the relationship between the crack length (a) and the fatigue life (N). In addition,
the fatigue crack behavior of Al/GFRP laminates was studied when the fatigue loading and the
interlaminar delamination took place at the same time during crack propagation. In conclusions,
(1) for the monolithic aluminum, 10% of the failure life at θ2=30° was more increased than that at
θ3=60°. (2) The crack length and the fatigue life behavior of Al/GFRP laminates according to the
location of the artificial defect were different from those of the monolithic aluminum. Namely, the
fatigue life of θ1=0° and θ2=30° were remarkably shorter than those of θ3=60° and θ4=90°.