bluuebunny/crossref_metadata_2025 huggingface dataset:
The Influence of Cathodic Protection on the Mechanical Properties of the X65 Pipe Weld
Authors: Lee Gyu Young , Bae Dong Ho , Kim Y.P. , Kim C.M. , Cho S.Y.
Published: March 2009

The cathode protection method is a very useful corrosion protection technology for the
underground pipelines. However, it has some problems that hydrogen generated by electrochemical
reaction on the wet surface of the pipelines is attacked into the pipe weld, and make degradation of
their mechanical properties. Therefore, in this study, welding residual stresses around of the X65
pipe weld, which is generally used as a material of the gas pipelines, were previously calculated.
And next, by using the cathode protection method, artificially degraded the X65 pipe weld
including base metal, assessed its influence on the mechanical properties of the X65 pipe weld.
Powdering in Coating Layer of Galvannealed Nb-Ti Free Extra Low Carbon Steel Sheet
Authors: Kim S.I. , Paik D.J. , Choi Shi Hoon , Kim D.W. , Yang Y.C. , Lee Young Seog
Published: March 2009

We have studied the fracture behavior of coating layer when low and high alloying
galvannealed (GA) steels are subject to forming process. To understand better powdering features in
the coating layer of the steel sheets, we carried out V-bending test and a series of finite element
analysis which simulates damage characteristics in the coating layer. Results showed that the
powdering behavior in the coating is significantly affected by the soundness and volume fraction of
phases in the coating layer. The hardness variation of coating layers attributed to different phases
leads to different deformation behavior of the coating layer itself.
An Electrical Method for Measuring Fatigue and Tensile Properties of Thin Films on Substrates
Authors: Keller R.R. , Barbosa N. , Geiss R.H. , Read D.T.
Published: March 2009

A novel approach for measuring thermal fatigue lifetime and ultimate strength of patterned
thin films on substrates is presented. The method is based on controlled application of cyclic joule
heating by means of low-frequency, high-density alternating current. Such conditions preclude
electromigration, but cause cyclic strains due to mismatch in coefficients of thermal expansion
between film and substrate. Strain and stress are determined from measurement of temperature.
Fatigue properties are a natural fit to testing by alternating current. Stress-lifetime (S-N) data were
obtained from patterned aluminum lines, where stress amplitude was varied by changing current
density, and lifetimes were defined by open circuit failure. Electron microscopy and electron
backscatter diffraction observations of damage induced by a.c. testing suggested that deformation
took place by dislocation mechanisms. We also observed rapid growth of grains – the mean diameter
increased by more than 70 % after a cycling time of less than six minutes – which we attribute to
strain-induced boundary migration. Ultimate strength was determined by extrapolating a modified
Basquin relation for high cycle data to a single load reversal. A strength estimate of 250 ± 40 MPa was
determined based on a.c. thermal fatigue data. In principle, an electrical approach allows for testing of
patterned films of any dimension, provided electrical access is available. Furthermore, structures
buried beneath other layers of materials can be tested.
Evaluation of Adhesive Strength in the Bonded Area of Shoes by Using IR Camera
Authors: Choi Choul Jun , Kim Jae Yeol , Choi Seung Hyun
Published: March 2009

The Infrared Camera usually detects only Infrared waves emitted from the light in order
to illustrate the temperature distribution. An Infrared diagnosis system can be applied to various
fields. But the defect discrimination can be automatic or mechanized in the shoes total inspection
system. The thermal images of the specimens were analyzed. In shoes, weak bonding due to the
separation of the bonded parts delamination causes defects. The most serious defect occurs in the
bonding between the outer covering of the shoe and the sole, and to up now, this defect has been
detected only by inspection with the naked eye. This study introduces a method for special shoes
nondestructive total inspection. Performance of the proposed method is shown through
thermo-Image. In search of superior inspection methods, we evaluated an applicable non-destructive
inspection method and also carried out basic research for developing an innovative nondestructive
inspection system for shoes. The total inspection system using infrared thermal camera for special
shoes, its applicability, and system configuration are introduced.
Microscopic Multi-Directional Permeability Coefficient of Human Lumbar Vertebral Cancellous Bone Tissue
Authors: Hong Jung Hwa , Park Young Hwan
Published: March 2009

The mechanical performance of cancellous bone is characterized using experimental
measure of parameters (elastic moduli, permeability, etc.) which apply poroelasticity theory.
Poroelastic investigations of bone are being extended to investigations of micro-mechanisms of
remodeling processes and transport of metabolic product in bone. To understand physiological and
pathological behavior of human skeletal system, the accurate measurement of biomechanical
properties for bone is the one of important works. Particularly, the microscopic measurement is very
important since the biomechanical behavior at the small scale of bone could be closely related to the
remodeling of bone. But microscopic measurement of permeability coefficient which is one of
important parameter of poroelasticity theory was never measured. In this study, a small scale
permeability testing machine was developed to measure accurate coefficient of microscopic
specimen permeability. Total of twenty one cylindrical cancellous specimens with a diameter of 500
from seven fresh male and female lumbar vertebrae (14, 39, 59, 61, 69, 75, and 77 years) were
fabricated using a micro-milling machine having a resolution of 10 . To determine the directional
permeability, bone coordinate was set to be x1 (longitudinal axis) and others were set as x2 (posteroanterior
axis) and x3 (latero-medial axis). The measured mean permeability (± SD) values of each
direction from x1 to x3 were 9 5.56 10− × (S.D. ± 10 7.10 10− × ), 9 6.66 10− × (S.D. ± 10 6.56 10− × ), and
9 7.04 10− × (S.D. ± 10 8.47 10− × ) m2/Pa/sec, respectively. Mean value in the x1 direction of specimens
were the smallest (p<0.01) in comparison to x2 and x3 directions.
Femtosecond Laser-Induced Precipitation and Manipulation of Noble Metal Nanoparticles in Silicate Glass
Authors: Hirao Kazuyuki , Hua Bin , Nishi Masayuki , Shimotuma Yasuhiko , Miura Kiyotaka
Published: March 2009

Femtosecond laser is a perfect laser source for materials processing when high accuracy and
small structure size are required. Due to the ultra short interaction time and the high peak power, the
process is generally characterized by the absence of heat diffusion and, consequently molten layers.
Various induced structures have been observed in glasses after the femtosecond laser irradiation.
Here, we report on space-selective precipitation and manipulation of noble metal nanoparticles in
the femtosecond laser-irradiated glasses.
Effects of the Deformed Volume and the Volume Fraction on the Local Deformation Behavior of W/Cu Composites
Authors: Ataya Sabbah , Korthäuer Marcus , El Magd Essam
Published: March 2009

Copper reinforced by tungsten particles has high potential applications in the fields of
electronics and electric contacts where high strength accompanied with good electrical conductivity is
required. The effects of different scaling parameters (deformed volume, tungsten volume fraction and
the tungsten particle size) affect the force needed for the machining of the W/Cu particle reinforced
composites.
W/Cu composites with different weight percentages of tungsten (80, 70 and 60 wt.%) were tested
under compression loading. Different sizes of the compression specimens were tested; the specimen
diameter DS was varied to be 1, 2, 4, 6 and 8 mm. The effect of the tungsten particle size was varied to
be 10 and 30-m. The compression tests were done at strain rates of 0.1s-1. The experiments were
carried out within a temperature range from 20 °C to 800°C. The mechanically tested specimens were
metallographically investigated to determine the degree of deformation of the tungsten particles in
different specimen geometries.
A clear dependence of the flow stress on the volume of the deformed specimens and the tungsten
volume fraction was found. This size effects were more obvious with increase of the tungsten volume
fraction at lower temperatures. The metallographic investigation was helped to understand the
observed size effect of the composites in relation to the volume fraction and the specimen size
Effect of Deformation Route on the Mechanical Properties of CP-Ti Deformed by Equal Channel Angular Pressing (ECAP)
Authors: Chon S.H. , Liu S.M. , Kim T.N. , Park Joong Kuen
Published: March 2009

The effect of deformation route on the mechanical properties of grade-1 CP-Ti deformed
by equal-channel angular pressing (ECAP) was studied using tensile testing, TEM observation, Xray
pole figure measurement, and ODF calculation. Route Bc showed high yield stress and
comparatively large uniform elongation, thus high ultimate tensile strength, because of its fine grain
structure with high angle grain boundary. The reason for this was because of the occurrence of
prismatic slip in route Bc, in addition to the commonly occurring basal slip. Route C showed
surprisingly high yield stress despite of its unfavorable grain structure because of the significant
contribution of texture hardening.
Polyurethane Coating on Coronary Stents
Authors: Bognár Eszter , Ring György , Marton Hilda Zsanett , Dobránszky János , Ginsztler János
Published: March 2009

Stents are special metallic or polymer endoprostheses of meshed structure and tube
shape. Their function is to prevent restenosis in the arteries. Stents can be coated or uncoated. In the
expanded part of the artery the chance of restenosis is bigger even without a stent so it is practical to
coat the stents.
The aim of this work is to present the results of the coating experiments made on the coronary
stents. Three types of commercially available polyurethanes were used for these experiments. The
coatings were produced by a dipping method. Electro-polished and non-electro-polished metallic
sheets and stents were used for these experiments. Contact angle measurements were done to
examine the wetting properties of the three different polyurethane coatings. The quality and the
changing of the coatings were examined by different methods (stereomicroscope, scanning electron
microscope and energy dispersive spectrometry).
A Study on Flexural Strength with the Spreading of the Negative Steel of Girder into the Adjoining Slab
Authors: Park Jung Hyun , Kim Hee Kyu , Hong Gi Suop , Hong Young Kyun , Yoon Jeong Bae
Published: March 2009

The study of girder-to-column joints under experiment and numerical analysis was carried
out to evaluate change of the flexural capacity of the joints with the 2-layer upper reinforcement of
girder within rectangular section and the single-layered upper reinforcement at the girder flange. The
distribution of the upper reinforcement of girder within the effective flange width was the variable in
the experiment and numerical study. The ultimate strength of the specimen with 2-layer upper
reinforcements of girder was larger than that of the single-layered specimen by maximum 17.4%.
Based on the results of this experimental study, for the single-layered tension reinforcement it is
recommended to provide 15% additional reinforcement at twice slab thickness on each side of the
main girder to attain the flexural capacity equal to the 2-layered case.
Bauschinger Effect’ Influence on the Componud Cylinder Containing an Autofrettaged Layer
Authors: Lee Young Shin , Park Jae Hyun , Kim Jae Hoon , Cha Ki Up , Hong Suk Kyun
Published: March 2009

Autofrettage is used to introduce advantageous residual stresses into cylinders. The
Bauschinger effect can produce less compressive residual hoop stresses near the bore than are
predicted “ideal” autofrettage solutions. A723 steel is used for compound cylinder. This paper
extends the analysis to material the addition of pressure or of shrink-fitting to the cylinders,
providing associated residual stress profiles following various amounts of further yielding due to a
net external pressure. The Bauschinger effects for “realistic” – Bauschinger effect dependent
autofrettage are obtained. The 2-D analysis is performed via the finite element method. The
Bauschinger effect is found to significantly lower the beneficial stress due to autofrettage.
Fracture Toughness of Epoxy Resins Containing Blends of Monomers with Different Molecular Weights
Authors: Haris Andi , Adachi Tadaharu , Araki Wakako , Hayashi Yu
Published: March 2009

The effect of adding a high molecular weight epoxy monomer (epikote 1001) to a low
molecular weight one (epikote 828) on fracture toughness properties was investigated according to
the crosslinking degree and density heterogeneity. To characterize the crosslinking degree and
density heterogeneity, the glass transition temperature, Tg, and fragility, m, were deduced from
thermo-viscoelastic properties. The characterization of Tg and m revealed that blends can be divided
into two groups: one group with (φ < 10 wt%) and another one with (φ > 10 wt%), where φ is the
weight ratio of epikote 1001 to epikote 828. The first group had the same average crosslinking
degree (the same Tg) but different density heterogeneities (m decreased). The other group had a lower
crosslinking degree (Tg decreased) and even more density heterogeneity (m decreased). The fracture
toughness results showed that KIC of blends of the first group was approximately constant because
the increase in density heterogeneity was still too weak (ineffective m), whereas KIC of blends of the
second group was higher due to the simultaneous decrease in average crosslinking degree and
increase in density heterogeneity. Therefore, the lower crosslinking degree (lower Tg) is and the more
heterogeneous the blend (lower m) is due to the addition of high molecular weight monomer, the
higher KIC becomes.
A Study on the Aging Behavior of Al-Li-Cu-Zr Alloy
Authors: Park Tae Won , Song Young Bum
Published: March 2009

Aging behavior of Al-2.1Li-2.9Cu-0.12Zr(wt%) alloy has been studied as functions of
aging time and temperature by using a differential scanning calorimetry(DSC) and transmission
electron microscopy(TEM). The aged specimens at 130, 160, 190°Cwere compared with the
as-quenched specimen in view of the aging behavior by observing the reaction enthalpy during the
heating period of DSC experiments. DSC peak associated with the formation of GP zone is not
observed at 130 and 160°C, but it does at 190°C, so it is found that the thermal stability of GP zone is
changed at between 160 and 190°C. At the aging temperature of 130°C, the heat absorption
corresponds to the formation of δ´ increases, while the heat evolution related with the formation of T1
reveals an opposite trend. In aging temperature of 160 and 190°C, aging time representing the drastic
decrease of heat absorption of δ´ is coincident with the transition time showing the decreasing of heat
evolution of T1. The micro-Vickers hardness of the specimens aged at 160°C and 190°C shows
maximum values about 182 and 165 at aging times of about 72 hr and 25hr, respectively. From
comparing reaction enthalpies for the dissolution of δ´ and the formation of T1 phases with the aging
time showing the maximum hardness, it is found that δ´ phase rather than T1 phase markedly
contributes to the hardening at an aging temperature of 160°C. In contrast, T1 phase plays an important
role in hardening at an aging temperature of 190°C.
Numerical Evaluation of Crashworthiness of Automotive Sheets
Authors: Ryou Han Sun , Lee Myoung Gyu , Kim Chong Min , Chung Kwan Soo
Published: March 2009

Crash simulations were performed for automotive sheets. To understand the influence of
crystal structures in sheet materials on crashworthiness, the effect of the yield function shape was
studied by adopting the recently developed non-quadratic anisotropic yield surface, Yld2004-18p.
The effect of the back-stress was also investigated by comparing simulation results obtained for the
isotropic, kinematic and combined isotropic-kinematic hardening laws based on the modified
Chaboche model. In addition, the effects of anisotropy and sheet thickness on crashworthiness were
evaluated.
Study of the Titanium Alloy Deformation Behavior in Equal Channel Angular Extrusion
Authors: Chen Dyi Cheng , Li Yi Ju , Tzou Gow Yi
Published: March 2009

The shear plastic deformation behavior of a material during equal channel angular (ECA)
extrusion is governed primarily by the die geometry, the material properties, and the processing
conditions. Using commercial DEFORMTM 2D rigid-plastic finite element code, this study
investigates the plastic deformation behavior of Ti-6Al-4V titanium alloy during 1- and 2-turn ECA
extrusion processing in dies containing right-angle turns. The simulations investigate the
distributions of the billet mesh, effective stress and effective strain under various processing
conditions. The respective influences of the channel curvatures in the inner and outer regions of the
channel corner are systematically examined. The numerical results provide valuable insights into
the shear plastic deformation behavior of Ti-6Al-4V titanium alloy during ECA extrusion.
Variability in Fatigue Behavior of a Zr-Based Bulk Metallic Glass (BMG) as a Result of Average Surface Roughness and Pronounced Surface Defects
Authors: Peter William H. , Wang G.Y. , Liaw Peter K. , Buchanan R.A. , Liu C.T. , Morrison M.L. , Brooks C.R.
Published: March 2009

Recent interest in bulk-metallic glasses (BMGs) has led to the development of amorphous alloys
designed for structural applications in various fields as aircraft frames, rotating equipment,
automobiles, and medical implants. Although the mechanical behavior of BMGs is being studied
extensively, little attention has been paid to their fatigue behavior. Moreover, early fatigue
characteristics have exhibited contradictory results. In the current research, uniaxial tension-tension
fatigue experiments were performed on notched Zr52.5Cu17.9Al10Ni14.6Ti5 button-head fatigue
specimens with various surface finishes. The fatigue studies were designed to better understand the
influence of the average surface roughness and/or critical surface defects on the fatigue behavior of
glassy alloys. It was hypothesized that geometric surface flaws would lower the observed life of a
BMG sample by shortening the crack initiation phase and providing local stress concentrators. The
current studies of surface conditions indicate that fatigue-endurance limits are greatly impacted by
the average surface roughness with possible reductions of greater than fifty percent.
A Study on the Fatigue Life Assessment for Urban EMU Structure
Authors: Chung Jong Duk , Pyun Jang Sik , Lee Ouk Sub
Published: March 2009

In these days, most urban railway vehicles have been serviced under the random load
application. However, it is considered to be a major factor of safety to predict the fatigue life for
structures. It is thus required that fatigue assessment method for cumulative damage approach while
Korea domestic regulations practices only the only has endurance limit approach. With this endurance
limit approach, fatigue life prediction is impossible. In this research, the fatigue assessment for urban
transit structure by using of cumulative damage approach method and related theories are presented.
Effect of Powder Size on Fatigue Behaviour in Mg2Si-Dispersed Magnesium Alloys Produced by Solid-State Synthesis
Authors: Tokaji Keiro , Uematsu Yoshihiko , Kamakura Mitsutoshi
Published: March 2009

The fatigue behaviour of newly developed Mg2Si-dispersed magnesium (Mg) alloys
produced by solid-state synthesis was studied. Rotary bending fatigue tests have been performed
using smooth specimens of materials produced with fine and coarse AZ31 alloy powders. Both
Mg2Si-dispersed Mg alloys exhibited lower fatigue strength than a conventional extruded AZ31
alloy and the powder size dependence of fatigue strength was clearly recognized, where the material
produced with fine alloy powder showed considerably higher fatigue strength than the counterpart.
Fatigue cracks invariably initiated at large Mg2Si particles immediately after cyclic loading was
applied and subsequent small crack growth was faster than the extruded AZ31 alloy. It was
concluded that the lower fatigue strength of Mg2Si-dispersed Mg alloys was attributed to premature
crack initiation at Mg2Si particles and faster small crack growth, and the observed powder size
dependence of fatigue strength was due to difference in the size of the particle from which the crack
initiated.
Fatigue Crack Growth Acceleration Due to Hydrogen in Type 304 Stainless Steel
Authors: Noda Hiroshi , Matsunaga Hisao
Published: March 2009

In order to investigate the influence of hydrogen on the fatigue strength of Type 304
meta-stable austenitic stainless steel, specimens were cathodically charged with hydrogen.
Hydrogen-charging led to a marked decrease in fatigue crack growth life. Crack growth paths and
slip bands morphology were changed by the hydrogen-charging. To elucidate the mechanism of the
degradation by hydrogen, the surfaces of both the uncharged and charged specimens were
examined by the hydrogen microprint technique (HMT). In the uncharged specimen, no hydrogen
emission from specimen surface was observed. On the other hand, in the hydrogen-charged
specimen, a hydrogen emission was observed, especially in the vicinity of fatigue cracks. Hydrogen
was mainly emitted from slip bands. These results suggest that the degradation of fatigue crack
growth resistance in hydrogen-charged specimens was caused by the diffusion of hydrogen to slip
bands, which accelerated the dislocation mobility and thereby facilitated the fatigue crack growth.
Short Crack Initiation during Low-Cycle Fatigue in SAF 2507 Duplex Stainless Steel
Authors: Marinelli M.C. , Degallaix Suzanne , Alvarez-Armas I.
Published: March 2009

In this work, the formation of fatigue cracks is considered as a nucleation process due
to the development of a characteristic microstructure formed just beneath the specimen surface.
Strain controlled cyclic tests were carried out at room temperature at total strain ranges εt = 0.8
and 1.2% in flat specimens of SAF 2507 Duplex Stainless Steel (DSS). The results show that for
this DSS, at εt = 0.8%, the correlation between phases (Kurdjumov-Sacks crystallographic
relation) plays an important role in the formation of microcracks. On the other hand, at εt = 1.2%,
microcracks initiate in the ferritic phase and the K-S relation does not seem to affect the formation
of the cracks.
Fatigue Behaviour of Case-Hardened P/M Steels
Authors: Seyedi Scheida , Lang K.H. , Löhe Detlef
Published: March 2009

Powder-metallurgical (P/M) produced components may be used as mass parts in a very large
quantity. Due to the multistage manufacturing process which consists of the pressing of the prepared
powder and the sintering of the green bodies also complex shaped components can be produced very
economically and precisely. They can be utilised without any further post-processing if the whole
production process is optimised. However, it is still difficult and only possible with considerable
technical and financial effort to produce highly stressable components profitably using the sinter
technique.
Therefore, the examinations on hand had the intention to create the basis for the use of the sinter
technology also for the production of highly stressable case-hardened components. To this, at first
bending specimens were fabricated with modern pressing procedures and sinter facilities and first
characterized in the as sintered state. Then the conditions for the case-hardening was analysed and the
parameters for an optimised case-hardening procedure fixed. With these parameters specimens were
case-hardened and their lifetime behaviour estimated under different bending loading conditions.
Finally it should be checked whether the knowledge gained from the specimens could be applied
to complex components. To this, gear wheels were produced using powder-metallurgy. The cyclical
tooth foot strength of this gear wheels were analysed in the only sintered as well as in the
case-hardened state. It could be demonstrated that the improvement of the fatigue strength of the
bending specimens by case-hardening also appears at the tooth foot strength of the gear wheels.
Failure Assessment Diagrams for a Solid with a Crack or Notch under Uniaxial and Biaxial Loading
Authors: Matvienko Yu.G. , Priymak O.A.
Published: March 2009

The cohesive zone model and the local failure criterion in the form of the average stress
limitation in the cohesive zone ahead of the crack/notch tip have been employed to describe the failure
assessment diagram for solids with a crack or notch under uniaxial and biaxial loading. The local
stress on the crack extension line has been described by the exact elastic Westergaard’s solution
taking into account the stress parallel to the crack plane. The cohesive stress ahead of the crack or
notch tip is treated according to von Mises yield criterion as a property of the material, the applied
stress and the stress biaxial ratio. Effect of the biaxial ratio is discussed for plates with a crack and
notch. The failure assessment curve for a plate with a crack shows no significant differentiation
among the three loading cases for plane stress, whereas the biaxial assessment curves move outward
from the uniaxial case for plane strain.
Development of Experimental Procedure Based on the Load Separation Method to Measure the Fracture Toughness of Zr-2.5Nb Tubes
Authors: Kim Young Suk , Matvienko Yu.G. , Jeong H.C.
Published: March 2009

The load separation method was employed to measure the pl η -factor, the growing crack
length and the applied J-integral during the course of the test of small curved CT specimen of Z-2.5Nb
pressure tube material. The effect of the notch tip radius of the notched (reference) CT specimen on
the separation parameter was analyzed to predict the crack growing length in the precracked
specimen. To avoid the effect of load relaxation in the reference specimen on the separation parameter
and the crack growing length estimation, the load was assumed to be maximum and constant value
behind the peak load in the reference curve.
Application of the Three-Dimensional Local Hybrid Method to the Structure with a Surface Crack Subjected to Bending Load
Authors: Machida Kenji , Ueno Takanori
Published: March 2009

We developed the 3-D local hybrid method to evaluate the 3-D stress field inside the
specimen from displacement data on the free surface obtained from the 2-D intelligent hybrid
method. When a uniform load was applied to the structure with a surface crack, high accuracy was
already acquired in stress analyses. The 3-D local hybrid method was anew applied to a structure
with a surface crack which is subjected to bending load. It is expected that the accuracy depends on
local model size. In this study, the width, the thickness and the height of the local model were
changed widely, and analyses were carried out. Then the size of the local model necessary for the
analyses was examined. Assessment of analyses was performed by comparing J integral value of a
whole model and a local model.
Stress and Displacement Fields at a Transient Crack Tip Propagating in Functionally Graded Materials
Authors: Lee Kwang Ho , Ban Gap Su
Published: March 2009

Stress and displacement fields for a transient crack tip propagating along gradient in
functionally graded materials (FGMs) with an exponential variation of shear modulus and density
under a constant Poisson's ratio are developed. The equations of transient motion in nonhomogeneous
materials are developed using displacement potentials and the solution to the displacement fields and
the stress fields for a transient crack propagating at nonuniform speed though an asymptotic analysis.
Experimental and Theoretical Studies of Slow Crack Growth in Engineering Polymers
Authors: Chudnovsky Alexander
Published: March 2009

The process zone (PZ) that surrounds and precedes a crack is a common feature of fracture
in engineering polymers. Depending on the material, the specimen geometry, the temperature, and the
loading conditions various types of microdefects such as crazes, shearbands, microcracks,
micro-voids, etc, constitute the process zone. The microdefects are formed in response to stress
concentration, and shield the crack tip from high stress level. There is a complex crack – damage
interaction, which is briefly addressed by means of a semi-empirical method. On a continuum
mechanics level, the PZ appears as a domain with effective elastic properties different from that of the
original material. The crack and PZ evolve as one system with multiple degrees of freedom. It is
regarded as a Crack Layer (CL) in contrast with the conventional image of crack as an ideal cut. There
are thermodynamic forces responsible for CL growth, which are defined as derivative of Gibbs free
energy with respect to the corresponding CL “coordinates”. The thermodynamic forces can be
expressed as integrals of the Energy Momentum Tensor of elasticity. Onsager type relations between
CL growth rates and corresponding CL forces constitute a system of constitutive equations for CL
propagation. Examples of solution of these equations, and comparison with experimental data as well
as with conventional models are presented in accompanying paper.
Finite Element Simulation of Crack Propagation Under Mixed Mode Loading Condition Using Element Removing Method
Authors: Kim H.S. , Kim K.S. , Lee Young Seog
Published: March 2009

In this study, we introduce an approach which simulates crack propagation under mixedmode
loading condition. In comparison with the conventional element removing method which
eliminates any element that satisfies a prescribed failure criterion near the crack tip, the present
approach selects a set of elements ahead of the crack tip on the crack growth direction and removes
them one by one when the element meets a prescribed failure criterion. Compact tension shear
(CTS) specimens of type 304 stainless steel were used for failure testing. Finite element simulation
has been carried out to simulate crack profiles and compared with observed ones. Results showed
the proposed element removing algorithm is useful for crack growth simulation under mixed mode
loading condition. The experimentally measured crack growth profile is in an agreement with the
predicted ones.
Microstructure and Bonding Strength in Overlaying of Stellite 6 Alloy on Spheroidal Graphite Cast Iron by Plasma Transferred Arc Process
Authors: Lin Hung Mao , Lui Truan Sheng , Chen Li Hui , Chan Wai Sing
Published: March 2009

In this study, stellite 6 alloy was overlaid on spheroidal graphite (SG) cast irons with various carbon contents
(1.5wt%~3.8wt%) and a fixed silicon content (approximately 2.5wt%) using the plasma transferred arc (PTA) process at
different overlaying current (140A~220A) while the travel speed of the PTA torch was maintained constant. Results
indicated that the solidification structures of the stellite 6 overlayers were dendritic and had a large amount of
interdendritic precipitates (M7C3 and M23C6 carbide) after the satellite 6 alloy had been overlaid on SG cast irons with
different carbon contents (1.5wt%~3.8wt%) at a low overlaying current (I=140A). The partially melted zones of the
substrates below the carbide-containing interfacial layers consisted of eutectic carbides (ledeburites) and fine pearlites.
The amount of the carbide-containing interfacial layers and ledeburites increased following the increase in the
overlaying current. The results of the tearing test reported that the occurrence of the carbide-containing interfacial layers
was detrimental to the bonding strength between the overlayers and the substrates. The metallography of the fractured
area of the tearing specimens after the bonding strength test revealed that fractures always occurred at the
carbide-containing interfacial areas. On the other hand, the overlayers were rich in iron content when the overlaying
currents were high (I=190A and 220A). Owing to the dilution effect, the matrices of the overlayers were α-Fe with
lamellar M7C3 carbides. The results of the tearing test indicated that the bonding strength of the overlaid specimens was
relatively low, and fractures always occurred in these highly diluted overlayers.
Approximate J Estimates for Circumferential Cracks in between Elbows and Attached Pipes
Authors: Song Tae Kwang , Oh Chang Kyun , Kim Yun Jae , Kim Jong Sung , Jin Tae Eun
Published: March 2009

The present work proposes a method for elastic-plastic fracture mechanics analysis of the
circumferential through-wall crack in between elbows and attached straight pipes, subject to in-plane
bending. Based on small strain finite element limit analyses, closed-form limit load solutions are
given first. Then applicability of the reference stress based method to approximately estimate J is
proposed. One interesting finding is that a popular approach to assume that the crack locates in the
straight pipe could lead to significantly different assessment results.
Damage Analysis and Limit Tending Design of Thrust Bearing in esPCP System
Authors: Wang Shi Jie , Jian Kang , Jianhua Lv
Published: March 2009

Thrust bearing is one of the most important components in esPCP system, which
determines the lifespan of the whole system under the restriction of some factors such as the depth
of downhole unit, the viscosity of petroleum oil to be pumped. To increase the high temperature
bearing ability of the bearings under the limitation of radial size, the damage reason of pre-applied
bearings was analyzed. Some different modified plans were put forward from two aspects of
structure and material. Contact problems were researched for different plans with finite element
analysis software of ANSIS. Comparison of results shows that, in the well of 5½" tube, the
optimum selection is ball thrust bearing with 8 balls of radial size of 10mm without keeper.
Behavior of Boron in 9Cr Heat Resistant Steel during Heat Treatment and Creep Deformation
Authors: Abe Fujio
Published: March 2009

The effect of boron on microstructure evolution and creep deformation behavior has been
investigated for a tempered martensitic 9Cr-3W-3Co-0.2V-0.05Nb steel at 650oC. Creep tests were
carried out at 650oC for up to about 6 x 104 h. The addition of boron retards the onset of acceleration
creep at low stress and long time conditions, which results in lower minimum creep rate and longer
time to rupture. The addition of boron also retards the Ostwald ripening of M23C6 carbides near prior
austenite grain boundaries (PAGBs) during creep. The retardation of the onset of acceleration creep
results from the retardation of the recovery of martensitic microstructure near PAGBs by pinning
effects due to fine M23C6 carbides. The main effect due to boron is considered to occupy vacancies
near growing M23C6 carbides, which makes it difficult to accommodate local volume change around
the growing carbides. This reduces the rate of Ostwald ripening of M23C6 carbides.
Accommodation of Grain Boundary Sliding in AZ31 Alloy
Authors: Kwon Yong Nam , Lee Young Seon , Kim S.W. , Lee Jung Hwan
Published: March 2009

Mg alloys could be the lightest alloys among the industrially applicable engineering alloys.
Since wrought Mg alloy has limited applications due to the poor formability, casting is currently the
main processing technique to fabricate Mg components even though wrought alloys are superior in
terms of mechanical properties and reliability. While a lot of research and development has been
focused on warm forming under the temperature condition of around 250°C where more formability
could be expected, superplastic forming could be another way to get over the low formability of Mg
alloys. Like other superplastic materials grain boundary sliding is the main deformation mechanism of
Mg superplasticity. Accommodation of stress concentration around triple point of grain boundary
should be done favorably if grain boundary sliding continues without any fracture. In the present study,
superplastic behavior of AZ31 alloys with several grain sizes was examined firstly. Accommodation
of grain boundary sliding of AZ31 alloy would be discussed on the basis of grain morphology and
texture evolution after tensile deformation.
Microfracture Observation of Zr-Based Bulk Metallic Glasses
Authors: Lee Jung G. , Sohn Kee Sun , Lee Sung Hak , Kim Nack , Kim Choong Nyun Paul
Published: March 2009

Microfracture mechanisms of Zr-based bulk metallic glass (BMG) alloy containing
ductile crystalline particles were investigated by directly observing microfracture processes using
an in situ loading stage. Strength of the BMG alloy containing crystalline particles was lower than
that of the monolithic BMG alloy, while ductility was higher. According to the direct microfracture
observation, crystalline particles initiated shear bands, acted as blocking sites of shear band or crack
propagation, and provided the stable crack growth which could be confirmed by the R-curve
analysis, although they negatively affected apparent fracture toughness. This increase in fracture
resistance with increasing crack length improved overall fracture properties of the alloy containing
crystalline particles, and could be explained by mechanisms of blocking of crack or shear band
propagation, formation of multiple shear bands, crack blunting, and shear band branching.
A Study on Fatigue Properties of Sc and Zr Added Al Alloy
Authors: Baek Un Bong , Park Jong Seo , Chung In Hyun , Park Tae Won , Nahm Seung Hoon
Published: March 2009

Al alloy is used extensively in several fields because specific strength is good and
workability is superior. It is known that If Sc is added to Al alloy, strength is increased and
re-crystallization temperature rises because microstructure becomes fine. The high cycle fatigue
properties of four kinds of Al-Mg-Si alloys without and with only scandium of 0.20 % or with both
scandium(Sc) of 0.20 % and zirconium(Zr) of 0.12% were investigated. The fatigue strength was
determined at R = -1.0 under constant amplitude loading conditions in air. The alloy with scandium of
0.20 % showed a little higher fatigue strength values. The alloy with 0.20 % Sc and 0.12 % Zr showed
highest tensile yield strength and highest fatigue strength. The fine grained Al 6061+0.20Sc+0.12Zr
alloy exhibited a higher resistance against fatigue crack nucleation in comparison to the coarse
grained Al 6061 alloy. The results can be explained mainly with the micro-structural differences
among four alloys. This results are due to the presence of coherent Al3 (Sc, Zr) precipitates and a very
fine sub-grain structure.
Evaluation of Un-Cracking Delamination by Pseudo Crack Model (PCM) in FRMLs
Authors: Kim Cheol Woong , Oh Dong Joon , Kang Ki Weon , Ko Young Ho
Published: March 2009

If Fiber Reinforced Metal Laminates (FRMLs) were delaminated, the decrease of
stiffness and fiber bridging effect would result in the sudden aggravation of fatigue characteristics.
It was reported that the delamination of FRMLs resulted from the crack of Al alloy layers and that it
depended on the crack growth. When FRMLs with circular holes was un-cracked but was
delaminated, it was impossible to analyze them by conventional fracture parameters expressed as
the function of cracks. Therefore, a new analytical model called Pseudo Crack Model (PCM) was
suggested to compare the delaminations whether cracks were made or not. The relationship
between the crack consumption rate (Ccrack) and the delamination consumption rate (Cdel) was
discussed and it was also known that the effect of the Ccrack was larger than that of the Cdel.
Fretting Wear Damage of the Corroded Fuel Cladding Tubes for Nuclear Fuel Rod against Supporting Grids
Authors: Kim Jin Seon , Kim Yong Hwan , Lee Seung Jae , Lee Young Ze
Published: March 2009

Fuel cladding tubes in nuclear fuel assembly are held up by supporting grids because the
tubes are long and slender. Fluid flows of high-pressure and high-temperature in the tubes cause
oscillating motions between tubes and supports. This is called as FIV (flow induced vibration), which
causes fretting wear in contact parts of tube-support. The fretting wear of tube-support can threaten
the safety of nuclear power plant. Therefore, a research about the fretting wear characteristics of
tube-support is required. The fretting wear tests were performed with supporting grids and cladding
tubes, especially after corrosion treatment on tubes, in water. The tests were done using various
applied loads with fixed amplitude. From the results of fretting tests, the wear amounts of tube
materials can be predictable by obtaining the wear coefficient using the work rate model. Due to stick
phenomena the wear depth was changed as increasing load and temperature. The maximum wear
depth was decreased as increasing the water temperatures. At high temperatures there are the regions
of some severe adhesion due to stick phenomena.
High-Toughening Alumina Composites Weakened by Metastable Hexacelsian Interphases
Authors: Lee Sang Jin , Lee Sang Ho
Published: March 2009

New laminate design for improved toughness in hexacelsian-alumina composite is
introduced. The composite is based on crack deflection in a weak interphase in the alumina matrix and
hexacelsian interphase. The strength and toughness of the laminated composite were studied both
qualitatively by electronic microscopy and measuring flexure strength. The metastable hexacelsian
interphases had partially microcracks to provide crack deflection in the composite, and the crack
deflection noticeably proceeded along the meta-stable hexacelsian interphase. Load-deflection curve
for the laminate showed improved work of fracture of 2.23 kJ/m2.
Friction Behavior for Micro-Scale Grooved Crosshatch Pattern under Lubricated Sliding Contact
Authors: Chae Young Hun
Published: March 2009

Some surface patterns of tribological application are an attractive technology of engineered
surface. Because of the friction reduction is considered to be necessary for improved efficiency of
machine. This study was investigated for the effect of friction property for angles of micro-crosshatch
groove surface pattern on bearing steel used pin-on-disk test. We obtain sample which can be
fabricated by photolithography process. We discuss the friction property depended on an angle of
crosshatch groove surface pattern. We can verify the lubrication mechanism as Stribeck curve which
has a relationship between the friction coefficient and a dimensionless parameter under the
lubrication condition. It was found that the friction coefficient was related to angle of crosshatch
groove pattern on contact surface.
Development of Bellows Type Vertical Micro Contact Probe
Authors: Kim Jung Yup , Choi Hyun Ju , Lee Sang Joo , Lee Hak Joo
Published: March 2009

In the semiconductor inspection, number of pads at unit area is increasing and pad array
have become irregular 2-dimensional. So we develop a bellows type micro contact probe. Our micro
contact probe is a vertical-type micro contact probe for area arrays and narrow pitch electrode pads.
We choose bellows type micro contact probe to prevent stress concentration. Our design targets are
120 um pad pitch, 20-50 um OD(over drive) and over 5 mN reaction force.
In this research, micro contact probe is made by electroplating(Ni-Co). structural analysis is
accomplished by FEM. And characterization of micro contact probe is done by our own mechanical
tester. So material property is measured for structural analysis and structural analysis result will be
compared with experimental result.
Micromechanical Modeling of Grain Boundary Resistance to Cleavage Fracture Propagation
Authors: Stec Mateusz , Faleskog Jonas
Published: March 2009

A micromechanical model representing two adjacent grains is developed. Rapid crack
propagation from one grain into another driven by a constant global stress state is simulated. The
normal of the crack face in the grain where the micro-crack initiates coincides with the principle
loading direction. In the adjacent grain, the propagation direction changes and separation occurs in a
mixed way, involving both normal and shear separation. The largest grain size that can arrest a
rapidly propagating micro-crack is defined as the critical grain size. The effects of the global stress
state and temperature on the critical grain size is examined. The influence of the mismatch in lattice
orientation between two neighboring grains is qualitatively described. The influence of temperature
is modeled by a temperature dependent viscoplastic response.
Dynamic Response of the Spectral Element Model by Using the FFT
Authors: Cho Joo Yong , Go Han Suk , Lee Usik
Published: March 2009

In this paper, a fast Fourier transforms (FFT)-based spectral analysis method (SAM) is
proposed for the dynamic analysis of spectral element models subjected to the non-zero initial
conditions. To evaluate the proposed SAM, the spectral element model for the simply supported
Bernoulli-Euler beam is considered as an example problem. The accuracy of the proposed SAM is
evaluated by comparing the dynamic responses obtained by SAM with the exact analytical solutions.
Analysis of Forging Plastic Stress by X.R.D and F.E.M
Authors: Kim S.Y. , Jeon S.K. , Kim J.H. , Yoon J.M.
Published: March 2009

Forging is applied for many industrial fields. Of course, there is no exception in nipple of
automotive hose. Finding method of forging process is metallic stress analysis, and we can predict
this possibility by finite element forging analysis. But there are many manufacturing procedure after
forging, and additional heat treatment or coating can vary metal texture. So, in this research, we
focus on the measuring and analysis of plastic residual stress distribution at overall manufacturing
process. First step, we measured real residual stress at each forging process by X ray diffract meter
from raw material to final product. Second step, we simulated parts-assembly process by nonlinear
finite element analysis. In this step, we can prove how Zn–Ni coating is more contributable to metal
strength than Zn coating. And we can conclude for robust design that manufacturing process
analysis must be observed carefully from raw material to final manufacturing state.
Finite Element Analysis of Adiabatic Shear Band Formation during Orthogonal Metal Cutting
Authors: Rhim Sung Han , Park Hyung Wook , Oh Soo Ik
Published: March 2009

In serrated chips of difficult-to-machining materials such as medium carbon steel and
titanium alloy during metal cutting process at high strain rates, the fine grain structure of the narrow
shear bands which results from thermal softening due to severe deformation have been observed.
However, the theories which have been developed to analyze continuous chip formation and most
FEM analyses based on the conventional models such as Johnson-Cook and Zerilli-Armstrong flow
stress model fail to explain the adiabatic shear band formation and the serrated chip formation. This
paper discusses the characteristic of the new flow stress model in the previous investigation [1,2] and
FEM simulation results to predict the serrated chip formation results are shown.