bluuebunny/crossref_metadata_2025 huggingface dataset:
Microstructure and Mechanical Properties of High Strength Al2O3p/6061Al Composites
Authors: Luan Bai Feng , Wu Gaohui , Liu Qing , Hansen Niels , Lei Ting Quan
Published: March 2009

An experimental study of microstructure and mechanical properties in the Al2O3
particulate reinforced 6061 Aluminum composites has been used to determine the effect of
extrusion and particle volume fraction (20, 26, 30, 40, 50, 60%Vf) in deformed metal matrix
composites. The microstructure of Al2O3 /6061Al composite before and after hot extrusion is
investigated by TEM and SEM. Results show that dislocation and subgrain generated after hot
extrusion as well as the particle distribution of composite become more uniform with extrusion ratio
of 10:1. The ultimate strength, yield strength and elongation of the composite also increase after hot
extrusion. Dispersion strengthening and subgrain boundary strengthening is discussed and also the
effect of precipitate introduced by heat treatment both after casting and after extrusion. The yield
stress (0.2% offset) of the composites has been calculated and predicted using a standard dislocation
hardening model. Whilst the correlation between this and the measured value of yield stress
obtained in previous experimental test is reasonable.
Stress Field of Fiber-Reinforced Composites with Graded Interphase
Authors: Ou Zhi Ying , Lei Dong Xia
Published: March 2009

A simplified approach for calculating the stress field of the fiber-reinforced composites is
developed to improve the work of Theocaris et al. (1985) in this paper. This approach considers that
the main factor affecting the stress field of composites is the existence of interphase between fiber
and matrix, which possesses different Young’s modulus than those of the constituent phase. A
parabolic law is adopted for the variation of Young’s modulus of graded interphase, versus the polar
radius from fiber to matrix, while the Poisson’s ratio of the interphase is assumed as constant. Space
axisymmetric model is applied to the Representative Volume Element (RVE) of the fiber-reinforced
composites to evaluate stress field of the composites. Also, the effective longitudinal modulus of the
fiber-reinforced composite can be obtained.
Microstructure Formation Mechanism of (Al2O3+TiB2+Al3Ti)/Al Composites Fabricated by Reactive Hot Pressing
Authors: Wang Gui Song , Geng Lin
Published: March 2009

The two (Al2O3+TiB2+Al3Ti)/Al composites were fabricated from Al-B2O3-TiO2 and
Al-B-TiO2 raw powders by reactive hot pressing, respectively. The microstructure of in situ two
composites was analyzed by OM, SEM and TEM. The results showed that coarse Al3Ti blocks with
several tens of micrometers size were formed during hot pressing. The equiaxed Al2O3 particulates
and hexagonal TiB2 particulates with finer sizes were formed in the composites simultaneously. The
microstructure formation mechanism of (Al2O3+TiB2+Al3Ti)/Al composites were discussed. The
results showed that Al2O3 reinforcements were formed on the surface of TiO2 or B2O3 powder and
TiB2 particles were formed on B or B2O3 powders. The formation of coarse Al3Ti block is result
from continuous diffusion of Ti in liquid Al during reactive hot pressing. In addition, there are fine
Al3Ti precipitates exist in the composite fabricated from Al-B-TiO2 powders. This contributes to
the improved mechanical properties in terms of yield and ultimate stresses and Young’s modulus of
the composite.
Influence of Fiber Orientation and Volume Fraction on Tensile Strength and Fatigue Life of CARALL Hybrid Composite
Authors: Yoon Han Ki
Published: March 2009

In this paper the tensile and fatigue life tests of carbon fiber-reinforced epoxy prepreg
(CFRP) were conducted in order to investigate the influence of volume ratio and fiber orientation.
CFRP/Al7075 laminate hybrid composite (CARALL) consists of alternating Al7075-T6 sheets and
carbon epoxy prepreg (epoxy 121oC #2560). The fiber orientations of CFRP were applied to the
extent of 0/90° and ±45°. The CFRP layers are 1ply, 3plies and 5plies in case of 0/90°, and 1ply and
2plies in case of ±45° of carbon fiber direction, respectively. The tensile strength decreased with the
volume ratio of CFRP in both the cases of fiber orientation 0/90° and ±45°. The fatigue life is lower
in large volume ratio of CFRP than in small volume ratio in both the cases of fiber orientation 0/90°
and ±45°.
Fabrication and Dynamic Mechanical Properties Offly Ash/Epoxy Composites
Authors: Wu Gaohui , Gu Jian , Zhang Qiang , Zhao Xiao
Published: March 2009

An inexpensive fly ash (FA), which is from a waste production, has been employed to
fabricate fly ash/epoxy composites in our work. Three kinds of fly ash with the most probable
diameters of 74"m, 119"m and 146"m were filled in the modified epoxy resin (EP). The purpose of
this study is to characterize the dynamic mechanical properties of such composites, and the dynamic
mechanical behaviors of the composites are investigated in the temperature range from -40 to 150oC
using a tension-compression mode. The results indicate that the dynamic elastic moduli for the fly
ash/epoxy composites are (1.4~2.0) GPa, and the peak values of loss factor (tanδ) for these
composites can reach (0.79~0.90) in the test specification. In addition, a scanning electron
microscope (SEM) has been used to observe the distribution of fly ash particles in the matrix, as well
as the photographs of fracture surface of composites.
Fatigue Life Estimation of Leakage for Excitation and Internal Pressure in Brazed Joints
Authors: Kim Jung Kyu , Kang Ki Weon , Shim Hee Jin , Shon Bum Seok
Published: March 2009

The study aimed at the fatigue life estimation for leakage of refrigerant used in household
air conditioner. The leakage of brazed joints was affected by the manufacturing faults with flaws
and service condition which is at the internal pressure and at the excitation. Therefore, the four
point bending tests were performed to estimate effects of internal pressure and excitation for the
fatigue life of brazed joints. In addition, to investigate effect of internal pressure and excitation on
the fatigue life, the orthogonal array table in Design of Experiment is adopted.
The Group Velocity Change in the Unidirectional Composite Materials
Authors: Rhee Sang Ho , Lee Jeong Ki , Lee Jung Ju
Published: March 2009

The group velocity of the S0 mode of a Lamb wave under the first cut-off frequency is
measured during the tensile loading for the unidirectional composite materials. The group velocity
of the S0 mode has the characteristic of increasing with the strain. The propagation velocity of a
wave is generally proportional to the square root of the ratio of the modulus to the density. The
elastic modulus is considered as a constant as the stress linearly increases with the strain. The
increase of the group velocity with the strain is caused by a decrease in the density. It is proposed
that the measurement of the group velocity of the S0 mode is useful for making an evaluation of the
tensile strain and of any degradation in the unidirectional composite materials.
Research on Weldability for Dual-Phase Steels Using Servo Gun Spot Welding System
Authors: Zhang Xiao Yun , Zhang Yan Song , Chen Guan Long
Published: March 2009

Dual-phase steel is a mixture of ferrite matrix and martensitic islands distributed at grain
boundaries with the possible addition of bainite. Its formability, capacity to absorb crash energy,
and ability to resist fatigue make it a desirable material for use in the automotive industry to
enhance automobile’s strength and reduce its weight. However, the resistance spot weldability of
dual-phase steel is sometimes limited by a propensity for weld metal failure due to the welding
process. To improve its weldability, a servo gun spot welding system is introduced to control
electrode force during the welding process. The paper take 1.5mm DP600 steels as an example,
experimental data shows that by optimizing electrode force during welding process, the width of
weld lobe can be enlarged from 0.9kA to 2.1kA and the weldability of dual phase steel is improved
greatly.
Improvement of Fatigue Strength of Stainless Steel by Using a Cavitating Jet with an Associated Water Jet in Water
Authors: Soyama Hitoshi , Mikami Mitsuhiro
Published: March 2009

Peening method using cavitation impacts have been developed. In this peening method,
cavitation bubbles were generated by a cavitating jet. In order to increase peening intensity, a low
speed water jet was injected around a cavitating jet, as the water jet swept away residual bubbles,
which weaken the cavitation impact. In the present paper, improvement of fatigue strength of
stainless steel by using a cavitating jet with an associated water jet was investigated compared with
the results of conventional cavitating jet. It was concluded that the cavitating jet with an associated
water jet can peen the stainless steel more effectively compared with the conventional cavitating jet.
Study on High Performance Warm Compacted Fe-2Ni-2Cu-1Mo-1C Powder Metallurgy Materials
Authors: Xiao Zhi Yu , Wang Jun , Luo Shu Hua , Wen Li Pin , Li Yuan Yuan
Published: March 2009

Warm compacting and sintering behaviors of pre-mixed Fe-2Ni-2Cu-1Mo-1C powders
were studied. Results showed that green density increased with compacting temperature and then
fell slightly; the maximum green density was obtained at about 120°C. Green compact density and
spring back effect of the pre-mixed powder increased gradually as the compacting pressure
increased. Sintered density first increased and then fell as the temperatures went up under different
sintering temperatures for 50 minutes, but the trends of sintering dilatation were first reduced and
then increased. Sintered density first reduced and then increased with the prolonged sintering time
at 1300°C, but the trends of dimension change after sintering were the very reverse. Tensile strength,
elongation and hardness of the warm compacted Fe-2Ni-2Cu-1Mo-1C materials generally increased
as sintering temperature and sintering time went up.
Study on the Microstructure and Properties of Prehardened Plastic-Mould SWFT Steel for Big Section
Authors: Luo Yi , Wu Xiao Chun , Wang Hong Bin , Min Yong An
Published: March 2009

In order to develop the prehardened plastic-mould SWFT steel for big section without
quenching and tempering, the influence of carbon on the microstructure and corresponding hardness
of steel under both air and sand cooling were investigated. It was demonstrated that when the
carbon content of steels increased, the stability of overcooling austenite increased and the hardness
difference decreased because of the decrease of bulk ferrite and the increase of bainite. The
microstructure of No.8 steel under both air and sand cooling was mostly bainite and the hardness
difference was less than 3HRC.And the No.8 steel had good machineability by the turning
comparative experiment of No.8 steel and 45# steel. The prehardened plastic mould SWFT steel for
big large section was produced successfully based on the experiment result.
Fractal Features of Surface Morphology of Uneven Eroded Hot-Dip Galvanized Steel
Authors: Han Qing Kai , Li Hui Ru , Wen Bang Chun , Chen Shui Yuan , Liu Chang Sheng
Published: March 2009

The corrosion surface of hot-dip galvanized steel is regarded to be fractal and contains
abundant self-similar information. In most cases, the corrosions of surface are not uniform as
considered. For such an uneven eroded surface, regional fractals are introduced here in order to
improve the analysis accuracy for local corrosions. Basing on the singular value decomposition of
surface image, fractal dimensions of the energy norm along with the energy scale are analyzed.
Combining energy norm of singular values and wavelet transform, the corrosion surfaces are
described in different scales and decomposed levels.
Development of Coating Material by In Situ Reaction Synthesis
Authors: Wang Y.G. , Zhang Di , Chen Ming
Published: March 2009

A type of wear resistance coating material composed by ternary-boride-based (TBB)
cermet coating and steel 65Mn substrate has been developed successfully by in-situ reaction
synthesis. The TBB cermet coating has been formed by the in-situ reactions among the mixed raw
metal powders during the process of casting. Microstructure has been studied using X-Ray Diffraction
(XRD) and scanning electron microscopy (SEM). Results show that the main composition of the
coating is ternary boride base hard phase Mo2FeB2 and ferrous base binder phase α-Fe, both of them
distribute uniformly in the coating. There is element diffusion in the interface of coating and steel
substrate. The bonding at the interface of coating and steel substrate is excellent which has been
confirmed by the three-point bend tests.
Prevention of Stress Corrosion Cracking in Welded Joint of Type 304 Stainless Steel by Laser Peening
Authors: Peng Wei Wei , Ling Xiang
Published: March 2009

In order to prevent stress corrosion cracking (SCC) of austenitic stainless steel weldment,
a novel technique -laser peening- has been introduced which is able to convert surface tensile
stresses in the weldment to surface compressive stresses. In this paper, water-immersed welded
specimens of type 304 stainless steel are peened by Q-switched Nd: glass laser with a wavelength of
1.06μm. A residual compressive layer is produced on the specimen surface by scanning laser pulse
to cover the heat affected zone (HAZ) along the weld line. The residual compressive stress value
based on X-ray measure is significant enough to prevent the initiation of stress corrosion cracking
that is also validated by the finite element analysis. The SCC accelerated tests for comparing the
potential against SCC of the specimens, which are unpeened and peened by laser pulse with
different laser spot coverage, are carried on. The results show that stress corrosion cracks on the
surface of unpeened specimen occur after immersion for 25 hours in boiling 42% MgCl2 solutions
at 143°C. In contrast, the specimen with 45% laser spot coverage cracks after immersion for 300
hours, while, cracks are observed on the surface of laser-peened specimen with 80% laser spot
coverage after 985 hours of testing. The results show that laser peening is an effective technique for
improving the residual stress distribution and the SCC resistance of 304 stainless steel weldment.
Study On the Corrosion Resistance Properties of the Ceramic Coating Obtained Through Microarc Oxidation on the Aluminium Alloy Surface
Authors: Fei Chen , Zhou Hai , Chen Chen , Lu Fan Xiu , Lu Fan Xiu
Published: March 2009

Oxidation ceramic coating was directly synthesized on LY12 aluminium alloy by
micro-arc oxidation (MAO) process in Na2SiO3 electrolyte solution with the
Na2WO4-KOH-Na2EDTA addition. The corrosion resistance of the coating was tested using
CS300P electrochemical corrosion workshop in 3.5% NaCl solution. Using the scanning electron
microscopy (SEM) and X-ray diffraction (XRD), the cross-section microstructure, the surface
morphology and the phase structure of the micro-arc oxidation ceramic coating were analyzed. The
results showed that the corrosion resistance of the micro-arc oxidation ceramic coating in 3.5%
NaCl solution was enhanced remarkably, the corrosion velocity was obviously slowed down. The
thickness of micro-arc oxidation ceramic coating was about 11μm. The final phases in the coating
were found to be α-Al2O3 and γ-Al2O3. The mechanism of the oxidation ceramic coating formation
was investigated too.
Thermal Vibration of Functionally Graded Circular Plates
Authors: Wu Lei , Ma Lian Sheng
Published: March 2009

Based on the nonlinear theory of von Karman plate, axisymmetric nonlinear vibration of a
functionally graded circular plate with clamped boundary condition is investigated under thermal
loading. It is assumed that the mechanical and thermal properties of functionally graded materials
vary continuously through the thickness of the plate and obey a simple power law related to the
volume fraction of the constituents. Motion equations for the problem are derived. Existence of
harmonic vibrations is assumed and then Ritz-Kantorovich method is used to convert the dynamic
Von Karman equations to a set of nonlinear ordinary differential equations. Finally a shooting method
is employed to numerically solve the resulting differential equations. Effects of amplitude A, thermal
load parameter λ and material constant n on the vibration behavior of FGM plate are discussed in
details.
Fatigue Characteristics of Vulcanized Natural Rubber for Automotive Engine Mounting
Authors: Shibata S. , Ochi K. , Aono Y. , Noguchi Hiroshi , Oshima Hideki
Published: March 2009

In order to investigate fatigue characteristics of vulcanized natural rubber (NR), fatigue
tests are carried out under various stress ratios R (R = minimum stress / maximum stress). It was
considered that the fatigue cracks were initiated from flaws in very early stage of total life. The
fatigue damage process was almost the fatigue crack propagation process and it is independent of R.
The crack growth rate was proportional to the crack length to about the first power, when the crack
length was defined as the length of the direction perpendicular to the loading direction. Miner’s rule
was examined to observe the fatigue crack behavior and checked by using two-step loading fatigue
tests experimentally. It seems Miner’s rule has a possibility to predict fatigue lives.
Mechanical Properties of 316L Stainless Steel with Nanostructure Surface Layer Induced by Surface Mechanical Attrition Treatment
Authors: Yang Xiao Hua , Dui Wei Zhen , Liu Gang
Published: March 2009

The mechanical properties of the 316L stainless steel subjected to surface mechanical
attrition treatment (SMAT) have been studied, these properties are hardness, tensile properties and
wear resistance. The research shows that the thickness of the hardened layer increases with the
increasing of the treating time. The refined microstructure in the treated layer led to increasing in
hardness, strength, and wear resistance. It is obvious that the surface layer hardness and bulk yield
strength are increasing when the SMAT time reaches 5 minutes. The increase of surface layer wear
resistance is obvious when the SMAT time is 15 minutes. The SEM observation of the wear scars
shows that the nanocrystalline layer might reduce the effect of adhesive wear of 316L stainless steel.
Therefore, the wear mechanism changes from adhesive abrasion to grinding particle abrasion after
SMAT.
Fracture Mechanics in Design Guidance and Practice
Authors: Sakamoto Haruo
Published: March 2009

This paper describes the state of the art in design codes and guidance using fracture
mechanics. In Germany, a railroad accident occurred in June, 1998, which resulted in about 100
passenger deaths due to a wheel fracture. In September, 1999, a water leak accident due to a crack in
a pipe happened at the Tsuruga nuclear plant in Japan. Such serious accidents are the result of
fracture events. Fracture mechanics is thought to be a tool to avoid such catastrophic fracture
accidents. The state of the art in designing mechanical components or structures applying fracture
mechanics was reviewed. The American Society of Mechanical Engineer, the Japanese Society of
Mechanical Engineers, the Japanese Welding Society, and the Japanese Industrial Standard were
mainly surveyed. This report suggests that a more consideration of fracture mechanics in the design
codes and guidance is needed for avoiding fracture accidents in components or structures.
Improvement of Oxidation Property of SUS304 by Gas Barrier Coating
Authors: Murakami Riichi , Fujikawa Katsuhiro , Yonekura Daisuke
Published: March 2009

Stainless steel is widely used as a corrosion-resistant material. However, stainless steel
corrodes at high temperature (573 K ~) due to the oxidization and grain boundary corrosion. To delay
the oxidation at high temperature, coating of gas barrier film will be useful method. The purpose of
this study is to improve the corrosion-resistant of SUS304 at high temperature by coating transparent
SiOxNy film which has gas barrier properties. In addition, the influence of inlet gas mass flow rate
ratio (N2/Ar+N2) on the oxidation properties at 773 K was examined. The SiOxNy films were
deposited onto polished SUS304 by unbalanced dc magnetron sputtering apparatus. To examine the
oxygen transmission rate (OTR) of SiOxNy films, PET was also used as substrate. The results showed
that good OTR was obtained for N2/Ar+N2 < 0.12 on PET substrate. The similar tendency was
obtained for SUS304 deposited film heated up to 773 K.
Influence of Ion Bombardment Process on Adhesion between CrN Coatings and Aluminum Alloy
Authors: Yonekura Daisuke , Ishikawa Tomoyuki , Murakami Riichi
Published: March 2009

Scratch tests were carried out to examine the influence of gas pressure during ion
bombarding on adhesion between CrN coatings and aluminum alloy using nitrogen and argon gas.
The critical load clearly increased with increasing the nitrogen gas pressure. However, argon gas
pressure hardly affected the critical load. The result of SIMS showed that ion bombardment in
nitrogen gas generated high Cr content layer at the aluminum substrate surface and the Cr content
increased with increasing the pressure. The ion bombardment in argon gas generated low Cr content
surface layer and the pressure hardly affected the critical load. Thus, the high Cr content layer by ion
bombardment in the high nitrogen pressure improved adhesion between CrN coatings and aluminum
alloy
The Research of Integral Cu-W Electric Contact by Friction Welding
Authors: Song Hua , Fu Li Hua , Duan Pei Lin , Sun Zai Bin
Published: March 2009

Electric contact is an important component of high voltage circuit breaker switch lubicle,
isolating switch and ground switch. It is composed of arc-extinction end and conduction end. The
usual material of arc-extinction end is copper-tungsten and the usual material of conduction end is
copper or chrome-copper. Currently, four process for making the integral electric contact such as
common brazing, vacuum brazing, electric-beam welding; liquid-phase sintering is of the best
integral technique capability. This article puts forward a process by friction welding for integral
Cu-W electric contact, and studies about the weldability between copper-tungsten and copper or
chrome-copper, and between copper and chrome-copper. In order to solve the worse weldability
between copper-tungsten and copper or chrome-copper, the design conception of intermediate layer
is tentatively suggested. From experimental results, using the production method of friction welding
is practicable to integral electric contact. It has some advantages, such as high availability of
material, high productivity, high ratio of finish products, and it has no any influence on
environment.
Interfacial Resistance Method for Quality Evaluation of Diffusion Bonded Joints
Authors: Xuan Fu Zhen , Zhang Bo , Tu Shan Tung
Published: March 2009

An interfacial resistance measuring method was proposed to evaluate the quality of
diffusion bonded joints. To study the feasibility of the method, a finite element (FE) model with
periodically distributed interfacial microdefects was presented. The influences of bonded area
fraction, width and length of microdefects on increments of resistance were analyzed by applying the
electromagnetic module in ANSYS software. Results indicated that the evolution of resistance
increment along with the interfacial bonded area fraction could be described by a hyperbolic function.
Based on the FE results, a modified theoretical solution was developed referred to Lodge’s work to
accommodate the size effects of interfacial microdefect and thus could lead to a more precise quality
evaluation for diffusion bonded joints.
Strength Predication for Load-Bearing Lugs of Three-Dimensional Braided Composites
Authors: Zheng Xi Tao , Sun Qin , Guo Ying Nan , Chai Ya Nan
Published: March 2009

Load response and failure modes of three-dimensional (3-d) four-directional braided
composite lugs were studied analytically and experimentally. The objective of the study was to get
information on the stiffness, strength and failure mode of the lug, as well as on the applicability of
the analysis method used to predict lug load response and failure. The test lugs were manufactured
with the RTM (Resin Transfer Molding) technique. The test specimens were loaded parallel to the
lug centerline. Two types of specimens were tested to failure. Three of them were instrumented
with 18 strain gages in each type of lug. There are three basic failure modes in braided composite
joints: net-tension, shear-out, and bearing. Net-tension failure is associated with matrix and fiber
tension failure due to stress concentrations. Shear-out and bearing failures result primarily from the
shear and compression failures of fiber and matrix. The analyses were performed using finite
element method. Shell elements were used. A steel pin was modeled to apply the loading. The
loading was applied with a constant force distribution through the center of the pin. A contact was
defined between the pin and the surrounding lug surface. The measured strains showed fairly good
correlation with the analysis results. The strain response was almost linear. It can be concluded that
with correct material properties the FE approach used in the analyses can provide a reasonable
estimate for the load response and failure of 3-d braided composite lugs
Effects of Chemical Composition and Welding Process on Fracture Resistance of Type 347 Stainless Steel Weld
Authors: Yoon Ji Hyun , Lee Bong Sang , Yoon Eui Pak
Published: March 2009

The present study is a systematic investigation of the effects of microstructural changes,
which have originated from the variations of filler metals and welding processes, on the J-R
properties of simulated welds. Two AISI Type 347 weld metals, with different carbon contents,
deposited by a GTAW process and two AISI Type 347 weld metals, with different carbon contents,
deposited by a SMAW process were used in this study. The J-R tests were conducted at 316oC (600oF).
The welds deposited by the GTAW process showed higher fracture resistances when compared to the
welds deposited by the SMAW process. The J-R fracture resistance of the Type 347-GTAW
processed weld with high carbon content was remarkably low when compared to the weld with low
carbon. The J-R fracture resistances were decreased by coarse Nb(C, N) precipitates in the Type 347
weld deposited by the GTAW process. In the case of the SMAW welds, mainly coarse Ti-rich
particles which had originated from the shielding of the welding rods deteriorated the fracture
resistances.
Isothermal LCF Behaviors of a NiCrAlYSi Coated Columnar-Grained Directionally Solidified Nickel Base Superalloy
Authors: Yu Hui Chen , Zhong Bin , Wu Xue Ren
Published: March 2009

The isothermal low cycle fatigue (LCF) behaviors of a directionally solidified (DS) nickel
base superalloy, coated with a NiCrAlYSi coating were studied. The study concerned NiCrAlYSi
coating formed by an arc-discharged physical vapor deposition (PVD) process for protection against
high-temperature corrosion and oxidation of gas turbine blades. The effect of protective coating on
LCF life of coating/substrate system was investigated at high temperatures and compared with
uncoated alloy. The test results show that coating has no or less effect on LCF life under high strain
range and the LCF life is governed by the fatigue behavior of substrate at different temperatures.
However, when strain range is smaller, crack initiation and propagation are observably affected by
temperature, which leads to a shorter LCF life of coating/substrate system at 500°C and a longer LCF
life at 760°C or 980°C.
A Study on Friction Stir Welding with Heating of Aluminum Alloy
Authors: Suzuki Riichi , Hioki Susumu , Yamamoto Naoki , Kaneko Yuuta , Takahashi Takehiko
Published: March 2009

Conventional Friction Stir Welding (FSW) is that weld materials are joint at room
temperature by stirring softened materials due to frictional heat of rotating tool. Therefore, high
speed and high efficiency would be expected, as pre-heating make weld materials more softened, as
well known that yield point goes lower due to heating. In this study, FSW was done to improve
welding speed on FSW of aluminum alloy (A5052) for high vacuum vessel for processing of
electronics devices. As the result, welding speed was 2.0 times to more than 3.0 at 300 oC
comparing with conventional FSW at room temperature, using improved a milling machine with
heater.
Fatigue Properties of a T Type Welded Joint in a Small-Sized Single Pass Boiler Header
Authors: Yamakawa Hiroshi , Yan Nu , Yonekura Daisuke , Murakami Riichi
Published: March 2009

The design of small-sized single pass boilers is usually based on the construction code for
small-sized boilers, in Japan. Design methods in this construction code and other country codes
have not been clearly defined, although most of small-sized boiler’s headers are constructed from
two concentric circular shells and cover plates. Therefore, Finite Element Analysis (FEA) with a PC
and measurement by strain gauges are mainly used in strength design of these boilers. A T type
welded joint of SS400 was adopted for the header of small-sized single pass boilers was studied.
The stress concentration was evaluated by the FEA, and S-N curves were re-drawn using maximum
elastic stress, Ktσmax.
Molecular Aspect of Osteoporotic Fracture Healing
Authors: Low Adrian K. , Yu Y. , Gifford K.J. , Walsh W.R.
Published: March 2009

Protein expression of growth factors involved in fracture healing and osteoporosis were
investigated in ovariectomised (OVX) rat fracture model using histological and
immunohistochemical analysis. The OVX model was confirmed by a significantly increased body
weight and reduced bone density of the non-fracture hind limbs. The tissue morphology and the
protein expression were assessed on the paraffin sections of the fracture callus at day 7, 14, 28 and
42 after fracture. Histology revealed a significantly higher ratio of fibrous tissue over bone or
cartilage over bone in the fracture callus at day 28 and 42 in the OVX rats than in the normal rats.
Immunohistochemical staining of IGF-I, IGF-IRα, MMP-1, TIMP-1 and 2 showed a different
pattern between the OVX and the control groups. A down-regulation of IGF-I and TIMP-1 and an
up-regulation of MMP-1 were observed in OVX rats, which may account in part for the delayed
healing of the osteoporotic fracture and may affect extracellular matrix composition, an important
determinant of callus strength.
Synthesis of Silicon Carbide Nanowires Doped with Al2O3
Authors: Jintakosol Thanut , Singjai Pisith
Published: March 2009

Synthesis of silicon carbide nanowires (SiC NWs) from an alumina doped silica-graphite
rod is reported. The rod was gradually heated up to a growth temperature by passing current
through it under constant flowing argon at atmospheric pressure. The as-grown layers, deposited on
the rod surface were separated from the inner core and characterized using scanning electron
microscopy, transmission electron microscopy, energy dispersive spectroscopy, selected area
electron diffraction, X-ray diffraction and Raman spectroscopy. A non-uniform layer thickness of
alumina coating on SiC NWs was clearly observed when the doping was increased from 1 to 2 and
3 wt.%.
Preparation of Iron Oxide Nanoparticles by a Pyrosol Technique
Authors: Thongsuwan W. , Suparerk Aukkaravittayapun , Singjai Pisith
Published: March 2009

Iron oxide nanoparticles were prepared from an iron nitrate solution by a pyrosol
technique. The precursor solution was atomized by a mist generator in order to form an aerosol
which was brought into a tube furnace by a controlled flowing air stream. The pyrolysis of the
aerosol was occurred to form the particles inside the furnace at 350 °C. Scanning electron
microscopy images have shown that a mean diameter of the particles is in good agreement with the
third root of the precursor concentration. X-ray diffraction patterns have revealed that the main
peaks from the samples are corresponding to the α-Fe2O3 phase.
Biomechanical Analysis on the Foot under Normal and Abnormal Gait for Orthotics Design
Authors: Lee Jae Ok , Lee Young Shin , Lee Se Hoon , Choi Young Jin , Park Soung Ha
Published: March 2009

The foot plays an important role in supporting the body and keeping body balance. An
abnormal walking habit breaks the balance of the human body as well as the function of the foot.
The foot orthotics which is designed to consider biomechanics effectively distributes the load of the
human body on the sole of the foot. In this paper, gait analysis is performed for subjects wearing the
orthotics. In this study, three male subjects were selected. The experimental apparatus consists of a
plantar pressure analysis system and digital EMG system. The gait characteristics are simulated by
ADAMS/LifeMOD. The COP (Center of Pressure), EMG and ground reaction force were
investigated. As a result of gait analysis, the path of COP was improved and muscle activities were
decreased with orthotics on the abnormal walking subjects.
Studying Effects of Bias Voltage on Properties, Wettability and Platelet Adhered Behavior of DLC Films Prepared By DC-MFCVAD
Authors: Wen Feng , Huang Nan , Leng Yong Xiang , Li Zhi , Cao Yang
Published: March 2009

Diamond-Like carbon (DLC) films were prepared under different bias voltage by direct
current magnetic filter cathode vacuum arc deposition (DC-MFCVAD). Bias voltages changed from
0 to -200 V. The study intends to investigate the effect on the properties of DLC films for
biomedical applications. X-ray photoelectron spectrum (XPS) was used to investigate composition
of the films. Nano-scratch tests were used to characterize effects of bias voltage to adhesion.
Furthermore, the wettability of the DLC films was investigated by contact angle measurements
using four common liquids. Finally, platelet adhesion experiments were done to evaluate the
interaction of blood with DLC films. The results showed that the adhesion, wettability and
hemo-compatibility of DLC films were affected by bias voltage.
Development of Bone-Like Composite Material and its Properties
Authors: Hisamori Noriyuki , Hagihara Yukito
Published: March 2009

Many kinds of materials are currently used as artificial bone substitutes. Hydroxyapatite
(HA), the same as the main inorganic component of bone, is one of commonly used bio-ceramics
and has excellent bioactivity and biocompatibility with hard tissues. However, it has problems as
the bone filler or bone tissue-engineering scaffold due to low fracture toughness and low
degradation rate. Recently, biodegradable materials for bone tissue have been developed to respond
the requirement. Collagen, the same as the main organic component of bone, is biocompatible,
biodegradable and promotes cell adhesion. A composites associated with HA is expected to have
early osteoconduction and bone replacement ability. The present study was to fabricate bone-like
composites consist of HA and collagen. Besides the ossiferous ability of the material in vivo is
evaluated by using rabbits. Bone-like composites were successfully fabricated in this study,
associating the collagen with HA. And the composites presented good osteoconductive and bone
replacement potential.
Evaluations of Elasto-Plastic Properties and Fracture Strength Using Indentation Technique
Authors: Yonezu Akio , Ogawa Takeshi , Takemoto Mikio
Published: March 2009

Evaluations of elasto-plastic properties and fracture strength were studied utilizing
indentation technique. The elasto-plastic properties of nine monolithic metals were estimated using
dual indentation method and compared to the properties under tensile loading test. This method could
predict stress - strain curve and was found to determine ultimate tensile strength. For brittle coating,
fracture strength of diamond -like carbon (DLC) film was estimated by hybrid indentation with
acoustic emission (AE), corrosion potential fluctuation (CPF) and finite element method (FEM). AE
and CPF data provided information on the timing of film cracking and its mechanism. Fracture
strength of the films could be evaluated using Vickers and Rockwell indentation.
Biomechanical Analysis of the Musculoskeletal System of Human Foot by Using Passive Elastic Characteristics of Joint
Authors: Choi Hyeon Ki , Kim Si Yeol , Choi Hyeon Chang
Published: March 2009

In this study we presented kinematic and kinetic data of foot joints by using passive
elastic characteristics of joints during gait. During the calculation process we used approximate
equations and partial plantar pressures. The maximum angular displacements of each
tarsometatarsal joint ranged from 4o to 7o and the maximum moments were from 200N⋅cm to
1500N⋅cm. It was relatively wide distribution. Foot kinematic data calculated from the
approximated equations, which were represented by the correlation between moment and angular
displacement, and the data from motion analysis were very similar. We found that the movements
of foot joints were mainly decided by the passive characteristics of the joints when ground reaction
force acts. The kinematic and kinetic analysis using approximated equations which is presented in
this study can be usefully applied to describing the movements of foot joints during gait.
Influence of Loading Frequency on Fatigue Behavior of High Strength Steel
Authors: Yan Nu , Wang Qing Yuan , Chen Q. , Sun J.J.
Published: March 2009

In order to investigate the influence of loading frequency on the fatigue behaviors of the
high strength steel, ultrasonic fatigue tests were carried out for a high-carbon-chromium steel and
the results were compared with those of fatigue tests using conventional rotary bending fatigue test
machine with a frequency of 52.5Hz. The different of fatigue strength at ultrasonic frequency level
and conventional frequency level is very small and the S-N curve obtained from 20 kHz or 52.5 Hz
shows the step-wise shape. The fatigue crack occurred from inclusions on the subsurface site in the
long life regime and the typical surface fracture occurred in the short life one though the loading
frequency level is different. It is indicated that ultrasonic fatigue method is an effective method to
investigate the fatigue properties in super-long life region.
Influence of Heterogeneity on Direct Tensile Failure Process of Rocks and Associated Fractal Characteristic of AE
Authors: Liang Zheng Zhao , Tang Chun An , Tham Leslie George , Zhang Y.B. , Xu T.
Published: March 2009

The investigation on the behavior of a specimen under uniaxial tension and the process of
microfracture attracts considerable interest with a view to understanding strength characterization of
brittle materials. Little attention has been given to the detailed investigation of influence of
heterogeneity of rock on the progressive failure leading to collapse in uniaxial tension. In this paper, a
numerical code RFPA3D (Realistic Failure Process Analysis), newly developed based on a
three-dimensional model, to simulate the fracture process and associated fractal characteristic of
heterogeneous rock specimen subjected to direct uniaxial tension. Specimens with different
heterogeneity are prepared to study tension failure. In a relatively homogeneous specimen, the
macrocrack nucleates abruptly at a point in the specimen soon after reaching peak stress. In more
heterogeneous specimens, microfractures are found to appear diffusely throughout the specimen, and
the specimens show more ductile failure behavior and a higher residual strength. Development of
fractal theory may provide more realistic representations of rock fracture. The fractal dimension of
distributed AE is computed during the fracture process. For all specimens, the fractal dimension
increases as the loading proceeds, and it reaches the peak value when macrocrack nucleates abruptly.
It is also found that fractures scatter more diffusely in relatively heterogeneous specimens, and the
fractal dimension has a smaller value. The homogenous rock specimens have flat and smooth rupture
faces which are consistent with the fractal results.
Non-Destructive Evaluation of Creep Damage of Ni-Based Superalloy Using A Scanning Blue Laser Microscope
Authors: Akahoshi Kuniaki , Ogawa Kazuhiro , Miura Hideo
Published: March 2009

In order to assure the reliability of advanced gas turbine systems, it is very important to
evaluate the damage of high temperature materials such as Ni-based superalloys under creep and
fatigue conditions quantitatively. The refractive index of the gamma-prime phase is found to be
smaller than that of the gamma phase in the Ni-based superalloy, when the wavelength of an
irradiated laser beam is shorter than 500 nm. Therefore, it is possible to evaluate the creep damage
of this material quantitatively and non-destructively by observing the change of the micro texture in
a grain (rafting) using a scanning laser microscope.
In-Process Damage Monitoring and Stress Analysis of Thermal Spray Coating
Authors: Taniguchi Koichi , Enoki Manabu , Tomita Koichi
Published: March 2009

AE method is a well-known technique for in-situ monitoring of damage behavior by
attached piezoelectric transducer. However, this conventional detection of AE signals has certain
limitations. In recent years, numerous efforts have addressed the substitution of laser-based
techniques for ultrasonic nondestructive evaluation in place of conventional piezoelectric
transducers. Especially, a laser interferometer can be used to measure a displacement or velocity at
materials surface using Doppler-shift. However, there are few reports referring to the detection of AE
signals in the practical materials and testing because of the difficulty of experiments. We developed
the AE measurement system with laser interferometer to apply this technique to microcrack
evaluation and reported the quantitative AE analysis in various materials. This paper demonstrates
AE results from thermal spray coatings at elevated temperature.
An Evaluation on Corrosion Effect of Carbon Steel Using the NDT
Authors: Lee Sang Ll , Lee Jin Kyung , Lee Joon Hyun
Published: March 2009

The nuclear power plant has lots of pipes that the fluid of high temperature and high
pressure flows. Among the pipe materials used at secondary circuit of the power plant the carbon
steels are sensitive to corrosion due to their material properties. In this study, both ultrasonic test and
acoustic emission test were used to study the corrosion effect for the carbon steel pipe
nondestructively. The carbon steel specimens were in the pipe under 473K temperatures and 10MPa
pressure conditions for corrosion processing. According to the degree of corrosion the strength of the
specimen was evaluated, and the thickness of the corrosion specimens was also measured by using the
ultrasonic wave. The experimental results showed that the attenuation factor was also increased as a
depth of corrosion increased. The measured depth of the real corrosion by ultrasonic test shows the
good agreement with that by an optical microscope. In order to understand the corrosion effect for the
failure mechanism of carbon steel, a failure test on the specimen with various corrosion conditions
was performed. An acoustic emission technique was also used to evaluate the degree of damage of
corrosion specimen in real time. Acoustic emission technique is proved a useful method for on-line
monitoring the microscopic failure mechanism and the damage location for the structures.
Quantitative Estimation of the Fastening Condition of a Bolt with Using Piezoceramic (PZT) Sensors
Authors: Wang Gao Ping , Hong Yong , Lee Jae Jung , Hong Dong Pyo , Kim Young Moon , Kim Jae Yeol
Published: March 2009

We present a study on the development of a practical and quantitative technique for the
assessment of the structural health condition with using piezoceramic (PZT) sensors. The electroimpedance-
based technique with the PZT patches is very sensitive for evaluation of the incipient
and small damage in a high frequency range, and however the commonly traditional modal analysis
method is effective only for considerably larger damages in low frequency range. The paper
presents the performance of the performance of the electro-impedance-based technique in detecting
and characterizing real-time damage on the specimen that is an aluminum plate fastened with bolts
and nuts by different torques. By using the special arrangement of the PZT sensors, the required
longitudinal wave is generated through the specimen. A large number of experiments are conducted
and the different conditions of the specimen, i.e. the location of loosening bolts and the loosening
extent of bolts are simulated, respectively. Since fixing and loosening the loosened bolt is controlled
by a torque wrench, we can control exactly the experiment of the different torques. Compared with
the simulated healthy condition, we can find whether or not there is a damage in the specimen with
using an impedance analyzer with the PZT sensors. Several indices are discussed and used for
assessing the different simulated damages. As for the location of bolt loosening, the RMSD is found
to be the most appropriate index for numerical assessment and as well the RMSD shows strongly
linear relationship for assessing the extent of the bolt loosening. The possibility of repeatability of
the pristine condition signatures is also presented and the appropriate frequency range and interval
are uniquely selected through large numbers of experiments. The analytical results strongly show
the sensibility and reliability of the electro-impedance based technique.
ANN-Based Crack Identification in Rotor System with Multi-Crack in Shaft
Authors: Yu Tao , Yang Ying , Han Qing Kai , Yao Hong Liang , Wen Bang Chun
Published: March 2009

Rotating machinery, such as steam turbo, compressor, and aeroengine etc., are widely used
in many industrial fields. Among the important rotor faults, the fatigue crack fault, which can lead to
catastrophic failure and cause injuries and severe damage to machinery if undetected in its early
stages, is most difficult to detect efficiently with traditional methods. In the paper, based on the truth
of the change of the mode shapes of the cracked structure, a new method by combining accurate finite
element model of rotor with multi-crack in shaft and artificial neural network (ANN) is proposed to
identify the location and depth of cracks in rotating machinery. First, based on fracture mechanics and
the energy principle of Paris, the accurate FE model of the rotor system considering several localized
on-edge non-propagating open cracks with different depth, is built to produce the specific mode
shapes. Then a set of different mode shapes of a rotor system with localized cracks in several different
positions and depths, which will be treated as the input of the designed ANN model, can be obtained
by repeating the above step. At last, with several selected crack cases, the errors between the results
obtained by using the trained ANN model and FEM ones are compared and illustrated. Meanwhile,
the influences of crack in the different position on the identification success are analyzed. The method
is validated on the test-rig and proved to have good effectiveness in identification process.
Stability of Two-Span Rotor-Bearing System with Coupling Faults of Crack and Rub-Impact
Authors: Luo Yuegang , Zhang Song He , Liu Xiao Dong , Wen Bang Chun
Published: March 2009

A dynamic model was set up for the two-span rotor–bearing system with coupling faults
of crack and rub-impact. Using the continuation-shooting algorithm for periodic solution of
nonlinear non-autonomous system, the stability of the system periodic motion was studied by the
Floquet theory. The unstable form of the rotor system with coupling faults is Hopf bifurcation when
the depth of crack is smaller. The influence to the response of the system increased along with the
depth of crack, the unstable form of the rotor system with coupling faults is period-doubling
bifurcation. The conclusions provide theoretic basis reference for the failure diagnosis of the rotorbearing
system.