bluuebunny/crossref_metadata_2025 huggingface dataset:
Effects of Distance and Alignment Holes on Fatigue Crack Behaviors of Cast Magnesium Alloys
Authors: Wang Xi Shu , Fan Jing Hong , Wu Bi Sheng , Li Ying
Published: March 2009

To study the fatigue microcrack initiation and propagation behaviors of cast
magnesium alloys, the small fatigue crack propagation tests were carried out using the in-situ
observation with scanning electron microscope (SEM). All initiations and propagations of fatigue
small cracks focused on effects of the interaction of artificial two small holes, which there are the
different distances and alignments of two small holes. The results indicate that the fatigue small
cracks of cast magnesium alloys occurred mainly at the defects or root of notch but the early stage
crack propagations were influenced on the distance and alignment between two small holes. For cast
AM50 and AM60B alloys, the fatigue small cracking prior to occurred at the weak dendrite boundary
and had some concomitances such as the plastic deformation on surface of α-Mg phase. For AZ91
alloy, the fatigue cracking characterization depended mainly on the brittle properties of β-Mg17Al12
phase, which the multi cracks occurred at the boundaries of β-Mg17Al12 phase. The effect of notch on
the fatigue cracking behavior becomes weaker when the radius of notch is over 3-4 times than that of
average α-Mg grain size. The fatigue crack propagation behaviors varied with the different
arrangements of two small holes. The effects of distance and alignment of two small holes on the
fatigue crack propagation behaviors are also obvious.
Experimental Analysis and FEM Calculation of the Thermal Deformation for the Spindle System of Machining Center
Authors: Ahmat Mutellip , Cheng Wei , Zheng Li
Published: March 2009

In this study, the chief heat sources of the spindle system for the TH6350 Machining Center
are analyzed, and an experimental system based on the virtual instruments technology is presented,
thirty-two thermocouple sensors are set at the spindle system of the machining center to measure the
thermal field, and five electric vortex sensors are used to measure the thermal error of the spindle by
five-point method. The FEM modeling of the thermal deformation of the spindle system is built up by
based of I-DEAS, the temperature field and the thermal deformation of it are calculated, and the
calculated values of the model tallies with the experimental values.The researching results provide a
theoretical foundation for the improving design􀋈temperature controlling and the error compensation
to the machining center.
Study on Rules in Material Removal Rate and Surface Quality of Short Electric Arc Machining Process
Authors: Zhou Jian Ping , Liang Chu Hua , Teng Wen Jing , Xu Yan , Zhou Bi Sheng
Published: March 2009

Short electric arc machining (SEAM) is a non-conventional machining process that utilizes
an arc to melt and vaporize workpiece material. A low voltage, high current supply is employed to
produce a continuous arc in either a water-air mixed medium or in air. This paper describes an
investigation into the optimization of the SEAM machining efficiency based on experimental design
which considers both electrical parameters and machine parameters. The work uses the orthogonal
experiment processes to research the influence of the process indicators on machining efficiency.
Fatigue Crack Growth Simulation Using S-Version FEM
Authors: Kikuchi Masanori , Wada Yoshitaka , Takahashi Masafumi , Li Yu Long
Published: March 2009

Fatigue crack growth under mixed mode loading conditions is simulated using S-FEM. By
using S-FEM technique, only local mesh should be re-meshed and it becomes easy to simulate crack
growth. By combining with auto-meshing technique, local mesh is re-meshed automatically, and
curved crack path is modeled easily. Plural fatigue crack problem is solved by this technique. For
two parallel crack problem, criteria of crack coalescence are proposed. By simulating this problem by
S-FEM, it is verified these criteria are conservative ones.
Shape Optimization and Strength Evaluation of Metal Welded Bellows Wave of Mechanical Seal
Authors: Musha Halida , Gheni Mamtimin , Buhalqam
Published: March 2009

In this paper, the iBone (Imitation Bone) model which is coupled with Turing
reaction-diffusion system and FEM, is used. The numerical simulation of bone forming process by
considering the osteoclasts and osteoblasts process are conducted. The bone mass is increased with
increase of the initial load value, then fibula and femur bones are obtained respectively by keeping the
required bone forming value. The new S shape wave of metal welded bellow of mechanical seal are
designed based on the the optimization results through this method. The S shape and V shape both
were analyzed with FEM method. The same boundary conditions were given for two types of wave.
The results are shown that the stresses mainly concentrated on the welded area. It is interesting that
the value of the stresses of the two types of wave basically same. However, compressibility of the two
types of wave is very different at the same computation stage. The compressibility of S shape wave
was higher than V shape.
Optimal Control of Sandwich Panels with Pyramidal Truss Cores Based on Energy Criterion
Authors: Liu Hua Rui , Yang J.L.
Published: March 2009

This paper is addressed to the optimal control of the simply supported sandwich panel
with pyramidal truss cores. Firstly, according to the sandwich theory proposed by Sorokin and
Ershova, the eigenfrequencies of the sandwich panel are studied. Then based on the energy
criterion, the weight coefficient matrix Q and R for the linear quadratic regulator method are
obtained. By solving the Riccati equation, the displacement and control force are given. The curves
for the displacement response at the center of the plate are shown. From the numerical results, it is
found that this method is effective in suppressing the vibration of the sandwich panel with
pyramidal truss cores.
Task Scheduling in Multi-Process with Resource Constraints under MG Workflow
Authors: Xiong Feng , Yuan Yi Ping , Wang Yu Ying , Wang Guang Wen
Published: March 2009

In manufacturing Grid workflow, multiple tasks share a common and limited resource pool.
In order to solve task scheduling in multi-process with resource constraints under MG workflow, the
Task-Resource Constrained model is set up to descript the assignment relation between task and
resource. The framework of the task scheduling and the scheduling policies are also presented that
can readjust the tasks according to the priority rules and the time parameters in the process. Then we
present a heuristic scheduling algorithm that includes multiple policies. The heuristic scheduling
algorithm will update the critical path of DAG (Direct Acyclic Graph) and the beginning time of
post-tasks. MG Workflow engine can dynamically schedule the resources according the task
requirement. An example is given to illustrate the method at last.
The Research of Execute Process and Service Selecting under Manufacturing Grid Workflow
Authors: Zhu Ying , Huang Hai Feng , Yuan Yi Ping
Published: March 2009

MG workflow can be defined as the composition of manufacturing activities which
execute on heterogeneous and distributed manufacturing resources in a well-defined order to
accomplish a specific goal. The execute process of MG workflow includes model building, service
finding, service selecting, service binding and service invocation. Service selecting is one of the most
critical components in MG workflow. So, this research brings forth AHP-based grid nodes choosing
method, which takes time, quality, cost, service, fidelity, reliability, policy (TQCSFRP) as rules, and
chooses best resource node as target. The dynamic service binding and invocation between an activity
request and an optimal service provider is realized when a workflow is in execution. Higher flexibility
and self-adaptability of workflow management are achieved. Furthermore, the application
architecture is depicted at the end of the paper to illustrate the utilization of MG workflow.
Simulation of Data Management in Group Purchasing System
Authors: Zou Zong Feng , Yu Tao
Published: March 2009

By Data Grid to handle data sharing problems of distributed position in Group Purchasing.
And so, evaluating and mining massive amounts of data is without fail required replication is
important techniques to provide fast data access. Several replication modeling algorithms are studied
in the paper. OptorSim provides a modular framework under different Grid environment. OptorSim
is used to achieve the Grid simulator to research the stability and transient action. Modern
group-companies are often made of many subsidiary companies. Stocking centralization can
economize much fund for its large-scale purchasing action. Subordinate companies hope to choose
the best provider according to reliable data in most possible area. Advanced data in variety units is
massive amounts of data that must be post-processed and organized to support provider evaluation
actions. Increasing data volumes from all of the companies challenge to state-of-the-art database
system and data-loading techniques. Grid concept is adopted to solve the problem in the project
which is named Price Comparison System (PCS). One of the key technologies in the system is to
improve the data access.
Fatigue Life of Multi-Lap Welding of Automotives Steel Sheet by QSTS
Authors: Shin Seung Chul , Yang Sung Mo , Yu Hyo Sun , Kang Hee Yong , Kim Chae Won
Published: March 2009

This paper shows how the number of lap of spot welded joints in automotive steel sheets
changes the life -cycle transform of itself. There has been significant developments in the life
extension of automotive steel sheets, as well as in passenger safety. We verified the validity of the
S-N curve of materials by QSTS test. Moreover, we used EZNCEN and HS40R, which are commonly
used as automotive steel sheets because of their excellence in increasing fuel efficiency. The purpose
of research was to compare the fatigue life of multi - lap of spot welded joints to there. In addition s,
we used the two different kinds of sheets together in the same welding under the same condition.
Through this whole process, the hypothesis on the life cycle of lethargy coefficients was found to be in
good agreement with the result of the experiment. That is, when using sheets of the same materials in
one welding, the fatigue life of two laps of a spot welded joint was found to be much superior by
EZNCEN 5~14%, HS40R 17~30%,and when using each sheet of different materials, we found the
decrease in fatigue life by 6~16%. Finally, the best value from the data was chosen based on the
experiment for the analysis of the fatigue life of each layer.
Experimental Study on Fatigue Life of Steel Beams Strengthened with a CFRP Plate
Authors: Deng Jun , Lee Marcus M.K. , Huang Pei Yan
Published: March 2009

The adhesive bonding between the steel beam and carbon fibre reinforced polymer (CFRP)
plate is the weakest link and fatigue performance is a major consideration. This paper gives details of
a fatigue test programme of a series of small-scale steel beams bonded with a CFRP plate. Two
phases of the fatigue life, including crack initiation life and crack propagation life, are considered.
Backface-strain technique was applied to monitor crack initiation. An S-N curve was developed from
the test results. The curve correlates the maximum principal interfacial stress at the plate end to the
crack initiation life. The fatigue limit of the S-N curve was found to be about 30% of the ultimate
static failure stress. In accordance with Paris Law, moreover, an equation was developed to predict the
number of cycles during the crack propagation. The empirical coefficients of the equation were
obtained from the fatigue test results. This equation can correctly predict the crack propagation life.
The fatigue load range affects the fatigue life, but its significance is much less than the magnitude of
the maximum load in the load range.
Evaluation of Fatigue Crack Growth of Interacting Surface Cracks
Authors: Kamaya Masayuki
Published: March 2009

Since mechanical interaction between multiple cracks affects the rate of crack growth due
to fatigue and stress corrosion cracking, it is important to consider its influence when predicting
growth. In this study, a procedure predicting the growth of interacting surface cracks was developed.
First, using the results of fatigue crack growth tests performed in a previous study, the transient
growth behavior during coalescence and growth under interaction was evaluated based on area of
crack face. It was shown that the area is a representative parameter of the growth of interacting surface
cracks as well as independent cracks. The growth in area showed good correlation with the crack
driving force defined using size of area. Then, in order to investigate the relationship between growth
of interacting cracks and their relative spacing, crack growth simulations were carried out. The body
force method was used to evaluate the change in stress intensity factors (SIF) during crack growth
under interaction, and the simulation could reproduce the crack configurations obtained in the fatigue
crack growth test. SIF of an interacting crack tip converges to that of a coalesced crack as the distance
between cracks decreases. It was concluded that when the distance between cracks is small enough,
the cracks can be replaced with a semi-elliptical crack of the same area of crack face for a growth
evaluation. The threshold offset distance for the replacement was suggested to be less than 0.1Rx,
where Rx is the span length of two cracks on the surface.
Fatigue Behaviors of a NiCrAlYSi Coated Directionally Solidified Nickel Base Superalloy
Authors: Yu Hui Chen , Zhong Bin , Wu Xue Ren , Shi Hui Ji
Published: March 2009

The fatigue behaviors of a directionally solidified (DS) nickel base superalloy, coated with
a MCrAlY coating (NiCrAlYSi) were studied. Two kinds of tests were performed. One kind of tests
are low cycle fatigue (LCF) test under strain control at different temperatures, another kind of tests
are stress controlled LCF test with SEM-servo hydraulic testing machine for in situ cracking
observation. The results show that the effect of coating on LCF life of coating/substrate system was
rather different according to different strain levels and temperatures. The coating has no or less effect
on LCF life under high strain range and the LCF life is governed by fatigue behavior of substrate in
spite of the difference of temperature. 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. This means the failure of
coating/substrate system is dominated by the cracking of surface coating under low strain range. The
brittleness at 500°C lower than DBTT results in rapid stage II crack propagation. The crack initiation
from coating surface was in situ observed at room temperature and 700 °C and it was found that
cracks usually initiated from the surface roughness of coating and then propagate to failure. The
brittleness and surface roughness are the basic acceptable causes leading to the early damage of a
coating/substrate system.
Study on Ductile Fracture Including Shear-Lip Fracture under Mixed Mode Loading Condition
Authors: Kikuchi Masanori , Sannoumaru Shougo
Published: March 2009

Dimple fracture tests are conducted under mode I and mixed mode lading conditions.
Dimple fracture zone and shear-lip fracture zone are observed by scanning electron microscope
precisely. It is found that crack growth direction is affected largely by the change of loading
condition. It is also found that the differences of fracture pattern between mid-plane and at free
surface are very large. Void diameter and crack growth direction are measured. Numerical
simulation is conducted to simulate fracture tests in three-dimensional field. Gurson’s constitutive
equation is used and large deformation analyses are conducted. It is assumed that void nucleation is
controlled by both plastic strain and stress. Numerical results are compared with those of
experiments. It is found that results of numerical simulation agree well with those of experiment
qualitatively.
Strain and Martensitic Phase Distributions around Fatigue Cracks in SUS304 Stainless Steel
Authors: Nakasone Yuji , Iwasaki Yoshifumi
Published: March 2009

The present study investigates the relations between distributions of strain with those of
martensitic volume fraction around fatigue cracks in SUS304 stainless steel. Specimens having
random pattern created by spraying on their surfaces were fatigued at room temperature (297K) in air.
The pictures around fatigue crack were taken during fatigue crack propagation experiments.
Distributions of strain were calculated by the digital image correlation (DIC) method with these
pictures. Distributions of martensitic volume fraction Vα’ were measured around fatigue cracks with
ferrite scope. The distributions of strain resembled those of Vα’. The higher the strain becomes, the
more the α’ martensitic phase was induced by the plasticity-induced transformation around fatigue
cracks. It was revealed that the same value of Vα’max is induced by strain regardless of static or fatigue.
Fatigue of Metal Free Reed due to Self-Excited Oscillation
Authors: Shimamura Yoshinobu , Tohgo Keiichiro , Araki Hiroyasu , Mizuno Yosuke , Kawaguchi Shoji , Hashimto Masaru , Inoue Tokuichi
Published: March 2009

Metal free reeds are used for musical instruments like harmonica. Free reeds are small, thin
cantilevers, and oscillate by blowing air. It is reported that free reeds break due to fatigue during play.
In order to elongate the life of free reeds, the fatigue properties should be investigated and a motion
analysis method should be developed. The experimental and analytical research on metal free reed,
however, has been rarely reported. In this study, two types of fatigue testing machines were
developed to obtain basic fatigue characteristics. The fatigue testing machines are designed for
bending fatigue of actual free reeds whose thickness is less than 400 μm. An S-N diagram is
successfully obtained up to 107 cycles by using the developed fatigue testing machines. The fracture
surfaces of fatigued specimens are in good agreement with those of free reeds failed in use. Then, an
analytical method for the self-excited oscillation of free reeds was developed based on a
mass-damper-spring model. The proposed method can take account for the shape of free reed. The
self-excited oscillation of free reeds with different shape are analyzed and in good agreement with
experimental results.
Characterizing Fatigue Crack Closure by Numerical Analysis
Authors: Li Ya Zhi , He Jing , Zhang Zi Peng , Wang Liang
Published: March 2009

The crack closure phenomenon has attracted great attention in the prediction of
fatigue crack growth. The finite element analysis of fatigue crack growth has been conducted
by many researchers mainly emphasized on the technique implementation of the simulation. In
this paper the behavior of plasticity induced fatigue crack closure was analyzed by the
elastic-plastic finite element method for middle crack tension (MT) specimen. The material was
assumed as linear-kinematic hardening. The crack growth was simulated by releasing the
“bonded” node pairs ahead of crack tip in stepwise. The calculations focused on the effects of
load cases and crack length on crack opening/closure levels. For constant amplitude cyclic
loadings with different load ratios, the crack opening/closure levels increases for a while and
then decreases continuously, with the increase of crack length. For the loadings with invariable
maximum stress intensity factors (briefly the constant-K loading), however, the crack tip plastic
zone sizes at different crack lengths remain unchanged and the crack opening and closing load
levels normalized by the maximum load levels keep constants as well. The results indicate that
the crack length does not affect the relative opening and closure levels and numerical analysis
for the constant-K loading case should play a key role in characterizing the fatigue crack growth
behavior.
Location of Initial Debonding and Stress Singularity at Interface End
Authors: Dai Ying , Zhou Li Lang , Fu Li Juan , Ji Xing
Published: March 2009

Interfacial stress distribution of bonded quarter-planes subjected to a concentrated force
was re-investigated based on Bogy’s solution[1]. The characteristic length of the singular interface end,
δ, was defined, and found varying in a very large size scale with the index of stress singularity from
millimeter to nanometer or even smaller scale. The influences the characteristic length scale on the
initial debonding of the interface end is a new question worth to pay attention. Photoelasticity
experiment was employed to verify whether the initial debonding is always located at interface end
with stress singularity. The test results show that the initial debonding does not start from singular
interface end if the index of stress singularity is small enough.
Analysis of the Load-Carrying Capability of the Casing Plug Joint of Steel Tube Structures Considering the Contact Effect
Authors: Jiang Xiu Gen , Yang Yang , Zhang Feng Jie , Ju Jin San , You Xiao Chuan
Published: March 2009

Nonlinear finite element model analysis of the casing plug joints of steel tubular has been
realized by ANSYS software. The law of load-carrying capability and stiffness of joint are separately
gained by changing the ratio of length and diameter (R/L) and the ratio of the casing length and the
main tube length (l/L). The influence of the casing thickness on the load-carrying capability and
stiffness are also discussed. The results indicated that the load-carrying capability and stiffness of the
joints both increase with the ratio(R/L) increment and the ratio of the casing length and main tube
length (l/L). When the main tube thickness is equal to casing thickness, the load-carrying capacity of
joints achieves the most.
Analysis of the Anti-Bird Impact Performance of Typical Beam-Edge Structure Based on ANSYS/LS-DYNA
Authors: Zhang Yong Kang , Li Yu Long
Published: March 2009

The 3-D finite element analysis model of beam-edge structure with spaced multiple layers
under bird impact is established. Numerical simulations are implemented by using the non-linear
contact-impact code ANSYS/LS-DYNA when the birds collide at three locations of the structure
respectively. The failure process of the structure and the equivalent plastic strain at supports are
obtained. The residual strength of the structure after impact is predicted. The results show that the
front spars are penetrated or cracked after the leading edge is perforated. The equivalent plastic strain
at the support is much higher when the bird impacts the structure at the central location. Both the
structure deformation and failure mode from the simulation are consistent with the results of full scale
test, which proves the validity of the method proposed in this paper.
Numerical Back Inversion Method of Compressive Creep Parameters of Rock Masses under Rigid Bearing Plate and its Application
Authors: Yang Wen Dong , Zhang Qiang Yong , Zhang Jian Guo
Published: March 2009

Due to lots of hypothesis, the theoretical analytical solution of the creep parameters
inversion can not reflect the in-situ conditions actually. In order to simulate the process of the
compressive creep tests of the in-situ bearing plate, the affection of the stratum distribution and the
influence of the geological status in site actually, FLAC3D is used and numerical back analysis
method of the creep parameters at dam site is set up. Based on the in-situ compressive creep tests’
data of the diabase rock masses at Dagangshan dam site, creep parameters are got with this method.
Results indicate that the numerical calculated displacements of the compressive creep are similar to
the in-situ monitoring displacements. It reveals that with this numerical method creep parameters
can be backing analyzed logically. This supplies technical assurances to stability estimate and
analysis of rock masses in slope projects.
Numerical Simulation of Void Growth Induced Creep Rupture in HAZ at Elevated Temperature
Authors: Yu Tao , Yatomi Masataka , Shi Hui Ji
Published: March 2009

In structural welded joints after long-term service under elevated temperature, fracture
occurred mainly in the heat affected zone (HAZ). Recently, the nucleation and growth of creep voids
in the fine-grained HAZ of weldments, recognized as Type IV fracture, has become an important
problem for ferritic heat resisting steel. In this paper, a new computational model was presented to
analyse the void growth induced creep damage development in HAZ. The new constitutive model
based on continuum damage mechanics (CDM) equations is combined with a
micromechanism-based model in order to account for the void growth process, which is different
from the previous studies of creep damage. Material properties used for the creep damage
computations are fitted from actual creep test data. Basic benchmark tests were performed to verify
the new computational model. Then the model was used to study the creep damage development in
the welded joints where four different material properties, base material, coarse-grained HAZ,
fine-grained HAZ, and weld material, are taken into account. The numerical simulation results for
creep lifetimes agreed well with the experimental results.
Dynamic Behavior of Tungsten Alloys
Authors: Song Wei Dong , Liu Hai Yan , Ren Hui Lan
Published: March 2009

The plate impact experiments have been conducted to investigate the dynamic behavior of
91W-6.3Ni-2.7Fe. Lagrangian analysis technique was introduced to discuss the mechanical properties
of the tungsten alloys under high strain rate and the stress-strain curves of the tungsten alloys were
given. Based on the experimental observations, the three-dimensional finite element models of
projectile and tungsten alloy target are established by adopting ANSYS/LS-DYNA, Dozens of cases
were performed to investigate the dynamic mechanical behavior of tungsten alloy target under impact
loading. A good agreement between numerical predictions and experimental results was obtained,
which suggests that the finite element model is efficient and credible to simulate the mechanical
properties of tungsten alloys.
Influence of Heat Treatment on Structures and Mechanical Properties of Cast Fe-B-C Alloy
Authors: Jiang Zhi Qiang , Feng Xi Lan , Shi Jin Fa
Published: March 2009

Influence of quenching temperature and cooling speed on the structures and properties of
cast Fe-B-C alloy containing more than 1.0%B and lower than 0.2%C was researched. The results
showed that the structures of Fe-B-C cast alloy changed from a great of pearlite + a small of
martensite 􀄗 a great of martensite + a small of pearlite 􀄗 martensite and the hardness increased with
the increase of quenching cooling speed. In the condition of water cooling, higher or lower quenching
temperatures were not advantageous to obtaining single martensite. Quenching at 950~1000oC, cast
Fe-B-C alloy could obtain the compound structures of fine lath martensite. The hardness and impact
toughness of cast Fe-B-C alloy excelled 55HRC and 15J/cm2 respectively.
Phase Field Simulation of Rafting Behavior of γ`Phase in Nickel Base Superalloy
Authors: Takahashi Akiyuki , Kobayashi Yutaka , Kikuchi Masanori
Published: March 2009

This paper describes phase field simulations of the rafting behavior of γ’ phase with a
simple interfacial dislocation network model. The interfacial dislocation network model accounts for
the effect of the network on the lattice misfit between γ and γ’ phases and the subsequent rafting
behavior. The model is implemented into the phase field simulation to see the dependence of the
rafting behavior of γ’ phases on the interfacial dislocation network. Without the dislocation network
model, the amount of the rafting was negligibly small. On the other hand, with the dislocation
network model, the γ’ phases shows a large amount of rafting, which is in good agreement with the
results of the experimental observations. Therefore, the combination of the phase field method and
the simple interfacial dislocation network model developed in this work is appropriate for the
simulation of the rafting of γ’ phases.
Study on Softening Property of 30Cr1Mo1V Steel
Authors: Mao Xue Ping , Xu Hong , Wang Gang , Ma Zhi Yong
Published: March 2009

Softening, namely degradation, is an important characteristic for the components
long-termly operating in high temperature environment. In this article, hardness is adopted to indicate
this effect. In order to study the independent effect of high temperature and stress on the material
properties, the zero-stress ageing experiments at 540 oC, 565 oC, 660 oC and the stress-accelerating
softening experiments (i.e. creep experiment) at 540 oC, 565 oC with interruption were carried out in
steel 30Cr1Mo1V, respectively. The stress range tested was from 240MPa to 320MPa. The Vicker’s
hardness was measured. The relationship between Larson-Miller parameter and the Vicker’s hardness
under zero-stress softening condition and under stress-accelerating softening condition is obtained.
Based on the extraction of the effects of temperature and time, the stress softening effect formulae are
established.
Microstructures and Mechanical Properties of Natural Fibers
Authors: Li Yan , Hu Yan Ping , Hu Chun Jing , Yu Ye Hong
Published: March 2009

Natural fibers are excellent substitute materials for man made fibers in making fiber
reinforced composites due to their high specific strength and modulus, low density, low price, easy
availability in some countries, recyclable and degradable properties. They have raised great attentions
among material scientists and engineers in the past decade. Many researches have been conducted to
study the mechanical properties, especially interfacial properties of natural fiber reinforced
composites. However, the properties, such as mechanical performances, moisture absorption
behaviors, et. al of natural fibers themselves have been seldom investigated. Knowing the relationship
between microstructures and properties of natural fibers are important for understanding the bulk
properties of natural fiber composites and also good instructions for designing bio-mimic materials.
In this study, four kinds of natural fibers which were extracted from different plant sources were
investigated. The microstructures of these natural fibers were revealed with the aid of optical
microscopy. Microstructure models were thereof set up and mechanical properties for the
representative volume element were assumed. Fiber bundle fracture models together with probability
statistics analysis were employed to calculate the mechanical properties of natural fibers. The results
were compared with the experimental measurements. Different mechanical behaviors of natural
fibers which were functioned differently in the nature were clearly explained by the above studies
Mechanical Properties of 2-D Lattice Materials
Authors: Zhang Yi Hui , Qiu Xin Ming , Fang Dai Ning
Published: March 2009

Lattice structures have ranges of thermo-mechanical properties that suggest their
implementation in ultralight structures, as well as for impact/blast amelioration systems and heat
dissipation media. Considering that proper anisotropy of structure could increase load efficiency, two
kinds of 2-D lattice materials designable in specific stiffness and strength of arbitrary direction have
been brought forward: variational thickness cell and variational direction cell. The mechanical
properties of variational thickness Kagome cell have been analyzed, including effective elastic
modulus, yield strength and elastic buckling strength in arbitrary directions. Since the shear buckling
of 2-D lattice materials is an important collapse mode especially when relative densities are low, shear
buckling strength of various 2-D lattice materials have also been calculated. It is found that compared
with the diamond cell, the variational thickness Kagome cell of thickness ratio, m=0.5, possesses the
same elastic modulus and yield surface, and higher buckling strength.
Experimental and Numerical Simulation of the Mechanical Behavior of Stratospheric Balloons Materials
Authors: Vialettes Pierre , Zhou Lina , Pan Bing , Zhuang Zhuo
Published: March 2009

The school of aerospace of Tsinghua University has started a project to develop new kind
of stratospheric balloons for earth observation. These balloons will be designed to stand in the same
position during a few days at 20 kilometers of altitude. To reach this goal, the first step is to select
adapted materials for the balloon envelope. The materials for stratospheric balloons application
should have specific properties adapted to the environment such as mechanical, thermo-optical, and
permeability properties. Thus, we have asked a material manufacture company to develop and
manufacture a material adapted to our application. In this paper, we will present the first results
concerning the mechanical properties of the material. Experimental facilities have been developed to
test the mechanical behavior of the materials at room and low temperature. The future development of
the project will be to identify behavior law adapted to our material that fits with the experimental
results.
The Moving Crack Problem of Orthotropic Functionally Graded Materials under Antiplane Loading
Authors: Li Jun Lin , Sui Zhong He , Yang Wei Yang
Published: March 2009

Dynamic problems of Yoffe mode crack are studied under antiplane shear impact in
infinite orthotropic functionally graded materials. The shear modules in two directions are assumed to
vary in terms with power function form of dual parameters of arbitrary time power. By using integral
transform-dual integral equations method, the stress field and dynamic stress intensity factor near
crack tip are obtained. And the influences of material in homogenous coefficient and graded
parameters and crack moving speed to dynamic stress intensity factor are analyzed in virtue of Matlab
software. Results show that the dimensionless dynamic stress intensity factor will decrease with the
increase of moving speed of crack, which is opposite to the result of the dynamic problem of infinite
strip in FGM. And the dimensionless dynamic stress intensity factor will decrease with the increase of
graded parameters and rise with the increase of material in homogenous coefficient.
Study on the Gear Modeling in SPH Analysis
Authors: Yao Zhi Gang , Imin Rahmatjan , Gheni Mamtimin
Published: March 2009

This article presents the gear modeling method in dynamic mechanical analysis using
SPH (Smoothed Particle Hydrodynamics) analysis method. The parameter equations of the
transition curve of gear root and the other parts of gear are decided. The 3D discrete particles model
is established based on the parameter equations. The SPH pre-process program of global and local
dividing is developed. The error between the divided discrete particles and theoretical profiles of
the gear has been analyzed. The analysis results show that this modeling method is a relatively
better method and the correct SPH discrete particles can be divided by this method.
Computer Modelling For 4-Stroke Direct Injection Diesel Engine
Authors: Ismail Abdul Rahim , Bakar Rosli Abu , Ali Semin , Ali Ismail
Published: March 2009

Study on computational modeling of 4-stroke single cylinder direct injection diesel
engine is presented. The engine with known specification is being modeled using one dimension
CFD GT-Power software. The operational parameters of the engine such as power, torque, specific
fuel consumption and mean effective pressure which are dependent to engine speed are being
discussed. The results from the simulation study are compared with the theoretical results to get the
true trend of the results.
Study on the Stress Intensity Factor for Mixed Mode Surface Crack under Three Point Bending
Authors: Xie Wei , Huang Qi Qing , Kikuchi Masanori
Published: March 2009

In the virtual crack closure method (VCCM), the energy release rate is computed based on
the results of finite element calculation, and the stress intensity factor (SIF) is computed from the
energy release rate. In this paper, the stress intensity factor of mixed-mode surface cracks under three
point bending is studied by using the three dimensional modified virtual crack closure method
(MVCCM). The modified virtual crack closure method is required to open one element face area
whose shape is arbitrary and finite element widths are unequal across the crack front. The effect of the
distance between the location of load and crack face, crack shape and crack depth to the stress
intensity factor is also discussed, along with practical results and conclusions.
Molecular Dynamics Simulation of Interaction between Screw Dislocation and Copper Precipitate in Iron
Authors: Takahashi Akiyuki , Aoki Yuji , Kikuchi Masanori
Published: March 2009

This paper provides the results of the MD simulations of the interaction between a screw
dislocation and a copper precipitate in iron. From the results, the screw dislocation has an attractive
interaction with the copper precipitate. Also, the dependence of the Critical Resolved Shear Stress
(CRSS) for the screw dislocation to break away from the copper precipitate on the size of the
precipitate and temperature is studied. Finally, the CRSS obtained by the MD simulations is
modeled statistically using a Russel-Brown model. Then we found that an addition of the Peierls
stress, which is calculated by the MD simulations, to the Russel-Brown model gives a good
prediction of the CRSS.
Three-Dimensional Crack Propagation Analysis Based on VCCM (Virtual Crack Closure-Integral Method) for Tetrahedral Finite Element
Authors: Okada Hiroshi , Kawai Hiroshi , Araki Kousuke , Miyazaki Tsubasa
Published: March 2009

This paper describes the development of a software to perform three-dimensional crack
propagation analyses. The software is based on the conventional finite element method with second
order tetrahedral element and an automatic mesh generation software. Hexahedral finite elements
have historically been used in fracture analyses and methodologies to compute the crack parameters
have been developed for the hexahedral elements. In present research, the authors have developed a
VCCM (virtual crack closure-integral method) for the second order tetrahedral finite element. Use of
the tetrahedral element allows us to utilize an automatic mesh generation software. The direction and
rate of crack propagation are predicted based on the stress intensity factors and the shape of crack is
updated. Hence, a software package containing the modules for mesh generation, for finite element
analysis, for stress intensity factor evaluation, for predicting the rate and the direction of crack
propagation and for updating crack configuration, can be developed.
Study on the Size Effect of the BaTiO3 Nanowires by LGD Theory
Authors: Hong Jia Wang , Fang Dai Ning
Published: March 2009

As the size of ferroelectric nanostructures decreases, the fundamental questions of the size
dependence of the ferroelectric properties, and of their possible disappearance at a finite critical size,
become crucial. In this paper, Landau-Ginzburg-Devonshire(LGD) theory is introduced to study the
size-dependent ferroelectric properties of BaTiO3 nanowires. Our results demonstrate that the Curie
temperature and mean polarization decrease with the reducing of nanowire diameters. We further
show that these size effects are significant only when the nanowire diameters are less than 20nm,
Above this, the ferroelectric behaviors of nanowires are almost the same as those of bulk materials
and size effect can be neglected.
Study on Fatigue Crack Nucleation of Electrodeposited Nanocrystalline Nickel
Authors: Xie Ji Jia , Wu Xiao Lei , Hong You Shi
Published: March 2009

The mechanism of fatigue crack nucleation for nanocrystalline (nc) nickel was
experimentally investigated in this paper. The samples of electrodeposited nc nickel were loaded
cyclically by using a three point bending instrument at first. Then, atomic force microscopy (AFM)
was used to scanning the sample surface after fatigue testing. The results indicated that, after fatigue
testing, there are vortex-like cells with an average size of 108nm appeared along the crack on nc
nickel sample. And, the roughness of sample surface increased with the maximum stress at the
surface
Micro Capacitive Tactile Sensor for Contact Loads
Authors: Chuang Chieh Tang , Chen Rong Shun
Published: March 2009

This paper presents a high sensitivity micro capacitive tactile sensor that can detect normal
forces which is fabricated using deep reactive ion etching (DRIE) bulk silicon micromachining. The
tactile sensor consists of a force transmission plate, a symmetric suspension system, and comb
electrodes. The sensing character is based on the changes of capacitance between coplanar sense
electrodes and it can reach the aim of large sensing range. High sensitivity is achieved by using the
high aspect ratio comb electrodes with narrow comb gaps and large overlap areas. In this paper, the
sensor structure is designed, the capacitance variation of the proposed device is analyzed, and the
finite element analysis of mechanical behavior of the structures is performed.
Effect of Box Microspring Size on Spring Constant
Authors: Wu Cho Chun , Chen Rong Shun , Lin Meng Ju
Published: March 2009

There are two kinds of microsprings often used: box microsprings and zig-zag (serpentine)
microsprings. Box microsprings are considered with larger spring constant k and more symmetric
structure keeping balance than zig-zag microspring. Density of spring number, N, is defined as the
numbers of turns within a constant total spring length to investigate performance of box microspring.
With applying the same force, the relation between spring constants and microspring sizes are
discussed. Under different size parameters of box microsprings: B, W, T, and L, the spring constants
decrease like exponential decay and approach a limit value as density of spring number increasing.
The results show density of spring number has significant effect on spring constant. Rate of change on
spring constant, Kt, is defined as the ratio of spring constant between N=1 and N=10. It means
normalization of spring constant that increase density of spring number from minimum to maximum.
The results show Kt decreases when B and W increase and increase as T and L increasing. Therefore,
the spring constant is coupled affected by different size parameters due to different tendency as results
shown. Such that the results can apply in microspring design by adjusting these size parameters to
obtain the spring constant.
Contact and Friction at Nanoscale
Authors: Liu X.M. , You X. , Zhuang Zhuo
Published: March 2009

Molecular Dynamics (MD) simulations of indentation and scratch over crystal nickel
(100) were carried out to investigate the microstructure evolution at nanoscale. The dislocation
nucleation and propagation during process were observed preferably between close-packed planes.
Dislocation loops are formed under both indentation and scratch process, and indentation and
friction energy were transferred to the substrate in the form of phonon of disordered atoms, then
part of the energy dissipated and rest is remain in the form of permanent plastic deformation.
A New Technique for Locating Coating Faults on Buried Metallic Pipelines
Authors: Di Biase Lucio , Cigna Ranieri , Fumei Osvaldo
Published: March 2009

Among the specialized electrical surveys to search for coating faults, assess possible external
corrosion conditions and verify Cathodic Protection effectiveness, DCVG (Direct Current Voltage
Gradient) survey, and in particular the Transverse DCVG is usually considered the most effective
technique for finding coating faults on transport pipelines for oil, gas, and water.
In this paper some preliminary results are reported that show that using a.c. current instead of direct
current the localization of the coating faults can be much more precise and simple to be performed
at the same time. Compared with the DCVG, the ACVG has many advantages among which: it does
not need ON/OFF cycles since the OFF conditions are almost constant in the absence of alternating
stray currents, it can be carried out with economic and simple instrument, the use of unpolarizable
reference electrodes (SCE) is not necessary and furthermore, it locates the faults and quantifies their
importance with much more accuracy.
Besides, the method needs shorter times and less manpower: one only operator is sufficient to
perform the survey and it is therefore cheaper than performing DCVG.
The results of the experiments carried out at the Training and Research Centre of Riyadh by
comparing the results of the two methods using the same current densities, clearly show the
different behaviour of the two techniques, in the presence of simulated / calibrated coating faults.
Further researches are in course with this quite new technique as the localisation of coating faults is
being made in terms of impedance rather than in terms of resistance. This has quite a huge
implication when corrosion conditions of real coating faults are concerned. In case of a.c.
interference (e.g. due to a.c. fed railways or electricity power lines) this could be a unique method
able to locate corroding coating faults on a buried, interfered metallic pipeline.
The method is being patented not only as a new technique for coating fault location, but also for its
promising further developments still under investigation, as capable of finding corroding faults in
case of a.c. interference.
Anodic Alumina Membranes as Template for the Synthesis of 1-D Metal Oxide and Hydroxide Nanostructures
Authors: Bocchetta P. , Santamaria M. , Di Quarto F.
Published: March 2009

Anodic alumina membranes with highly ordered cylindrical pores and tuneable geometry have been
prepared (pore diameters=20−200 nm; pore density 1012-1014 pores/m2; thickness: 20-100 mm) by
controlling the anodizing process of aluminum in phosphoric, oxalic and sulphuric acid. The
influence of different parameters (initial treatment of aluminium surface, composition of electrolyte,
temperature and applied potential) on the final characteristics of the membranes have been
investigated. The use anodic alumina membranes as template for the electrosynthesis of some metal
hydroxides and oxides 1-D nanostructures (nanowires and nanotubes) will be also proved.
The Effect of Heat Treatment and Welding Parameters on the Corrosion Behaviour of a Friction Stir Welded 6056 Aluminium Alloy
Authors: Monetta T. , Montuori M. , Squillace Antonio , Bellucci Francesco
Published: March 2009

The current research has assessed the correlation between welding parameters and corrosion
behaviour for friction stir welded 6056 aluminium alloy. Different thermal treatments and welding
parameters were considered. For the welding parameters studied in this project, the data strongly
indicate that sensitivity to corrosion is linked to the welding parameters employed. Substantial
differences were found for the higher and lower speed welding parameters, with the lower speed
parameters appearantly resulting in less corrosion resistance. The most widespread form of
corrosion observed was pitting; however, intergranular corrosion (IGC) was also seen. While the
T78 thermal treatment appears to decrease the corrosion resistance of the parent alloy, the weld
region tends to improve, with the nugget being cathodic.
Corrosion Control Cost Reduction through Improved QA Information Management - An OSD Funded Joint Navy Army Initiative
Authors: Hock Vincent F. , Drozdz Susan , Seelinger Andrew , Doyle Delmar
Published: March 2009

When the coating application does not meet the required standards, the lifetime of the
coating can be substantially reduced. In the worst case, the coating may catastrophically fail
immediately after being placed into service. This ongoing joint project conducted by the U.S. Navy
and the U.S. Army is intended to demonstrate and provide for the automation of data collection for
painting projects on critical structures and the make this data a more effective resource for making
effective management decisions for the protection of DoD assets.