bluuebunny/crossref_metadata_2025 huggingface dataset:
Development of Low Size Dispersion, High Volume Fraction and Strong Quantum Confined CdSxSe1-x Quantum Dots Embedded in Borosilicate Glass Matrix and Study of their Optical Properties
Authors: Verma A. , Bhatnagar P.K. , Mathur P.C. , Nagpal S. , Pandey P.K. , Kumar J.
Published: March 2009

Quantum Dots (QDs) of CdSxSe1-x embedded in borosilicate glass matrix (BGM) have been grown using colored glass filter (RG695). Double-Step (DS) annealing method was adopted in which nucleation is achieved at a lower temperature (475°C) without any crystallization. To obtain crystallization on these nucleation centers, the annealing temperature is raised to 575°C at which the nucleation rate is negligible. QDs of various average radii and volume fractions are grown by varying the annealing duration from 3 to 11hrs. QDs corresponding to higher annealing duration are found to have low size dispersion (SD) and high volume fraction but weak quantum confinement, while, the QDs corresponding to lower annealing durations have high quantum confinement due to their much lower radii as compare to Bohr exciton radius, their SD is high and volume fraction low. For nonlinear optical applications the SD must be low and volume fraction should be high. Attempt has been made to optimize the two parameters. Further it has been concluded that there is no contribution of the band edge recombination to the PL and the origin of the PL is due to shallow traps existing in the volume of the QDs. Studies of absorption and PL have also been made on the samples aged for 18, 24 and 36 months. It is found that the effect of aging is to increase the absorption coefficient, reduce the shallow trap centers and reduce the SD.
Surface and Structure of Porous Silicon Layers
Authors: Lu Jing Mei , Cheng Xuan
Published: March 2009

The porous silicon (PS) layers were fabricated on n(100) and n(111) silicon by applying
the constant and repeated currents in different HF solutions. The electrochemical impedance
spectroscopy (EIS) was used to in-situ characterize the Si/electrolyte interface before and after the
PS formations. The surface and structure of PS layers were examined in terms of
electrochemical/surface parameters.
Distributed Feedback Laser Using Buried Dielectric Grating
Authors: Teng Jing Hua , Chong Lip Fah , Dong J.R. , Chua Soo Jin , Ang Norman Soo Seng , Wang Yan Jun , Lim Ee Leong
Published: March 2009

In this paper, we report a DFB laser diode with a buried SiO2 grating. Epitaxy lateral
overgrowth by metalorganic chemical vapour deposition (MOCVD) is conducted to grow the p-type
InP cladding layers in the nano-patterned dielectric grating template. The large refractive index
difference between SiO2 and InP results an index coupling coefficient κ of about 250 cm-1. The
fabricated DFB laser showed a side mode suppression ratio larger than 45 dB measured. The
technology developed can also be used for other applications that require high efficiency grating
structure.
Design and Analysis of 2D Photonic Crystal Waveguides for High Coupling Efficiency
Authors: Wu Ming , Liu Hai Rong , Tong Wei Jun , Huang De Xiu
Published: March 2009

In this paper we have proposed a photonic crystal structure to enhance the coupling efficiency between photonic crystal waveguide (PCW) and the conventional dielectric waveguide. The proposed waveguide characterized with employing the taper structure and varying the holes’ radius in the taper. Two-dimensional (2D) finite-difference time-domain (FDTD) method has been used to analyze the structure. The simulation results show that the coupling efficiency can be achieved as high as 81.6% at the wavelength of 1.55um.
Enhanced UV Photodetector Responsivity in Porous GaN/Si(111) by Metal-Assisted Electroless Etching
Authors: Chuah Lee Siang , Zainuriah Hassan , Haslan Abu Hassan
Published: March 2009

This paper presents the structural and optical studies of porous GaN sample compared to the corresponding as grown GaN. The samples were investigated by scanning electron microscopy (SEM), high resolution x-ray diffraction (HRXRD), and photoluminescence (PL). The porous area is very uniform, with pore diameter in the range of 80-110 nm. XRD measurements showed that the (0002) diffraction plane peak width of porous samples was slightly broader than the as-grown sample. PL measurements revealed that the near band edge peak of the porous samples were redshifted. Metal-semiconductor-metal (MSM) photodiode was fabricated on the samples. For as grown GaN sample, this detector shows a sharp cut-off wavelength at 362 nm. A maximum responsivity of 0.258 A/W was achieved at 360 nm. For the porous GaN sample, this detector shows a sharp cut-off wavelength at 364 nm. A maximum responsivity of 0.771 A/W was achieved at 363 nm.
Surface Optical Waves in Semi-Infinite One-Dimensional Photonic Crystals Containing Alternating Layers of Positive and Negative Media
Authors: Soltani Vala A. , Barvestani J. , Kalafi M.
Published: March 2009

An analytical direct matching procedure within the Kronig-Penney model applied to
analyze the dispersion behavior of the localized surface states supported in the surface of a semiinfinite
one-dimensional photonic crystals truncated with air. The photonic crystal containing
alternating layers of positive and negative media. In the case of the conventional indices, as the
incident light changes from normal to oblique incidence, the surface modes shifts into higher
frequencies. For this reason, the phenomenon of photonic band gap has been used only under a
narrow range of frequencies of light incident at a particular angle or in a particular angular range.
We have showed that by choosing some proper value for the PC parameters, zero and negative
dispersion of surface modes emerge in a large range of k|| , and, due to the different nature of the
band structure the surface modes are more localized compared to those appeared in the conventional
PC.
Influence of Hydrogen Dilution of Silane on the Properties of nc-Si:H Films Grown by Layer-by-Layer Deposition Technique
Authors: Tong Goh Boon , Ab. Gani Siti Meriam , Rahman Saadah Abdul
Published: March 2009

Hydrogenated nanocrystalline silicon (nc-Si:H) films produced by layer-by-layer (LBL)
deposition technique were studied. The films were grown at different hydrogen to silane flow-rate
ratio on crystal silicon (111) substrate. The properties of films were investigated by X-ray
diffraction (XRD), micro-Raman scattering spectroscopy, Fourier transform infrared (FTIR)
spectroscopy, optical transmission spectroscopy, atomic force microscopy (AFM) and field
emission scanning electron microscopy (FESEM). These properties showed dependence on the
hydrogen dilution of silane. Appearance of XRD peaks at diffraction angles of 28.4 o and 56.1 o
which correspond to silicon orientation of (111) and (311) respectively, were observed in all films
indicating evidence of crystallinity in the films. Raman scattering results indicated that crystallinity
in the films was due to the presence of nanocrystallites embedded in an amorphous matrix. The
energy gap of the films showed dependence on the hydrogen content in the films. Increase in
nanocrystallite size resulted in increase in disorder at low hydrogen dilution films but films remain
homogenous with increase in nanocrystallite size for the high hydrogen dilution films.
Characteristics of Ge Nanocrystals Grown by RF Magnetron Sputtering
Authors: Singha R.K. , Das K. , Das S. , Dhar A. , Ray S.K.
Published: March 2009

We report the self-assembled growth of Ge islands of different shapes and sizes on p-Si
(001) by r.f. magnetron sputtering by varying the r.f. power, growth temperature and postdeposition
annealing condition. The well known Stranski-Krastanov growth mechanism due to
lattice mismatch between Si & Ge leads to the formation of Ge islands, similar to a more
sophisticated MBE growth, albeit at a much higher pressure in our study. Ge nanocrystals
embedded in SiO2 matrix have also been grown. Optical properties of nanocrystals exhibiting
visible luminescence at room temperature are presented.
Fabrication of Photonic Crystals by Holographic Lithography Method
Authors: Yeo Jong Bin , Lee Hyun Yong
Published: March 2009

In this study, we found out the new fabrication process condition for Photonic
crystals(PCs). PCs were fabricated by holographic lithography(HL), instead of commonly used
electron beam lithography(EBL). HL process enable periodic large area fabrication of PCs. Also this
method can easily control the pitch of periodic patterns. We set up holographic lithography system by
laser and some optical components. The source of light used laser of 442 nm wavelength.
Photo-resist(PR) used DMI-150 model. The viscosity of PR is diluted with propylene glycol
monomethyl ether acetate(PGMEA) which is solvent for DMI-150. This experiment is holographic
lithography of rotated double exposure method for PCs pattern. The method use only one beam.
Result data is shown by atomic force microscope(AFM), scanning electron microscope(SEM) and 3D
contour image. At the this study, we conclude conditions which we need periodic structure for PCs. It
is some factor. For example, incident angle, exposure time, rotation angle, etc. And we show incident
angle calculation recipe for needed size of periodic patterns. We already manufacture PCs structure
design and simulation tool. Nano structure of this paper’s result is applied to designed PCs patterns.
Investigation on the Deformation of TiNi Shape Memory Alloy with a Crack Using Moiré Interferometry
Authors: Wang Qing Hua , Xie Hui Min , Jiang Hai Chang , Li Yan Jie , Dai Fu Long , Chen Peng Wan , Zhang Qing Ming , Huang Feng Lei
Published: March 2009

Martensitic phase transformation can greatly affect the mechanical behaviors and the
stress-strain response of shape memory alloys (SMAs). In this study, the effect of martensitic phase
transformation on the deformation of a single-crystal TiNi SMA specimen with a triangle crack was
investigated experimentally by means of moiré interferometry method. A typical displacement field
and the corresponding strain field in areas both around and far from the tip of the crack were measured
in a certain time during the loading process in which the tensile load is coupled with the
stress-induced martensitic phase transformation. Some characteristics of the deformation and the
martensitic phase transformation of the specimen are revealed. These results may provide a reliable
support for revealing the fracture mechanism of single crystal TiNi SMAs, and may enable further
development in putting forward the failure criterion of SMAs.
Numerical Simulation of Flows in a Pipe with an Aneurismal Sac (Effects of Aneurismal Models and Stents)
Authors: Wahap Gulbahar , Kobori Tatsuya , Takakura Yoko , Arai Norio , Konishi Yoshifumi , Fukasaku Kazuaki
Published: March 2009

Recently, the intravascular therapy using microcoils and stents to treat aneurysms has
attracted researcher’s interest. In this study, in order to evaluate the effects of the stents, a numerical
simulation of two-dimensional flows has been carried out for a pipe with a model of an aneurismal
sac. Using aneurismal models with different inclined angles to the pipe, inflow conditions with
steady states or pulsations have been applied in the range of Reynolds number in human blood
flows. First, the computational results are compared with experiments under the steady inflow
condition, which has shown the reliability of the numerical simulation. Furthermore, the mechanism
of flows with an aneurismal model is discussed in the case with or without a stent, and consequently
the effect of the stent is clarified.
Relationship Between Sand Ripple Moving Speed and Wind Speed under Local Wind Tunnel Experiment by Using Natural Sand in Taklimakan Desert
Authors: Matruzi Jurat , Gheni Mamtimin , Abdureyim Ilham , Abdikerem Xamxinur
Published: March 2009

In this study, the directionally fixed air tunnel testing equipment are used for obtain nearly
close natural uniform wind and provide more stable wind speed for tunnel test. The changes of sand
ripple moving speed in different location are observed under given wind speed condition. The sand
ripple lines formation and moving process are tested on flat surface of sand, in Taklimakan desert.
The results shown that the sand ripple forming rapidly from non ripple surface to ripple surface and
moving along the wind direction. Though the sand ripples in the testing region have some difference
about its moving speed, the sand ripple moving speed appear linearity relationship between sand
moving displacement and the moving time. This phenomenon indicate that the sand ripple almost
occurs and moving at the same time in the uniform wind stream field.
Numerical Simulation of Sand Ripple Formation with Periodically Uniform and Non-Uniform Stream Field
Authors: Abudoureheman Abudoukelimu , Abdikerem Xamxinur , Gheni Mamtimin
Published: March 2009

In this study, for the numerical simulation of the sand ripple’s forming process which
caused by the sand flow, the simulation models based on the fluid dynamics and the sand flow field by
the wind are analyzed. Due to sand field’s characteristics is very complex, the establishing process of
stream flow field constitutive equations analyzed at first, and then the implication relations and
independency between stream flow field and the sand flow field analyzed. Finally, the sand ripple
forming and moving process simulated in uniform and non-uniform stream flow field.
Decision-Making Model and Evaluation Architecture for Intelligent Fault Diagnosis
Authors: Han Yan Ling , Cao Shou Qi
Published: March 2009

Diagnosis decision-making and evaluation analysis is two closely-related contents in the
process of intelligent fault diagnosis, correct decision-making could be made only based on objective
and fair evaluation. This paper brought up decision-making objective and corresponding
decision-making model for intelligent fault diagnosis, and gave its evaluation indicator architecture.
Combining grey correlative analysis with hierarchical analysis method, multi-hierarchy grey
correlative analysis was brought forward to apply into intelligent fault diagnosis, its principle,
algorithm and evaluation execution process were researched deeply, and finally the analysis sample
was given.
Design and Penetration Performance of Annular Shaped Charge Structure
Authors: Cheng Wang , Ma Tian Bao , Ning Jian Guo
Published: March 2009

Based on the principle of the equivalent momentum of the corresponding elements for
internal and external liners, annular shaped charge structure is proposed. The generatrix analytical
equations for the external surfaces of the external liner and external charge are deduced. Experimental
and numerical studies are conducted to investigate the formation and penetration process of the jet for
the annular shaped charge under different initiation radiuses, and the initiation radius corresponding
to the detonation wave front matched with the liner is optimized. At this radius, shaped charge can
form an ideal cylindrical jet. Moreover, the diameter of the jet approximates the theoretical diameter
of the jet, and has satisfactory symmetry and focus.
Study on Erosion-Resistance of Electro-Thermal Explosion Ultra-High Speed Spraying MoSi2-Based Coatings
Authors: Hou Shi Xiang , Liu Zong De , Liu Dong Yu , Zhao Li Ping , Ma Yi Min
Published: March 2009

A new method, electro-thermal explosion ultra-high speed spraying, was utilized to
produce the Mo-Si or Mo-Si-B coatings. Experimental results showed that submicron-grain pure
MoSi2 phase coating and boron alloyed MoSi2-MoB2 multiphase coatings were in-situ synthesized on
GH3039 nickel-based superalloy substrate. Erosion-resistance test of GH3039 nickel-based
superalloy and MoSi2-based coatings were performed under high temperature(800°C) with GW/CS –
MS erosion wear tester. Quartz sand was employed as erosive material. Experimental results showed
that the erosion-resistance of the MoSi2-based coatings is better than that of the GH3039 nickel-based
superalloy.
Erosion Behavior of TiC-xNi Composite Coatings In Situ Synthesized by Electro-Thermal Explosion Ultra-High Speed Spraying
Authors: Liu Jing Jing , Liu Zong De , Zhao Li Ping
Published: March 2009

With aim to investigate the effect of the content of Ni on erosion behavior of the TiC-xNi
coating at elevated temperatures, The TiC-xNi (x=0, 5, 10, 15 , 20wt.%) composite coatings were
in-situ synthesized on nickel-based alloy substrate by the self-developed electro-thermal explosion
ultra-high speed spraying (EEUSS) device with the cored wire. Erosion properties of the coatings
were assessed by the erosion tester under 90° incidence angle and 650°C. X-ray diffraction (XRD)
and microhardness tester were used to investigate the coating phases and microhardness. The coatings
consisted of TiC phase and Ni binder phase, as well as the residual C. The microhardness of TiC-xNi
coating with the Ni content from 5 wt.% to 20wt.% decreased with the increase of the content of Ni.
Elevated temperature erosion test indicate that the spiculate quartz particles impact the surface of the
coating which lead to the loss of material. The erosion resistance of the TiC-xNi coatings increased
first and decreased afterwards with the increase of the content of Ni. The relative erosion resistance of
coating with 10 wt.% Ni addition is excellent which is about 2 times than that of TiC-20Ni coating
under 650°C and 90° incidence angle.
Performance Prediction of Pre-Corroded Aluminum Alloy Using Genetic Algorithm-Neural Network and Fuzzy Neural Network
Authors: Fan Chao Hua , He Yu Ting , Li Hong Peng , Li Feng
Published: March 2009

Genetic algorithm is introduced in the study of network authority values of BP neural
network, and a GA-NN algorithm is established. Based on this genetic algorithm-neural network
method, a predictive model for fatigue performances of the pre-corroded aluminum alloys under a
varied corrosion environmental spectrum was developed by means of training from the testing dada.
At the same time, a fuzzy-neural network method is established for the same purpose. The results
indicate that genetic algorithm-neural network and fuzzy-neural network can both be employed to
predict the underlying fatigue performances of the pre-corroded aluminum alloy precisely.
Repeatedly Dehiscence and Residual Stress of Liquefied Gas Spherical Vessel
Authors: Zhang Yi Liang , Zhang Zhen Hai , Xu Xue Dong
Published: March 2009

Comprehensive residual stress of a 1500m3 liquefied petroleum gas spherical vessel was
measured and analyzed after many cracks arised. The results show that the general residual stress was
at a high level in the field with cracks as well as the field without cracks. Furthermore, the
measurements were taken at the same place to evaluate the effect of the heat treatment after this
spherical vessel was re-welded and the integral heat treatment was performed. Meanwhile, the
measurement to the stress in the vertical direction with X-Ray was finished after a set of special
treatments in the outfield.
A New Global Optimization Algorithm and its Application
Authors: Lu Ying Hui , Wang Shui Lin , Jiang Hao , Ge Xiu Run
Published: March 2009

In geotechnical engineering, based on the theory of inverse analysis of displacement, the
problem for identification of material parameters can be transformed into an optimization problem.
Commonly, because of the non-linear relationship between the identified parameters and the
displacement, the objective function bears the multimodal characteristic in the variable space. So to
solve better the multimodal characteristic in the non-linear inverse analysis, a new global
optimization algorithm, which integrates the dynamic descent algorithm and the modified BFGS
(Brogden-Fletcher-Goldfrab-Shanno) algorithm, is proposed. Five typical multimodal functions in
the variable space are tested to prove that the new proposed algorithm can quickly converge to the
best point with few function evaluations. In the practical application, the new algorithm is employed
to identify the Young’s modulus of four different materials. The results of the identification further
show that the new proposed algorithm is a very highly efficient and robust one.
Development of the Optimized Manufacturing Process Model by "TAGUCHI METHOD"
Authors: Sakamoto Hidetoshi , Tsukamoto Kimihide , Ohbuchi Yoshifumi , Inoue Hisahiro
Published: March 2009

Authors tried to construct multimedia base support system of the manufacturing process
with use of the knowledge base and the inference engine on the www server. This knowledge
database systematized the knowledge which was obtained from the document and the skilled engineer
as much as possible by using a knowledge engineering technique. However, it is difficult for beginner
to find the best processing condition under the condition of the material, the machine and the tool on
grinding operation by using the conventional database. Especially, when they encountered the
manufacturing condition which is not built into the conventional data base, the past optimum
conditions cannot be obtained from the expert system. The best method of obtaining the optimum
conditions as the solution of this problem is to execute some experiments for this new case. This
research proposed the system, which presented a minimum combination of the multi factor
experiments for the best manufacturing condition search by using the Taguchi method. We were able
to obtain the best condition to use the proposed robust engineering by only 18 times.
Manufacturing Grid Workflow Framework and Model
Authors: Yuan Yi Ping , Nian Mei , Sun Wen Lei
Published: March 2009

The Manufacturing Grid domain is characterized by rapid and substantial change over
time. The entire process of product development can be quite complex. The activities are expected to
be executed on heterogeneous resources which are geographically distributed. However, traditional
modeling systems use static workflow models which can not automatically redesign the business
process and mask the isomerism of the resources. In this article, an open and extensible framework of
MG workflow is given, which complies with the standard of WFMC and GGF. A formalized
definition workflow model is proposed including process model, organization model, resource
model, and service mode. The integrated workflow model can be used to dynamically represent a
business process and other aspect s of Manufacturing Grid workflow.
Six Sigma Robust Design of Composite Hand for LCD Glass Transfer Robot
Authors: Nam Hyun Wook
Published: March 2009

This research studied robust design of composite hand for LTR (LCD glass Transfer
Robot). 1st DOE (Design of Experiment) was conducted to find out vital few Xs. 108 experiments
were performed and their results were statistically analyzed. Pareto chart analysis shows that the
geometric parameters (height and width of composite beam) are more important than material
parameters (E1, E2) or stacking sequence angle. Also, the stacking sequence of mid-layer is more
important than that of outer-layer. The main effect plots show that the maximum deflection of LTR
hand is minimized with increasing height, width of beam and layer thickness. 2nd DOE was conducted
to obtain RSM (Response Surface Method) equation. 25 experiments were conducted. The CCD
(Central Composite Design) technique with four factors was used. The coefficient of determination
(R2) for the calculated RSM equation was 0.989. Optimum design was conducted using the RSM
equation. Multi-island genetic algorithm was used to optimize. Optimum values for beam height,
beam width, layer thickness and beam length were 24.9mm, 186.6mm, 0.15mm and 2402.4mm,
respectively. An approximate value of 0.77mm in deflection was expected to be maximized under the
optimum conditions. Six sigma robust design was conducted to find out guideline for control range of
design parameter. To acquire six sigma level reliability, the standard deviation of design parameter
should be controlled within 2% of average design value
Structural Feasibility Study on the Slidable One-Touch Extension Fitting for Plastics Pipes with Virtual Assembly and Experiments
Authors: Pyo Soo Ho , Suh Young Ho , Choi Sun Woong , Suh Yeong Sung
Published: March 2009

Structural feasibility study on a Slidable One-Touch Extension (SOTE) fitting for profilewalled
drainage and sewer pipes was performed. SOTE fitting was developed for the purpose of
accommodating large thermal deformation that could occur during installation, which if not treated
properly in design can cause problems such as loosening of the pipe and in some cases cracking of the
support constraint. SOTE fitting assembly process was examined via virtual assembly to determine
the structural soundness and thermal deformation behavior was investigated for its design efficiency
and performance. For both analyses the finite-element method was utilized and corresponding
experiments were also performed to support the findings. Finally, cyclic fatigue tests were carried out
on fittings followed by the leak proof test to determine integrity of the SOTE fittings. Through
analysis and experiments SOTE fitting was shown to perform its designed functions with required
structural stability.
Fatigue Life Evaluation of Spot Weldment Using GA and FEM
Authors: An Jong Kyo , Yang Sung Mo , Kang Hee Yong , Sin Su Rok
Published: March 2009

HS40R and EZNCEN are extensively used as components of vehicle bodies because they
satisfy environmental standards and improve fuel ratio. Because vehicle body sheets are becoming
thinner and stronger, it is difficult to satisfy the design standards of spot welding joints. This research
presents the optimization of the welding condition for various welding variables of a spot welding
specimen by genetic algorithm (GA). After obtaining the optimum welding condition by use of the
genetic algorithm, the fatigue properties of HS40R and EZNCEN spot welded joints are evaluated by
using the finite element method (FEM) to determine the durability and stability of a structure.
Crack Growth Life Estimating for MSD Panel
Authors: Zhang Jian Yu , Bao Rui , Zhao Li Bin , Long Li Ping , Fei Bin Jun
Published: March 2009

The problem of multiple site damage (MSD) has got more attention in ageing structures.
Cumulative effects of interacting cracks may significantly degrade the damage tolerance capacity of
structures. Cracks caused by MSD are extremely difficult to detect and greatly reduce the residual
strength, fatigue life and overall structural integrity of aircraft panels. This paper presents a simple
numerical method, which use the principles of fracture mechanics and the computation results, to
predict the fatigue crack growth life of MSD structure. Comparing with calculating crack growth life
cycle by cycle, this method will save much time. To verify the validity of the proposed method,
experiment was conducted and reported with simulation specimen of representative MSD structure
with 5 details. The comparison between the calculated a-N curves and the crack growth lives and the
test results shows that the prediction result with this fast method is acceptable. A discussion was
carried out by numerical analysis; in with typical MSD structures with different initial crack length
were adopted. Crack interaction effect was found obviously, but it occurred mainly in the last part of
the crack growth lives. The relative size of MSD cracks depends significantly on the distribution of
the initial cracks.
Research on the Plastic Work Rate Consumed in the Process Zone for the Growth of Triaxial-Stress-State Crack
Authors: He Yu Ting , Li Feng , Cui Rong Hong , Fan Chao Hua , Li Hong Peng
Published: March 2009

When studying the growth of triaxial-stress-state crack, the plastic work rate consumed in
the process zone at crack tip should be described clearly. Fracture for a cracked specimen is related to
rupture of a simple uniaxial tensile specimen by nature. By equaling the crack tip stress-strain field to
uniaxial stress-strain field, it is obtained that the plastic work rate consumed in the process zone at
crack tip can be expressed by the plastic energy density WF multiplied by the equivalent size of the
process zone hF. The plastic energy density WF can be expressed by virtue of uniaxial true stress-strain
curve. And analytical form of hF for triaxial stress state is presented by recourse to three-dimensional
analyses on material behaviors. The expression of plastic work rate consumed in the process zone is
verified by the predicting fracture toughness.
Effect of Load Direction on Crack Propagation in High-Temperature Fatigue of Directionally Solidified Superalloy
Authors: Yamamoto Masato , Kitamura Takayuki , Ogata Takashi
Published: March 2009

Directionally solidified (DS) superalloys, which have elongated large grains, are used for
gas-turbine blades. Since the grain size is not small enough in comparison with the crack size
observed often in a real component, the inhomogeneous microstructure due to the aligned grains may
strongly affect the crack propagation property. Center-cracked-plate specimens with three different
orientations, TP0 with the parallel DS axis to the load, TP90T with the perpendicular DS axis to the
load and the crack propagation direction, and TP90L with the perpendicular DS axis to the load and
parallel to the crack propagation direction, are subjected to high-temperature (1143K) fatigue. The
specimens after the tests show the transgranular cracking perpendicular to the load axis in TP0,
intergranular one parallel to the DS axis in TP90L, and intergranular / transgranular one parallel to the
DS axis in TP90T. The crack propagation rate da/dN shows a good correlation with effective stress
intensity factor range Keff in each cases. However, the magnitude of da/dN at a same Keff in TP90L
is relatively higher than that in TP0, and that in TP90T remarkably fluctuates. A microscopic
observation of TP90T reveals that the high da/dN is caused by the intergranular cracking, while the
low da/dN is observed on the transgranular cracking. A procedure for the prediction of crack
propagation is proposed on the basis of the two types of cracking; transgranular and intergranular
cracks perpendicular to the load axis. The validity of the proposed procedure is discussed by the
comparison of tested and predicted results of crack propagation in a fatigue condition.
Study of Fretting Fatigue Crack Initiation For Riveted Al 6xxx Components
Authors: Guo Ran , Lin En Qiang , Duan Rui Chun , Mesmacque Gerard , Amrouche Abdelwaheb
Published: March 2009

Riveting is a procedure widely used for fitting together two or more elements of a
structure, that could be of the same or different material. In these assemblies the stress field is
complex and a number of parameters, including effect of the geometrical discontinuities, contact
between elements, tightening, material properties and applied load must be considered. The current
work focuses on the study of fretting fatigue crack formation in common 6XXX aluminum alloys,
used in land transportation equipments, and the determination of the characteristic crack initiation
sites by means of both experimental and numerical methods. 3D finite element models were validated
by the experimental results obtained with strain gauges. The influence of the contact friction
coefficient at the fretting surface and fastening forces on the initiation of cracks, are discussed by the
comparison of the different numerical results.
Optimization of Integrally Stiffened Panels Based on Crack Propagation Life
Authors: Yin Zhi Ping , Huang Qi Qing , Zhang Bing Hui
Published: March 2009

Recent development in structure optimization offers the potential for significant
improvements in the design of more durable structures. The present paper reveals the importance of
structural optimization with crack propagation life of integrally stiffened panels. In the full paper, we
explain in detail how to optimize structural fatigue life and design the structure of integrally stiffened
panels which has the optimization life. The first topic is: the review of existing structural optimization
design method. The second topic is: optimization methodology with crack propagation life. In our
optimization methodology, the RSM (Response Surface Methodology) and GA (Genetic Algorithm)
are successfully applied for structural optimization design with crack propagation life. The third topic
is: damage tolerance optimization of integrally stiffened panels with crack propagation life. In this
paper, structural parameters: the height and location of stringer, are the design variables. The
structural weight is a fixed value. Through analyzing, the optimization structure with maximum life
can not simply be chosen, and the maximum life would not increase all ways while the high of stringer
increased. At last, the optimization structure, which has maximum crack propagation life, is given on
the integrally stiffened panels.
Experimental Study on Fatigue Crack Growth and Residual Strength of Steel 30CrMnSiNi2A under Mixed Corrosive Environments
Authors: Wang Sheng Nan , Li Yi , Qin Jian Bo , Liu Ya Long , Zhou Yue Quan
Published: March 2009

The effects of five single and three mixed corrosive environments on the fatigue crack
growth and residual strength of steel 30CrMnSiNi2A were experimentally studied. The crack
growth rates in corrosive environments, obtained by using Paris equation, were compared with
crack growth rate in lab air. The results showed that the interactions of aggressive environments
with fatigue loads caused the accelerations of fatigue crack growth rates in steel 30CrMnSiNi2A.
But the effects of various environments on the fatigue crack growth rate are different. Among the
environments the most detrimental one was oil-box zone, followed by cookroom&washroom, tank
seeper, 3.5%NaCl, moist air, high altitude and dried air. Also, the test data showed the less effect of
various corrosive environments on critical crack length, that is, no direct infection of corrosive environments
on residual strength capability dominated by fracture toughness.
Damage Identification of Multi-Type Joints with Using Electro-Impedance Method by Smart Sensors
Authors: Wang Gao Ping , Hong Yong , Han Byeong Hee , Hong Dong Pyo , Kim Young Moon
Published: March 2009

The use of multi-type joints, such as rivet joints, adhesive joints, lap joints, L-shape joints,
etc., has been driven by the need for stronger and lighter structures, particularly in bridges, aerospace
structures, pipeline systems, automobiles industry. Among the multi-type joints, lap joints and
L-shape joints possess a considerably important position. Moreover, in many real-field situations, it is
not accessible to such joints, and thus it gives additional difficulties to detect damages. Fortunately,
the electro-impedance method based on the use of smart sensors provides special opportunities for
damage detection of such joints, which are not easy or impossible to be accessible. The
piezoelectric-ceramic sensors which simultaneously act as an actuator and sensor are widely used for
structural health monitoring. In the high frequency range, the electro-impedance-based technique
using a piezoelectric-ceramic patch is very sensitive for the evaluation of the incipient and small
damages. A large amount of experiments were executed and several conditions were imposed to
simulate real-time damage, such as the bolt loosening and bolt absence. The different indices are
discussed and executed to efficiently quantify the damage conditions. The theory behind this
technique and the experimental investigations are presented in this paper. The analytical results
strongly show the detectability and reliability of this method.
Experimental Investigation of the Size Effects on the Fracture Toughness and Tearing Modulus
Authors: Wang Zhao Xi , Shi Hui Ji , Zhang Xiao Liang
Published: March 2009

Detailed experiments of fracture toughness in which SENB specimens of five different
thicknesses were included were carried out to investigate the size effect in the ductile to brittle
transition temperature region. It is found that the fracture toughness of the upper shelf increases with
the thickness of the specimens with the similar geometry. While the fracture toughness of the lower
shelf decreases with the thickness in the range of 4mm to 12mm and then drops up from 12mm to
16mm with the appearance of shear lips which present the shearing fracture under the plane stress
state. The tearing modulus dJ/da which determines the resistance to stable crack growth increases
with the increment of thickness and the reduction of the temperature. The results of the stress
triaxiality increasing with the reduction of the thickness explain well the experimental results.
Research on Mode I and Mode II Dynamic Fracture in High Strength Steels under High Loading Rates
Authors: Xu Ze Jian , Li Yu Long , Kikuchi Masanori
Published: March 2009

The Mode I and Mode II dynamic fracture toughness (DFT) values, KId and KIId for high
strength steels 40Cr and 30CrMnSiNi2A were evaluated using a combined experimental-numerical
method. The tests were performed on three point bend (3PB) and shear specimens with Hopkinson
pressure bar. The time of crack initiation was determined by a strain gauge. With the assistance of
3-D transient finite element analysis, the temporal evolution of the dynamic stress intensity factor
under different loading rates was obtained, and the DFT was determined by the fracture initiation
time. In Mode I tests, a brittle transgranular fracture was found in 40Cr, while evidence for ductile
fracture was observed on the failure surface of 30CrMnSiNi2A. In Mode II tests, both tensile cracks
and adiabatic shear bands were found for the two steels. The effect of ligament size on fracture
toughness was discussed. The correlations of KId and KIId with loading rate were also investigated.
The micromechanisms of loading rate effect on the DFT were discussed for both modes.
Effect on Dynamic Biaxial Fracture Behaviors by Different Heat Treatments on Magnesium Alloy
Authors: Shimamoto Akira , Kubota Ryo
Published: March 2009

The dynamic fracture experiments were conducted on the heat treated magnesium alloys;
AZ31B-O, AZ31B-200 °C, and AZ31B-430 °C. Cross shaped specimens with the crack on their
center were used for the experiments. Dynamic fracture behavior near a crack tip under equal and
unequal biaxial stress was observed by the caustics method. From the observation, the stress intensity
factor and the fracture toughness value were calculated. As a result, the effect of heat treatment was
found. However, no clear relation such as correlation between dynamic stress intensity factor and heat
treatment temperature was deduced.
Finite Geometrically Similar Element Method for Dynamic Problem of a Cracked Specimen
Authors: Li You Tang , Ma Ping , Wei Yao Bing
Published: March 2009

A group of geometrically similar elements is automatically generated layer by layer
around the tip of crack. By taking advantage of the same stiffness and similar mass of similarly
shaped elements, the combined stiffness matrix and combined inertia matrix in area can be
expressed by the displacement row matrix of outer polygon. The global stiffness matrix will be
obtained if the combined stiffness matrix and combined inertia matrix of area are assembled to
those of another elements according to corresponding nodes. The small set of generalized
coordinates can be obtained through solving the equation, and then the dynamic stress intensity
factor of crack will be obtained. The three points bending with single crack and shearing model
with double cracks in explosive loading were calculated with finite geometrically similar element
method.
Evaluation and Characterization of Plastics-Made Sheet Type Components under Impact
Authors: Machmud M. Nizar , Omiya Masaki , Inoue Hirotsugu , Kishimoto Kikuo
Published: March 2009

Experimental works using a drop weight impact test method have been performed on a
circular sheet specimen to evaluate and to characterize the impact resistance of the sheet-type plastic
components designed for automotive wheel covers. Evaluation has been conducted for a set of
engineering plastics: polycarbonate (PC), acrylonitrile-butadiene-styrene (ABS) and their blend
(PC/ABS). The testing results showed that the PC/ABS blend specimens failed in brittle manner
under higher impact speeds with very few of whitening zones. Secondary cracks captured
perpendicular to fracture surface were also found in the mid-plane of the scattered PC/ABS blend
specimens. Investigation is then focused on this blend and the testing results describe that impact
resistance of the specimen made of this alternative material is determined by ABS not by PC.
Combination of structures between PC and ABS through the thickness in the core due to their
immiscibility was observed by scanning electron microscope (SEM) on the etched PC/ABS specimen.
This latter result well correlates the results obtained from the testing. It therefore reveals that
immiscibility between PC and ABS in the blend plays an important role in determining the impact
resistance of the components. This paper also presents simulative results of the test obtained from a
FEA work by introducing a 3D- layered finite element (FE) model of the PC/ABS specimen to take
into account effect of a layer in the core on the behavior of the blend.
Study of Initiator’s Shock-Resistibility Through Impact Using Hopkinson Pressure Bar
Authors: Deng Qiong , Li Yu Long , Suo Tao , Chen Chun Lin , Chang Xing Min
Published: March 2009

This paper attempted to study the properties of Slapper detonator non-energetic elements
through exerting impact on them by Hopkinson Pressure Bar and evaluating the acceleration that
samples received in accordance with one-dimensional stress wave theory. The results showed that the
velocity pulse width could be controlled and acceleration pulse width be improved by varying the
pulse shaper material and strike bar length. And the critical acceleration causing the failure of the
initiator was closely connected with acceleration pulse width as well as acceleration amplitude. When
the strike bar length were 126 mm, 190 mm, 270 mm and 460 mm, the acceleration pulse width were
58 μs, 93 μs, 130 μs and 160 μs, respectively, and the critical acceleration causing the failure of the
initiator were about 240 000 g, 130 000 g, 74 000 g and 72 000 g, respectively. The accurateness and
reliability of acceleration value was accredited to the methods of changing sampling frequency,
smoothing velocity and acceleration curve, and fitting curve. The FEM analog simulation was also
conducted by using the LS-DYNA finite element program. Good agreements were achieved between
the acceleration curve and the simulation results.
Torsion Fracture Behavior of Drawn Pearlitic Steel Wires with Different Heat Treatments
Authors: Wang Zhi Jia , Wu Xiao Lei , Hong You Shi
Published: March 2009

In this paper, torsion fracture behavior of drawn pearlitic steel wires with different heat
treatments was investigated. Samples with different heat treatment conditions were subjected to
torsion and tensile tests. The shear strain along the torsion sample after fracture was measured.
Fracture surface of wires was examined by Scanning Electron Microscopy. In addition, the method of
Differential Scanning Calorimetry was used to characterize the thermodynamic process in the heat
treatment. A numerical simulation via finite element method on temperature field evolution for the
wire during heat treatment process was performed. The results show that both strain aging and
recovery process occur in the material within the temperature range between room temperature and
435 °C. It was shown that the ductility measured by the number of twists drops at short heating times
and recovers after further heating in the lead bath of 435 °C. On the other hand, the strength of the
wire increases at short heating times and decreases after further heating. The microstructure
inhomogeneity due to short period of heat treatment, coupled with the gradient characteristics of shear
deformation during torsion, results in localized shear deformation of the wire. In this situation, shear
cracks nucleate between lamella and the wire breaks with low number of twists.
Shrinkage Cracking Test and Analytical Model for Concrete Considering Creep Behaviour at Early Age
Authors: Li Yun Feng , Yao Yan , Wang Ling
Published: March 2009

Cracking due to the restrained shrinkage stress has been frequently observed at early age in
concrete construction. The early-age shrinkage cracking reduce the structural performance of concrete
and may accelerate deterioration to shorten the service life. Two kinds of strategies and
instrumentation have been developed to assess early age cracking: ring tests with a restraining core,
longitudinal tests where the restraint is at the end grips of the specimen. Early-age concrete exhibits
creep or relaxation behavior that is a typical response of viscoelastic materials. Viscoelastic
constitutive model should be used to analyze stress development of the restrained concrete. The
assessment of the risk of cracking can be based on the model with input of the estimated concrete
deformation.
Microstructure and Grain Abrasion Properties of TiC-xNi Coatings Prepared by Electro-Thermal Explosion Ultra-High Speed Spraying
Authors: Liu Zong De , Li Bin , Wang Zhang Qi , Liu Jing Jing , Ji W.
Published: March 2009

In this work, a new method, electro-thermal explosion ultra-high speed spraying (EEUSS),
was utilized to synthesize the titanium carbide based and nickel bonded (TiC-xNi) coatings. The
nickel content was varied at the weight percents of 5, 10, 15 and 20%. The microstructure and
properties of the coatings were studied by means of scanning electron microscope (SEM), X-ray
diffraction (XRD) and microhardness tester, respectively. The TiC-xNi coatings had the metallurgical
bonding with the substrate, and consisted of submicron grains. The grain abrasion tests results
showed that the abrasion resistance of the coatings was affected by the contents of Ni.
The Plane Problem Solution of Piezoelectric Material with a Line Crack
Authors: Liu Shu Hong , Du Yan Liang , Qi Yue Qin , Yang Cong Juan
Published: March 2009

A two-dimensional electromechanical analysis is performed on a transversely isotropic
piezoelectric material containing a line crack of length 2a, which is subjected to uniform distributed
forces with intensity q along the crack faces and uniform electric displacement fields at infinity.
Based on the impermeable electric boundary conditions, the closed complex form expression for the
electromechanical fields are deduced in the vicinity of the crack. Taking PZT-4 ceramic into
consideration, electromechanical fields under different loads are illustrated through several examples.
It can be seen that electromechanical fields show 1/2 order singularity at the crack tip, and the
piezoelectric effect can’t be negelected.
Fatigue Crack Growth Simulations and Experimental Findings for SEN-Specimens under Different Loadings
Authors: Buchholz Friedrich G. , Wiebesiek J. , Teichrieb Victor , Fulland M.
Published: March 2009

In this paper the rather complex 3D fatigue crack growth behaviour in a SEN-specimens
under anti-plane shear or torsion loading is investigated by the aid of the programme
ADAPCRACK3D and by application of a recently developed 3D fracture criterion. It will be shown
that the computationally simulated results of fatigue crack growth in the FE-models of the
specimens are in good agreement with experimental findings for the development of two antisymmetric
cracks, which originate from the two crack front corner points, that is where the crack
front intersects the free surfaces of the laboratory SEN test-specimens. Consequently, also for these
cases with a rather complex 3D crack growth of two anti-symmetric cracks, the functionality of the
ADAPCRACK3D-programme and the validity of the proposed 3D fracture criterion can be stated.