bluuebunny/crossref_metadata_2025 huggingface dataset:
Enhancement of the Quality of the ZnO Thin Films by Optimizing the Process Parameters of High-Temperature RF Magnetron Sputtering
Authors: Lee Chong Mu , Kim Choong Mo , Kim Sook Joo , Park Yun Kyu
Published: March 2009

ZnO thin films were deposited on sapphire (α-Al2O3) substrates by RF magnetron sputtering at
substrate temperatures of 500, 600, 650 and 700°C for 3h at rf-powers ranging from 60 to 120 W. The
FWHM of the XRD (0002) peak for the ZnO film was reduced down to 0.07° by optimizing the chamber
pressure at a substrate temperature of 700°C. Sharp near-band-edge emission was observed in the
photoluminescence (PL) spectrum for the ZnO film grown at room temperature. Excess RF power
aggravates the crystallinity and the surface roughness of the ZnO thin film. Pole figure, AES and PL
analysis results confirm us that RF magnetron sputtering offers ZnO films with a lower density of
crystallographic defects. ZnO films with a high quality can be obtained by optimizing the substrate
temperature, RF power, and pressure of the RF magnetron sputtering process.
Preparation and Characterization of ZnO Thin Film Doped with Eu via Sol-Gel Method
Authors: Xue Dao Qi , Zhang Jun Ying , Feng Hai Bing , Wang Tian Min
Published: March 2009

ZnO:Eu3+ films were obtained by dip-coating method and influence of heat treatment on luminescent properties was investigated. Emission and excitation spectra revealed that the organic and nitrate molecules, which adhered on the surface of films when the samples were treated at lower temperatures (300oC-400oC), played an important role on the luminescent properties. At higher temperatures (500oC-800oC), the luminescence spectra of ZnO and Eu3+ were quite different with those treated at lower temperatures. Energy transferred from ZnO host to Eu3+ was obviously observed in the emission and excitation spectra. The luminescence mechanism was discussed briefly.
Synthesis of Ultrafine Lu2Hf2O7/Tb Phosphor by Solution Combustion Process
Authors: Liao Yi Kun , Jiang Dan Yu , Xu Yun Peng , Shi Jian Lin
Published: March 2009

Ultrafine terbium-doped Lu2Hf2O7/Tb phosphor powders are prepared by a solution
combustion process using glycine and urea as fuel. Phase evolution of the synthesized powder is
determined by X-ray diffraction (XRD) techniques. Single-phase cubic Lu2Hf2O7/Tb crystalline powder
is obtained by calcining the amorphous materials at 800oC and no intermediate phase is observed.
Transmission electronic microscope (TEM) morphology shows that the resultant Lu2Hf2O7/Tb powders
have uniform size and good homogeneity. The photoluminescence (PL) spectra of Tb3+ substituted for
Lu3+ in Lu2Hf2O7 with different content has been measured on samples calcined at 1000oC.
Ferromagnetic Properties of Ni0.2Cu0.2Zn0.6Fe2O4-PZT Composites
Authors: Qi Xi Wei , Yu Zhi Yong , Li Ming Ya , Zhou Ji , Yue Zhen Xing
Published: March 2009

A series of novel composites with the composition of xNiCuZn-(1-x)PZT (NiCuZn: Ni0.2Cu0.2Zn0.6Fe2O4; PZT: PbZr0.52Ti0.48O3.) were prepared by solid-state reaction methods. The presence of ferromagnetic NiCuZn ferrite phase and ferroelectric PZT phase was confirmed by XRD analysis. It was revealed that composite materials exhibit typical ferromagnetic hysteresis behaviors. With the increase of phase fraction of NiCuZn ferrite, the permeability of composites increases and the natural resonance peak appears. Meanwhile, the maximum of quality factors shifts to the lower frequency.
Influence of Extrusion Temperature on the Thermoelectric Properties of p-Type Ag Added (Bi0.25Sb0.75)2Te3 Alloys Prepared by MA-PDS
Authors: Min Wang Kee , Lee Chang Ho , Park Yong Ho , Park Ik Min
Published: March 2009

The direct extrusion process using the powder as raw materials was applied to prepare the
thermoelectric materials. The mechanically alloyed powders of Ag added (Bi0.25Sb0.75)2Te3 were extruded
by pulse discharge sintering method in the temperature range of 345°C ~ 425°C. High quality products
were obtained by hot-extrusion method and their texture and thermoelectric properties were measured.
The intensity of (110) plane increased with extrusion temperature up to 385°C and altered in the range of
above 405°Cwhich coincided with the variation of power factor. The measured Power factor ranged from
3.5 ~ 4.0 × 10-3 W/K2·m. The figure of merit (Z) of the material extruded at 385°C was 3.1 × 10-3 /K, the
highest value among the prepared materials.
Preparation of Mullite Powder by Aluminum Sulfate and Silica in Molten Sodium Sulfate
Authors: Zhu Bo Quan , Li Xue Dong , Hao Rui , Wang Hou Zhi
Published: March 2009

Mullite powder was prepared through reaction of aluminum sulfate and silica in molten sodium sulfate media. The phase composition and microstructure of mullite powder were investigated. The results showed that high purity mullite is prepared by this method. The mullite powder exhibits needle-like whisker crystal with 50~100 nm in diameter and 3~8 #m in length. It is found that by this method mullite starts to form at 900oC, the quartz phase is disappeared about 1000oC, and mullite begin to decompose when the temperature is over 1100oC. Thus, the reasonable synthesizing temperature is about 1000oC. This synthetic method is characterized by process simplicity, the temperature of mullite formation is lower than 200-400oC compared with other conventional methods.
Combustion Synthesis of Magnesium Silicon Nitride Powders in the Mg-Si-N System
Authors: Wang Fei , Shen Wei Ping , Bai Ling , Ge Chang Chun
Published: March 2009

A combustion synthesis process was developed for the synthesis of magnesium silicon nitride
powders in the Mg-Si-N system. The effects of ammonium halide addition and the nitrogen presssure on
the phase composition and microstructure of the final product were discussed in detail. It was found that
ammonium halides were helpful to enhance the nitrogen infiltration, decrease the agglomeration degree
and improve the nitridation reaction. Furthermore, the nitrogen presssure greatly influenced the reaction
process and the properties of the final MgSiN2 products, especially the phase composition. MgSiN2
powders with low level of impurities (MgO and free Si) could be synthesized through combustion
synthesis process in the Mg-Si-N system.
Ultraprecision Ductile-Regime Cutting of Brittle Materials
Authors: Zhou Ming , Liu X.D. , Huang S.N.
Published: March 2009

Soda-lime glass is a typical brittle material, which is difficult to realize ductile-regime machining by using conventional cutting technology due to the extremely small critical depth of cut. In this work, the micro-deformation characteristics of this kind of materials were analyzed by micro indentation. Ultrasonic vibration assisted diamond cutting was performed in order to investigate the effect of tool vibration on material removal process and surface quality. The profiles of cut surfaces were measured and compared with those obtained by conventional diamond cutting. Real depths of cut in ultrasonic vibration cutting correspond well with the nominal ones. The change in the tribology of the cutting process as well as the alteration of the deformation mechanism of the work material might be responsible for the reduction in tool wear in vibration cutting.
Fabrication of Freeform Optics in Ultra-Precision Raster Milling
Authors: Wang Su Juan , Cheung Chi Fai , To Sandy , Lee Wing Bun
Published: March 2009

Recently, the high quality and high productivity in fabrication of freeform optics has been
of primary interest in manufacturing industries, such as die and mould manufacturing, aerospace part
manufacturing, and so forth. However, the fabrication of freeform optics is currently expensive and
vastly complex. Ultra-precision raster milling can produce non-rotational symmetric surfaces with
sub-micrometric form accuracy and nanometric surface finish without the need for any subsequent
post polishing. While, there is little research work focus on this kind of machining method. This paper
presents a framework of a tool path generation system for freeform surface ultra-precision raster
milling. This system includes model of freeform optics, tool path generator, interference monitor and
an optimization model of machining parameters. The tool path generation system can generate
interference free and optimal tool path for machining freeform surfaces. Some simulation results have
been presented to illustrate the performance of the system.
Effects of Actively Cooled Coolant for Grinding Ductile Materials
Authors: Gao Y. , Lai H.
Published: March 2009

An active cooling approach for coolant during ductile material grinding is proposed and
examined. The aim is to enhance surface quality and to enhance productivity. The problem associated
with the cryogenic cooling approach and the one with the chilled air approach are addressed. An
active cooling prototype was developed utilizing a compact heat pump design, which is easy to use,
movable, and can be easily fitted into different type of machine designs with relatively low costs. The
system is based on the use of forced convection of the heat generated during the machining process.
Experimental and computational studies of the effects of actively cooled coolant for grinding ductile
materials are carried out. The experimental results show that the use of actively cooled coolant is able
to improve surface quality by up to 29.95% on average in terms of surface roughness Ra.
Computational testing results show that the heat can be taken away more effectively by using the
proposed approach. The results of optical and SEM examinations also confirmed that the proposed
approach is advantageous.
Simulation and Analysis of a Micro-Fluidics Cooling System
Authors: Liu Xiao Wei , Chuai Rong Yan , Zhang You Feng , Tao Q.F.
Published: March 2009

The paper presents a micro-fluidics cooling system which is designed on a silicon substrate
including a micro-pump, two temperature sensors, a flow sensor and some microchannels. To design
the cooling system optimally, a finite element model is built. The temperature distribution on the
silicon substrate is analyzed using the model. Moreover, the quantitative relation is given of the
temperature distribution, flow velocity and driving capability of the micro pump. Consequently, the
structure parameters and design requirements of the cooling system are obtained.
Forecasting of Surface Roughness and Cutting Force in Single Point Diamond Turning for KDP Crystal
Authors: Wang Jing He , Dong Shen , Wang H.X. , Chen Ming Jun , Zong Wen Jun , Zhang L.J.
Published: March 2009

The method of single point diamond turning is used to machine KDP crystal. A regression analysis is adopted to construct a prediction model for surface roughness and cutting force, which realizes the purposes of pre-machining design, prediction and control of surface roughness and cutting force. The prediction model is utilized to analyze the influences of feed, cutting speed and depth of cut on the surface roughness and cutting force. And the optimal cutting parameters of KDP crystal on such condition are acquired by optimum design. The optimum estimated values of surface roughness and cutting force are 7.369nm and 0.15N, respectively .Using the optimal cutting parameters, the surface roughness Ra, 7.927nm, and cutting force, 0.19N, are obatained.
Evaluation of Strain Concentration in Carbon Nanotube with Bend Junction
Authors: Kinoshita Yusuke , Umeno Yoshitaka , Kitamura Takayuki
Published: March 2009

Carbon nanotubes (CNTs) have been attracting attention because of their prominent
mechanical and electronic properties. In this study, we investigate the deformation of a single-walled
carbon nanotube (SWCNT) with a bend junction using atomistic modeling with Brenner potential to
analyze strain concentration caused by macroscopic tube shape and microscopic interatomic bond
structure. The simulation model consists of (8,8) and (14,0) CNTs connected with a flexion angle of
30 degrees. For geometric reasons five and seven-membered rings are introduced at the inside and
outside of the bend junction. After the structure under no external load is determined, tensile load is
applied to the model. Then, we analyze the strain concentration at the bend junction, and high tensile
strain is observed at the inside of the bend junction. The strain at the seven-membered ring at the
inside of the bend junction has higher strain compared to the neighboring rings due to the microscopic
effect.
Strain-Rate-Dependent Deformation Behavior of Carbon-Black-Filled Rubber under Monotonic and Cyclic Straining
Authors: Tomita Yoshihiro , Azuma K. , Naito M.
Published: March 2009

The constitutive equation of rubber is derived by employing a nonaffine molecular chain
network model for an elastic deformation behavior and the reptation theory for a viscoelastic deformation
behavior. The results reveal the roles of the individual springs and dashpot, and the strain rate dependence
of materials and disentanglement of molecular chains in the monotonic and cyclic deformation behaviors,
particularly softening and hysteresis loss, that is, the Mullins effect, occurring in stress-stretch curves under
cyclic deformation processes.
Coupling Analysis between Stress Induced Anisotropic Damage and Permeability Variation in Brittle Rocks
Authors: Zhou Hui , Shao Jian Fu , Feng Xia Ting , Hu Da Wei
Published: March 2009

In this paper, a coupling constitutive model is proposed for anisotropic damage and
permeability variation in brittle rocks before cracks fully coalesce. In this coupling model, an
anisotropic damage model is employed to perform the mechanical analysis, and a statistical
penetration model is set up to describe the effective porosity and permeability evolution in brittle
rocks. For the coupling analysis, anisotropic damage model offers statistical penetration model the
crack length in various directions, and statistical penetration model inversely provides anisotropic
damage model with permeability of rock for coupling hydro-mechanical analysis. The proposed
coupling model is applied to Lac du Bonnet granite, and generally a good agreement is obtained
between numerical simulations and experimental data.
Genetic Analysis of Concrete Crack in Hydroelectric Station's Plant Based on FEM
Authors: Huang Shu Ping , Peng Xuan Mao , Ling Qi , Dai Yi Hua , Du Cheng Peng
Published: March 2009

This study is mainly in temperature-control and anti-cracking of plant concrete in
hydroelectric station. By means of FEM of three-dimension thermal creep stress and imitating
construction progress, an emulator calculation is performed from construction period to operation
period and distribution regularity of thermal creep stress is brought to light in the theory. The text
described the developing process of concrete’s temperature and thermal stress, and then combined
concrete’s time-varied thermotics and mechanics performance to analyze the possibility of yielding
crack in different period and position.
Analysis of Soil-Structure Interaction with Finite Element Method
Authors: Liao Hong Jian , Liu Jian , Zhao Yan Gang , Xiao Zheng Hua
Published: March 2009

Analysis of dynamic behavior of soil-structure interaction (SSI) is a complicated problem
due to the complexities of soil behaviors and dynamic analysis. It is difficult to solve SSI with
analytical methods. However, numerical methods with highly developed computer technique are
efficient. Based on the advanced nonlinear finite element analysis software MSC.Marc, SSI on loess
ground is studied. An approach for the application of MSC.Marc in SSI analysis is presented and an
example is given. Hyperbolic soil constitutive relationship and viscous boundary conditions are
adopted in the soil model. Moreover, contact between the embedded columns and the adjacent soil
is considered. Response spectrum analysis of the result is carried out. Some conclusions about the
seismic response of soil-structure system under different soil stiffness and different soil-layer
thickness conditions are given. A new way of analyzing SSI for loess ground is provided.
Study of Design and Evaluation of Drum Assembly for High Speed Dehydration in Washing Machine
Authors: Kim Eui Soo , Kim Byung Min
Published: March 2009

Because customers are requiring front-loaded washing machine to handle big capacity laundry and
have faster rotation speed to increase drying ability, there are being a lot of studies for achievement of
high speed dehydration, high-strength and lightweight of washing machine in the latest washing
machine business. It is essential that strength of Drum Assembly which is composed of spin drum,
shaft, flange is improved to attain that target. In term of spin drum, it is difficult to realize joint
strength required at high speed operation because joint strength of mechanical press-joining method is
low remarkably in comparison with welding. Also in case of shaft system, stress from bending and
twisting are complexly loaded onto the shaft supporting the horizontal drum, causing problems in
fracture strength and fatigue life. The results of this study show optimal joining condition for
mechanical press-joining by performing lots of tensile joining strength test with various specimen
under multi-change of important design factor such as seaming width, bead area and bead depth etc.
and the optimal design of shafting system for big capacity, high-rotation drying through strength
analysis, experiment and evaluation.
Reliability Analysis for Effects of Reservoir Water Level Change on Embankment Dam
Authors: Han Bo , Liao Hong Jian , Sassa Kyoji , Wang Fa Wu
Published: March 2009

This paper is mainly concerned with the saturated-unsaturated seepage analysis of
embankment dams based on unsaturated soil theory and the reliability analysis of embankment dam
based on conception of reliability. The transient seepage due to change of the water level is
calculated using the finite element method based on unifying saturated-unsaturated seepage
governing equations. The transient pore water pressures are then used for stability analyses of
embankment dam considering the effects of suction on shear strength of unsaturated soils.
Meanwhile, combined with reliability computation, the Monte-Carlo stimulation method is used to
calculate the corresponding reliability index dealing with the stochastic features of soil parameters.
The reliability of different water level condition of embankment dams has been analyzed. The
effects of different reservoir water level drawdown and raise speeds on reliability of embankment
dam are discussed.
Analysis of Hydrogen Diffusion in Notched High-Strength Steel Wires
Authors: Bing Lin
Published: March 2009

Fick's laws were used to model the hydrogen diffusion in notched high-strength steel
wires loaded in tension under elastic-plastic conditions. The plastic deformation at the notch tip has
an effect on the peak distribution of the hydrostatic stress ( h σ ). So, in stress-assisted diffusion
analysis, elastic-plastic material behavior should be considered. Coupled diffusion elastic-plastic
finite element analysis was implemented in the finite element program ABAQUS using the user
element subroutine (UEL) and the coupled temperature-displacement solver routine to solve the
variational form of the diffusion equation in order to obtain the hydrogen concentration distribution
ahead of the notch tip in high-strength steel wires under plane strain conditions. The analysis results
are compared with those obtained from elastic analysis, which shows that, if a critical hydrogen
concentration is regarded as a local fracture criterion, the elastic-plastic analysis results can be used
to evaluate the hydrogen embrittlement of high-strength steel wires.
The Production and Performance Estimation of Dunnage for Transportation of a Steel Roll Coil
Authors: Kwac Lee Ku , Kim Hong Gun , Kim Hang Woo
Published: March 2009

The common transportation methods for the consumers of the ironwork such as the steel
roll coils manufactured from the steelworks were either by the land transportation or the sea
transportation. In order to transport the steel roll coil effectively and safely to the destination, the
stability of the steel roll coil which induced the minimum movements during the transportation was
strongly required. The basic transportation equipment for the steel roll coil such as the dunnage is
made of 100% imported wood known as the apitong. However, the material characteristic such as the
rigidity has caused permanent damages to the steel roll coil and the damaged steel roll coils were not
easily restorable thus they were unsuitable for other purposes. Therefore, the introduction of new
materials manufacturing dunnages which would have a good recovery performance and thus enable
the damage prevention or reduction to the steel roll coil or any other products during the
transportation is needed. This investigation was to develop the new and improved type of a dunnage
from observing the current dunnage in the following areas; the array or the types of reinforcements
that established the construction of the dunnage, the dunnage forming shapes of a rectangle and a
trapezoid, the direct impacts to dunnage in the presence of vibration when the carrier was moving and
stopping, and the critical impact to the dunnage due to the edge loading. Ultimately, the development
of new type of dunnage that consisted of characteristics being soft and recoverable than the existing
apitong dunnage and induces little or no damages to the steel roll coils are required.
Multi Stage Seaming Process for Large Tubular Mechanical Bonded Structure
Authors: Kim Yoon , Kang Dong Woo , Ku Tae Wan , Kim Jeong , Kang Beom Soo
Published: March 2009

This study is dedicated to three-dimensional finite element analysis of seaming process,
which consists of bending, curling and caulking process, of a large tubular mechanical bonded
structure. The seaming process is often used to improve a high bonding strength as avoiding any
kind of defect. Finite element simulations of the seaming process were preformed for two different
initial conditions with pre-analyzed results and without those from bending process. The
mechanical bonding strength of the seamed area in the large tubular structure was estimated and
compared through finite element analysis among several different analysis conditions of the
bending and the caulking. Tensile test for the specimen extracted from the large tubular mechanical
bonded structure was also executed and compared with the results of finite element analysis, in
order to verify which initial condition in finite element analysis was suitable for this kind of multi
stage seaming process. As a result, the effect on an accuracy of finite element analysis for the multi
stage seaming process was evaluated in this study. Finally, it is noted that the pre-analyzed results
from bending process should be considered in order to obtain the accurate results from finite
element analysis.
Finite Element Simulation of Self-Piercing Riveting of Three Aluminium Alloy Sheets
Authors: Kato T. , Abe Y. , Mori Kenichiro
Published: March 2009

The joinability of three aluminium alloy sheets using a self-piercing rivet was evaluated
from a finite element simulation and experiment. The self-piercing riveting is hopeful as
replacement of spot resistance welding generally used for steel sheets, because it is not easy to
apply the resistance welding to joining of three aluminium alloy sheets due to the high thermal
conductivity. Defects in the riveting are categorized into the penetration through the lower sheet, the
necking of the lower sheet and the short overlap of sheets to obtain optimum joining conditions.
The penetration and the necking are caused by small total thickness. The short overlap tends to
occur as the ratio of lower sheet and total thickness is small. In addition, the cross-tension test was
simulated by the finite element method to evaluate the joint strength.
Self Loosening Behavior of Metal Thread Joints under Transverse Cyclic Loading
Authors: Nishimura Naoya , Hattori Toshio , Yamashita Minoru , Hayakawa Naoyuki
Published: March 2009

Considering the productivity and the maintenance, most of machine and product has
many joints (fastening, welding and adhesive joint). Especially, the thread joint has been used the
most mainly as a machine element. However, many troubles on strength and reliability of these
machine and product are generating in these joints. In this paper, we have evaluated the sliding and
the self loosening behavior of thread joints under transverse loading, where the entire response of
the thread joint portion exhibits an inelastic one. The finite element analysis using a simple model
of thread joints with respect to the relative sliding motion between the parts was performed and
compared with the experimental results under quasi-static loading. The critical relative slippage
(Scr), less than the value which thread joints can keep the fastening, was obtained by the result of
cyclic loading tests. In addition, this critical relative slippage was estimated according to the
theoretically obtained equation considering the bolt bending and the geometrical constraint
condition. The inclination compliance (kw) of the bolt head used in this equation was evaluated by
the comparison of experimental and analytical results from theoretical equation. In consideration of
the nonlinearity of kw with respect to the bolt axial tension, the Scr is well estimated by this
equation.
Dependence of Localized Deformation on Point Defect Development Caused by Intersected Cross Slip among Dislocations
Authors: Kobayashi Michiaki , Aoyama Naohiro , Hashiba Shou , Miura Setsuo , Shibano Junichi
Published: March 2009

In this paper, via experimental results of ultrasonic wave velocity changes and FEPM
simulations of slip system under the pure shear plastic deformation of a pure Aluminum single
crystal, the authors verify that the ultrasonic longitudinal wave velocity depends upon the
development of point defects caused by intersected cross slip among dislocations and also examine
the correlation of the point defect dependence of the longitudinal wave velocity with the elastic
stiffness degradation due to plastic deformation damage which is closely related to the deformation
instability mechanism.
Dynamic Tensile Characteristics of TRIP-Type and DP-Type Sheets for an Auto-Body
Authors: Kim Seok Bong , Huh Hoon , Park Sung Ho , Lim Ji Ho
Published: March 2009

This paper investigates the dynamic tensile characteristics of TRIP600, TRIP800, DP600
and DP800 at the range of strain rate from 0.003 to 200/s. The tensile test acquires stress−strain curves
and the strain rate sensitivity of each material. Experimental results show two important aspects for
TRIP-type and DP-type sheets quantitatively: the flow stress increases as the strain rate increases; the
elongation is not a monotonic function of the strain rate and increases at the same level of the strain
rate even when the strain rate increases.
In order to investigate the pre-strain effect for two types of metals at the high strain rate, TRIP600
and DP600 were elongated with the pre-strain of 5 and 10% at the strain rate of 0.003/s. Then,
dynamic tensile tests were carried out at the strain rate of 0.003, 1, 10 and 100/s. The results
demonstrate that the material properties of TRIP600 and DP600 are noticeably influenced by the
pre-strain when the strain rate was over 1/s. The ultimate tensile strength as well as the yield stress
increases due to the pre-strain effect.
Counterintuitive Dynamic Behavior in Elastic-Plastic Structures
Authors: Yang Gui Tong , Wu Gui Ying , Zhang Nian Mei
Published: March 2009

The counterintuitive phenomena of elastic, perfectly plastic beam, circular plate and
square plate are investigated numerically and experimentally. The unsteady areas and uncertainty
of response are observed numerically. At the end, the law of thermodynamics and the theorem of
Lyapunov instability are employed to state the formation mechanism of counterintuitive behavior.
A Dynamic Damage Model for Uniaxial Compressive Response of AD90 Alumina
Authors: Ren Hui Lan , Li Ping
Published: March 2009

The dynamic response of polycrystalline alumina were investigated in the pressure range
of 0-13Gpa by planar impact experiments. Manganin gauges were employed to obtain the
stress-time histories. From the free surface particle velocity profiles indicate the dispersion of the
“plastic” wave for alumina. Using path line principle of Lagrange Analysis the dynamic mechanical
behaviors for alumina under impact loading are analyzed, such as nonlinear, strain rate dependence,
dispersion and declination of shock wave in the material. A damage model applicable to ceramics
subjected to dynamic compressive loading is developed. The model is based on the damage
micromechanics and established on wing crack nucleation and growth. The results of the dynamic
damage evolution model are compared to the experimental results and a good correlation is
obtained.
On Dynamical Systems at the Portevin-Le Chatelier Effect
Authors: Béda Peter B.
Published: March 2009

This paper studies Portevin-Le Chatelier (PLC) effect as a form of dynamic material
instability. In such phenomenon negative rate dependence is coupled with the appearance of a selfsustained
oscillatory behavior in solid bodies. The tools of the investigation are of the theory of
dynamical system. By selecting a proper form of the constitutive equation of the rate dependent
material, a dynamical system will be constructed from the basic equations of continua. Then the
birth of a self-sustained oscillation is detected at the conditions of a dynamic material instability
mode. This results show an interpretation of PLC as a flutter type of loss of material stability.
Periodic Motions and Bifurcations of a Plastic Impact Machine
Authors: Luo Guan Wei , Zhang Yan Long , Yao Hui Ming
Published: March 2009

A mathematical model is developed to describe the characteristic behavior of a small
vibro-impact pile driver. Dynamics of the small vibro-impact pile driver is represented by a
three-dimensional map. The map is of piecewise property due to synchronous and non-synchronous
motion of the driver and pile immediately after the plastic impact, and singularities caused by
grazing contact of the driver and pile. The pile driver exhibits two different types of single-impact
periodic motions in different regions of the forcing frequency due to the plastic impacts. Transition
of two types of single-impact periodic motions is demonstrated, and the influence of the piecewise
property, singularities and various parameters on the performance of the pile driver is analyzed.
Finite Element Analysis of Alternate Hard and Soft Multi-Layers under Circumscription Loading
Authors: Li Li Juan , Lin Min , Liu Feng
Published: March 2009

For a quantitative analysis and better understanding of the stress-strain response and their
effects on interface debonding and crack initiation and propagation of alternative hard and soft
multi-layers under circumscription loading, to explore methodologies of optimum design of surface
multi-layers, large strain elasto-plastic finite element method is used to evaluate the mechanical
behaviors of TiN/Ti multi-layer films on rigid substrate under hard asperity indentation. The
results show that with the same total thickness of the film, the alternate hard and soft multi-layers
with larger ratio could endure larger circumscription loading, and the different total thickness of
multi-layers could affect the circumscription loading greatly. So there must be a circumscription
loading in this multi-layer film structures. Generally speaking, the circumscription loading has
something to do with the material modulus, the radius of the press-head, the thickness ratio of soft
and hard layers, and the total thickness of alternate hard and soft multi-layers. For a quantitative
analysis of this problem, finite element method is utilized to analyze the phenomena of the plastic
indentation. According to analysis of the film deformation, the maximum bending stress, and the
surface bending stress, and those parameters that have influence on different alternative films are
studied. The study of this paper is expected to provide some theoretical basis for the optimum
design of multi-layer film structures.
Development of Stereolithography Simulation Process Based on the Dynamic Finite Element Method
Authors: Huang You Min , Jiang Cho Pei
Published: March 2009

In this study, a general simulation code is developed to analyze the shrinkage effect of
polymerization and optimize the fabrication parameters including the scanning path, exposure time
and scanning speed for the stereolithography system. The code is based on the dynamic finite element
method. Liquid element is preconstructed without curing properties till the absorption energy exceeds
the critical value of dynamic stiffness matrix assembling. A unit element block is utilized with a
weight coefficient for expressing a laser Gaussian energy distribution during the discretizing of the
scanning path into increments. A fan blade is proposed to validate the agreement between the
simulation and experimental results. The prototype is a fabrication and the surface of blade was
measured by the digitizing system ATOS (Advanced TOpometric Sensor) for comparing the
deformation with analysis prediction. Consequently, the simulated result closely conforms to the
experimental result.
An Elasto-Plastic Finite Element Simulation of the UO-Tube Processes of Sheet Metal
Authors: Chen Tsung Chia , Huang You Min
Published: March 2009

This study aims to clarify the process conditions of the UO-tube of a sheet metal of steel. It
provides a model that predicts not only the correct punch load for drawing, but also the precise final
shape of products after unloading, based on the tensile properties of the material and the geometry of
the tools used. An elasto-plastic incremental finite-element computer code, based on an updated
Lagrangian formulation, was developed to simulate the UO-tube process of sheet metal; the results
are compared with corresponding experimental results. Special care was taken to formulate accurate
boundary conditions of penetration, separation and alternation of the sliding-sticking state of friction,
as the contact conditions between the tools and the sheet varied throughout the entire processes of
U-bending and successive O-bending. Calculated sheet geometries and forming force agree well with
experimental data. In particular, selective reduced integration was adopted to formulate the stiffness
matrix. The extended r-minimum technique was used to deal with the elasto-plastic state and contact
problems at the tool-metal interface. A series of simulations were performed to validate the
formulation in the theory, leading to the development of the computer codes. The whole deformation
history, the distribution of stress and the distribution of strain during the forming process were
obtained by carefully considering the moving boundary condition in the finite-element method. The
simulation demonstrates clearly the efficiency of the code to simulate various bending processes that
proceed under complicated deformation- and contact-history.
Development of PC Cluster Parallel Processing Scheme of 3-D Rigid-Plastic Finite Element Method Using Diagonal Matrix
Authors: Mori Kenichiro , Kanno Y.
Published: March 2009

The 3-D rigid-plastic finite element method using a diagonal matrix was applied to
parallel processing using a distributed memory type PC cluster. The cluster composed of cheap PCs
becomes common as a low-cost system in the parallel processing. Since the computers in the
distributed memory type PC cluster have individual memory units, the transfer of date among
computers during the computation is required, and thus the time for the data transfer is taken into
consideration. The renewal of data in each computation is limited because of the time of data
transfer unlike the shared memory type workstation. This brings about the delay of data renewal. A
data transfer scheme was investigated to optimize the total computational time in the parallel
processing. The effect of the delay of date renewal on the convergence of the solution was
examined in the simulation of upsetting of rectangular block with an inclined tool by means of a
cluster composed of 4 PCs and 100MBit/s Ethernet.
The Dependence of the Energy-Absorption Capacity of Metal Hollow Sphere Materials on their Relative Density
Authors: Yu T.X. , Karagiozova D. , Gao Z.Y.
Published: March 2009

Experimental, numerical and theoretical analyses are carried out to obtain the relationship
between the stress and relative density of metal hollow sphere (MHS) materials during their large
plastic deformation in order to estimate the energy absorbing capacity of these materials under
uniaxial compression. Based on a numerical parametric analysis empirical functions of the relative
material density are proposed for the elastic modulus, yield strength and ‘plateau’ stress for FCC
packing arrangement. Analytical stress-strain dependences are suggested for the yield strength and
material strain hardening properties as functions of the relative density of MHS materials under
uniaxial compression.
A Gray Prediction Model for Unequal-Interval Time Sequence and its Application in Creep Fracture Mechanics
Authors: Chen You Liang , Li Lin
Published: March 2009

The gray prediction theory has already been widely applied to solving all
kinds of social, scientific and technical problems. It is also used for the prediction of
engineering mechanical and material scientific problems. But the traditional gray
prediction model is applicable only for equidistant time sequences. In order to extend
the scope of application, an improved gray prediction model is put forward. By
weighted summation, the new developed gray prediction model can also be applied to
the situation of non-equidistant time sequence. The improved gray prediction model is
used for the prediction of creep fracture time of rocks and gypsum. The deduced
results are proven to be very accurate. The research work of the current paper opens
many opportunities for further thoughts of the prediction of many other engineering
mechanical problems.
Estimation of Hysteretic Energy of MDOF Structures Based on Equivalent SDOF Systems
Authors: Li Hong Nan , Wang Feng , Lu Zhao Hui
Published: March 2009

It is important for obtaining the relationship between seismic energies of single
degree-of-freedom (SDOF) systems and multiple degree-of-freedom (MDOF) structures in
engineering. In this paper, the formula of hysteretic energy between the MDOF structures and
equivalent SDOF systems is developed. Here is also presented the procedure for estimating
hysteretic energy of MDOF structures subjected to severe ground motions employing the energy
relation equation based on equivalent SDOF systems. Eight examples for two regular and six
irregular MDOF structures show that the procedure to obtain the hysteretic energy demands of
MDOF structures may be used as a simple and effective energy estimation method.
Fracture Parameters on Three-Dimensional Sliding Mode Fracture
Authors: Xu Fei , Li Yu Long , Guo Wan Lin
Published: March 2009

In the recent years three-dimensional (3D) elastic-plastic analyses have been conducted
extensively for the opening mode (mode I) fracture and the constraint effects are discussed in detail.
However less work is focused on other modes as sliding mode (mode II), tearing mode (mode III)
or the mixed mode fracture in three-dimensional. In this paper the thickness effect on pure mode II
case is discussed by the finite element method (FEM). Modified Boundary Layer (MBL) model is
used, which has the ability to take into account the combined effects of the in-plane constraint
(T-stress) and the out-of-plane constraint (finite thickness). The result demonstrates the weak
thickness dependence on the near tip stress and strain fields under mode II loading. And the size of
the 3D zone at mode II loading is determined to range from 1.0 to 1.2 times the thickness. Two
fracture parameters of J integral and crack tip sliding displacement (CTSD) are discussed, which are
almost same at different thickness planes except those very near the surface. It is interesting to find
that the relations between J and CTSD keep linear at different thickness planes. T-stress is
symmetry on stress and strain distributions along the crack plane. However its effects indicate weak
thickness dependent on the CTSD and J integral fracture parameter.
Characteristics of Complementary Plastic Energy Produced by Hysteresis Curves and Analyses of Microstructures in Fatigued Metals
Authors: Matsuno Hiroshi
Published: March 2009

Experimental characteristics of complementary plastic energy produced by a stress-strain
hysteresis curve at a saturated stage in low cycle fatigue are investigated for some steels, and mechanical
models for analyzing microstructures of fatigued metals are discussed. As a result, it is
found that volume of a cell is varied in inverse proportion to plastic strain range: the density of cells
is in proportion to plastic strain range. Consequently, the total number of cells is proportional to
plastic strain range. This final conclusion is similar to Winter's opinion concerning persistent slip
band structures in high cycle fatigue [1] where, although wall spacing of a cell is invariable and
inde-pendent of plastic strain range, a region occupied by persistent slip bands increases
proportionally to plastic strain range and consequently the number of cells is in proportion to plastic
strain range.
EBSD-AFM Hybrid Analysis of Crack Initiation in Stainless Steel under Fatigue Loading
Authors: Wang Yun , Kimura Hidehiko , Akiniwa Yoshiaki , Tanaka Keisuke
Published: March 2009

Both EBSD and AFM methods were used to investigate the active slip systems and
fatigue crack initiation behavior in face-centered cubic polycrystalline metal, austenitic stainless
steel, SUS316NG, under cyclic torsional loading. Most active slip planes are the primary slip planes
having the largest Schmid factor. Grains with slip band cracks or transcrystalline cracks have larger
Taylor's factors. On the basis of EBSD and AFM observations, h, the depth of intrusion vertical to
the surface, S, and the component of the slip displacement perpendicular to the surface trace, SB,
showed a sharp increase at the onset of crack initiation. The critical value of SB at crack initiation
was 170 nm.
A Numerical and Experimental Analysis on the Forming Limit of AA 3105 Aluminum Alloy in Radial Extrusion Process
Authors: Min K.H. , Ko B.D. , Ham B.S. , Ok J.H. , Hwang Beong Bok , Koo H.S. , Seo Jung Min
Published: March 2009

In this paper, the forming limit of flange in radial extrusion process was analyzed by the
rigid-plastic finite element method. The selected model material for simulation and experiments was
AA 3105 aluminum alloy. The predictions from simulation were made in terms of axial and
circumferential strains. Experiments also have been conducted to compare with the simulation results
with regards to deformation pattern. Furthermore, the deformation pattern in forming of flange
section was closely investigated and categorized in three cases such as sticking, separating and
cracking. The analysis in this paper is focused on the transient extrusion process of material flow into
the gap in radial direction for different gap heights and die corner radii. The results of present study
were summarized in terms of evolution of surface strains in axial and circumferential directions
measured from the finite element meshes located in the region where surface cracking occurred in
experiments. The forming limit line was drawn in the relationship of circumferential and axial strain.
It was concluded from this study that the forming limit line is influenced mainly by circumferential
strain on free surface of flange. It was also predicted that ductile fracture on flange surface is likely to
occur in the middle of flange gap under the condition of sticking deformation and near bottom of
flange gap under the condition of separating deformation, respectively. The forming limit of flange in
terms of flange diameter was expected about 2.5do, which is 2.5 times the diameter of original billet.
Formability of Roll Cast Recycled Aluminum Alloy
Authors: Nakamura Ryoji , Ikawa Masaki , Kumai Shinji , Watari Hisaki
Published: March 2009

Fe was added to 6016 aluminum alloy as the impurity, and this alloy was used as the model
of the recycled 6016 aluminum alloy. The content of the Fe was from 0.18 mass% up to 1.0 mass%.
6016 including impurity-Fe was cast into the strip using a high speed twin roll caster at speed of 60
m/min. The increase of the content of impurity-Fe makes castability better rather than worse. The
formability was investigated by tension test and 180 degrees bending test. The increase of Fe did not
have influence on the bending test. There was no crack at outer surface of T4-heat treated strip after
180 degrees bending. The formability of 6016 strip including impurity-Fe cast by the high speed twin
roll caster was enough for hem forming. The ductility of Fe added 6016 was improved by the high
speed twin roll caster. It is thought that Al-Si-Fe impurity became fine by the effect of the rapid
solidification, and deterioration could be improved.
A Study on the Pressure Distribution along the Powder-Die Interfaces in Powdered Metal Compaction Process
Authors: Koo H.S. , Jayasekera V.R. , Min K.H. , Seo Jung Min , Jang Dong Hwan , Ok J.H. , Hwang Beong Bok
Published: March 2009

This paper is concerned with the pressure distribution along the die-powder interface in
long parts. The pressure exerted on the interface at various points on the moving and stationary punch,
and also on the sidewall of container was investigated by the finite element method. A plasticity
theory describing asymmetric behavior of powdered metals in tension and compression was briefly
summarized. The yield criterion applied to the sintered powdered metals had been modified for
describing this asymmetric behavior. The material properties of copper powders under compaction
were also briefly described for the completeness of the paper. The copper powders were selected as a
model material in the present study. The main purpose of this study is to investigate the pressure
distribution along the interface of tooling quantitatively by the finite element method so that the
results could be applied usefully to the design of tooling, especially container design for powdered
metal compaction. Geometrical condition for analysis was confined to the Class II components which
is very long parts without steps. It was concluded from the simulation results that the pressure exerted
on the moving punch increases sharply near the outer circumference of punch and the pressure on the
sidewall decreases at a distance from moving punch to fixed punch. It was also seen from the
simulation that the pressure on the stationary punch is not significantly built up and decreases toward
outer periphery. These trends were seen amplified with severe frictional conditions imposed on the
tooling and powder interface.