bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of Different Doping on the Structure and Field-Stability of PMNT Ceramics
Authors: Wen Xiao Wei , Feng Chu De , Chen Li Dong , Huang Shi Ming
Published: March 2009

Effect of co-doping two different elements and incorporating SrBi2Nb2O9 (SBN) on structure
and field-stability of dielectric properties in PMNT ceramics were investigated. Single-phase cubic
Perovskite structure is more easily obtained by appropriate co- doping of La3+ and Zn2+. X-ray diffraction
patterns of PMNT/SBN composite showed that there is no SBN grains in PMNT/SBN as a secondary
phase. Co-doping of La3+ and Zn2+ as well as incorporation of SBN markedly increased the field-stability
of dielectric constant. The mechanism of improving field-stability was tentatively discussed.
Propagation and Deflection of Electric-Field-Induced Microcracks in 0.69Pb(Mg1/3Nb2/3)O3-0.31PbTiO3 Ferroelectric Single Crystals
Authors: Zhang Yong , Xu Z.
Published: March 2009

Propagation and deflection of microcracks driven by electric loading in <001>-oriented
0.69Pb(Mg1/3Nb2/3)O3-0.31PbTiO3 ferroelectric single crystals were investigated using an in-situ
transmission electron microcopy (TEM) technique. The static observation of the domain pattern
revealed the coexistence of sub-micrometer and nano-meter domains. Electric field induced deviation
from the main microcrack path and subsequent propagation along the direction almost perpendicular
to the electric field were observed directly. A qualitative analyses is given based on the maximum
energy release rate criterion.
Structure and Electrical Properties of Rapid Thermally Annealed PZT Films Deposited through Sol-Gel Process
Authors: Qiang Liang Sheng , Tang Dong Yan , Han Mu
Published: March 2009

In present work, sol-gel process is used to direct the organization of high quality and pore-free
parasite PZT thin films with a composition near the morphotropic phase boundary (Zr/Ti = 52/48). The
PZT transparent sol can be obtained by dissolving the zirconium oxynitrate, butyl titanate and lead acetate
in ethylene glycol with the molar ratio of 0.52:0.48:1 and the PZT gel can be gained by spin-coating. In
such process, PZT thin films can be readily prepared by hydrolysis on hot plate at 350°C for 20min and
annealing in RTA at 650°C for 1 minute. The structural and electric characteristics of the films have been
carried out by XRD, AFM and the C-V measurements, etc. Experimental results have indicated that by
treating film RTA at 6508 for 1 minute film with perfect crystallization and good surface morphology
with a RMS roughness of 2.0nm can be obtained, and the remnant polarization Pr (28.5 μC/cm2) and
coercive field Ec (39.8kV/cm) are obtained in the P-E hysteresis loops. The films have a dielectric
constant ε of 1080 and a dielectric loss tanδ of 0.01 at 1 kHz. Ferroelectric polarization fatigue test of the
films has shown that high fatigue resistance up to 3 × 1010 cycles before Pr is decreased by 50%.
Proton Conductivity of Amorphous Hydrated Zirconia-Yttria Solid Solutions
Authors: Dell'Agli Gianfranco , Mascolo Giuseppe , Mascolo Maria Cristina , Pagliuca Concetta , Perna Paolo , Scotti Di Uccio Umberto
Published: March 2009

Mechanical mixtures of zirconia xerogel with variable content of crystalline Y2O3 up to 25
mol%, were hydrothermally treated by microwave route at 110 °C for 2 hours in the presence of 0.2 M
solution of (KOH+K2CO3) mineralizer. The resulting amorphous hydrated zirconia-yttria solid
solutions with a maximum solubility of Y2O3 content between 20 ~ 25 mol%, showed a remarkable
reduction of the surface area at the increasing Y2O3 content of the starting mixture. The
as-synthesized products and the corresponding calcined powders at 400 °C were uniaxially pressed
into pellets (10 x 7 x 2 ~ 4 mm, in width) at 150 MPa. Conductivities were measured at 25 °C by AC
impedance method with a frequency range from 10 Hz to 1 MHz with the pellets equilibrated either
under silica gel or under increasing relative humidity (RH) up to ~90 %. The effects of composition,
surface area, calcination temperature and relative RH on the proton conductivity of the amorphous
solid solutions are discussed.
Structural and Morphological Transformation of NaX Zeolite Crystals at High Temperature
Authors: Kim Young Mi , Kim Ik Jin
Published: March 2009

Well-shaped octahedral crystals of NaX zeolite of a large size of 30μm were synthesized by
a hydrothermal method in a mother solution having a 3.5Na2O : Al2O3 : 2.1SiO2 : 593~2000H2O
composition. Thermal treatment of NaX zeolite crystals results in the formation of an intermediate
amorphous phase (T < 1000oC) and crystalline phase of aluminium silicate at temperature above 800
and 900oC. Environmental scanning electron microscopy (ESEM), High resolution Transmission
Electron Microscopy (HRTEM), X-ray powder diffraction (XRD), Fourier transform infrared(FT-IR)
spectroscopy, DTA/TGA and BET analysis were used to characterize the initial materials and the
obtained products after various heat treatments.
Improvement of the Electrochemical Performance of LiFePO4 Cathode Composite Material Using a In Situ Pyrolysis Carbon Synthesis Procedure
Authors: Luo Shao Hua , Tang Zi Long , Lu Jun Biao , Li Jun Rong , Zhang Zhong Tai
Published: March 2009

LiFePO4/Carbon composite cathode material was prepared by pelleting and subsequent pyrolytic cracking process in N2 atmosphere with carbon source of polyvinyl alcohol (PVA). XRD crystal analysis indicates that single LiFePO4 phase and amorphous carbon can be found in the products. SEM observation shows a special micro-morphology of sample, which is favorable for enhancement of electrochemical properties. The discharge capacity of the LiFePO4/C composite was 135 mAh/g, close to the charge capacity of 153 mAh/g at low rate of 0.1C. At 0.2C, the specific capacity was about 117.4 mAh/g, which is satisfied for power source of Electric Vehicle for its flat discharge platform.
Manufacturing Processes of Solid Oxide Fuel Cell Components
Authors: Jiang Xian Feng , Han Min Fang , Peng Su Ping
Published: March 2009

The all processes for manufacturing materials parts of solid oxide fuel cell (SOFC) are discussed in the paper. The films are made in one step by the ways of APS, VPS, EVD, which are usually used to produce the electrolyte and interconnect. The films are thin and good gas-resistance, but with relatively high cost. All parts of SOFC are made by the following ways, such as sol-gel, tape casting, tape calendaring and screen printing, which are suitable for manufacturing samples in industry with the cheapest process by co-sintered together ways.
Liquid Desiccant Drying Method for Gelcasting PTC Ceramics Based on BaTiO3
Authors: Gong Shu Ping , Huang C. , Zhou Dong Xiang , Zheng Zhi Ping
Published: March 2009

In this work, aqueous gel-casting (AGC) method was used for preparing PTC (positive temperature
coefficient) ceramic green body based on BaTiO3. We studied on modeling of liquid desiccant
drying method for gelcasting ceramic bodies, and compared with the conventional drying methods.
An Investigation on the Optimum Conditions for Preparation of Pure Mn-Mg-Zn Ferrite Powder
Authors: Seyyed Ebrahimi S.A. , Pishgahi Fard Z.
Published: March 2009

Manganese- Zinc ferrite is one of the most important spinel ferrites which is used in the electronics applications. These ferrites have an open lattice and can tolerate large amounts of the other metallic ions in their lattice. One of these divalent ions that can sit in the unit cell of Mn-Zn ferrites is Magnesium. Mn-Mg-Zn ferrites are new materials which is thought to be a good candidate for dielectric applications. In this work, a suitable relative values of raw materials for preparing pure Mn-Mg-Zn ferrite powder have been determined. It is carried out by using XRD experiments. The optimum temperature and time of calcination were also investigated by DTA/TGA, XRD and SEM techniques.
Effects of Different Antimony Dopants on ZnO-V2O5 Based Varistor Ceramics
Authors: Zhao Ming , Wang Wei Min , Liu Xiang Chun , Tian Chang Sheng
Published: March 2009

The effects of pre-synthesized V2O5/Sb2O3 compound, SbVO4 and Sb2O3 on the microstructure
and electrical properties of ZnO-V2O5 based varistor ceramics have been studied. The general homogeneous
microstructure and phase composition of the ceramics have not been influenced by the antimony
doping form changes, except for the gradual decrease in average grain size and the increase in spinel
formation within the ceramics. The ultimate cause of micro-structural variations with the antimony
doping form changes seems to have been the gradual increase in Sb3+ concentration within the ceramics.
This change in micro-composition, together with the changes in microstructure, caused the electrical
characteristics of the ceramics to vary. The pre-synthesized V2O5/Sb2O3 compound is the most effective
antimony dopant in term of its effect on the ceramics.
Preparation and Properties of Ni-Si-O Thin Film Prepared by Sol-Gel Method
Authors: Zhao Rong Juan , Lin Yuan Hua , Cai Jing Nan , Nan Ce Wen , Xie Dan
Published: March 2009

Ni-Si-O thin films on Si substrate have been prepared by a sol-gel method. The microstructure
and phase composition of the films were investigated by XRD, SEM, FTIR. The XRD results showed that
the films are amorphous while annealed at 800oC for 10 min, the SEM imagines proved that the films are
smooth and thickness is about 190 nm. Electrical property of the film indicated that the leakage current
was as low as 10-6A/cm2 at an electric field of 1MV/cm. The dielectric properties of Ni-Si-O thin films
can be improved as increasing the annealed temperature.
Thermoelectric Properties of Ag1-xPbmSbTe2+m Compounds
Authors: Yan Yong Gao , Tang Xin Feng , Liu Hai Jun , Yin Ling Ling , Zhang Qing Jie
Published: March 2009

Ag1-xPbmSbTe2+m (m = 6, 10, 18; x = 0, 0.5, 0.75) compounds were prepared by melting-spark plasma sintering (SPS) process. The effects of m and x on the thermoelectric properties of the compounds were investigated. The results indicate that all samples are n-type conduction. For Ag1-xPb18SbTe20 (x = 0, 0.5, 0.75), the electrical conductivity decreases, whereas Seebeck coefficient increases, with increasing Ag concentration. For AgPbmSbTe2+m (m = 6, 10, 18), as m increases, the Seebeck coefficient slightly decreases and the electrical conductivity increases first, with a maximum at m =10, and then decreases. The thermal conductivity increases with increasing m.
Fabrication and Mechanical Properties of High-Pure Ti3SiC2 Bulk Materials Directly by Hot-Pressing its Powder
Authors: Song Yang , Wang Chang An , Peng Chun Qing , Huang Yong
Published: March 2009

High-pure bulk Ti3SiC2 samples were fabricated by directly hot-pressing (HP) high-pure Ti3SiC2 powder without any additives at 1200°C to 1500°C for 0.5–2 hours in flow argon atmosphere. X-ray diffraction (XRD) and scanning electron microscope (SEM) were used for phase identification and microstructure evaluation. The fabricated Ti3SiC2 materials have relative high density with high purity, flexural strength of 500-700MPa and fracture toughness of 9-12MPa·m1/2. The influence of sintering temperature and soaking time on the mechanical properties of Ti3SiC2 materials was discussed. The sintering mechanism for Ti3SiC2 powder without any additives was considered to be related with the fragile-ductile transformation of Ti3SiC2 at 1100°C.
Finite Element Method Predicts the Distribution of Cutting Temperature in Diamond Turning
Authors: Zong Wen Jun , Li Dan , Sun T. , Cheng K.
Published: March 2009

In this paper, a coupled thermo-mechanical FE model is proposed to simulate the cutting temperature’s distribution produced in diamond turning. Simulated results indicate that the heat converting from plastic work has prominent effects on the distribution shape of cutting temperature field, and with an increment in cutting velocity, the locating site of maximal cutting temperature shifts from the contact area between tool tip and chip root to the contact area between rake face and chip. Cutting edge radius has minute influence on the distribution shape of cutting temperature field, but the bigger the cutting edge radius is, the higher the maximum cutting temperature in cutting region. Rake angle also has slight effects on the maximal temperature when it is more than 10○. While clearance angle reaches to 6○, the maximum cutting temperature approaches the smallest.
A Novel Approach to Quantifying Surface Roughness in Grinding
Authors: Ju Chun Hua , Xie Yi
Published: March 2009

Surface roughness is an important quality characteristic in grinding. Measurement of
surface roughness by means of mechanical stylus is widely done in metrology. In this paper, a new
machine vision system has been utilized to quantify the surface roughness of machined surfaces
(ground and milled). Compared with other measurement methods, it is accurate, quick and credible.
This system is mounted on the grinding machine and automates the measurement process by using
computer control to automatically position the CCD and capture digital images of machined
surfaces between grinding cycles. It was proposed that the proportional formula was used in
calibrating this system, and calibration precision meets application requirement. Not only the
statistic character of gray image but also which of edge image were calculated out. These characters
include the mean value of pixels (Mean), standard deviation (σ), maximal value (Max) and minimal
value (Min), the number of pixels on the examine line(Count), etc. It was found out that the
standard deviation value σ of the gray image could express the surface roughness most. The
correlation between σ and Ra is established by interpolating σ value used Lagrange interpolation
law, and the σ value is converted into Ra value through the calculation procedure finally.
Static Characteristic Analysis of a 3-DOF Micropositioning Table for Grinding
Authors: Tian Yan Ling , Zhang Da Wei , Yan Bing
Published: March 2009

In order to improve the machining accuracy of the precision surface grinding machine, a
3-DOF micropositioning table is used as an auxiliary table to form the dual infeed system with
nanometer level positioning accuracy. This paper mainly deals with the static characteristics of the
micropositioning table. The direct and inverse kinematic models are obtained under different
orientation descriptions, and the inherent relationship between different orientation descriptions is
investigated. By use of Eular angle description, the reachable orientation space of the
micro-positioning table is obtained. The theoretical static stiffness on the top surface of the table is
also given, and the experimental tests are carried out to verify the established models.
Design and Control of a Piezo-Based Fast Tool Servo System for Precision Diamond Turning
Authors: Yang Y.H. , Chen Shi Jin , Cheng K.
Published: March 2009

A novel fast tool servo driven by piezoelectric actuator for precision diamond turning is
designed in this paper. To overcome the inherent hysteresis and drift nonlinearity effect of the
piezoelectric actuator, a closed-loop control system is established using strain gauge integrated in
the actuator for position feedback, which has compact structure and can avoid interference in the
machining. Furthermore, a fuzzy PI control algorithm is presented. It has not only the advantages of
agility and adaptability of fuzzy control, but the characteristics of high accuracy of PI arithmetic. At
last, experiments are carried out and the results show that the fuzzy PI control provides significantly
better tracking accuracy and robustness against hysteresis and drift effects.
MD Analysis on Tip Geometry Effects in AFM-Based Lithography Process
Authors: Yan Yong Da , Sun Tao , Dong Shen , Liang Ying Chun
Published: March 2009

A three dimensional molecular dynamics model is employed to simulate AFM-based
lithography process. To investigate effects of tip geometry, three kinds of tip models are proposed:
a cone-shape tip with a hemisphere at the end, a round-edged three sided pyramid tip with a
hemisphere at the end and a sharp-edged three sided pyramid tip. These models simulate scratching
behaviors of AFM tip at different scratching depths. Results showed that materials removal
behavior and scratching forces were significantly affected by tip geometry, depending on the
scratching depth and scratching directions. The specific energy using a sharp-edged three sided
pyramid tip displayed a different behavior comparing to that using a round-edged three sided
pyramid. However, scratching orientations exhibited no effects on the specific energy.
Design and Fabrication of Micro Hot Embossing Mold for Microfluidic Chip Used in Flow Cytometry
Authors: Du L.Q. , Liu C. , Liu H.J. , Qin J. , Li N. , Yang Rui
Published: March 2009

Micro hot embossing mold of microfluidic chip used in flow cytometry is designed and
microfabricated. After some kinds of microfabrication processes are tried, this paper presents a
novel microfabrication technology of micro hot embossing metal mold. Micro metal mold is
fabricated by low-cost UV-LIGA surface micro fabrication process using negative thick photoresist,
SU-8. Different from other micro hot embossing molds, the micro mold with vertical sidewalls is
fabricated by micro nickel electroforming directly on Nickel base. Based on the micro Nickel mold
and automation fabrication system, high precision and mass-producing microfluidic chips have been
fabricated and they have been used in flow cytometry
Features of Machine Variables in Thermosonic Flip Chip
Authors: Li Jun Hui , Han Lei , Duan Ji An , Zhong Jue
Published: March 2009

An assembly bed on thermosonic flip chip bonding was set up, two different structures of
tool tips were designed, and a series of experiments on flip chip and bonding machine variables
were carried out. Lift-off characteristics of thermosonic flip chip were investigated by using
Scanning Electron Microscope (JSM-6360LV), and vibration features of tool tips driven by high
frequency were tested by using PSV-400-M2 Laser Doppler Vibrometer. Results show that, for
chip-press model, slippage and rotation phenomena between tool tip and chip have been solved by
using tool with greater area tip pattern during flip-chip bonding process, and welding failures
appeared in chip-collet model have been controlled. Greater area pattern on tool tip is better than
small area pattern. The power of ‘n’ bumps on flip chip bonding is far smaller than that of n×(the
power of single wire bonding). The power is directly proportion to vibration displacement driven by
the power, high-power decrease positioning precision of flip chip bonding or result in slippage and
rotation phenomena. The proper machine variables ranges for thermosonic flip chip had been
obtained.
Dynamic Modeling of Predicting Chip Formation Based on Artificial Neural Networks and Real-Time Simulation of Chip
Authors: Wang Wen Jin , Wang Tai Yong , Fan Sheng Bo , Wang W.Y. , Wang G.F. , Zhang W.
Published: March 2009

For the problem of process monitoring of chip generation in CNC machining, the
dynamic modeling of predicting chip formation using artificial neural networks based on real-time
condition intelligent monitoring was studied. The dynamic model of predicting chip formation is
established in this paper. Based on mathematical model of chip space motion path, the 3D model of
chip shape was developed. The real-time simulation of chip generation was realized in the virtual
reality environment.
High Speed Wire Electrical Discharge Machining (HS-WEDM) Phenomena of Insulating Si3N4 Ceramics with Assisting Electrode
Authors: Guo Yong Feng , Bai Ji Cheng , Deng Guan Qun , Lu Ze Sheng
Published: March 2009

Advanced engineering ceramics are more and more widely employed in modern
industries because of their excellent mechanical properties such as high hardness, high compressive
strength, high chemical and abrasive resistance. This paper investigates the high speed wire
electrical discharge machining (HS-WEDM) of Si3N4-based ceramics by assisting electrode method.
The theory of assisting electrode method is introduced. The machining phenomena under different
electrical parameters were studied and the optimized machine pulse width was got. The material
removal mechanisms change with the increase in the power of single pulse.
A Study of Micro V-Groove Fabrication in Ultra-Precision Freeform Machining
Authors: To Sandy , Cheung Chi Fai , Wang Su Juan , Lee Wing Bun
Published: March 2009

Optical communication is gaining popularity in telecommunications; most obviously
evident is the increase in demand for a large variety of fiber optic components. V-groove structure
quality is critical to the functionality of the fiber connector as it governs the position of the optic
fibers. The main parameters, which determine the V-groove quality, include core pitch, surface
roughness and the position of centerline. In this paper, a series of cutting conditions were applied to
investigate the effect of different machining parameters on the V-groove quality. In the experiment,
the V-groove structure is machined by a 40° single crystal diamond tool on aluminium alloy with
different cutting conditions. Based on the findings, the relationship between the cutting conditions on
the surface roughness was explored. The implications of these findings on the improvement of the
surface finish of V-groove profile are discussed.
A Micro-Deposition Method by Using EDM
Authors: Jin Bai Dong , Cao Guo Hui , Wang Zhen Long , Zhao Wan Sheng
Published: March 2009

A new micro EDM method is described. First, the basic principles of micro EDD are
analyzed and realized conditions are predicted. Then with an ordinary EDM shaping machine and
electrode brass, steel and tungsten, a large number of experiments are carried out in air to obtain the
effects of different processing parameters on micro EDD. A micro cylinder with 0.19mm in
diameter and 7.35mm in height is formed on high-speed steel surface. By exchanging the polarities
of electrode and workpiece the deposited material can be removed selectively, thus the reversible
machining is realized. In the end, measurements show that the deposited material is compact and
hardened, whose components depend on the tool electrode material although Zn in brass electrode
is oxidized to ZnO.
Optimum Size Consideration of Machine Tools
Authors: Mishima N.
Published: March 2009

As has been demonstrated in the “microfactory” which is a miniature manufacturing system proposed by the author’s research group, small machine tools that are comparable in size to their target products lead to large reductions in energy consumption and area. Experiments showed that they were capable of micro mechanical fabrication. However, the design of miniature machine tools has not been fully optimized. The author proposed a design method to estimate machine tool performance. In this paper, the design tool is applied to find miniaturizing strategies. By applying the design tool, it is possible to determine which of the design parameters and error sources would significantly affect machine performance. From the results of calculation, the tool can clarify the effect of machine tool sizes imposed on the machine performances. This leads to some suggestions regarding machine tool sizes. Finally, design guidelines for miniature machine can be obtained.
Development of Parallel Grinding System of Aspheric Optics
Authors: Li L.J. , Zhang Fei Hu , Dong S.
Published: March 2009

The roughness and profiles accuracy of aspheric surface are two key factors affecting the
resolution and other characteristics of optical instruments. In this paper a new grinding
system-parallel grinding system was built, and an CNC system controlled by PMAC (programmable
multi-axis controller) was developed, the parallel grinding system can realize Arc Envelope Grinding
Method (AEGM) only through controlling 2-axis and the wear of wheel was diminished, the tool path
calculation was simplified. Using this system, the roughness and profile accuracy of aspheric surface
are improved.
A Framework of a Model-Based Simulation System for Prediction of Surface Generation in Fast Tool Servo Machining of Optical Microstructures
Authors: Cheung Chi Fai , Lee Wing Bun , To Sandy , Li H.F. , Wang Su Juan
Published: March 2009

The fabrication of high-quality optical microstructural surfaces is based on fast tool servo (FTS) machining. It makes use of auxiliary piezo-electric driven servos to rapidly actuate the diamond tool with a fine resolution and a sufficiently high bandwidth for machining optical microstructures with submicrometer form accuracy and a nanometric surface finish without the need for any subsequent post processing. However, the achievement of a superior mirror finish and form accuracy still depends largely on the experience and skills of the machine operators, acquired through an expensive trial-and-error approach to using new materials, new mircostructural surface designs, or new machine tools. As a result, this paper, a model-based simulation system is presented for the optimization of surface quality in the FTS machining of optical microstructures. Preliminary experimental work and the results are also presented.
VSPDT: An Optimizer for Single Point Diamond Turning
Authors: Li Jian Guang , Lee Wing Bun , Cheung Chi Fai , To Sandy , Du J.J. , Yin Z.Q.
Published: March 2009

Virtual manufacturing (VM), which primarily aimed at reducing the lead times to market
and costs associated with new product development, offers various test-beds for the time-consuming
and expensive physical experimentation. Since surface roughness and form accuracy play essential
roles in the functional performance of the products machined with ultra-precision machining
technology. An optimizer, VSPDT (virtual single point diamond turning) system was developed for
the purpose of form error compensation and optimal cutting parameters selection. In this paper, the
keys issues for developing VSPDT using virtual manufacturing technology were highlighted such as
framework of system, virtual workpiece, virtual machining and inspection, etc. At the end of the
paper, A VSPDT was developed and applied to predict and compensate the form error, select optimal
cutting parameters by using a 2-axis CNC ultra-precision turning machine.
ELID Grinding Characteristics and Surface Analysis for Micro Fabrication of Advanced Ceramics
Authors: Katahira Kazutoshi , Ohmori Hitoshi
Published: March 2009

The present paper describes the highly efficient and precise ELID grinding method and
presents a discussion on the ELID grinding process and the grinding characteristics of several kinds
of ceramic materials. The following conclusions are obtained; (1) Good ground surface roughness
and accuracy are achieved using the #4000 metal-bonded grinding wheel in through-feed centerless
grinding for ZrO2 optical fiber ferrules. (2) Efficient and precise grinding of spherical lens molds
with cup wheels using the ELID CG-grinding process was proposed and tested in the present study. (3)
The ELID grinding method can be used to fabricate machined surfaces exhibiting desirable
characteristics for hard AlN ceramics. The ELID ground AlN demonstrated a surface hardness and
sliding characteristics that were superior to those of the polished series. These advantages may be
attributable to the diffusion phenomenon of the oxygen element produced by the ELID grinding.
High Strain Rate Deformation Behavior of Mg–Al–Zn Alloys at Elevated Temperatures
Authors: Watanabe Hiroyuki , Ishikawa Koichi , Mukai Toshiji
Published: March 2009

High temperature deformation behavior of AZ31 and AZ91 magnesium alloys was
examined by compression tests over a wide strain rate range from 10–3 to 103 s–1 with emphasis on
the behavior at high strain rates. The dominant deformation mechanism in the low strain rate
range below 10–1 s–1 was suggested to be climb-controlled dislocation creep. On the other hand,
experimental results indicated that the deformation at a high strain rate of ~103 s–1 proceeds by
conventional plastic flow of dislocation glide and twinning even at elevated temperatures. The
solid-solution strengthening was operative for high temperature deformation at ~103 s–1.
Seismic Performance of a Reinforced Lightweight Aggregate Concrete Frame
Authors: Fang Cong Qi , Yi Mei Ying
Published: March 2009

It has been assumed that the use of lightweight aggregate concrete structures can largely
reduce dead loads and thus reduces the earthquake effects without increasing the total cost.
However, one of the primary concerns for these structures has been the plastic deformation capacity,
ductility, and energy dissipation capacity. Tests were conducted for seismic performance of
reinforced lightweight aggregate concrete (RLAC) frames that consisted of beams and columns of
different cross-sections. Quasi-static reversed cyclic loads were performed on 1:2 scale RLAC
model frames that had special cross-sections. It was demonstrated that the RLAC frames had
inherent defects regarding seismic performance. This, however, did not have substantial influence
on the integral seismic performance of the structures. It was concluded that the RLAC frames met
normal service requirement with sufficient strength reservation. The RLAC frames may represent a
viable alternative for ordinary reinforced concrete framed structures in low- to medium-rise
buildings in frequent-occurring earthquake areas.
Reduction of Residual Stress of Welded Joint Using Local Plasticity Caused by Ultrasonic Vibration
Authors: Aoki Shigeru , Nishimura Tadashi , Hiroi Tetsumaro , Hirai Seiji
Published: March 2009

Welding is widely used for construction of many structures. It is well known that residual
stress is measured on welded joint. In this paper, a new method for reduction of residual stress using
ultrasonic vibration during welding is proposed. Two thin plates are butt-welded. When ultrasonic
vibration is used on one plate, tensile residual stress is reduced at center of the bead. Second,
ultrasonic vibrations with different frequencies are applied on both plates. In this case, reduction rate
of residual stress increases. Next, reduction of tensile residual stress is demonstrated by simulation
method using an analytical model with dynamic characteristics of welded joint.
Evaluation of Dynamic Behaviors and Damage Mechanism of Ancient Timber Architectures
Authors: Che Ai Lan , Ge Xiu Run , Iwatate Takahiro
Published: March 2009

An urgent is needed on the preservation of Chinese architectural heritages, since
environmental and time impacts have been abating their structural resistance capability. It is of
great importance in protecting and rehabilitating the ancient architectural culture of China to study
the structural characteristics of ancient Chinese timber architectures. As a typical example of
ancient timber architectures-Yingxian Wooden Pagoda in west of Shanxi Prince, the dynamic
characteristics and damage mechanics of the tower are investigated experimentally and numerically
by micro tremor measurements and means of finite-element-method (FEM). The micro tremor
measurements are conducted on the tower (each floor) and the surrounding ground. From the micro
tremor observation data, the predominant frequency of the surface ground and natural frequency,
vibration mode and the damage distribution characteristics of the tower were evaluated. Based on
the experimental studies, the tower is created by a delicate finite element model. And in order to
simulate the mortise and tenon joint---bucket arches in the structure, which is a combination of a
series of timber structures, a special beam-element group is developed. Numerical simulation of the
seismic response of the tower shows that the second and third floors of the tower would be damaged
more seriously than other floors for their severe stresses when acted by seismic loading. The present
analysis of the tower shows the same phenomena. The results provide basis for repairing and
reinforcing the ancient timber tower.
The Effect of Strain Rate on the Material Characteristics of Nickel-Based Superalloy Inconel 718
Authors: Song Jung Han , Huh Hoon
Published: March 2009

The dynamic response of the turbine blade materials is indispensable for analysis of
erosions of turbine blades as a result of impulsive loading associated with gas flow. This paper is
concerned with the dynamic material properties of the Inconel 718 alloy which is widely used in the
high speed turbine blade. The dynamic response at the corresponding level of the strain rate should be
acquired with an adequate experimental technique and apparatus due to the inertia effect and the
stress wave propagation. In this paper, the dynamic response of the Inconel 718 at the intermediate
strain rate ranged from 1/s to 400/s is obtained from the high speed tensile test and that at the high
strain rate above 1000/s is obtained from the split Hopkinson pressure bar test. The effects of the
strain rate on the dynamic flow stress, the strain rate sensitivity and the failure elongation are
evaluated with the experimental results. Experimental results from both the quasi-static and the high
strain rate up to 3000/s are interpolated in order to construct the constitutive relation that should be
applied to simulate the dynamic behavior of the turbine blade made of the Inconel 718.
Effect of Mean Stress on Fatigue Strength of Short Glass Fiber Reinforced Polybuthyleneterephthalate
Authors: Oka Hideki , Narita Ryoichi , Akiniwa Yoshiaki , Tanaka Keisuke
Published: March 2009

Tension-compression fatigue tests under various mean stress conditions were conducted
with round bar specimens of short glass fiber reinforced polybuthyleneterephthalate made by
injection molding. Under cyclic loading with high mean stresses, the creep phenomenon became
predominant and the ratcheting deformation increased with the number of cycles. This phenomenon
is characteristic of plastics including short glass fiber reinforced plastics. The experimental data of
the fatigue strength at the stress ratios above 0.7 were lower than the prediction based on the
modified Goodman diagram. We propose to use the creep rupture strength, σc, instead of the
tensile strength, σB, as the strength without mean stress and the parabolic equation for a constant
life in the amplitude-mean stress (σa-σm) diagram. Our new design equation for the mean-stress
effect on the fatigue strength on plastics is as follows: σa = σw – (σw / σc
2) σm
2, where σw is the
fatigue strength at the stress ratio R=-1 and σa is the stress amplitude under a mean stress of σm.
We also proposed a method to obtain the constant-life relation from limited experimental data.
Micro-Indentation of Metal Matrix Composite - An FEM Investigation
Authors: Pramanik Alokesh , Zhang Liang Chi , Arsecularatne Joseph A.
Published: March 2009

Micro-indentation has been widely used to evaluate the mechanical properties of
materials. It has also been considered to be an important measure in the study of machinability of
difficult-to-machine materials such as metal matrix composites (MMCs). Because of the complexity
of deformation of an MMC and the interaction in the vicinity of contact zone between the indenter
and work material, an analytical or experimental method is unable to predict the detailed
deformation process. The present paper uses the finite element method to investigate the behavior
of MMCs subjected to micro-indentation by a spherical indenter including the development of
stress and strain fields in the MMCs during loading/unloading. Particle fracture, debonding and
displacement, and inhomogeneous deformation of matrix material were explored and compared
with the experimental results reported in the literature. The analysis also provides an insight for
understanding the formation of residual stresses in machined MMC components.
Dynamic Strain Aging during the Plastic Flow of Metals
Authors: Guo Wei Guo
Published: March 2009

In the present paper, in order to better understand the third type “dynamic strain
aging” occurring during the plastic flow of metals, the uniaxial compressive experimental
data ever obtained in University of California, San Diego using an Instron servo-hydraulic
testing machine and the Hopkinson technique are systematically analysed. These experimental
data cover the plastic flow stress of several fcc, hcp, bcc polycrystalline materials and several
alloys at a broad range of temperatures (77K – 1,100K) and strain rates (0.001/s – 10,000/s).
In analysis, the appearing region of the “dynamic strain aging ” under different temperatures
and strain rates are respectively plotted by the curves of stress vs temperature, and stress vs
strain for fcc, hcp and bcc metals. The results show that: (1) this third type “dynamic strain
aging ” occurs in all hcp, bcc and fcc polycrystalline or alloy materials, and there are different
profiles of stress-strain curve; (2) the “dynamic strain aging ”occurs in a matching
coincidence of the temperature and strain rate, its temperature region will shift to higher
region with increasing strain rates; (3) bcc materials do not have an initial pre-straining strain
as the onset of work-hardness rate change for the “dynamic strain aging ”; and (4) based on
the explanations of dynamic strain aging with serration curves (Portevin-Lechatelier effect)
and other explaining mechanisms of references, The mechanism of third DSA is thought as
the rapid/continuous formation of the solute atmospheres at the mobile dislocation core by the
pipe diffusion along vast collective forest dislocations to result in a continuous rise curve of
flow stress. Finally, several conclusions are also presented.
Grain Refinement and Strengthening of a Cylindrical Pure-Aluminum Specimen by Using Modified Equal-Channel Angular Pressing Technique
Authors: Yamane Takuya , Kondou Ryouji , Makabe Chobin
Published: March 2009

A new grain refinement and strengthening technique by modified ECAP (equal-channel
angular pressing) technique was proposed in this study. ECAP technique is an effective technique
for grain refinement and strengthening of metal material. This technique gives high shear plastic
strain to the material without geometric transformation of the specimen. However, traditional ECAP
technique is restricted by material type and size, especially length. Such kinds of restrictions cause
various problems in practical use. We modified traditional ECAP dies and processes to allow high
plastic strain for long-length pure-aluminum specimens. Then, grain distribution was observed
using a microscope, grain size was determined by the Jeffries and the Heyn methods, and
strengthening was investigated by micro-Vickers hardness test. Then the effectiveness of proposed
grain refinement or strengthening techniques was discussed.
Preparation and Evaluation of Poly(γ-glutamic acid)-Based Anti-Adhesion Membranes
Authors: Ko Young Gwang , Yoon Kwan Han , Park Chung , Sung Moon Hee , Kwon Oh Kyoung , Ahn Chang Hyun , Kim Young Jin , Kwon Oh Hyeong
Published: March 2009

Poly(γ-glutamic acid)(γ-PGA) based nanofiber sheets were prepared by using
electrospinning technique to evaluate the ability of the prevention of postoperative tissue adhesion.
The anti-adhesion membranes were prepared from poly(γ-glutamic acid) and PLGA with different
compositions by electrospinning. Also nonsteroidal anti-inflammatory drug (ibuprofen) was
incorporated during fabrication of nanofibers. Various electrospun nanofibers were characterized by
the measurements of microstructure (surface morphology and fiber diameter by SEM), ATR-FTIR,
water contact angle and in vivo animal study using Sprague Dawley rat model. The average
diameter of nanofibers electrospun from trifluoroacetic acid (TFA) solution ranged from 300 nm to
900 nm, approximately. From in vivo animal study, it was observed that ibuprofen-incorporated γ-
PGA nanofiber sheet was significantly effective in preventing tissue adhesion and inducing wound
healing, probably due to the appropriate hydrophilicity of γ-PGA preventing shrinkage of the sheet
and appropriate barrier property, while PLGA nanofibrous mat was dramatically contracted in in
vivo due to its high hydrophobicity resulted in insufficient coverage of wound.
Evaluation of Bonding Stress for the Newly Suggested Bone Cement: Comparison with Currently Used PMMA through Animal Studies
Authors: Heo S.J. , Park S.A. , Shin H.J. , Lee Y.J. , Yoon T.R. , Seo H.Y. , Ahn K.C. , Kim S.E. , Shin Jung Woog
Published: March 2009

PMMA remains the most popular material of bone cement for orthopaedic surgeries.
However, conventional PMMA bone cement still has some problems. For this, we suggested new
composite material (BBC) consisting of hydroxyapatite (45%), chitosan (10%) and PMMA. The
purpose of this study was to evaluate the bonding stress at the interface of PMMA with additives
and host bone using a rabbit model. After 6, 12 weeks of operation, the bonding stresses were
evaluated by measuring shear stress through push-out test. The results of the tests showed that after
6 weeks the shear stress of the BBC was 2.65±0.29MPa and the PMMA was 1.21±0.31MPa
(p<0.05). However, after 12 weeks, there were no significant differences between BBC and
conventional PMMA bone cement. In SEM analysis, bone surface of BBC showed higher
roughness than that of conventional PMMA bone cement after push-out test. From the study we
conducted, addition of HA particles and chitosan to conventional PMMA bone cement showed
promising results. The BBC has clinical potential of bone substitutes replacing conventional
PMMA.
Two Point Incremental Forming with Two Moving Forming Tools
Authors: Meier Horst , Smukala V. , Dewald O. , Zhang Jian
Published: March 2009

This paper describes a new development of an incremental, robot based sheet metal
forming process for the production of sheet metal components for limited-lot productions and
prototypes. The kinematic based generation of the shape is implemented by means of two industrial
robots, which are interconnected to a cooperating robot system. Compared to other incremental
sheet metal forming machines this system offers a high geometrical form flexibility without the
need of any workpiece dependent tools.
The principle of the procedure is based on flexible shaping by means of a freely programmable
path-synchronous movement of two robots. So far, the final shape is produced by the incremental
infeed of the forming tool in depth direction and its movement along the contour in lateral direction
on each level. The counter tool, with its simple geometry, was used to support the sheet metal on the
backside by moving synchronously along the outer contour, constantly on the same level. This
corresponds to a fixed backplate used in other incremental sheet metal forming processes.
Due to the use of a new robot system with extended control algorithms for cooperating robots, it
will be possible to release the counter tool from its constant path on the outer contour and support
the forming tool right on the opposite side of the sheet to generate a predefined gap between the two
hemispherical tools. This way at each moment a small part of a full die, as it is used in other
processes, is simulated without the need of producing a workpiece dependent die.
The extended payload of the new robot system gives the opportunity to form steel blanks, for the
first time.
Achieving Operational Excellence Through Systematic Complexity Reduction in Manufacturing System Design
Authors: Matt Dominik T.
Published: March 2009

The complexity of a manufacturing system is determined by the uncertainty in achieving
the system’s functional requirements and is caused by two factors: by a time-independent poor
design that causes a system-inherent low efficiency (system design), and by a time-dependent
reduction of system performance due to system deterioration or to market or technology changes
(system dynamics). To maximize the productivity of a manufacturing system, its entire complexity
must be reduced. Many valid methods have been developed so far addressing different single
manufacturing and quality issues. But to continuously increase the productivity of a manufacturing
system within a turbulent environment its entire complexity must be reduced. This requires a
holistic understanding and knowledge about the system. To reduce a system’s complexity, its
subsystems should not overlap in their contribution to the overall system’s functionality, they must
be mutually exclusive. On the other hand, the interplay of system’s components must be collectively
exhaustive in order to include every issue relevant to the entire system’s functionality. This paper
introduces a concept for complexity reduction in manufacturing systems with the help of Nam P.
Suh’s Axiomatic Design principles. In a first step, time-dependent elements are separated from
time-independent elements. To eliminate the real complexity of the time-independent elements (so
called manufacturing modules), a set of alternative design parameters are defined that fit the system
range of the manufacturing module’s set of functional requirements. To reduce the time-dependent
combinatorial complexity, a methodology is proposed to systematically define an entire
manufacturing system’s functional requirements within very short times in order to guarantee a fast
reconfiguration of the system considering internal and external system dynamics. With the help of
practical examples and the obtained results, the validity of the approach is illustrated.
Sheet Metal Forming - A New Kind of Forge for the Future
Authors: Geiger Manfred , Merklein Marion
Published: March 2009

Within the last years in sheet metal forming a trend towards forming at elevated
temperatures as well as temperature assisted forming technologies can be observed. This
development is caused by the increasing need on light and high strength materials in order to fulfill
the demands of light weight structures. The decision which kind of temperature assistance is the
most useful in order to improve the formability of the material depends on a hugh number of
process influencing parameters, like e.g. the material itself, the geometry of the component, the
number of forming operations etc..
In this paper the general possibility to separate different temperature assisted forming processes
with regard to the used materials will be introduced. The different forming procedures will be
explained and discussed. Examples with an industrial relevance are shown.
Nanoindentation Techniques: A Critical Assessment of the Current Methods of Data Analysis
Authors: Chaudhri Munawar M. , Lim Yong Yee
Published: March 2009

Although instrumented indentation machines have existed since the 1950s, it is only
during the past 20 years or so that there has been a very rapid rise in their use and popularity for
determining mechanical properties of bulk solids, thin films and biological materials. Nowadays,
machines are available with which indentation experiments are conducted automatically and the
data obtained are also analyzed automatically using software, which is based on certain hypotheses
and simplifying assumptions. By carrying out several series of comprehensive experiments, using
rigid and elastic indenters and elastic substrates, it is shown that the current methods of
nanoindentation data analysis are fundamentally flawed, which can lead to incorrect and misleading
results. A new experimental approach has been suggested here, which is free from such flaws.