bluuebunny/crossref_metadata_2025 huggingface dataset:
Research on a Bionic Fuzzy-PID Vibration Control System for Ultra-Precision Device
Authors: Yao Zhe He , Yang K.J.
Published: March 2009

By imitating the vibration isolation mechanism and special organic texture of woodpecker’s brain, a bionics mechanics-based structure model is constructed for the vibration isolation system of ultra-precision device. In consideration of compound vibration environment and non-linearity of the ultra-precision device, a fuzzy-PID (PID stands for Proportional, Integral and Derivative.) active vibration control system is developed, its operation is that fuzzy control is adopted while the error is big and PID control is adopted while the error is small. The performance of the vibration control system is validated by numerical simulation. The simulation results show that the bionic vibration control system has good performance against floor disturbances and direct disturbing force. It can be applied to the vibration isolation system of the ultra-precision measuring and manufacturing device.
Motion and Environment Error Compensation for Ultra-Precision Lathe
Authors: Kwac Lee Ku , Kim Jae Yeol , Cho Young Tae
Published: March 2009

Recently, the demand for Ultra-precision products is rapidly increasing, especially in such industries as semi-conductors, computers, aerospace, and precision machinary. Ultra-precision processing is also extremely needed for NT in the field of mechanical engineering. Lately, together with drastic advancement of electronic and photonics industry, the need of Ultra-precision processing is increased in the manufacturing of various kernel parts, which are connected with these industrial
fields. Especially, motion accuracy to nanometers is required in order in stroke of hundreds millimeters according as the diameter of the processed object great and the processing accuracy rises. In this case, the response speed absolute delay due to inertial mass of the moving parts is very large. Therefore, real-time motion error compensation becomes the barest necessity. In this paper, we used ultra-precision cutting unit (UPCU) to cope with the problem. A special UPCU was designed and tested to obtain sub-micrometer from accuracy in diamond turning of flat surfaces. The thermal growth spindle error was compensated in real time using the UPCU driven by piezoelectric actuator along with a laser encoder displacement sensor.
Functional Assessment of an Anti-Abrasive Elbow for Particle-Laden Gas Flows
Authors: Kim Young Jin , Kim H.S.
Published: March 2009

The characteristic of flow fields in elbow has been numerically studied to develop
anti-abrasive elbows, which is typically equipped in coal-burning power plants, for conveying highvelocity particle-laden fluids. Specially, a vortex flow field in the pipe experiencing particle abrasion was formed and particle flow simulation was conducted. The governing equations for threedimensional, turbulent flow fields were discretized by FVM and solved by the SIMPLE algorithm.
Improvement in Strength of 2024 Al Alloy by Enhanced Solution Treatment
Authors: Xu Xiao Jing , Kim Seock Sam , Zheng Y.S.
Published: March 2009

In this paper the effects of an enhanced solution and aging on the strengthening behavior of commercially available 2024Al alloy were investigated using tension testing and scanning electron microscopy. A differential scanning calorimeter (DSC) was used to measure the incipient melting behavior and then determine the technological parameter of an enhanced solution heat treatment for strengthening the 2024Al alloy. The results show that the incipient melting behavior of the commercially available 2024Al alloy was characterized by a small amount of liquid phase between the temperatures 773K to 788K. A solution treatment, appropriately enhanced by slowly increasing the solution temperature from 773K to 783K at a heating rate of 5K/h, can make the final solution temperature of the alloy higher than the conventional solution temperature of 773K. This improves the constituent phase solution without the formation of overheated microstructures. The results are the strength, especially the yield strength, and the resistance to over-aging can both be considerably improved without a large deterioration to tensile ductility.
Shear Strength and Fracture Behavior of SiCw/Al2O3 Composite-Carbon Steel Brazed Joints
Authors: Qu Shi Yao , Zou Zeng Da , Wang Xin Hong
Published: March 2009

Shear strength and fracture behavior of Al2O3 matrix ceramic composite brazed joints to carbon steel with Ag-Cu-Ti brazing alloy in flow argon have been studied by means of SEM, EDX and all-purpose testing machine. Results have shown that there is a close relationship between the shear strength and the fracture form of brazed joints. The fracture occurring completely in the composite near the composite/filler metal interface corresponds to the low strength of a joint, and the
strength of the joint fractured partially in the composite usually increases with decreasing the proportion of the composite on the fracture surface in the steel side. When the fracture occurs in the reaction layer between the composite and the filler metal, the closer the fractured position comes to the composite/reaction layer interface, the higher the joint strength. The maximum shear strength is obtained when the fracture occurs fully at the interface.
Mechanical Properties of Nano Grained Ni20Cr20Fe5Nb1Y2O3 Composite and Ni20Cr20Fe5Nb2Al Alloy
Authors: Kim Il Ho , Kim Yong Hwan , Kim C.S.
Published: March 2009

The effects of adding Al, Y2O3 and the use of H2O as a PCA (process control agent), on the mechanical properties of mechanically alloyed Ni20Cr20Fe5Nb alloy were studied. The addition of Y2O3 and Al caused an increase in the tensile strength at room temperature, 400°C and 600°C. However, it was confirmed that the increase of tensile strength at room temperature and 400°C was predominantly caused by addition of Y2O3, while that at 600°C was mainly due to addition of Al.
These results can be attributed to the dispersion strengthening of Y2O3, preventing the formation of Cr2O3 and the change of fracture mode at 600°C by the addition of Al. Therefore, the Ni20Cr20Fe5Nb2Al alloy using H2O as a PCA showed superior tensile strength at room temperature, 400°C and 600°C. The increase in the tensile strength at room temperature and 400°C can be attributed to the strengthening of the solid solution induced by the increase in the amount of Nb solid solution, resulting from the prevention of NbC formation, while the increase in the tensile strength at 600°C can be attributed to the strengthening of the grain boundary afforded by the presence of Al1.54Cr0.46O3 formed by the addition of Al. After aging treatment for 10 hours at 600°C, g²(Ni3Nb) precipitates were formed in the Ni20Cr20Fe5Nb2Al alloy in which H2O used as the PCA, and the formation of these precipitates caused an increase in hardness.
Effect of Sintering Additives on Fabrication Properties of Liquid Phase Sintered SiC
Authors: Yoon Han Ki , Park Yi Hyun , Park Joon Soo , Kohyama Akira
Published: March 2009

SiC has been extensively studied for high temperature components in advanced energy system and gas turbine because of its excellent high temperature mechanical properties and good thermal-chemical stability etc. However, the brittle characteristics of SiC such as low fracture toughness and low strain-to fracture still impose a severe limitation on practical applications of SiC materials. For these reasons, SiCf/SiC composites can be considered as a promising for various structural materials, because of their good fracture toughness compared with monolithic SiC. But, high temperature and pressure lead to the degradation of the reinforcing fiber during the hot pressing. Therefore, reduction of sintering temperature and pressure is key requirements for the fabrication of SiCf/SiC composites by hot pressing method. In the present work, monolithic Liquid Phase Sintered SiC (LPS-SiC) was fabricated by hot pressing method in Ar atmosphere at 1800oC under 20MPa using Al2O3, Y2O3 and SiO2 as sintering additives. The starting powder was high purity β-SiC nano-powder with an average particle size of 30nm. The characterization of LPS-SiC was investigated by means of SEM and three point bending test. Base on the composition of sintering additives-, microstructure- and mechanical property correlation, the compositions of sintering additives are discussed.
A Numerical Investigation of the Progressive Failure of Jointed Rock Slope Subjected to Transient Seepage
Authors: Au S.K. , Wang Shan Yong , Lam K.C. , Tang Chun An
Published: March 2009

Disastrous rock slope failures have been posing a hazard to people’s lives and causing enormous economic losses worldwide. Numerical simulation of rock slope failure can lead to improve the degree of understand of such phenomenon so as to predict and avoid the occurrence of these disastrous events. In order to simulate the global behaviors of rock slope failure under the high seepage pressure and the local behaviors of the occurrence of hydraulic fracture in the pre-existing rock joints effectively, a powerful finite element tools F-RFPA2D, is adopted. The simulation takes into account of the growth of existing fractures and the initiation of new fractures under various of hydraulic pressure in different heterogeneities medium. The behavior of fluid flow and damage evolution, and their coupling action are studied in small specimens that are subjected to both hydraulic and biaxial compressive loadings. The influence of the ratio (the initial horizontal stress to the initial vertical stress) and the distance between the two existing cracks on the fracture propagation behaviors are investigated. Moreover, based on the fundamental study of hydraulic fracture, the progressive failure of rock slope under the influence of the increase in hydraulic pressure was also studied in the paper.
Fracture Behavior and Water Migration in Heterogeneous and Porous Rocks
Authors: Li Lian Chong , Tham Leslie George , Yang Tian Hong , Li Xia
Published: March 2009

Based on the heterogeneous and porous characteristics of rock materials, a flow-stressdamage (FSD) model, implemented with the Rock Failure Process Analysis code (RFPA2D), is used to investigate the behavior of fluid flow and damage evolution, and their coupling action in rock sample that are subjected to both hydraulic and uniaxial compressive loading. A highly heterogeneous sample, containing grains, grain boundaries and weak zones, is employed in the numerical simulation. The simulation results provide a deep insight in the physical essence of the evolutionary nature of fracture phenomena as well as the fluid flow in heterogeneous materials, especially when they are highly stressed. The simulation result suggests that the nature of fluid flow and strength character in rocks strongly depends upon the heterogeneity of the rocks.
System Oriented Plant Maintenance
Authors: Lee Woo Bang , Min Sung Mok , Park Bok Kwi , Kim Dong Jo
Published: March 2009

Nuclear power company plant maintenance has been conservative since it was born. Before we adopted DREAMS system, most of PM documents were handled with paperwork and we spent much time to perform plant maintenance. Last year KHNP constructed and implemented the computerized PM system, which was part of SAP system named DREAMS, and it made KHNP cut down expenses, save time, decrease trouble and optimize work intervals. To make PM system much better, we are trying to import equipment reliability process and we have a plan to initiate it within a year. Therefore the purpose of this paper is not only introducing an advanced methodology of plant maintenance, but showing the optimized PM system (equipment reliability process), considering safety and cost-effectiveness simultaneously.
High Temperature Performance of 316L-SS Joint Produced by Diffusion Bonding
Authors: An Zi Liang , Luan Wei Ling , Xuan Fu Zhen , Tu Shan Tung
Published: March 2009

Two types of joining specimens with and without Ni foil interlayer between 316L–SS bar have been prepared by diffusion bonding in a temperature range of 850- 1050°C, under a uniaxial pressure of 10MPa for 1hours. The relationship between the bonding parameters and the tensile strength of the joints at elevated temperature was studied. Optimized processing parameters were suggested based on the testing results. It was found that the introduction of the interlayer may reduce the room temperature strength but increase the high temperature strength. This was attributed to the transformation of Fe0.64Ni0.36 formed in bonding process into FeNi3 at high temperature.
Crack Propagation Behavior in Nano Size HCP Crystals by Molecular Dynamic Simulation
Authors: Ando Shinji , Oyabu Katsuhiro , Hirayama Kousei , Tsushida Masayuki , Tonda Hideki
Published: March 2009

A crack propagation behavior of hcp crystal has been simulated by molecular dynamics method using Lennard-Jones type potential. A notch was introduced to model crystals with free surfaces. The size of the model was 13nm×24nm×4.6nm and about 80000 atoms were included in the model. A crack propagated by applying tensile strain on top and bottom layer of the model crystal. A definite dependence of crystallographic orientation on crack propagation behavior was obtained. In a model crystal with initial notch plane and direction were (101 0), [1 210], the crack propagated parallel to notch plane and two sets of prismatic slips were occurred at the crack. Therefore, the crack in this crystal is deduced to extend by alternating shear on two intersecting {101 0}, <1 210> prismatic slip systems. In a model crystal with (0001), [101 0] initial crack, {101 1} first order pyramidal slip occurred at crack tip and following {101 2} twin was also observed. In a model crystal with (10 1 0), [0001] initial crack, the crack propagates parallel to initial crack plane. Crack propagation rate of the crack near surface is faster than the crack in interior of the model. In this case, two prismatic slips were occurred in front of the crack. This result explains a mechanism of forming ‘Herring-born pattern’ which was observed in the titanium single crystal. Results obtained by these three models are well described the fatigue crack propagation behavior in hcp titanium crystals.
High-Speed Bonding of Resin-Coated Cu Wire and Sn Electrode with Ultrasonic Bonding for High-Frequency Chip Coil
Authors: Shohji Ikuo , Sakurai Tsukasa , Arai Shinji
Published: March 2009

High-speed ultrasonic bonding method has been developed to join resin-coated Cu wire on Sn electrodes for high-frequency chip coils. Two-step amplitude method, which decreases the ultrasonic amplitude in the bonding process, was effective to join the resin-coated Cu wire on Sn electrodes. The surface roughness treatment for a bonder head accelerated the deformation of the wire in the bonding process and improve the bondability compared to using the bonder head without that treatment. This paper also describes bonding properties of the joint and the bonding mechanism.
Effects of Current and Voltage on Welding Strength of Lap Joint with CO2 Welding Process
Authors: Choi Jun Yong , Song Jun Hee , Lim Jae Kyoo
Published: March 2009

The application of fracture mechanics is being increased gradually to assess the safety of welding crack-containing structures. The joint parts of vehicle frame are mostly made up of welding joint. Due to the impact and fatigue load, cracks initiate and propagate in the welding joint part, as a result, the frame comes to a final failure. Therefore it is necessary to improve the welding performance and fracture resistance of welding part in structure. This study presents a most suitable way of welding process for lap joints by CO2 arc welding which is widely used in the the vehicle structure. Also this paper makes an evaluation to tensile strength and fatigue strength under various welding condition
Control Effect on Fatigue Crack Propagation of TiNi Fiber Reinforced PMMA Composites
Authors: Lee Cheong Cheon , Shimamoto Akira
Published: March 2009

In this paper, the TiNi fiber reinforced/PMMA (Poly methyl methacrylate) composite is developed, and its effectiveness of controlling fatigue crack growth is studied. The TiNi fiber reinforced/PMMA composite’s mechanical property enhancement and deformation resistance are also studied. The fatigue behavior and crack propagation are observed with a SEM servo-pulser (fatigue testing instrument with scanning electron microscope) while increasing temperature. As the results, it is confirmed that the fatigue life and resistance are improved. How the shape memory effect and expansion behavior of the matrix caused by temperature increasing affect the fatigue crack propagation control is examined. It is verified that the control of fatigue crack growth is attributed to the compressive stress field in the matrix due to shrinkage of the TiNi fibers above austenitic finishing temperature (Af).
Fatigue Design Criterion of LCV Leaf Spring Based on Road Load Response Analysis
Authors: Sohn Il Seon , Bae Dong Ho , Jung Won Seok , Jung Won Wook
Published: March 2009

Suspension system of light commercial vehicle (LCV) has enough endurance to protect passenger and freight. Leaf spring is major part of LCV suspension system. Thus, fatigue strength evaluation of leaf spring based on road load response was carried out. At first, the strain of leaf spring was measured on the city mode driving condition and proving ground driving condition. And , the damage analysis of road load response was carried out. After that, fatigue test of leaf spring was also carried out. Based on ε-N life relation, fatigue life of leaf spring was evaluated at Belgian mode, city mode and drawing test specification called the 3 steps test mode. Next, it is compared the design life of leaf spring and evaluated fatigue life by the 3steps test mode. From the above, new target of Belgian mode and city mode was proposed to gratify design specification of leaf spring. It is expect that the proposed target can be satisfied leaf spring fatigue endurance at specific road condition.
The Failure Analysis of the Fractured Steel-Wire-Rope of Electric Glass Lifter in Car
Authors: Jian Wu , Zhang Jing Jiang , Sidong Luo , Zhongliang Shen , Hailin Gu
Published: March 2009

Steel-wire-rope (SWR) is a key part of the electric-glass-lifter (EGL) in a car, which has a strong effect on the life and reliability of EGL. This paper investigates the operation process and the fracture surface morphology of the SWR of EGL under three different conditions. Experimental result indicates that the fracture character of the SWR of the EGL in car is the typical microvibration-
fatigue fracture, which results from micro-crack propagation of the contacting microasperities on the surface of the SWR. In addition, the fracture mechanism of the SWR is analyzed.
Fracture and Viscoelastic Behavior of Some Polymers at High Temperatures
Authors: Ishikawa Keisuke , Takaku Yasuhiro , Kobayashi Yasuo
Published: March 2009

Polymers are vital materials in better performance of specific strength. However their
application can be restricted by the lower glass transition temperature, Tg. Some polymers have been developed as engineering plastics for the high temperature applications. We examined the high temperature strength of polymers at constant applied stress. The creep rupture and viscoelastic behavior were scrutinized for PC (polycarbonate) and PMMA (polymethyl methacrylate), which were quite different in the molecular structures. The former contains benzene rings and the latter is a single polymer. Tg is 423 K for PC and 378 K for PMMA. The large difference in the creep behavior was observed near Tg. The creep life strongly depends upon the applied stress just below Tg. The creep life is a function of the applied stress as follows. n life t − µ s . The stress exponent, n depends upon the
temperature. Mechanical models were applied to evaluate the viscoelastic properties of the polymers at high temperatures. The viscosity rapidly decreased near Tg , regardless of the smaller decrease in the elastic constant. The results would be due to the difference in the molecular structures. The benzene ring could contribute to the higher resistance against the creep deformation through the higher
viscosity.
Analysis to Nonlinear Creep Behavior of Viscoelastic Materials with Structure Varieties by Means of Irreversible Thermodynamics (Ⅱ)
Authors: Dai Guang Ze , Deng Bin , Wang Guozhi , Ni Qing Qing
Published: March 2009

The so-called structure parameters are firstly introduced to indicate their influence on nonlinear viscoelastic behavior and the corresponding nonlinear evolution equation is then derived based on the linear one proposed by Biot by means of thermodynamics of irreversible process. As a worked example, the above nonlinear evolution equation is applied to a viscelastic rod of the ideal viscoelastic solid to predict its uniaxial creep behavior. Under the strain-induced anisotropic effect
due to the configurationally structure changes, the originally isotropic rod gradually becomes transversely isotropic one during the creep deformation process. The final results show that (i) when the applied longitudinal stress is below a certain value, the creep strain will get towards an asymptotic value at a decreasing strain rate, and that (ii) when over this value, it will initially increase at a decreasing strain rate and then at an accelerative rate after overcoming a critical point.
Some Fundamental Aspects of High Temperature Defect Assessment
Authors: Tu Shan Tung , Xuan Fu Zhen
Published: March 2009

Current research efforts in the development of high temperature defect assessment
procedure are summarized. Creep exemption criteria are proposed for the assessment of defective structures at high temperature in consideration of the effects of loadings, operating temperature and service time. Time-dependent failure assessment diagram (TDFAD) is developed that covers major failure mechanisms of defective high temperature structures. Challenges due to the welding effect are discussed. TDFAD for weldments is derived for various combinations of materials. In order to develop a unified assessment method to cope with material and loading complexity, a new failure assessment diagram based on continuum damage concept is proposed to reflect the damage effect on ductile creep failure and brittle creep fracture.
Fracture Behavior of Single- and Polycrystalline Silicon Films for MEMS Applications
Authors: Son Dong Il , Kim Jong Jin , Kwon Dong Il
Published: March 2009

Fracture behaviors of silicon films were evaluated by microtensile methods. We fabricated two types of specimens using surface micromachining, one for a test device for microtensile testing only and the other for a microtensile-compatible resonating device driven by alternating electrostatic force. The piezoelectric-driven uniaxial stress-strain measurement system was designed to evaluate the mechanical properties of thin films. We used UV adhesive to grip the device to the microtensile system, and the grip was made of UV-transparent glass in order to cure the underlying UV adhesive layer. To assess fracture toughness, we used newly proposed methods combining resonance frequency and microtensile methods. The fracture strength of single- and polycrystalline silicon showed dependence on geometry and doping condition. By varying the geometry, we analyzed the effect of the CMP side and the dry-etched side on changes in the mean fracture strength. Atomic force microscopy observation showed that the larger flaws of the dry-etched side were significant in decreasing the mean fracture strength. Fracture toughness based on fracture mechanics with a precrack was evaluated by newly proposed methods combining resonance frequency and microtensile techniques. The measured toughness was independent of specimen geometry but dependent on doping condition. The measured fracture toughness of notched specimens was 33% higher than that of pre-cracked specimens, even though the notch radius was as small as 1.4µm. The effects of notch-tip radius and doping on fracture toughness of silicon film were also analyzed.
Dynamic Behavior of Underground Structures in Multi-Layered Media
Authors: Park Sung Woo , Rhee Jong Woo , Song Weon Keun , Kim Moon Kyum
Published: March 2009

This study performs dynamic analysis of underground structures on multi-layered half planes in frequency domain by using the coupled finite and boundary element method. The near field including underground structures is modeled with onventional finite elements, while the far field is modeled with boundary elements which satisfies radiation conditions. In evaluating the dynamic fundamental solutions, semi-analytical solutions due to line loads are employed. Therefore, the range of wavenumber integration can be reduced significantly. These solutions satisfy the reflection and
transmission conditions of waves at each layer interface, so that the multi-region problem can be analyzed. Numerical examples are given to demonstrate the accuracy and efficiency of the proposed method.
Application of Artificial Neural Network for Fatigue Life Prediction
Authors: Azid Ishak Abdul , Oon Lee Kor , Eu Ong Kang , Seetharamu K.N. , Quadir Ghulam Abdul
Published: March 2009

An extensively published and correlated solder joint fatigue life prediction methodology is incorporated by which finite element simulation results are translated into estimated cycles to failure. This study discusses the analysis methodologies as implemented in the ANSYSTM finite element simulation software tool. Finite element models are used to study the effect of temperature cycles on the solder joints of a flip chip ball grid array package. Through finite element simulation, the plastic
work or the strain-energy density of the solder joints are determined. Using an established methodology, the plastic work obtained through simulation is translated into solder joint fatigue life [1]. The corresponding results for the solder joint fatigue life are used for parametric studies. Artificial Neural Network (ANN) has been used to consolidate the parametric studies.
Evaluation of Electrode Performances of Single-Chamber Solid Oxide Fuel Cells
Authors: Hori Mikihiro , Nagasaka Keisuke , Miyayama Masaru , Trunfio Giuseppe , Traversa Enrico
Published: March 2009

The interfacial resistances of La1-xSrxCo1-yFeyO3-δ (denoted LSCF(10(1-x)/10x/10(1-y)/10y)) cathodes, and the catalytic activities of a Ni-Ce0.85Y0.15O1.925 (Ni-YDC) anode and an LSCF(2/8/8/2) cathode of a single-chamber solid oxide fuel cells (SOFCs) were investigated. LSCF cathodes with high oxide ion conductivities gave low interfacial resistances. LSCF cathodes with suitable thermal expansion coefficients formed favorable interfacial structures with a ceria-based electrolyte. Ni-YDC showed a higher conversion efficiency for CH4 and a lower selectivity for CO2 than LSCF(2/8/8/2). The single-chamber SOFC based on the Sm-doped ceria electrolyte with the Ni-YDC anode and LSCF(2/8/8/2) cathode showed a maximum power density of 186 mW/cm2 at 800°C.
Micropatterning of Monodisperse Spherical Particles by Electrophoretic Deposition Process Using Interdigitated Microarray Electrode
Authors: Hamagami Jun Ichi , Hasegawa Kazuhiro , Kanamura Kiyoshi
Published: March 2009

Micrometer wire consisting of microbeads was successfully fabricated onto a patterned conductive electrode substrate by an electrophoretic deposition (EPD) process with precise control of electric field distribution generated in the colloidal suspension. Monodisperse polystyrene microspheres with 320 nm in diameter and an interdigitated microarray Au electrode having 10 μm in width and 5 μm in spacing were used in this EPD system. A micropattern of polystyrene particles with two dimensional arrays was formed onto the patterned electrode by the EPD process with two electrode system using an electrostatic interaction between the electrodes and the charged particles in the suspension.
Size Effect of Dielectric Properties for Barium Titanate Particles and Its Model
Authors: Wada Satoshi , Hoshina Takuya , Yasuno Hiroaki , Ohishi Masanori , Kakemoto Hirofumi , Tsurumi Takaaki , Yashima Masatomo
Published: March 2009

Powder dielectric measurement of barium titanate (BaTiO3) fine particles from 17 to 1,000 nm revealed a maximum dielectric constant at a certain particle size. The sizes with maximum dielectric constants were strongly dependent on preparation methods. When BaTiO3 fine particles were prepared in vacuum of 10-2 torr, a dielectric maximum of 15,000 was observed at 70 nm. On the other hand, when BaTiO3 fine particles were prepared in air, a dielectric maximum of 5,000 was observed at 140 nm. Structure refinement of BaTiO3 particles using a Rietveld method revealed that all of BaTiO3 particles were composed of two parts; (a) surface cubic layer and (b) bulk tetragonal layer. Moreover, a thickness of surface cubic layer for BaTiO3 particles prepared in vacuum was much thinner than that for BaTiO3 particles prepared in air. To explain the differences, a new model on the basis of “surface relaxation” was proposed.
Influence of Surface Treatment on Pore Structures of Cement-Based Materials
Authors: Chen Chien Hung , Ho Ming Chin , Yeh Shaing Hai , Huang Ran
Published: March 2009

The objective of this investigation is to evaluate the effect of surface treatments on
cement-based materials, which include mortar and concrete samples. Penetrated sealers and methyl methacrylate (MMA) were used as surface treatment materials. Two concrete mixes (w/c = 0.35, 0.55) were selected and cubic/cylindrical specimens were prepared according to ASTM specifications. The treated specimens have higher compressive strengths than the control specimens. Also, the absorptions and total charge passed of rapid chloride penetration test (RCPT) are lower in the treated specimens. Scanning electronic microscope (SEM) was utilized to estimate the microstructure of the specimens. Denser pore structures and narrower pore-size distribution were observed in SEM micrographs and mercury intrusion porosimetry (MIP) spectrum for the treated specimens, which are correspondent to the macro-observation. The positive effect is most prominent in polymer treated specimens. For higher w/c ratio mix, large capillary pores were filled by most of treatment materials and compressive strength significantly increased, while, for lower w/c ratio mix, polymer and silicate sealer filled in medium capillary pores as indicated by MIP and RCPT results.
Ecological Impact and Economic Aspects of Advanced Concrete Technologies
Authors: Rosignoli Dario , Martinola Giovanni , Bäuml Martin
Published: March 2009

Reinforced concrete structures are often conceived for a certain time span of serviceability. Due to the superposition of different kinds of loads and particularly due to the presence of aggressive substances the resistance of construction materials is insufficient in numerous cases. Hence, many structures have to be repaired before the end of their designed life span. In case of reinforced concrete structures these repair measures are not only very expensive but they also consume high amounts of energy and materials which causes strong environmental impacts. The main challenge in developing reliable concrete technologies is the capability to enhance the life span of new and already repaired structures to a reasonable maximum. When aiming this objective not only durability related material properties have to be accomplished but their environmental impact has to be minimized simultaneously. This paper evaluates different concrete technologies and materials from diverse perspectives: Durability (simulating expected life span using numerical analyses), ecology (product life cycle and environmental impact assessments) and economy (estimating life cycle costs by investment appraisals). This kind of combined analysis facilitates the efficient design of structural elements and repair measures and provides the possibility to significantly increase the life span of new and repaired concrete structures.
Research on Preparation of Ultra-High Strength & High Performance Concrete with Low Quality Fine Aggregate
Authors: Pu Xin Cheng , Wang Chong , Yang Chang Hui , Wang Zi Qiang
Published: March 2009

This paper researches on the feasibility of preparing ultra-high strength & high performance concrete with low quality fine aggregate, such as super fine sand (fineness moduls≤1.10), chippings and manufactured sand. The results shows: with low quality fine aggregate, ultra-high strength & high performance concrete can be prepared, and with excellent fluidity and a compressive strength range of 70~120 MPa.
Application of Polypropylene Fiber Concrete in Bridge Deck Pavement
Authors: Shan Jun Hong , Zhou Ming Kai , Li Bei Xing , Cai Ji Wei , Xu Fang
Published: March 2009

The Badong highway bridge over the Yangtze River is a grand bridge in Enshi, Hubei Province of China. Its deck pavement consists of C40 polypropylene fiber concrete, 100 millimeters thick. Experiments show that C40 concrete incorporating polypropylene fibers at dosage of 1.35 kg/m3 has the excellent properties against cracking, permeation, impact, wearing, etc. Thus polypropylene fiber concrete as deck pavement can extend service life of the deck and decrease the maintenance cost and traffic inconvenience for reparation. It can be widely applied in construction
of deck pavement and road pavement.
Strength of Roller Compacted Concrete
Authors: Shi Yan , Fang Kun He
Published: March 2009

The aim of this paper is to provide the credible evidence for existing theory. Rc、Rpl、 Rl and body shear strength of roller compacted concrete (RCC) are investigated. According to the database of Chinese RCC projects, eight regressive equations were set up by using the method of correlation analysis. Including relations for Rc、cementitious material/water ratio and content of fly ash, increasing rate of Rc and age, increasing rate of Rpl (or Rl ) and age, Rpl (or Rl ) and Rc, Rpl and Rl and body shear strength and age.
Age-Adjusted Effective Modulus Method for Creep of High-Performance Concrete
Authors: Han Bing , Wang Yuan Feng
Published: March 2009

This paper discusses the suitability of using several creep theories of common concrete for creep of high-performance concrete (HPC). Based on the Age-Adjusted Effective Modulus method (AEMM) for creep of concrete, Improved Dischinger (ID) method and the Elastic Continuation and Plastic Flow (ECPF) theory for calculating relaxation coefficient and considering characteristics of HPC, a method is set up for calculating the creep of HPC under changing stresses,
and comparing results gotten by the method with some experimental data, it can be considered that the above methods are suit for the calculation of creep of HPC.
Researches on Dressing Diamond Grinding Wheels on Line by a Diamond Pen Aided with Laser Beam Preheating Based on Optical Fiber Delivering
Authors: Deng Qi Lin , Xie An Ning , Sun K.K. , Zhou G.C. , Song Jian Li
Published: March 2009

The dressing on line of diamond grinding wheels used in NC optical curve grinding machines are very difficult. A method has been researched in this paper that is dressing the diamond grinding wheels by a diamond pen aided with laser beam preheating . Its principle has been stated. The temperature mathematics model of laser beam preheating diamond grinding wheels has been set up. The temperature field of resin substrate diamond grinding wheels has been calculated. Through the analyses on the results of the temperature field, it has been known that the distance between laser beam preheating central and the diamond pen dressing point be very small. A new method that is delived laser beam by optical fiber in dressing on line of diamond grinding wheels by a diamond pen aided with laser beam preheating has be proposed. Uasing this new method, a high precision and high efficiency in dressing diamond grinding wheels on line can be fulfiled.
Analysis of the Breakage of Diamond Wire Saws in Sawing of Stone
Authors: Huang Guo Qin , Xu Xi Peng
Published: March 2009

An investigation is reported on the breakage of the diamond wire saw during stone processing. A Lot of breaken wire samples were collected from factories and observed macroscopically and microscopically. The results indicate that the breakages were mainly fatigue failure. And statistic of results show that all the breakage sites centralize on two sections. Reasons for the two break sections are also discussed in detail. Furthermore, sawing experiment was conducted to study the effect of the process parameters and the results reveal that the breakage of the wire saw is sensitive to the processing parameters. Finally, some proposals for manufacture and application were presented.
Control System Configuration for Grinding Machine with Two Moving Axes and One Circumrotating Axis Ganged Function
Authors: Chen Shao Bo , Zheng Zhi Dan , Yan Qiu Sheng , Zhang Zi Qiang , Li Y.
Published: March 2009

By applying NC system with three axes ganged function to M1432 universal cylindrical grinding machine, a NC grinding machine with two moving axes and one circumrotating axis ganged function is designed and developed. Besides two moving axes ganged function, this machine has a special function of driving the form wheel dresser to circumrotate around the Y axis. Ordinary grinding machine with two axes ganged function can’t machine complicated parts such as seaming roll with steep gradient groove. But a grinding machine with this special unction can do this by precisely dressing the form wheel with various aspheric curves. With the set-in PLC
function of NUM1020 NC system and the correlative parameters to be respectively setup, the new machine can be used to machine some complicated parts such as seaming roll. The system receives machining process codes which is pretreated by computer firstly and dresses the form wheel in DNC mode, then machines parts with the form wheel later.
Analysis of Chatter Marks in Accurate Grinding on Optical Curve Grinder
Authors: Xu Li Ming , Hu De Jin , Zhao X.M. , Ma Chun Xiang , Huang K.F.
Published: March 2009

Chatter marks that limit ground surface finish have been observed in accurate grinding by using optical curve grinder. To reveal the mechanism of chatter marks, the relationships between grinding parameters and chatter marks are experimentally studied. The profile of the ground surface is analyzed through microscope as well as FFT method. It is found the dynamic characteristics of grinder and the vibration test are efficient tools for this study. Modeling of grinding chatter marks is proved effective for the result of simulation showing consistent with that of experiments. The results of study point out the way to eliminate chatter marks and establish the basis for detection and prediction of the marks.
Study on Dynamic Strength Model of Contact Layer in Quick-Point Grinding
Authors: Xiu Shi Chao , Cai Guang Qi , Li Chang He
Published: March 2009

Ultra-high grinding speed and point contact are the salient natures of Quick-point
grinding. Based on the damage dynamics theory, there are impact damages with a lot of micro-cracks and micro-defects and adiabatic shearing caused by ultra-high strain rate in the contact layer in such grinding manner. The micro-damages are relation to the strain rate and the materials properties, and increase with raise of strain rate. Because of the weakening effect of strain rate, the dynamic strength of the contact layer in Quick-point grinding is decreased and the grinding performance of ductile and brittle materials is also changed. The dynamic strength model of the contact layer in Quick-point grinding was built in this paper, and the weakening effects of strain rate caused by impact micro-damages on the dynamic strength of the layer and the materials removal mechanism in grinding layer were analyzed through the study on the theory and the experiments.
Synthesis and Characterization of Nanocrystalline Ni3Al Intermetallic via Mechanical Alloying and Reaction Synthesis
Authors: Ismail Roslina , Yaacob Iskandar Idris
Published: March 2009

Stoichiometric nanocrystalline Ni3Al was prepared by mechanical alloying of elemental Ni and Al powders under argon gas atmosphere for different time (4-48h). The nanostructured Ni3Al powders were consolidated into bulk compacts and sintered in a small DTA furnace under flowing Argon to observe the exothermic reaction between the stoichiometric Ni and Al. The estimated crystallite size showed that the mechanically alloyed Ni3Al grain size decrease from 127 nm to 9.36nm with increasing mechanical alloying time from 4h to 48h. Agglomerations of the powder particles prevalently occurred as observed from the SEM micrographs. Saturation magnetization, Ms value of the mechanically alloyed powders decreases as milling time increases due to smaller amount of elemental nickel responding to the applied fields. Following reaction synthesis of the compacted powders, thermal profile analysis revealed the presence of exothermic peaks in the DTA curves at about 400oC. Relative densities of the sintered compact were measured and found to be from 77- 88% with the exception for the 48h mechanically alloyed sintered compact from milling balls contaminations. XRD results of the sintered compacts mechanically alloyed for 18h and above revealed the formation of pure nanocrystalline Ni3Al. Crystallites size estimations showed the occurrence of grain growth during sintering.
Love Wave Propagation in a Layered Piezoelectric Structure Immersed in a Viscous Fluid
Authors: Peng Fei , Liu Hua Rui , Hu S.Y.
Published: March 2009

This paper is addressed to the Love wave propagation in a layered piezoelectric structure immersed in a viscous fluid. The layered piezoelectric structure consists of an isotropic layer and a relatively thicker transversely isotropic piezoelectric substrate. The velocity of the Love waves changes due to the presence of the viscous fluid. The exact theory is accurate but not convenient to apply because it is generally difficult to get an explicit relation between the quantities we interest. In this paper, the perturbation approach is applied to obtain the explicit relations for the phase velocity and attenuation of Love waves. The result is useful for the measurement of the viscosity and mass density in Love wave sensors.
Development of a Bulk-Micromachined Single Crystal Silicon Gyroscope of Wide Operating Range at Atmospheric Pressure
Authors: Sung Woon Tahk , Kim Seong Hyok , Lee Jang Gyu , Kang Tae Sam
Published: March 2009

In this paper, presented are the design and the fabrication of the novel bulk-micromachined gyroscope with its detection and control circuit. The proposed structure is designed to have good properties such as heavy proof mass, a large movement and high moving velocity of the proof mass at an operating frequency. Despite of an appropriate design of the proof mass and comb electrodes, the
high-Q property and the capacitance measurement scheme inevitably bring on nonlinear property and limited bandwidth of the system. Moreover, temperature variation degrades the stability of the performance. In this paper, we adopt a feedback control scheme to achieve a linear output and a less sensitive operation to the temperature variation. Through experiments, it is confirmed that the
designed gyroscope and the control circuit achieve performances of wide input range of 1,000 deg/sec and bandwidth of 80 Hz.
A Simple Strain-Life Approach for the Fatigue Life Evaluation of Welded Joints with Residual Stresses
Authors: Goo Byeong Choon , Yang Sung Yong , Lee Dong Hyung
Published: March 2009

We surveyed literature and proposed a procedure to identify the fatigue properties from the Brinell hardness and Young’s modulus. And we developed a parameter similar to the S.W.T. parameter with the Brinell hardness and Young’s modulus. Using the parameter and finite element analyses, we evaluated fatigue lives of four kinds of welded joints. The predicted results are in a good agreement with experimental results.
Numerical Analysis of Kidney Stone Fragmentation by Short Pulse Impingement: Effect of Geometry
Authors: Mihradi Sandro , Homma Hiroomi , Kanto Yasuhiro
Published: March 2009

To better understand the behavior of stresses generated inside a kidney stone by direct pulse impingement during extracorporeal shock wave lithotripsy (ESWL), numerical analyses are performed in this work. LS-DYNA, an explicit Finite Element code for non-linear dynamic analysis is employed to investigate the effect of stone geometry to the stress field evolution inside the stone when subjected to short pulse wave. Circular disks with parts removed from the front and the back are used
to model the stones that assumed have already had initial fracture. The other variation of spherical geometry such as ellipse is also considered in the numerical calculation.
Real-Time and Full-Field Deflection Measurement of Thin Films Electroplated on the Single Crystal Silicon Wafers
Authors: Li Xi De , Wei Cheng
Published: March 2009

A special speckle microinterferometer has been developed to test the mechanical properties of thin films electroplated on the single crystal silicon wafer. A piezo-actuated micro-loading unit is synchronized with the microinterfermeter to measure thin film deflection in bending with an accuracy of sub-micrometers. All of the film specimens were microfabricated to be the type of microbridge samples. They are made of Cu and NiFe, the sizes from 1102.9µm to 213.7µm long, 491.0µm to 9.7µm wide. The corresponding thicknesses are 9.4µm and 7.6µm, respectively. Deflections of the microbradge samples can be measured full-field and real-time by using the microinterferometer and no patterning or marking of the specimen surface is needed. The loading force is directly measured using a miniature load cell. The Young’s moduli are calculated for both material and sample size from the load-deflection curves. Test techniques, procedures and factors which affect on the deflection measurements are briefly presented along with detailed analyzes of the results.
The Dielectric Properties of Pb0.65Ba0.35ZrO3 Thin Films
Authors: Kim J.S. , Park B.H. , Choi T.J. , Shin Se Hyun , Lee Jae Chul , Lee Man Jong , Seo S.A. , Yoo I.K.
Published: March 2009

Pb0.65Ba0.35ZrO3 (PBZ) thin films have been grown on MgO (001) substrates by pulsed-laser deposition (PLD). We have compared the structural and dielectric properties of PBZ films grown at various temperatures. A highly c-axis orientation has appeared at PBZ film grown at the deposition temperature of 550oC. The c-axis oriented PBZ film has also shown the largest tunability among all the PBZ films in capacitance-voltage measurements. The tunability and dielectric loss of the PBZ film was 20% and 0.00959, respectively. In addition, we have compared the
temperature coefficient of capacitance (TCC) of a PBZ film with that of a Ba0.5Sr0.5TiO3 (BST) film which is a well-known material applicable to tunable microwave devices. We have confirmed that TCC value of a PBZ thin film was three-times smaller than that of a BST thin film.
Preliminary Study on the Progressive Failure of a Layered Rock Slope under Explosions
Authors: Liu Y.Q. , Li Hai Bo , Dai H.C. , Li Jun Ru , Zhou Qing Chun
Published: March 2009

The progressive failure process of a layer rock slope under explosions is simulated using two-dimensional Universal Distinct Element Code (UDEC). It is shown that the failure process of the slope can be divided into three phases, the formation and growth of local failure area as well as coalescence of sliding plane. In addition, the displacement components of a critical point of the slope are also suggested to be a progressive process.