bluuebunny/crossref_metadata_2025 huggingface dataset:
Study on a Semi-Active Shock Isolation Technology with Magnetorheological Devices
Authors: Wang Yu Fei , He Lin , Yang Xue
Published: June 2010

A semi-active shock isolation technology with magnetorheological devices was systematically studied. The magnetorheological devices consist of magnetorheological dampers (MRD) and magnetorheological elstomers (MRE) isolator. Based on the method of Lyapunov function, the semi-active control strategy and the control algorithm were developed to minimize the relative movement of the system. The simulation results show that, compared with the passive devices, the semi-active control technology in the paper is effective to reduce the relative displacement and the shock acceleration of protected equipment. And the system will go back to the stable state within ultrashort time.
Distribution Network Planning Based on Entropy Fuzzy Comprehensive Method
Authors: Jia Zheng Yuan , Fan Zhou , Jiang Miao Miao
Published: June 2010

Comprehensive evaluation of distribute network planning is a multi-factors decision-making problem in complicated system. Combining with the factors of distribute network planning, established for the distribution network planning project evaluation fuzzy comprehensive evaluation model, and the entropy weight method is led into comprehensive fuzzy evaluation. It overcomes the shortages of traditional method, which requires to the independence of each index, and the weight coefficients of factors are automatically determined according to the opinion of experts. Finally, one example is used to verify the feasibility and practicality of the method.
Uncertainty Propagation Analysis for Turbine Cooling Blade Multidisciplinary Design
Authors: Yu Kua Hai , Ni Jun , Yang Xi , Yue Zhu Feng
Published: June 2010

This paper presents an uncertainty propagation analysis method using the Convex Model Theory (CM) for turbine cooling blade multidisciplinary design. Convex Model is used to describe the design variables’ uncertainty, and it’s propagation equation is derived. Monte-Carlo(MC) method and Convex Model Theory (CM) are all employed to calculate target variable’s variation. Result shows that CM method is more time-saving than MC method. First order second moment method is employed to calculate the reliability of target variable’s variation to evaluate the difference of the results of the two methods. As the actual probability density function of design variables is unknown, so reliability analysis considers different probability density functions. Response surface method is used to construct the approximation of the multidisciplinary analysis. Reliability analysis result shows that CM method keeps the same accuracy with MC method.
Study for the Method of Automobile Oil Consumption Measuring Based on Ultrasonic Wave
Authors: Fu Bai Xue , Hu Sheng Hai
Published: June 2010

In response to the problems of automobile oil consumption direct test and indirect test, Ultrasonic technology and microcontroller control technology can be used to research automobile oil consumption testing technique. Deciding on the method of automobile oil consumption testing is based on the fluid testing principle of ultranonic wave technology and build a mathematical model of automobile oil consumption tesing, According to the functional requirements of oil consumption, design the automobile oil consumption system hardware, control circuit and control automation programming to achieve the oil consumption inteligence non-disintegrated measuring. By means of tests and data processing analaysis and modifying the theoretical model, the theory used by the system is feasible and oil consumption measuring system with low power consumption and high accuracy.
Research on Cutter’s Position and Pose for Chamfering Spiral Bevel Gear Addendum
Authors: Wei Xiu Ting , Liu Jing Cheng , Du Qiang
Published: June 2010

The cutter’s position and pose are key elements for chamfering addendum automatically and a new method for calculating the cutter’s position and pose is as follows: 1) Finding the chamfering boundary curves of addendum by offsetting the two top curves (convex and concave) of spiral bevel gear addendum respectively; 2) Dispersing the chamfering boundary curves; 3) Calculating the center position of the tangent circle along the chamfering boundary curves and taking this as the cutter’s center; 4) solving the tilt angle through the center position and the dispersed points on boundary curves. The proposed method lays foundation for chamfering automation.
Measurement on Fatigue Cracking Thresholds of the Cast Steel for Chinese Railway Rolling Wagon Bogie Frames
Authors: Hu Hai Bin , Zhao Yong Xiang
Published: June 2010

Measurement on fatigue cracking thresholds is investigated to the grade B cast steel for China railway rolling wagon bogie frames. Compact tensional specimens are fatigued under a continuous decreasing loading mode for present study. Results reveal that the minimum test values have different crack growth rates without meeting the code-based rate requirement. Therefore, the test results can not be directly used for measuring the thresholds. A probabilistic modeling in the form of a non-linear law is developed for reflecting the scattered test data. The thresholds at specified reliability levels are then derived in meeting the threshold definition with a specified growth rate. The measurement for the present material has verified the availability of the present modeling.
Fatigue Limit Measurement of the Cast Steel for Chinese Railway Rolling Wagon Bogie Frames
Authors: Yu Lian You , Zhao Yong Xiang
Published: June 2010

Fatigue limit measurement is investigated experimentally on the grade B cast steel for Chinese railway freight car bogie frames. Small sample up-and-down test method was employed for the present study. Results reveal that fatigue cracks initiated mostly from the material cast shrinking cavities. Distinct river-like flowers and second cracks appeared on fracture surface in perpendicular to fatigue crack path. Lots of dimples are distributed in transient fracture district to indicate that present material is ductile. Maximum likelihood approach is applied for measuring the probabilistic fatigue limits, in which the limits are defined as the fatigue strengths following normal distribution at an expected fatigue life. Statistical parameters are then estimated by a likelihood function method. A comparison analysis to the existent conventional, Dixon-Mood and Zhang-Kececioglu approaches indicates that the maximum likelihood approach is the approach meeting the definition.
The Safety Study on Corrosion Damage of LC4 Aluminum Alloys by Finite Element Method
Authors: Wang Zhen Guo , Lv Sheng Li , Xu Cheng Long , Zhang Wei
Published: June 2010

. The corrosion damage data are obtained through the pre-corrosion accelerated experiment which is performed under three different time levels: 24h, 48h and 72h. Based on the corrosion damage data, a three-dimension (3D) solid model is created by CAD. An analysis procedure is developed using CAD and finite element analysis to predict stresses and residual strength due to corroded pits. The residual strength results of specimens are obtained from the model based on the corrosion damage data. The simulation results are compared with the true testing static intensity results and the method is proved that it is reliable and effective in engineering.
Fatigue Life Prediction of Spot-Welded Structure under Different Finite Element Models of Spot-Weld
Authors: Zhu Tao , Xiao Shou Ne , Yang Guang Wu , Miao Bing Rong
Published: June 2010

In order to accurately and conveniently simulate spot-weld in FEA, based on the typical specimen of stainless steel, three typical finite element models (FEM) of spot-welds have been created as analysis objects. Firstly, based on the calculation theory of the spot-weld fatigue, two sets of analytical solution, which were the maximum principle stress of the specimen around the spot-weld nugget, were obtained under the action of stretching and shearing, respectively. Then, their linear elastic FEM were established, and the stress states around the spot-weld nugget and the adjacent sheets were analyzed. Finally, according to the results compared between the analytical solution and simulation solution, it can be seen that, when the specimen was stretched, using the brick model to simulate the nugget can get the smallest absolute error of the principle stress, so its spot-weld fatigue damage is the most consistent with the actual situation, a stiff beam model followed, and an umbrella model is the worst; when the specimen was sheared, using the brick model to simulate the nugget can also get the smallest absolute error of the principle stress, so its spot-weld fatigue damage is also the most consistent with the actual situation, the umbrella model is followed, and the stiff beam model is the worst. The results show that appropriate selection of spot-weld FEM is extremely essential for fatigue life prediction under the initial design of products.
Optimizing of Turning Parameters Using Multi-Objective Genetic Algorithm
Authors: Mahdavinejad Ramezan Ali
Published: June 2010

In this research, the turning parameters of steel are optimized via multi-objective genetic algorithm and multi-objective harmony research algorithm. These two algorithms are known as strong and powerful tools in optimization of engineering problems. The stock removal rate and surface roughness, as two main of output parameters are the target function and have been considered to be optimized. Since, there are two functions here; we can not use the ordinary optimization method with single-objective algorithm. In steel machining, the stock removal rate usually decreases with the surface finishing and visa versa. Therefore, it is necessary to define the weight of these parameters. In this paper the importance of each of these parameters are determined with weight sum method. In this research, the optimization methods to solve the problems via these two algorithms are discussed first. Then, the steel samples are machined and the output data are analyzed and optimized.
Failure Rate Analysis and Model Consisting of Four Elements for Components
Authors: Wang Zheng , Xie Li Yang , He Hong , Guo Kai
Published: June 2010

Factors affecting the shape of failure rate curve are analyzed, and four elements including load, strength, degradation and lifetime index (namely, the number of load application and time) are proposed for calculating the failure rate of components. Taking the number of load application and time as the life index, respectively, the failure rate models of components consisting of four elements is developed, which can embody the effect of parameters of load, strength, degradation and life. Then, the rules that the reliability and failure rate changes as life index are studied. The result shows that the failure rate curves are partially or whole bathtub-shaped. For different parameters of load, strength and strength degradation, the curves of reliability and failure rate of components changing with time present different shapes. The models derived in this paper can calculate the failure rate of components as long as the parameters of load, strength and degradation and life index are known.
Theoretical Research and Experiment of Vibration Friction on Vibratory Compaction Experiment System
Authors: Li Xiao Peng , Liu Chun Shi , Huang Jie , Wen Bang Chun
Published: June 2010

Friction under vibration condition presents extremely different complex characteristics from that of the conventional state. Practice shows that machine power rises obviously with the significant decrease of the fiction. However, occurrence mechanism of the vibration is not fully studied or revealed; therefore, how to further develop the benefits of vibration, there is no concrete and clear measures yet. From this actual situation, this work want to reveal the characters of nonlinear dynamic of the vibration friction, analyze the relationship between vibration and friction, discuss the impact of vibration’s parameters on the friction mechanism, Theoretical study and experimental verification were conducted to improve the work efficiency of the related equipments with the benefits of the vibration friction.
Design of a Biped Toy Robot with an Automatic Center of Gravity Shifting Mechanism
Authors: Pa Pai Shan , Jou Jinn Bao
Published: June 2010

The design of the biped toy robot in this study, presents a brand new concept compared to that of the conventional mechanical biped robots on the market. These conventional mechanical products rely mainly on a large sole area to stabilize the wobbling movement during walking. In this design walking stability is not achieved by large sole areas, but by having more degrees of freedom and automatically shifting the center of gravity as the robot walks. A single motor is used to drive the biped toy robot trunk so that the center of gravity is automatically shifted to achieve walking stability. The two feet are driven by four connecting rods for striding and leg-lifting action. More particularly, an equal parallel crank mechanism is provided that uses a single motor to drive the connecting rods, thereby swinging the center of gravity of the toy robot in time with striding frequency. In addition, the concept of the zero moment point is utilized in the shifting of the center of gravity allowing the biped robot to lift its legs, change step, and move forward in balance. This study also discusses the use of the four connecting rods, and the shifting of the center of gravity of the robot, as an alternative to the servomotors commonly used in conventional robots which are bulky, expensive and hard to control.
Perception of Constraints in Conceptual Design within the Automotive Industry
Authors: Kaur S. , Mullineux Glen , Matthews Jason
Published: June 2010

Many previous researchers have shown design to be essentially the process of negotiating and resolving constraints. This has lead to a multitude of different design methods and approaches purely based on constraints; much of this work has concentrated on the late conceptual and embodiment phases of the design activity. The work presented in this paper has shown initial investigations into expanding these approaches to the earliest stages of the conceptual phase. The research has reviewed previous academic work, and the current approaches and understanding of designers working in the automotive domain. The findings of this research are presented and analysis given.
Analysis of Thermal Properties of Super-High Speed Hybrid Journal Bearing Based on ANSYS
Authors: Xiu Shi Chao , Gao Shi Qiang , Sun Zhi Li
Published: June 2010

Hybrid journal bearings are used in the high and super high speed cases mainly, such as the super-high speed spindle system. Since the bearing operates under high speed conditions, the excessive temperature rise of the bearing is a major reason to lower the accuracy of the main shaft system and limit the bearings working speed higher, as a result, restrict the bearing applications. In this paper, the thermal properties and the heat mechanism of such bearings are analyzed. The mathematical model of hybrid journal bearing is established to analyze the mechanism of generating heat. In addition, the temperature field distribution for the certain hybrid journal bearing at speed of 10000 rpm is studied by means of software ANSYS considering the heat transfer characters between fluid and solid. An improved measure about temperature rise of hybrid journal bearing is presented.
The Development of the Sustainable Manufacturing Processes
Authors: Ding Lian , Qiu Xiao Li , Mullineux Glen , Matthews Jason
Published: June 2010

Sustainable manufacturing will be the dominate factor in the design of the future factory. Any manufacturing operation within these factories will affect the environment, be it through the waste it creates, the resources it uses, or the energy it consumes. All can be significant, but not all have been properly examined or documented. This paper presents an initial investigation into these issues related to subtractive machining and evaluates research finding against the waste hierarchy. The paper concludes by discussing the findings and presents some requirements and suggestions for the factory of the future.
Very High Cycle Fatigue Behavior and Thermographic Analysis of High Strength Steel
Authors: Shao Chuang , Bathias Claude , Wagner Danièle , Tao Hua
Published: June 2010

Very high cycle fatigue behavior of high strength steel, were investigated using ultrasonic fatigue testing equipment at 20 kHz up to 109cycles. S-N curves at room temperature with different stress ratio (R=0.01 and R=0.1) was determined. The experimental results show that fatigue strength decrease with increasing number of cycles between 105 and 109. SEM examination of fracture surface reveals that fatigue damage was governed by the formation of cracks, and subsurface crack initiation was in the very long life range. The results shown that the portions of life attributed to subsurface crack initiation between 107 and 109 cycles are 99%.
Research on Economical Evaluation for Disseminating Nanomaterials Based on Sustainable Development
Authors: Li En Zhu , Liu Chang Lin , Liao Jia Ming
Published: June 2010

Sustainable development and nano-materials is the focus of widespread concern in today's world. Nano-material not only is the main way of material development, but also is closely related to requirement of sustainable development. This paper states the influences of disseminating nano-materials to sustainable development and the traditional system of accounting scientifically, these influences include form of conception of sustainable development, establishment of value system of natural resource and introducing the evaluation system based on data of accounting for enterprises. The aim of these researchs will be references for evaluating the economic effectiveness of resources invested in disseminating nano-materials.
Optimization of Electronic Nose Sensor Array and its Application in the Classification of Vinegar
Authors: Men Hong , Liu Hai Yan , Wang Lei , Zhou Xuan
Published: June 2010

Five kinds of vinegars were measured by a gas sensor array composed of six TGS gas sensors. The sensor array should be optimized by the minimal Wilks statistic value, then, the four best sensor array used to detect the type of vinegars were formed, Principal Component Analysis (PCA) and Linear discriminant analysis (LDA) were applied to analyze the data of primary and optimized sensor array. The results indicated that optimization sensor array could be more adaptable to recognize the five kinds of vinegars. Thereby the given optimization method is effective.
Semi-Automatic Liver Segmentation Using Improved GVF Snake Model
Authors: Jiang Hui Yan , Gao Xi He
Published: June 2010

Snakes are extensively used in computer vision and Image processing. However, when it comes to the liver segmentation from computed tomography (CT) image, the application of the models is limited because it can not extend to certain boundary indentations of the liver. In order to solve this problem, we developed an improved GVF snake model by adding an external force field which can efficiently attract the initial contour to these depression areas, such as the top of the left lobe of liver. The proposed method includes two steps. Firstly, combined with the threshold method and the morphology operation, our model can acquire the initial contour of the liver. Secondly, we create an imposed external force field through the interaction with the system, and we make the initial contour converge under the influence of both GVF field and imposed external force field to get the accurate contour of the liver. The application of this method on abdominal CT image is demonstrated, both qualitatively and quantitatively.
The Basic Tacit Knowledge Acquisition Model of Industrial Organization and its SD Simulation
Authors: Wei Ming Liang , Feng Tao
Published: June 2010

Knowledge is increasingly becoming one of the most important productive factors those which create the value of the industrial organization. In fierce market competition, the tacit knowledge is the vital resource for corporation to build and obtain competition advantage. From the perspective of the basic model of tacit knowledge acquisition, this paper studies how the tacit knowledge spreads between two corporations, and uses the theory of System Dynamics (SD) to analyze it by the method of Computer-aided Simulation.
A Network-Friendly Architecture for Multi-View Video Coding (MVC)
Authors: Wang Liang Hao , Xi Ming , Li Dong Xiao , Zhang Ming
Published: June 2010

Multi-view Video Coding (MVC) is very promising in applicable field for its 3D effect and interactive functions (multi viewpoint). In this paper, a network-friendly architecture for MVC is proposed. To exploit temporal as well as inter-view dependencies between adjacent cameras, two main features of the coder are used: hierarchical B picture and FGS (fine granularity scalable). Coding results are shown for the proposed multi-view coder and compared to the traditional coding architectures to show that our presented coding scheme outperforms the other approaches for the tested sequence.
Safety on Food Supply Chain Game Basing on Profit Distribution
Authors: Zhang Kui , Qi Hai Feng , Shi Cheng Hua
Published: June 2010

The security of food has a direct relationship with consumers’ health and safety, which is the most basic material condition for human society’s survival and development. In the food market, information asymmetry exists in the entire food supply chain process, and the member companies are in game relationship during the operating process about food safety. The solution to the problem of food depends on the establishment of a reasonable distribution mechanism about food suppliers. Based on game theory, this paper builds and analyzes the profit distribution model of food supply chain and points out that a reasonable profit distribution mechanism plays an important role on the safety of food.
Modeling and Simulation on Ship Power Station under Large Disturbance
Authors: Liu Yan Cheng , Wang Chuan
Published: June 2010

This paper presents a non-linear math model on ship power station and numerical simulation, aiming at describing dynamic characteristic of electric propulsion ship shipboard power system precisely. Non-linear differential algebraic equations are given by differential equation modeling theory, concerning with diesel engine speed characteristics, electromagnetic and electrical transient characteristics (Φd, Φq, Ed", Eq", E'q, ω, δ as status variables) of synchronous generator and voltage characteristics of excitation system. Then the non-linear equations are solved by implicit trapezoidal integration method, finally dynamic curves of status variables such as voltage, speed of rotor, three phase current of stator and so on are drawn based on simulation program written by C#.NET. Simulation results demonstrate that the non-linear math model proposed by this paper is reasonable, and the results are theory foundation of transient stability on ship integrated power system for further research.
Uncertainty Description of GIS Attribute Data in Hierarchical Approximate Space
Authors: Liao Wei Hua
Published: June 2010

GIS attribute data is the property of GIS entity, it has fuzziness and uncertainty. The binary relation for GIS entity object and attribute is meet to the property for approximate space. We choose the object and attribute of GIS information system in our study, use lattice concept, and we think the GIS entities can form partial order relation, and lattice(P(A), ) can form one complete partial order lattice. GIS entities can form hierarchical approximate space in subsection space relation, and the knowledge granularities are thining along with the increasing of attribution.
Estimates for the Lower Bounds on the Inverse Elements of Strictly Diagonally Dominant Tridiagonal Matrices in Signal Processing
Authors: Dong Chuan Dai
Published: June 2010

In the theory and practical applications, tridiagonal matrices play a very important role. In this paper, Motivated by the references, especially [2], we give the estimates for the lower bounds on the inverse elements of strictly diagonally dominant tridiagonal matrices.
Effect of Residual Stress on Mechanical Property of Monolithic Bulk Metallic Glass
Authors: Lee Min Ha , Jun Joong Hwan , Eckert Jürgen
Published: June 2010

Mechanical treatments such as deep rolling are known to affect the strength and toughness of metallic glass due to the residual stress. It is well known that compressive residual stress states usually enhance the mechanical properties in conventional metallic materials. We present investigations on the change of fracture behavior related with mechanical properties of “brittle” bulk metallic glass by cold rolling at room temperature. Improvement of the intrinsic plasticity is observed not only after constrained cyclic compression but also after cold rolling. Moreover, neither nanocrystallization nor phase separation occurs during deformation. By these findings we provide a unique fundamental basis by considering the introduction of structural inhomogeneity and ductility improvement in metallic glasses. The experimental evidence clearly supports that such an inhomogeneous glassy can be produced by residual stress in well known “brittle” bulk metallic glasses, and does not depend on a specific pinpointed chemical composition.
Amorphous Magnesium Sheet Produced by Twin Roll Casting
Authors: East Daniel R. , Kellam Michael , Gibson Mark A. , Seeber Aaron , Liang Daniel , Nie Jian Feng
Published: June 2010

Sheets of a Mg60Cu29Gd11 alloy were produced by twin roll casting with all operational variables, except roll speed, being kept constant. As a function of the roll speed, the structure of the as-cast sheet changed from being crystalline to fully amorphous and then back to crystalline. Through careful selection of the casting speed that is suitable for the selected alloy system and with which the exit temperature of the sheet remains within the supercooled liquid region, a malleable sheet with no surface defects is produced. This work shows that twin roll sheet casting is a viable process for the production of magnesium-based bulk amorphous sheet in a continuous manner and on an industrial scale.
High Bs FeSiBPCu Nanocrystalline Wide Ribbons Using Industrial Raw Materials
Authors: Urata Akiri , Matsumoto Hiroyuki , Yoshida Shigeyoshi , Makino Akihiro
Published: June 2010

Nanocrystalline Fe-Si-B-P-Cu wide ribbons, with 15-30mm width, using industrial raw materials have been investigated. A homogeneous nanocrystalline structure composed of α-Fe grains with around 10 nm in diameter was realized after crystallization and the nanocrystalline alloys exhibit the high Bs of 1.74-1.82 T, the low Hc of 6.5-7.2 A/m and the low W at 50Hz-1.7T of 0.42-0.60W/kg. Therefore, the nanocrystalline Fe-Si-B-P-Cu soft magnetic alloy has a large economical advantage of low material cost by using industrial raw materials.
Controlled Growth of 1-D Nanomaterials Base on Electro-Deposited Nanocrystalline Films: A Overview
Authors: Pan Chun Xu , Chen Jian Chun , Li Xiao Zhu , Liu Yue Li
Published: June 2010

This paper introduces a novel process for growing one-dimensional nanomaterials. That is, firstly, preparing a pure metal nanocrystalline film by using pulse electro-deposition, then, using this film as a catalyst for synthesizing variant one-dimensional carbon nanomaterials and one-dimensional metal oxide nanoneedles. Comparing with the nanoparticle catalyst, the growth mechanism of the present one-dimensional nanomaterials belongs to the “base growth model”, and it has advantages such as a much simpler process and no post purification requirement. In addition, the present method provides a possibility for diameter control of the one-dimensional nanomaterials through grain size control of the nanocrystalline film by adjusting the pulse electro-deposition parameters.
Shape-Controlled Synthesis and Formation Mechanism of Cobalt Nanopowders by a PVP-Assisted Method
Authors: Zhang Bing Cong , Yu Hong Ying , Sun Dong Bai
Published: June 2010

Three different kinds of morphologies including spherical, chainlike and wirelike cobalt nanopowders, have been synthesized by chemical reduction of coblat chloride solution with hydrazine hydrate in basic solution. The products were characterized by X-ray diffraction (XRD) and field emission scanning electron microscopy (FESEM). It was revealed that the morphologies of the nanopowders depend on the concentration of Co2+ and the way of adding reducing agent (hydrazine hydrate). These two features affected the nucleation sites and the number of nucleuses. When the concentration of Co2+ was low, nucleuses formed in the soft template, while the reducing of the reducing agent added drop wise, a little number of nucleuses was formed. Based on that, a mechanism of formation, as a basis of gram-scale syntheses, was proposed.
Atomic-Scale-Deformation-Dynamics (ASDS) of Nanowires and Nanofilms
Authors: Zhang Ze , Zhang Yue Fei , Zheng Kun , Yue Yong Hai , Wang Li Hua , Liu Pan , Han Xiao Dong
Published: June 2010

Nanowires and nanofilms are fundamental building blocks of micro and nano-electronics for both of bottom-up and top-down technologies. Monitoring and recording the mechanical property dynamics at atomic scale are important to understand the atomic mechanism of new and surprising nano-phenomena and design new applications. Through years’ endeavors, we developed tensile and/or bending in-situ atomic-lattice resolution electron microscopy methods and equipments for nanowires and successfully conducted atomic-lattice resolution mechanical tests on individual nano-objects. With this, we observed the brittle materials SiC and Si nanowires (NWs) become highly ductile at room temperature. The crystalline structural evolution processes corresponding to the occurrence of unusual large strain plasticity includes the dislocation initiation, dislocation accumulation and amorphorization as well as the necking of the one dimensional nanowires were fully recorded at atomic scale and in real time. We also expand the experimental methods and equipments to two-dimensional nanofilms. An example of tensile experiment on nano-crystalline Au films is presented. The deformation mechanisms of nano-crystalline gold films were observed at the atomic scale and real-time. At the mean time, an atomic scale the crack blunting behavior was captured and the plastic deformation mechanism of the single nano-crystalline was revealed.
Work-Softening, High Pressure Phase Formation and Powder Consolidation by HPT
Authors: Umemoto Minoru , Long Bui Duc , Todaka Yoshikazu , Tsuchiya Koichi
Published: June 2010

Among the various severe plastic deformation (SPD) processes, high pressure torsion (HPT) has several unique characteristics. These are applicability of very large strain and deformation under high pressure. Due to these abilities of HPT, several unique phenomena have been observed. In the present paper, three topics were reviewed; 1) work-softening in pure Cu, 2) high pressure phase formation in pure Ti and 3) synthesis of Cu-NbC composite. Work softening in pure Cu was observed when low strain rate and high pressure were applied. In Ti high pressure ω phase is obtained after unloading only when the deformation at high pressure was applied. The volume fraction of ω phase increased with the increase in the amount of strain. In pure Fe, high pressure ε phase was not retained at ambient pressure. The bulk Cu-NbC composite was synthesized starting from elemental powders. This demonstrates that HPT is an efficient tool for mechanical alloying and cold consolidation.
The Effect of Oxygen on the Brittle-to-Ductile Transition in Silicon Single Crystals
Authors: Hong Youn Jeong , Tanaka Masaki , Higashida Kenji
Published: June 2010

The brittle-to-ductile transition (BDT) in Czochralski (CZ) grown silicon single crystals and floating-zone (FZ) grown silicon single crystals was investigated by three-point bending. The temperature dependence of the apparent fracture toughness was measured in three different cross-head speeds. It was found that the BDT temperature in the CZ silicon crystal was higher than that in FZ silicon crystal, suggesting that the solute oxygen decreases dislocation mobility. However, the activation energies obtained from the strain rate dependence of the BDT temperatures were nearly the same in both the CZ and FZ silicon crystals, indicating that the dislocation mobility is not influenced by the solute oxygen. In this paper, the origin of the difference in the BDT temperature is discussed, focusing the role of the solute oxygen on the dislocation glide.
Influence of Roll Speed Schedule on Transverse Wall Thickness Evenness of Shell Elongated by Mandrel Mill
Authors: Li Sheng Zhi , Zhang Zhi Chao , Bao Hai Yan , Zhou Zhi Yang
Published: June 2010

The seamless steel tube continuous rolling process with 8-stand full-floating mandrel is simulated with the aid of commercial FE code MSC. SuperForm. The relationship is analyzed between the distribution of the transverse wall-thickness and the speed schedule of the rollers. The result shows that the transverse evenness of the wall thickness of the tubes can be enhanced by optimizing the speed schedule. Furthermore, by adopting meliorated method to measure the wall-thickness of the shell, the error is reduced while data reliability is increased. When using the existing equipments (mandrel mill), it is an effective way to improve the transverse wall-thickness accuracy of the shell tube by adjusting the speed schedule. Compared with present roll speed schedule, the transverse wall-thickness accuracy can be increased by 10% for the rolling of elongated shell with 152.5mm in OD and 6mm in wall thickness tube under the 3# speed schedule put forward in this paper.
Directional Solidification and Characterization of Al2O3/Er3Al5O12 Eutectic In Situ Composite by Laser Zone Remelting
Authors: Su Hai Jun , Zhang Jun , Deng Yang Fang , Song Kan , Liu Lin , Fu Heng Zhi
Published: June 2010

Directionally solidified (DS) oxide eutectic in situ composites are attracting increasing attention because of their unique properties and potential applications to high temperature structural materials, optical or electronic devices. Among the alumina-based eutectic composites, DS Al2O3/Er3Al5O12(EAG) eutectic is considered to be promising candidate for use as selective emitter at high temperature. In this work, eutectic in situ composites of Al2O3/EAG rods having smooth surface and full density are successfully prepared by directional solidification using the laser zone remelting method, aiming to investigate the growth characteristic of this novel binary eutectic under high temperature gradient. The microstructure is investigated by scanning electron microscopy (SEM), energy disperse spectroscopy (EDS) and X-ray diffraction (XRD). The Al2O3/EAG eutectic presents a very fine irregular network structure consisting of only -Al2O3 and Er3Al5O12 phases without grain boundaries and amorphous phases between interfaces. The eutectic interphase spacing is strongly dependent on the laser scanning rate, rapidly decreasing at the sub-micron levels for the samples grown at high rate. Furthermore, the microstructural formation and evolution of the composite are analyzed and discussed.
Analysis of an Equiaxed Dendrite Growth Model with Comparisons to In-Situ Results of Equiaxed Dendritic Growth in an Al-Ge Alloy
Authors: McFadden Shaun , Schaffer Paul L. , Mathiesen Ragnvald H. , Browne David J.
Published: June 2010

The Lipton Glicksman Kurz (LGK) growth model is commonly used to predict growth rates for equiaxed dendrites in solidifying mushy zones. However, the original LGK method treats an isolated dendrite growing in an infinite volume of liquid. In an equiaxed mushy zone, with multiple nucleation events, thermal and solutal interactions take place between the equiaxed dendrites. A modified version of the LGK model was developed that allows for measurement of the solute build-up ahead of the dendrites. To investigate the validity of the model, comparisons are made with results obtained from in-situ synchrotron X-ray videomicroscopy of solidification in a Bridgman furnace of an Al-12wt.%Ge alloy inoculated with Al-Ti-B grain refiner. Comparisons between the original LGK and modified LGK models are presented for discussion. The modified LGK model shows realistic tip temperature trends.
The Influence of External Mechanical Stresses on Agglomeration and Bending of Solidifying Crystals
Authors: Otarawanna Somboon , Gourlay Christopher M. , Laukli Hans Ivar , Dahle Arne K.
Published: June 2010

The influence of external mechanical stresses on agglomeration and bending of solidifying crystals has been investigated by microstructural characterisation of hypoeutectic Al cast specimens. The samples were produced by near-static cooling, gravity die casting and high pressure die casting (HPDC), where the solidifying crystals experience different levels of mechanical stresses. Electron backscatter diffraction (EBSD) technique was used to acquire grain misorientation data which can be linked to crystal agglomeration and bending behaviour during solidification. The length fraction of low-energy grain boundaries in HPDC samples was substantially higher than in gravity diecast and ‘statically cooled’ samples. This is related to the high amount of shear applied on the solidifying alloy, which promotes crystal collisions and agglomeration. In-grain misorientations were significant only in branched dendritic crystals which were subjected to significant shear stresses. This is attributed to the increased bending moment acting on long, protruding dendrite arms compared to more compact crystal morphologies.
Monte-Carlo Modeling of Recrystallization Kinetics of Cold-Rolled Titanium
Authors: Chun Y.B. , Semiatin S. Lee , Hwang Sun Keun
Published: June 2010

The recrystallization behavior of cold-rolled, commercial-purity titanium was studied experimentally and with Monte-Carlo (MC) modeling. Utilization of EBSD-OIM as input for MC modeling resulted in realistic predictions of recrystallization kinetics, microstructure and texture, which were in good agreement with experimental results. MC modeling of recrystallization kinetics predicted that the non-uniform stored energy distribution, heterogeneous nucleation of recrystallization and recovery in combination leads to a negative deviation from linear JMAK kinetics. It was found that concurrent recovery that takes place during recrystallization is an important process that controls both the overall recrystallization kinetics and the deviation of linear JMAK kinetics. On the other hand, the non-uniformly distributed stored energy itself has little effect on the negative deviation from JMAK kinetics but intensifies the deviation when heterogeneous nucleation is combined. Modeling results also revealed that heterogeneous nucleation of recrystallized grains and their early impingement in local areas of high deformation are essential for producing a log-normal distribution of grain size and a typical recrystallization texture of rolled titanium.
Numerical Simulation on Semi-Solid Metal Slurry Preparation by A-EMS
Authors: Zhang Zhi Feng , Xu Jun , Chen Xing Run
Published: June 2010

A computational model coupling electromagnetic stirring with a macroscopic heat and fluid flow in semisolid A357 alloy slurry preparation by A-EMS was developed. Effects of electromagnetic field on flow field and temperature field were presented successfully. It is shown that more intensive magnetic field, velocity field and thereby temperature field were uniformly distributed in the stirred melt even at commercial frequency, and thus more uniformly fine microstructures were obtained in comparison with normal EMS.
Phase Field Modelling of Dendrite Fragmentation during Thermal Shock
Authors: Guo Z. , Mi Jia Wei , Grant Patrick S.
Published: June 2010

The dendrite grain growth of a succinonitrile based transparent alloy, their fragmentation under an intense thermal shock and the subsequnet morphology evolution during solidification have been simulated using a two-dimensional binary alloy phase field model coupled with heat and solute transfer. The effect of a sudden, rapid change in the thermal environment (thermal shock) was implemented in the model and the resulting effect on the incipient dendritic grain morphology was studied. Thermal shock effectively promoted the fragmentation of the dendritic grains, providing a significant grain multiplication effect to refine the final solidification microstructure.
Physical and Numerical Simulation of Flow and Temperature in Molten Pool during Strip Casting Process
Authors: Ren San Bing , Fan Jun Fei , Yu Yan , Fang Yuan
Published: June 2010

In strip casting process, surface wave and temperature distribution in the molten pool directly affect the process stability and the quality of products. In this paper, physical model and numerical model have been set up and simulated. It has been found that in the corner of the molten pool there is a large wave amplitude on the surface. However, in the middle of molten pool the surface wave is low. The temperature distribution of molten pool showed that the present feeding device need to be optimized.
Microstructure and Tensile Properties of ODS Ferritic Steels Produced by Mechanical Alloying in Argon and Hydrogen Gas Environments
Authors: Iwata Noriyuki Y. , Kasada Ryuta , Kimura Akihiko , Okuda Takanari , Inoue Masaki , Abe Fujio , Ukai Shigeharu , Ohnuki Somei , Fujisawa Toshiharu
Published: June 2010

Two types of oxide dispersion strengthened (ODS) ferritic steels have been produced by mechanical alloying (MA) either in argon or in hydrogen atmosphere, and vacuum hot pressing (VHP). A drastic reduction in the oxygen and nitrogen contents after VHP was strongly affected by hydrogen gas used as the MA atmosphere. MA in hydrogen was found to be effective for refining the steel matrix and enhancing the tensile ductility of the ODS ferritic steels.
Direct Measurement for Electric Resistance of Ferromagnetic Metal- Nano-Contact in Oxide Layer
Authors: Sahashi Masashi , Watanabe Yoshiyuki , Kawasaki Shohei , Miyake Kousaku
Published: June 2010

Nanocontacts Magneto-Resistive (NCMR) Spin-Valve devices using NOL (Nano-Oxide Layer) have been reported to show some kind of a new MR effect. If the NC resistivity nears to the bulk's value without limit, the NC resistance will be almost dominated by the sharvin resistance at the NC with 1 to 2nm size, which conductance regime dominates the NC resistance of our NCMR attract much interest for understanding MR mechanism of our NCMR, where the NC size is certainly just 1 to 2nm but the NC resistivity is still unknown. So, in this study we constructed the home-made circuit for directly measuring each conductive channel-current through each nano-contact with in-situ conducting AFM and tried to evaluate quantitatively the resistivity of each single NC in the NOL.
Phase and Morphology of Carbides in ASTM F75 Co-Cr-Mo-C Alloys Formed at 1473 to 1623 K
Authors: Mineta Shingo , Alfirano Alfirano , Namba Shigenobu , Yoneda Takashi , Ueda Kyosuke , Narushima Takayuki
Published: June 2010

The phase and morphology of precipitates in heat-treated Co-28Cr-6Mo-xC (x = 0.12, 0.15, 0.25, and 0.35mass%) alloys were investigated. The as-cast alloys were solution-treated in the temperature range of 1473 to 1623 K for 0 to 43.2 ks. Complete precipitate dissolution was observed in all four alloys, each of which had different carbon contents. The holding time for complete dissolution was greater for alloys with greater carbon content. The curve representing the boundary between the complete- and incomplete-dissolution conditions for each alloy is C shaped. Under the incomplete precipitate dissolution conditions of the Co-28Cr-6Mo-0.25C alloy, an M23C6 type carbide and a π-phase (M2T3X type carbide with β-Mn structure) were observed at 1548 to 1623 K, and starlike precipitates with a stripe pattern and with a dense appearance were both observed; the former comprised the M23C6 type carbide + γ-phase, and the latter was the π-phase. In contrast, only a blocky-dense M23C6 type carbide was observed at 1473 to 1523 K.
Mechanical Properties Evaluation of Nano-Structured Materials in Scanning Electron Microscope
Authors: Nahm Seung Hoon , Jang Hoon Sik , Jeon Sank Koo , Lee Hak Joo
Published: June 2010

To apply nano-structured materials in micro/nano system, understanding of the mechanical properties of nano-structured materials is required. In order to perform the mechanical test of nano-structured materials, the mechanical testing system was installed in a scanning electron microscope (SEM). The nano-manipulator was set up in the SEM, and the force sensor formed as a cantilever was mounted on the nano-manipulator. Then, the force sensor can be controlled by using the nano-manipulator. The nano-structured materials were dispersed on the transmission electron microscope (TEM) grid, and both end of the nano-structured materials were welded on the TEM grid and the tip of force sensor by exposing E-beam of the SEM. The tensile tests for carbon nanotubes, ZnO nanorods and ZnS nanowires were carried out in the SEM, respectively. The load response during the mechanical test was obtained by force sensor. The dimension of nano-structured materials was obtained by determining the configuration measured from the TEM. And, strain-stress curve was obtained after mechanical test. The elastic modulus of the nano-structured materials after the tensile tests were calculated and compared. The elastic modulus for multi-walled carbon nanotubes, ZnO nanorod and ZnS nanowire were ~0.98 TPa, ~59 and ~39 GPa, respectively.
Effects of Doping Elements on Residual Oxygen/Nitrogen Contents in Red Pigment of Tantalum Nitrides (Ta3N5)
Authors: Park Eun Young , Pee Jae Hwan , Kim Yoo Jin , Cho Woo Seok
Published: June 2010

Tantalum nitride (Ta3N5) is a nontoxic red pigment that is being developed as a substitute for Cd-related pigments Ta3N5 is produced by the nitridation and heat treatment of amorphous Tantalum precursors. Doping elements were added in the precursor manufacturing stage to improve the red color tone of tantalum nitride. Grain growth was observed in nitrides that formed second phases, such growth led to an increase in the average grain size comprared to undoped nitrides, and the colors declined as the oxygen content increased. Nitrides that did not form second phases in response to doping elements remained a single-phase Ta3N5 and exhibited an excellent red color with a high nitrogen content. We determined that a change in the oxygen/nitrogen contents affected the color manifestation, which depended on the amount by which doping was increased.
Mechanical Properties of Hypereutectoid Steel with Microduplex (α+θ) Structure Formed by Hot Deformation of Undercooled Austenite
Authors: Li Long Fei , Chen Wei , Yang Wang Yue , Sun Zu Qing
Published: June 2010

Microstructure evolution and mechanical properties of hypereutectoid steel with the microduplex (α+θ) structures formed by hot deformation of undercooled austenite were investigated by hot uniaxial compression tests in a Gleeble-1500 simulation test machine, and the effects of subsequent annealing and the addition of Al were analyzed. The results indicated that at the beginning of hot deformation of undercooled austenite the formation of proeutectoid cementite was retrained and only lamellar pearlite was produced. With further strain, dynamic spheroidization of pearlite took place, leading to the formation of microduplex (α+θ) structure consisting of ultrafine ferrite matrix and dispersed cementite particles. In comparison with the normal microstructure consisting of lamellar pearlite and proeutectoid cementite, the microduplex (α+θ) structure presented higher strengths with similar ductility. Subsequent annealing could make the microduplex (α+θ) structure more uniform, which demonstrated better balance between strength and ductility. The addition of Al is disadvantageous to the formation of microduplex (α+θ) structure, but can result in the further refinement. With the addition of Al, the strength of microduplex (α+θ) structure was improved and the ductility was not deteriorated markedly.