bluuebunny/crossref_metadata_2025 huggingface dataset:
Sliding Mode Control of Magnetic Bearing System Based on Variable Rate Reaching Law
Authors: Mao Jing Feng , Wu Ai Hua , Wu Guo Qing , Zhang Xu Dong
Published: January 2011

In order to eliminate the chattering phenomena caused by conventional sliding mode control (SMC) method in magnetic bearing system control, this paper proposes a variable rate reaching law approach based sliding mode controller to achieve higher system stability and robustness. In this control law, system states’ normal numbers are brought in to automatic adjust the gain of the switching control part of SMC. The controller output amplitude of chattering can be progressively damped, and the system will converge to zero asymptotically. The system stability is proved by Laypunov theory, and the prerequisite of control law parameters design is deduced out. Simulation results show that the proposed SMC control method has effectiveness in dynamic suspension position tracking performance and obtaining system robustness.
Analysis of the Surface Integrity Machined by Short Electric Arc Machining
Authors: Zhou Jian Ping , Gheni Mamtimin , Liang Chu Hua , Xu Yan , Zhou Bi Sheng
Published: January 2011

In order to research the surface integrity of SEAM, the surface figure, surface heat-affected zones (HAZ ) and surface hardness are analyzed. The author mainly researches the influence factors of water pressure, air pressure, cathode feed rate and relative line speed on processing indictor. The orthogonal experiment results indicate that the main influence factors of surface roughness and HAZ are air pressure, gap voltage and cutting depth. In SEAM, certain scope pressure atomization of dielectric liquid has deionization and arc-extinguishing effect, and takes away melted metal and heat from the discharge channel in time. Workpiece surface will be smoothness. However, the enlarged air pressure will break normal electrode discharge and make the surface smoothness worse. The research of influence of gap voltage on surface quality are accomplished.
Stress Intensity Factor of a Central Interface Crack in a Bonded Strip under Arbitrary Material Combination
Authors: Noda Naoaki , Zhang Yu , Lan Xin , Takaishi Kentaro
Published: January 2011

Although a lot of interface crack problems were previously treated, few solutions are available under arbitrary material combination. This paper deals with one central interface crack and numerical interface cracks in a bonded strip. Then, the effects of material combination on the stress intensity factors are discussed. A useful method to calculate the stress intensity factor of interface crack is presented with focusing on the stress at the crack tip calculated by the finite element method. For one central interface crack, it is found that the results of bonded strip under remote uni-axial tension are always depending on the Dunders’ parameters , and different from the well-known solution of the central interface crack under internal pressure that is only depending on . Besides, it is shown that the stress intensity factor of bonded strip can be estimated from the stress of crack tip in the bonded plate when there is no crack. It is also found that when , when , and when . For numerical interface cracks , values of and with arbitrary material combination expressed by , are obtained.
Effects of Different Fillers on Microstructure and Tensile Properties of Welded AA6061-T6
Authors: Azhar Abdul Aziz Aendraa , Ibrahim Muhammad Faizol Ahmad , Jalar Azman , Syarif Junaidi , Abdullah Shahrum , Rashdi Nasrizal Mohd , Kornain Zainudin
Published: January 2011

Several different groups of filler metal are known to be compatible in welding of AA6xxx series. The aim of this investigation is to study the effects of different filler alloys toward mechanical properties and microstructure of welded AA6061 aluminium alloy using gas metal arc welding. Single V butt joint configuration has been used for joining the plate’s. Butt-joint welds were made on 6 mm thick plates using 21 – 22 V arc voltage. Tensile test was carried out using 100kN, electro-mechanical controlled hydraulic Instron 8801 universal testing machine. The results showed that the yield strength of base metal were 330 MPa and while the yield strength of ER5356 joints and ER4043 joints were 200 MPa and 235 MPa, respectively. The difference properties of strength in both weld metal was due to the difference major element in the both filler composition. The amount of silicon content in ER4043(Al-Si5%) filler is believed to play a role in the mechanical strength on weld metal. Microstructural examination was carried out using a light optical and electron microscope. The different filler alloys give different weld metal microstructure.
Fracture Behavior of Inconel 718 at High Temperature
Authors: Bapokutty Omar , Sajuri Zainuddin , Syarif Junaidi , Said A.R.
Published: January 2011

The effect of heat treatment on tensile and creep properties of nickel-base superalloy, Inconel 718 in room and at high temperature was investigated. Solution treatment was applied on the as-received material at 980oC for 1 hour before water quenched followed by double aging treatments at 720oC and 621oC for 8 hours, respectively and then cooled in air. The tensile strength at elevated temperatures of 550oC and 650oC were slightly deteriorated for heat treated and as-received materials. Beside strength, significant difference was observed in the elongation. The elongation of heat treated samples drastically reduced to 4 to 5% only compared to that of the as received materials which exhibited more than 30% elongation. The significant increased in tensile strength is suspected due to the present of γ’, γ” and δ precipitates which pinned the movement of grain boundary and sliding. However, the present of these precipitates caused the material to become harder and brittle. Moreover, the increase in load from 70% to 90% UTS and in temperature significantly accelerated the creep rate.
Effect of Hook Location for Ultra Fine Pitch Wirebonding Pull Testing Method
Authors: Harun F. , Jalar Azman , Abdullah Shahrum , Yunoh Mohd Faridz Mod
Published: January 2011

Over the years the methods for checking bonding quality during volume production still remains the same. These inspection methods like ball shear to test the first bond quality and wire pull to test the second bond integrity and quality have proven to be acceptable and achievable for many current industrial needs. However, driven by the relentless pursuit of dimensional reduction in wire bonding technology which calls for reduction in wire diameter, these conventional methods may not be sufficient. The interaction between machine, bonding tools, materials and the different categories of failure modes and mechanism during this quality test has become much more sensitive. The intent of this paper is to study and define the different categories of failure modes during 2nd bond test for ultra fine gold wire from 15 micron diameter up to 50 micron diameter. Therefore, lifted stitch or lifted 2nd bond which is a failure description known to be a ‘reject’ before can be re-visited. Analysis found that the two different test locations revealed that test location B or placing the hook as near possible to the leads where the 2nd bond was bonded is the better method to test the 2nd bond strength and performance as compared to the earlier bond pull method (location A).
Comparing Study of Energy-Absorbing Behavior for Honeycomb Structures
Authors: Wang Yan , Xue P. , Wang J.P.
Published: January 2011

Honeycomb materials，as a type of ultra-light multifunctional material，have been examined extensively in recent years and have been applied in many fields. This study investigated the energy absorption capacity and their mechanisms of honeycomb structures with five different cell geometry (square，triangular，circular, hexagonal，kagome). It has been shown that the honeycomb structure with kagome cells is the best choice under the targets of the energy absorption capacity, peak force and plateau stress, when relative density and cell wall thickness of the five kinds of honeycombs are the same. Besides, honeycomb with hexagonal cells and honeycomb with triangular cells are also ideal structures for energy absorption purpose.
Development of Green Insulation Boards from Kenaf Fibres Part 2: Characterizations of Thermal and Water Absorption
Authors: Ibraheem Sameer Adnan , Ali Aidy , Khalina Abdan
Published: January 2011

The aim of this study was to investigate the thermal performance, water absorption and dimension stability against water of the green insulation boards. The results show that the thermal conductivity decreased with increasing fibre contents and reached its minimum value (0.0535 w/mk) for the 60/40 kenaf / PU weight %. Contrarily, thermal resistance increased with increasing fibres contents, up to its maximum value (0.09 k.m2/w) for the 60/40 kenaf / PU weight %. The minimum water absorption percentage and thickness swelling were recorded at a weight of 50% kenaf fibres. The effects of the alkaline treatment were significant enough to increase the thermal conductivity.
Effects of Thermal Aging on Ductile-to-Brittle Transition Temperature Behavior of Welded A516 Steel
Authors: Khattak M.A. , Khan M.A. , Tamin Mohd Nasir
Published: January 2011

Prolonged high temperature exposure of welded C-Mn steels is likely to cause microstructural changes leading to an inrease in the ductile-to-brittle transition temperature (DBTT) of the welded joint. Consequently, such degrading material properties should be quantified in view of establishing accurate component life prediction model. This study examined effects of isothermal aging on DBTT behavior of the heat affected zone (HAZ) in welded Type A516 Gr 70 steels. Microstructures of the as-received weld region revealed the presence of pearlite and ferrite in the base metal while upper and lower bainite are found in the HAZ and weld metal, respectively. Hardness measures for the weld metal region, HAZ and base steel are 172, 209 and 150, respectively. Aging at 420 oC, 500 hours lowers hardness value of the HAZ by 20 %. A series of Charpy impact tests on V-notched specimens are performed for as-received and thermally aged samples at 420 oC for 500, 800 and 1200 hours. Results showed that the absorbed impact energy displays a sigmoidal variation with test temperatures. DBTT ranges from -60 to 5 oC for HAZ while narrow range from -25 to 12 oC for weld metal region. Absorbed impact energy variations in samples aged for durations up to 800 hours display another saturation level over test temperatures between -30 to 10 oC. Fractographic analysis on HAZ fracture surface indicated brittle fracture at -60 oC while ductile failure dominated at 27.7 oC. A mix-mode fracture mechanism is displayed for test conducted at -38 oC.
Electrically Conductive Fibers/Yarns with Sensing Behavior from PVA and Carbon Black
Authors: Xue P. , Tao Xiao Ming , Park Keun Hoo
Published: January 2011

In this study, electrical conductive yarns were prepared by wet-spinning technique and a physically coating process. Carbon black (CB) was used to make the fiber gaining electrical conductivity. The electrical conductivity and morphological characteristics of the developed conductive fibres were studied and compared. The results show that linear resistivity of the produced conductive yarns ranges from 1 to a few hundred kΩ per centimeter, mainly depending on processing technique and substrate fibers. It is also shown that the physically coating processes will not significantly affect the mechanical properties of the fibers and yarns. These conductive yarns are lightweight, durable, flexible, and cost competitive; and able to be crimped and subjected to textile processing without any difficulty.
Necking Prediction in Tube Hydroforming by Stress-Based Forming Limit Diagrams
Authors: Jaamialahmadi A. , Kadkhodayan Mehran
Published: January 2011

Path-independent stress based forming limit diagrams for anisotropic materials along with the Hill 48 yield function; power law strain hardening and isotropic hardening are derived. Bifurcation analyses via solving equilibrium equations of a pointed vertex on subsequent yield loci are utilized. The presented practical forming limit diagrams (FLSDs) show more acceptable agreements with experimental data compared with those obtained by other methods. A typical neck detection macro in APDL is developed by FEA simulation for a free bulge tube hydroforming to confirm the significant simplicity and straightforwardness of the mentioned FLSD.
Premature Failure of Gas Turbine Blade
Authors: Sajuri Z. , Said A.R. , Ibrahim M.L. , Syarif Junaidi
Published: January 2011

A set of first stage stationary blade of gas turbine was prematurely replaced due to severe cracking after 5,000 hours in operation. Failure investigation was conducted on damaged blades by non-destructive penetrant inspection, microstructure examination, chemical analysis, hardness mapping and fracture surface observation. The blade material, verified as IN738LC nickel superalloy, exhibited presence of elongated grain boundary carbides, TCP phases formation, and grain boundary creep void on the airfoil. Morphology of γ' precipitation, however, was normal throughout the blade with size of approximately 1μm and no significant coarsening. Presence of welding structure and possible brazing layer on the airfoil was detected suggesting that the blade was previously refurbished. Primary crack occurred on previous welding repair and propagated in transgranular mode. It was concluded that the blade failure was caused by improper welding repair despite evidence of base material degradation.
Microstructural Behaviour Study and FEA-Based Fatigue Simulation on Parabolic Leaf Spring
Authors: Refngah Fayyadh Nakhaie Ahmad , Abdullah Shahrum , Jalar Azman , Chua L.B.
Published: January 2011

It is compulsory to have a good fatigue life to a component that is heavily subjected to cyclic loading. One of the good examples is parabolic spring, which is one of the components in suspension system for large vehicles. It serves to absorb, store and release back the damping energy due to road irregularity, bump and holes. These activities involve a lot of camber deflection that caused by the tension and compression loads. In reality, the loading that subjected to parabolic spring is variable amplitude loading, but most of the manufacturer used constant amplitude (CA) loading for the fatigue test. The objective of this paper is to relate the simulation result with the microstructure behaviour of the leaf spring that failed due to fatigue. A full scale fatigue test was carried out until that parabolic spring meet failure. In order to investigate the fatigue life, CA signal was generated based on an actual fatigue test on the parabolic spring, and it was then analysed using the FEA-based fatigue simulation. A microstructure study was then performed for both fracture and non-fracture area. From the FEA-based simulation, it gave the prediction on damage that occurred at the critical area and also the prediction on the lowest cycle with respect to the FEA model. In the actual fatigue test, the failure was occurred at the centre part of the spring, which is at bolt join of assembly hole. The microstructure analysis showed that the grain at the fracture area indicated some different from the non-fracture area in term of size, phase and precipitation of carbon.
Far Field Solution of Circular Inclusion and Linear Crack by SH-Wave
Authors: Li Hong Liang
Published: January 2011

Circular inclusion exists widely in natural media, engineering materials and structures, and defects are usually found around the inclusion. When a composite material with circular inclusion and cracks is impacted by the dynamic load, on the one hand, the scattering field produced by the circular inclusion and cracks determines the dynamic stress concentration factor around the circular inclusion, and therefore determines whether the material is damaged or not; on the other hand, the scattering field also presents many characteristic parameters of the inclusion and cracks such as defect composition, location and shape, so the research on the scattering far-field is important to the geological prospects, seismological investigation, non-destruction evaluation and the other fields. In the ocean acoustics, the scattering far-field of the acoustic wave is also used in the under-water survey, object distinguishing and so on. In theory, the scattering solution of elastic waves is one of the basic topics of reverse problems on elastic wave. On the basis of literature, few paper concentrates on the scattering far-field solution of SH-wave by a circular inclusion and a linear crack around the inclusion. In the paper a new model and a new method are presented in order to investigate deeply on this kind problem. The paper uses the Green’s function to study the scattering far-field of an elastic wave by a circular inclusion and a linear crack. The Green’s function should be a fundamental solution of displacement field for an elastic space possessing a circular inclusion while bearing out-of-plane harmonic line source force at any point. In terms of the solution of SH-wave’s scattering by an elastic space with a circular inclusion, anti-plane stresses which are the same in quantity but opposite in direction to those mentioned before, are loaded at the region where the linear crack is in existent actually; Then, the expressions of the displacement and stresses are given when the circular inclusion and linear crack exist at the same time. When the special Green’s function has been constructed and close field solution has been illustrated, the far field of scattered wave is studied. The displacement mode of scattered wave at far field and scattering cross-section are given. At last, an example is given and its numerical results are discussed.
Green's Function Solution of the Semi-Space with Double Shallow-Buried Inclusions
Authors: Wu Guo Hui , Li Hong Liang
Published: January 2011

In mechanical engineering and modern municipal construction, shallow-buried inclusion structure is used widely. In this paper, Green's Function is studied, which is the solution of displacement field for elastic semi-space with double shallow-buried inclusions while bearing anti-plane harmonic line source force at any point. In complex plane, considering the symmetry of SH-wave scattering , the displacement field aroused by the anti-plane harmonic line source force and the scattering displacement field impacted by the circle inclusions comprised of Fourier-Bessel series with undetermined coefficients which satisfies the stress-free condition on the ground surface are constructed. Through applying the method of multi-polar coordinate system, the equations with unknown coefficients can be obtained by using the displacement and stress condition of the circle inclusions in the radial direction. According to orthogonality condition for trigonometric function, these equations can be reduced to a series of algebraic equations. Then the value of the unknown coefficients can be obtained by solving these algebraic equations. Green's function, that is, the total wave displacement field is the superposition of the displacement field aroused by the anti-plane harmonic line source force and the scattering displacement field. By using the expressions, an example is provided to show the effect of the change of relative location of the circle inclusions and the location of the line source force. Based on this solution, the problem of interaction of double circular inclusions and a linear crack in semi-space can be investigated further.
Finite Element Analysis of Rate- and State-Dependent Frictional Contact Behavior
Authors: Ozaki Shingo
Published: January 2011

In the present study, the rate- and state-dependent friction model [Hashiguchi and Ozaki, 2008] is implemented in the dynamic finite element method. The typical rate- and state-dependent frictional contact problems, which are consisted by elastic and rigid bodies having simple shapes, are then analyzed by the present method. The validity of the present method for the microscopic sliding and stick-slip instability is examined under various dynamic characteristics of the system, such as contact load, elastic stiffness, driving velocity and frictional properties. It is shown that the present method can solve simultaneously not only rate- and state-dependent frictional behavior on the contact boundary but also coupling effects with internal deformations, whereas it cannot predicted by the conventional finite element analysis with the Coulomb’s friction law.
Strength Properties of Cellulose Nanofiber Green Composites
Authors: Takagi Hitoshi
Published: January 2011

Environmentally friendly cellulose nanofiber green composites were newly developed by combining two dispersion-type biodegradable resins: polylactic acid (PLA) and chemically modified starch, and cellulose nanofibers of two kinds. The nanoscale cellulose fibers were prepared by homogenization of wood pulp. The 10–100 nm diameter nanoscale cellulose fibers have a web-like network microstructure. The mixture of dispersion-type biodegradable resin and cellulose nanofibers was dried in an air-circulating oven to make composite preform sheets. Cellulose nanofiber composite samples were fabricated by press-forming of the preform sheets. Their mechanical properties were evaluated using room-temperature tensile tests. The composite composed of PLA-based resin and highly homogenized cellulose nanofibers showed higher mechanical properties than those of starch-based resin and coarse cellulose fibers. It is suggested that coarse cellulose fibers act as a defect, resulting in low mechanical properties. Maximum tensile strength reaches approximately 90 MPa at fiber weight contents of 60% by weight. This mechanical property is comparable to that of conventional glass-fiber-reinforced plastics.
A Novel Approach to Determine the Elastic Properties of the Interphase between the Aggregate and the Cement Paste
Authors: Qu Hong Chang , Zhang Peng
Published: January 2011

Concrete is a three-phase material consisting of cement paste matrix, discrete inclusions of sand (aggregate), and an interfacial transition zone (ITZ) between the matrix and the inclusions. In order to calculate the elastic properties of the ITZ of cement mortar, We model the material as a composite formed by a matrix with embedded spherical particles; each surrounded by a concentric spherical shell. With help of the generalized self-consistent method (GSCM), equations of bulk modulus and shear modulus of ITZ are deduced, and Elastic properties of ITZ are computed by using experimentally known elastic properties of the composite. It is found that the shear modulus of ITZ is about 50% of that of the cement paste matrix.
Cracking of NiTi Thin Films Deposited on Cu Substrate
Authors: Li Yong Hua , Meng F.L. , Zheng Wei Tao , Wang Y.M.
Published: January 2011

This study has investigated the cracking of Ti-51.45at.%Ni thin films deposited on Cu substrate. An analysis is presented that relates the crack spacing and the Vickers microhardness values to the strain in the film. Tensile tests are carried out on CSS-44100 electron universal testing machine. The strain rate is 1.1 × 10-4 s-1. The average crack spacing is obtained using scanning electron microscopy (SEM). The Vickers microhardness values are determined by Everone MH-6 microhardness tests. The results have showed that a series of parallel cracks grew in the film and the cracks are equally spaced. The minimum crack spacing is about 87 μm. The mean crack spacing is dependent on the tensile strain in the film. The crack spacing decreases as the film elongation increases. The Vickers microhardness values increase as the film elongation increases.
Effect of Sandblasting and Surface Mechanical Attrition Treatment on Surface Roughness, Wettability, and Microhardness Distribution of AISI 316L
Authors: Arifvianto B. , Suyitno  , Mahardika Muslim
Published: January 2011

Surface roughness and wettability determines the stability of bone-implant integration. Stable implants can be found in those with a rough and hydrophilic surface. Sandblasting and surface mechanical attrition treatment (SMAT) are among the current techniques to obtain surface with such typical properties. In addition, both treatments increase mechanical strength of metal through surface grains refinement. In this paper, the effect of sandblasting and SMAT on surface roughness, wettability, and microhardness distribution of AISI 316L is discussed. All treatments were conducted for 0-20 minutes. The result shows a rougher and a more hydrophilic surface on the sandblasted samples rather than on those with SMAT. A harder surface is yielded by both treatments, but the SMAT produces a thicker hardened layer.
Surface Modification of Pure Titanium by Nitrogen Ion Implantation at Different Beam Energy and Dose
Authors: Ali Nurdin , Samekto Haryanti , Ghazali Mohd Imran , Ridha M.
Published: January 2011

The implantation of nitrogen ion is one of the important techniques for modifying the surface characteristics to improve wear and corrosion resistance of commercially pure (cp) Titanium. Although nitrogen ions implanted titanium in various dose demonstrated significant changes of the wear and corrosion resistance, the variable energy implanted is still not yet fully studied. Nitrogen ions were implanted in cp Titanium surface with varies of both dose of 0.5; 1.0 and 2.0 x1017 ions cm-2 and energy of 80, 100 and 115 keV. The nitrogen ion implanted cp Titanium demonstrated an increase in the surface hardness and improvement in corrosion behavior. The maximum surface hardness was delivered by the specimens implanted with the dose of 2.0x1017 ions cm-2 at energy of 80 keV. Grazing incidence x-ray diffraction studies indicated that TiN phase was formed on near surface substrate. Electrochemical tests in 3.5%-wt NaCl solution depicted significant improvements in corrosion resistance for specimens implanted with dose of 0.5x1017 and 1.0x1017 ions cm-2 at energy of 80 keV, dose of 1.0x1017 and 2.0x1017 ions cm-2 at energy of 100 keV. The dose of 2.0x1017 ions cm-2 and energy of 100 were the best implantation parameter in this study.
Fully Automated Mixed Mode Crack Propagation Analyses Using VCCM (Virtual Crack Closure-Integral Method) for Tetrahedral Finite Element
Authors: Okada Hiroshi , Kawai Hiroshi , Tokuda Takashi , Fukui Yasuyoshi
Published: January 2011

The authors have been developing a crack propagation analysis system that can deal with arbitrary shaped cracks in three-dimensional solids. The system is consisting of mesh generation software, a large-scale finite element analysis program and a fracture mechanics module. To evaluate the stress intensity factors, a Virtual Crack Closure-Integral Method (VCCM) for the second-order tetrahedral finite element is adopted and is included in the fracture mechanics module. The rate and direction of crack propagation are predicted using appropriate formulae based on the stress intensity factors.
The Effect of Eva on Composite that Made of PP Nanoclay
Authors: Hasnah K.S. , Khalina Abdan , Ali Aidy , Jamaliah S.
Published: January 2011

This study presents an investigation of the effects of Ethylene Vinyl Acetate (EVA) on Polypropylene (PP)/Clay type of composite. The PP/EVA/clay composite samples are prepared via melt blending technique. The chemical characterization is carried out using fourier transform infrared (FT-IR) spectroscopy. The mechanical properties are characterized in terms of tensile, flexural and impact tests. The presence of high EVA content in PP nanoclay decreases the flexural and tensile strength. The addition of EVA reveals significant increment in impact strength. Thermal properties of composites are studied using thermogravimetric analysis (TGA). The decomposition temperature increases with an addition of EVA content up to 15 phr, but decreases of the crystallinity and melting temperature.
Study on Long Span Transmission Tower’s Typical Malfunctions
Authors: Wang Hai Lin , Gao Qiang
Published: January 2011

In this paper, several typical malfunctions of the long span transmission tower are analyzed, such as the material stiffness reduced by atmospheric corrosion over a long time, the loose of bolt joint caused by accidental factors or man-made sabotages, and foundation settlement. And establish finite element models according to the characteristics of different malfunctions. By analyzing the models, we discuss the safety of the long span transmission tower at different malfunctions. It is shown that the proposed method is of efficiency and practicality.
Bio-Design and Develop of Robot Fish
Authors: Song Tian Lin , Lu Ya Ping , Shi Lei
Published: January 2011

Based on the characteristics of fish swimming, the robotic research significance and future application, the pattern of fish propulsion, and the mode of carangide crescent-shape caudal fin, this article designs and develops a simple bio-robotic fish. The paper focuses on the design of robot fish system, including the mechanical structure design, selection and installation of steering gear, hardware control system design, and remote control system deign, and software design and development.
Analysis on Mean Value Model of Gasoline Engine in HEV Applications
Authors: Zhou Jian Hao , Yuan Yin Nan , Mao Gong Ping , Du Jia Yi
Published: January 2011

A mean value model of the 1.5L gasoline engine was established. It mainly consists of fuel film model, transient fuel film compensation model and dynamic output model. After the validation of steady state, the power and economic performances were analyzed with NEDC drive cycle. Together with engine operating points, special attention was such key parameters as paid to engine speed, engine torque and fuel consumption. The dynamic model is validated. The air-fuel ratio fluctuation was studied to validate the fuel film model.
Design of Greenhouse Wireless Sensor Network Control System Based on Fuzzy Neural Network
Authors: Zhang Rong Biao , Wang Li Hong , Huang Xian Lin , Guo Jing Jing
Published: January 2011

This paper proposed a greenhouse control system utilizing wireless sensor network (WSN) to overcome the wiring difficulties and poor mobility in the application of traditional cable-used control systems. Each wireless sensor node in the WSN collects the environmental data of temperature, humidity and CO2 concentration, and transmits the data to the control center via the sink nodes. A fuzzy neural network with three inputs and six outputs was designed to improve the control accuracy. By analyzing the relationship between the mentioned environmental factors above and the actuators of the system, a fuzzy rule was made and combined with the neural network. The simulation results showed that the proposed method could respond in a short time with high accuracy, and had small overshoot as well as good stability.
An Implementation of Petri Net Based on Graphical Programming Language
Authors: Du Tian Yan , Zhao De An , Huang Li
Published: January 2011

This paper deals with an implementation method of component-based Petri nets system based on a graphical programming language (LabVIEW). LabVIEW is not only a graphical programming language, but also a virtual instrument platform which is widely used in virtual measurement and control system. The Places (token number) of Petri nets are represented by Numeric Controls of LabVIEW. The Transitions of Petri nets are represented by subVIs of LabVIEW. Transition subVI will change the tokens of Places by the Numeric Controls' Reference when it is fired. This method will make it ease to implement a Petri net by simply combining Place and Transition components (subVI). The example implementing a special Petri net shows that the Front Panel of the controller reflects the system operating state directly; the Block Diagram is similar to the topology of original Petri net. The combination of two graphic languages makes the modeling, analysis and formal verification of measurement and control system based on Petri nets easier.
Order Picking Path Optimization Based on Genetic Algorithm
Authors: Chen Zai Liang , Xie Shu Xin , Wu Dong Min
Published: January 2011

Optimizing order picking path of wares properly has been an effective method of advancing automated warehouse operation efficiency. By analyzing the work characteristics of automated warehouse order picking, an automated warehouse order picking mathematical model is proposed which takes total travel time of order picking as the target function. Adopting the strategy of combination of roulette selecting and the optimal individual preservation to implement selecting operation in solving the mathematical model, a good experimental simulation result is received.
State-of-the-Art of Green Water on FPSO in Harsh Environment
Authors: Ni Tao , Wang Yun , Li Bing Nan , Tang Shen Tao , Zhang Yong Kang
Published: January 2011

The phenomena of green water are the maximum vertical extent of wave uprush over freeboard on the deck with the result of damage to the deck, bow and auxiliary equipment. The FPSO with Single-point mooring system or disconnectable mooring system always operates in the severe deepwater or ultra-deepwater environment such as Gulf of Mexico or Southeast Asia, which should be allowed to weathervane. Therefore, FPSO is always exposed to wave runup and overtopping. Nowadays green water problem has become one of the most important factors to endanger offshore structures, such as FPSO, TLPs and SPARS. This paper gives a comprehensive review of the state-of-the-art in green water, including the forming mechanism, numerical simulation and model test of wave runup. Finally the prospect of simulating green water is discussed.
Experimental Study of Micro-Scale Laser Shock Peening on Copper Foils
Authors: Zhu W. , Zhou Jian Zhong , Wang M , Huang Shu , Wei Deng Hui , Fan Yu Jie
Published: January 2011

Micro-scale laser shock peening (μLSP) is a flexible and precise process that can potentially be applied to metallic structures in micro devices to improve strength and reliability performance. In order to understand the mechanism of μLSP process, a typical experiment was carried out for copper foils specimen with various process parameters. Surface morphology, deformation and hardness of the specimens were observed and characterized by 3D microscope system and situ nano-mechanical test system respectively. It was found that overlapping rate of laser spot has a little effect on microscopic deformation depth which increases slowly with the increasing of laser energy, and micro-hardness of the laser treated specimens was improved significantly.
Experimental Study of Micro Deep Drawing for H62 Brass
Authors: Lu Guang Hua , Xu Zhen Ying , Wang Rong Mao , Wang Yun
Published: January 2011

In this paper, the influence of grain size and blank hold force on micro deep drawing stress and displacement are studied by self-made device. The results show that drawing stress decreases and elongation rate increases with the increase of grain size, the concentrated force area of cylinder-shaped part is transferred from the area punch fillet to die fillet area. Twin grain ratio and twinning degree near the punch fillet are increasing. Twin grain distribution becomes uneven with the increase of grain size. In micro deep drawing, the displacement increases with the increase of blank hold force, meanwhile, forming stress almost remains constant. The flange wrinkling can be inhibited.
Research on Cutting Performance of High-Speed Steel Drills during Drilling the Powder Metallurgy Nickel-Based Superalloy
Authors: Qiao Yang , Ai Xing , Liu Zhan Qiang
Published: January 2011

The present paper is an experimental investigation on the machinability of powder metallurgy (PM) nickel-based superalloy during drilling using high-speed steel (M42) drills. The effect of machining parameters on the cutting force, cutting temperature and tool wear were investigated during the experimentation. The effect of machining parameters on the tool wear was examined through SEM micrographs. The research work findings will also provide useful economic machining solution by utilizing economical high-speed steel drills during drilling processing of powder metallurgy nickel-based superalloy, which is otherwise usually machined by costly coated carbide tools or CBN tools. The present approach and results will be helpful for understanding the machinability of powder metallurgy nickel-based superalloy during drilling for the manufacturing engineers.
The Effect of Process Parameters on Strain Rates in Laser Shock Forming
Authors: Jiang Yin Fang , Tang Zhen Zhou , Fang Lei , Li Zhi Fei
Published: January 2011

Laser shock forming (LSF) is characterized in non-contact load, high pressure and high strain ratio. It has many promising applications in aerospace, automotive, metal and many other industries. However, despite the extensive experimental and modeling study in literature, seldom investigations are about the effect of laser parameters on strain rates. With the variation of strain rates in LSF, the failure mechanism and plastic instability theory are different. Therefore, the variation of strain rates should be considered in the process of establishing LSF theory. Based on this, the article discussed the effect of laser shock parameters on the strain rates. Taken the 3003-H16 aluminum alloy as the specimen, the finite element (FE) analysis for LSF was performed.
The Analysis about Double-Wall Carbon Nanotubes Resonant with the Phenomenon of Energy Dissipation
Authors: Zhou Qu Zhu
Published: January 2011

In this paper, the double-wall carbon nanotube oscillator resonant phenomena and energy dissipation are simulated by use of molecular dynamics simulation. The simulation run at different temperatures , and the double-walled carbon nanotube oscillator resonance phenomenon is verified，the vibration displacement curve which carbon tubes versus time and the changes in restoring force of carbon tubes suffered in the process of oscillation process are obtained and the friction is discussed from the point of view of energy dissipation. By statistical calculation, the double-walled carbon nanotube resonant amplitude of the process is found quickly decay with temperature increasing, and the friction per atom will enlarge with temperature increased, but the restoring force of inner tube is almost constant.
Effect of Carbon Nanotubes on the Properties of Natural Rubber Composites
Authors: Jiang Hong Xia , Ni Qing Qing , Natsuki Toshiaki
Published: January 2011

Carbon nanotubes (CNTs) reinforced natural rubber (NR) composite was fabricated in a solvent casting method. The tensile properties and electrical resistivities were investigated. As a comparison, carbon black (CB) reinforced NR was also prepared in the same method. The initial modulus of NR/3 wt% CNT composite was about 1.6 times as large as that of NR/ 3wt% CB composite. NR/CNT composite had a percolation threshold value of about 5 wt% CNTs. The morphology of fillers and composites were observed by transmission electron microscopy (TEM) and scanning electron microscopy (SEM). The improved properties of NR/CNT composites were attributed to the excellent mechanical and electrical properties of CNTs and its formed network, which must be benefit to electromagnetic interference shielding properties of NR composites.
Numerical Simulation and Calculation of the Temperature Field during Laser Surface Melting the Pure Al
Authors: Cui Xi Gui , Cui Cheng Yun , Cheng Xiao Nong , Xu Xiao Jing , Lu Jin Zhong
Published: January 2011

Temperature field during laser surface melting the pure Al was numerically simulated by the Laplace integral transform technique using the MathCAD software. The influences of laser power densities on the surface temperature of the pure Al were analyzed. Mathematical expressions for the temperature distribution of the heating and cooling process on the pure Al surface were obtained.
Crack Tip Shielding from a Plastic ‘Inclusion’
Authors: James M. Neil , Christopher C.J. , Lu Yan Wei , Tee K.F. , Patterson Eann A
Published: January 2011

This paper presents a very brief overview of the philosophy underlying a plastic inclusion approach to defining the boundary stresses imposed on the applied elastic stress or displacement field by the plastic deformation attendant on crack growth in a ductile material. It leads to two new fracture mechanics parameters, KR and KS. KR defines a retardation component arising from wake contact and the Poisson’s contraction associated with the plastic zone, whilst KS describes a compatibility-induced component arising from shear at the elastic-plastic interface. These additional components imply that KF is not directly comparable with KI, as it describes the net driving force on the crack from the applied load.
Damage of Multilayer Polymer Materials under Creep Loading
Authors: Zouhar Michal , Hutař Pavel , Náhlík Luboš , Knésl Zdeněk
Published: January 2011

Failure of layered materials is frequently caused by the existence of interfaces between single layers. In structures loaded by long-term constant stress the damage can be described on micro-scale by material changes due to active creep mechanism and at the macro-level by a corresponding change of the stress and strain field. In the contribution the behavior of a crack propagating through the interface is analyzed. Primary attention is devoted to a crack with its tip at the interface under creep exposition. The step change of material properties at the bi-material interface means that standard fracture mechanics access is not applicable and a modified approach based on generalization of the classical concept has to be used. The approach is illustrated on the damage of a plastic pipe with protective layer.
Case Criterion of Crack Onset in Orthotropic Bi-Material Notches
Authors: Profant Tomáš , Klusák Jan , Kotoul Michal
Published: January 2011

A bi-material notch composed of two orthotropic parts is considered. The stresses and displacements are expressed using the Stroh-Eshelby-Lekhnitskii formalism for plane elasticity. The potential direction of crack initiation is determined from the maximum mean value of the tangential stress or the local minimum of the mean value of the generalized strain energy density factor in both materials [1, 2]. The matched asymptotic procedure is introduced to derive the change of potential energy for the debonding crack and the crack initiated in the determined direction [3].
Fatigue Crack Growth Rate under Different Bending to Torsion Ratios in 10HNAP Steel
Authors: Marciniak Zbigniew , Rozumek Dariusz
Published: January 2011

The paper contains the fatigue test results of rectangular cross-section specimens made of 10HNAP steel. The specimen height to width ratio was 1.5. Bending with torsion tests were carried out for the following ratios of bending to torsional moments MaB / MaT = 0.47, 0.94, 1.87 and the loading frequency 26.5 Hz. The tests were performed in a high cycle fatigue regime for the stress ratio R = - 1 and phase shift between bending and torsion loading equal to  = 0.
Structure and High-Temperature Oxidation of Ti-Al-Nb and Ti-Al-Ta Intermetallics
Authors: Vojtěch Dalibor , Popela Tomáš
Published: January 2011

Ti-Al based intermetallics are prospective high-temperature materials showing low weight combined with a relatively high strength, high creep resistance and good oxidation resistance at high temperatures. Beside Ti and Al, these materials commonly contain other additives modifying their properties. In the present work, structure and oxidation resistance of two Ti-Al-Nb and Ti-Al-Ta alloys are studied. The alloys are prepared by vacuum arc melting and oxidation is conducted in air at 800-1000°C. It is found that there are significant differences in the structure depending on the ternary additive. There are also differences in oxidation behavior and these differences are discussed in relation to oxidation mechanism.
Cracks Detection in Mg Alloy by Electro-Ultrasonic Spectroscopy
Authors: Tofel Pavel , Sikula Josef , Hajek K. , Trojanová Zuzanka , Bumbalek L.
Published: January 2011

New non-destructive testing (NDT) method is based on the effect of the ultrasonic vibrations on the electron transport in samples with macroscopic defects as cracks or defect centers affecting electrical conductivity. On the frequency given by the subtraction of exciting frequencies new intermodulation signal appears. Its value is given by electric resistance modulation by the defects and un-homogeneities in the sample structure. In our experiment we used the ultrasonic actuator with frequency fU when the period of wave is longer than the dielectric relaxation time in analyzed sample. In this case the effects of electron bunching by ultrasonic wave are negligible. The ultrasonic wave length is much larger than the electrons mean free path and the wave period is much longer than the mean free time among the electrons collision with scattering centers and defects. Then the electron transport is described by the quasi-steady state transport equation in one-electron approximation. Because of the requirement of charge neutrality, no net AC electric current with the ultrasonic wave frequency fU can be carried by the wave. Similar situation exists for samples excited by standing ultrasonic waves. The electrical conductivity varies with time due to that the cracks geometry is changed with frequency of the ultrasonic vibration. The sample conductivity is affected mainly by the presence of cracks and defects boundaries perpendicular to the electric current density vector. In our experiment the amplitude of ultrasonic vibration is so low that no new cracks are generated and then the proposed testing method belongs to NDT.
Influence of Slip Localization on Surface Relief Formation and Grain Boundary Microcrack Nucleation
Authors: Sauzay Maxime , Evrard Pierre , Bavard Karine
Published: January 2011

Slip localization is often observed in metallic polycrystals after cyclic deformation (persistent slip bands) or pre-irradiation followed by tensile deformation (channels). To evaluate its influence on surface relief formation and grain boundary microcrack nucleation, crystalline finite element (FE) computations are carried out using microstructure inputs (slip band aspect ratio/spacing). Slip bands (low critical resolved shear stress (CRSS)) are embedded in small elastic aggregates. Slip band aspect ratio and neighboring grain orientations influence strongly the surface slips. But only a weak effect of slip band CRSS, spacing and grain boundary orientation is observed. Analytical formulae are deduced which allow an easy prediction of the surface and bulk slips. The computed slips are in agreement with experimental measures (AFM/TEM measures on pre-irradiated austenitic stainless steels and nickel, copper and precipitate-strengthened alloy subjected to cyclic loading). Grain boundary normal stresses are computed for various materials and loading conditions. A square root dependence with respect to the distance to the slip band corner is found similarly to the pile-up stress field. But the equivalent stress intensity factor is considerably lower. Analytical formulae are proposed for predicting the grain boundary normal stress field depending on the microstructure lengths. Finally, an energy balance criterion is applied using the equivalent elastic energy release rate and the surface/grain boundary energies. The predicted macroscopic stresses for microcrack nucleation are compared to the experimental ones.