bluuebunny/crossref_metadata_2025 huggingface dataset:
Characterization of Tensile Damage for 3D-C/SiC Composites by Acoustic Emission
Authors: Chang Yan Jun , Zhang Ke Shi , Hu Hui Juan , Jiao Gui Qiong
Published: March 2010

The various damage mechanisms in 3D-C/SiC composites are identified using acoustic emission (AE) signal parameters, and the Felicity effect is studied on different unloading stress. As a result, the damage mechanisms in 3D-C/SiC composites can be identified successfully by the amplitude, average frequency and relative energy, and there are several damage modes together during uniaxial tensile process. The Kaiser effect is almost absent and the Felicity ratio fluctuates at 0.95 on lower stress stage and drops when the relative stress is above 65%.
On Three-Dimensional Fatigue Crack Propagation under Constant Amplitude Loading
Authors: He Yu Ting , Shu Wen Jun , Liu Ren Yu , Cui Rong Hong
Published: March 2010

The equation of fatigue crack propagation rate is indispensable to precisely predict the fatigue life of structure containing three-dimensional crack under constant amplitude loading. Considering the crack closure effects and thickness effects in real structures, the equation of fatigue crack propagation rate under tri-axial stress state is presented. And the fatigue propagation lives of LY12-BCZYU aluminium alloy plate specimens with central through crack are predicted by this equation and validated by experimental results. Validation against calculations by the model and experimental data shows a good agreement.
Effect of Compressive Deformation on Degenerate Pearlite Transformation in a Fe-C-Mo Alloy
Authors: Yu Hong Wei , Wu Kai Ming
Published: March 2010

The isothermal transformation of pearlite in an Fe-0.27%C-3.15%Mo (weight percent) alloy applying large compressive deformation was investigated by means of thermal simulation, optical and scanning electron microscopy. The pearlite transformation was promoted by large compressive deforming on austenite, which is attributed to the effect of large compressive deformation on nucleation of pearlite transformation.
An Efficient Sampling Method for the Actual Reliability of Engineering Calculation and Design
Authors: Liu Chang Hong , Liu Xin Tian , Zhou Dong , Zhao Li Hui , Huang Hu , Xuan Fu Zhen
Published: March 2010

Firstly, according to the theory of dual variable, a procedure of the calculating fracture probability of the pressure vessel is presented. Secondly, according to the results of calculating the random numbers of the parameters in the fracture probability model, the dual variable method for the fracture probability of pressure vessel is proved to be a good technical to reduce variance. Finally, the results between the simple sampling and the dual variable method showed that dual variable method is very simple and can be widely used in engineering.
Effect of Recessing in Bondline on Stress in Co-Axial Lap Joint
Authors: Zheng Xiao Ling , Zhao Mei Rong , You Min , Li Zhi , Yan Jia Ling
Published: March 2010

The effect of recessing on the stresses distributed along the mid-bondline in both standard single lap joints and co-axial ones were analyzed using elasto-plastic finite element method (FEM). The results obtained show that the values of the peak stresses of all the stresses distributed in the mid-bondline were changed greatly as the preformed angle in over lap zone was about 10 0 when the high elastic modulus adhesive is used. The effect of the elastic modulus level on the stress distribution (especially the peak stresses) is small in the middle part of the lap zone. When taken the stress distributed in the middle part of the lap zone into account, there is nearly no significant difference between the peel stress distributed in the standard joint and co-axial single lap joint when the adhesives with lower elastic modulus was used. It is recommended that a co-axial joint is suitable for the recessing joint made by aluminum alloy and a higher elastic modulus adhesive.
Manufacture of the Wear Corrosion Resistance High-Cr Cast Iron Impeller
Authors: Han Yan Jun , Zhi Xiao Hui , Guo Wen Wu
Published: March 2010

A wear corrosion resistance high-Cr cast iron was introduced in this paper, and the cast forming technique of 150ZGB impeller was also presented. The produced impellers, according to the technique, met the quality demands, such as no crack, surface smoothness, and high hardness. The service life of the impellers, in phosphoric acid slurry condition, were 4 to 6 times as long as that made from UB6 (0Cr20Ni25Mo5).
Positron Annihilation & Micro-Hardness Measurement of 6063 and 6066 with Compromise with Ingot Al
Authors: Abdel-Rahman M.A. , Aldeen Ahmed Alaa , Badawi Emad A.
Published: March 2010

The aim of this work was to study the resistance of this type of alloy to quenching. Hardness measurements can be defined as macro-, micro- or nano- scale, according to the forces applied and the displacements obtained. This effect can also be studied using a nuclear, (PALT): positron annihilation lifetime, technique [1]. Microhardness is the hardness of a material, as determined by forcing an indenter such as a Vickers or Knoop indenter into the surface of the material under a 15 to 1000gf load; the indentations are usually so small that they must be measured using a microscope. These samples were quenched at different temperatures ranging from 50 to 500oC. We studied the effect of the quenching temperature upon the hardness measurements. We also studied this variation via the positron annihilation (lifetime) parameter. It is clear from the Vickers hardness that 1050 has the lowest value of Hv, while 6063 is higher and 6066 has the highest values of Hv. Also we could observe ( recognize) that the Hv (number) is reduce as a function of temperature (6066) but for (1050) and (6063) there is no observation of a variation in Hv (number) as a function of quenching temperature. The same observation was also made for 1050, 6063 and 6066 via the lifetime measurements. Here, 6063, 6066 give higher values than 1050. It is clear that the data from both techniques (positron annihilation lifetime and Vickers hardness) for 1050 ingot Al gives lower values of both parameters for Hv and lifetime technique. While Hv for 6066 is higher than the values of 6063 alloy at the same quenching temperature. Using the lifetime technique, one cannot distinguish between the 6063 and 6066 alloys. The applied force has no real effect upon the levels of the hardness values. Also, alloys 6066 and 6063 were defined as heat-treatable alloys but 1050 is not a heat-treatable alloy. The Hv of the 1050 is not affected by the changes in quenching temperature. Alloy 6066 heat-treatable alloy is more affected by the heat treatment than is 6063 alloy, and this is related to the structure of the precipitates in these alloys since 6066 alloy has much more Si and Mg than does the 6063 alloy. The Hv values vary from 14 to 23.9 for 6063 alloy and from 15.7 to 69.8 for 6066 alloy; in comparison with ingot alloy (1050) where it varies from 10.4 to 18.6.
Multi-Scale Analysis of Viscoelastic Behavior of Laminated Composite Structures
Authors: Shibuya Y. , Sekine Hideki
Published: March 2010

For high temperature applications of laminated composite structures, viscoelastic behavior of laminated composite structures is investigated by multi-scale analysis based on a homogenization theory. Effective viscoelastic properties of the laminas are evaluated by a boundary integral method at a micro-scale level, and viscoelastic analysis for laminated composite structures is performed by a finite element method at a macro-scale level using the effective viscoelastic properties of lamina obtained by the micro-scale analysis. In the multi-scale analysis, the Laplace transformation is adopted and the correspondence principle between elastic and viscoelastic solutions in the Laplace domain is applied. The inverse Laplace transform is formulated by the Duhamel integral, and is calculated numerically. As a numerical example, a laminated composite plate with a hole is treated and the viscoelastic behavior of the laminated composite structure is elucidated.
Damage Mechanism and Apparent Fracture Strength of Notched Fiber-Reinforced Composite Laminates
Authors: Kamiya Shoji , Sekine Hideki
Published: March 2010

Apparent fracture strength of notched fiber-reinforced composite laminates depends on the notch tip radius even if it is evaluated in terms of the local parameters such as the stresses at a notch tip or the stress intensity factors. Although numbers of phenomenological explanations have been made, this phenomenon has not yet been physically clear enough. In order to elucidate its key mechanism, our interest is here focused on the interlaminar crack extension from a notch tip in cross-ply laminates subjected to mode-I loading. We find a stochastically expected upper bound of interlaminar crack length due to the probabilistic breakage process of fibers in load-bearing laminas inside the delaminated zone. This upper bound, i.e., the critical length of interlaminar crack, is inherent to the laminate and corresponds to its notched strength. The well-known variation in apparent fracture strength of notched fiber-reinforced composite laminates with respect to the notch tip radius is clearly explained as the scale effect of this constant critical length in different displacement distributions ahead of notch tips of different radii.
Numerical Simulation of the Prestressed Laser Welding of 7075－T7451 Aluminum Alloy Sheet
Authors: Wang Hong Feng , Zuo Dun Wen , Miao Hong , Wang Hong Jun
Published: March 2010

The heat source model and the heat input model were built by analyzing welding process. The rationalities of model were verified by finite element simulation. The method of prestressed welding was employed in order to reduce welding residual stress. The welding residual stress would be widely impacted by imposed prestress of 90% yield strength welding. At the same time the propagation of welding heat cracking in the heat-affected zone was properly controlled by prestressed welding.
Flow Stress Determination of Aluminum Alloy 7050-T7451 Using Inverse Analysis Method
Authors: Wang Zhong Qiu , Li Jian Feng , Sun Jie , Jiang Feng , Zhou Jun
Published: March 2010

In the present study, two-dimensional orthogonal slot milling experiments in conjunction with an analytical-based computer code are used to determine flow stress data as a function of the high strains, strain rates and temperatures encountered in metal cutting. By using this method, the flow stress of Al7050-T7451 is modeled. Through the comparison of cutting forces between FEM and experiment, the FEM model using predicted flow stress can give precise cutting forces. The work of this paper provides a useful method for material constitutive equation modeling without doing large number of cutting experiment or expensive SHPB tests.
Research Code Management System Based on J2EE
Authors: Xue Shan Liang , Wei Qing Yan , Jiao Guang Ming , Zuo Dun Wen
Published: March 2010

Web-based Code Management System (WCMS) is an essential tool for realizing information exchange in distant collaborative product design and manufacturing among global-based enterprises. A framework for WCMS is built up on a three-tier client/server system and the WCMS is developed utilizing JAVA and J2EE technologies. The developed WCMS mainly uses servlets and JSP to handle user inputs and manage and retrieve code data from the database through the JDBC driver, with the server components stored on a middleware program called Tomcat. The WCMS developed in this work has been successfully implemented in an enterprise.
Optimization of Cutting Parameters for Surface Roughness in Cold-Air Milling Ti6Al4V
Authors: Jiang Feng , Li Jian Feng , Sun Jie , Zhang Song , Yan Lan
Published: March 2010

In this study, orthogonal arrays were applied in the design of the experiments and Ti6Al4V end-milling experiments were performed on the DAEWOO machining center. The white light interferometer was used to obtain the average surface roughness (Ra). A quadratic model was proposed to fit the experimental data of the surface roughness. And the fit model was used to optimize the cutting parameters in the given material removal rate. Finally the verification experiments showed good agreement with the estimated results.
Virtual Assembly Operation Modeling Based on Colored Petri Net
Authors: Chen Peng , Xia Ping Jun , Lang Yue Dong , Yao Ying Xue
Published: March 2010

In this paper, a Colored Petri Net modeling method for early stage design of virtual assembly operation is presented. The characteristics of virtual assembly system, Petri Net and Colored Petri Net are analyzed. Some previous work in Petri Net application in assembly and virtual assembly system is discussed. The theoretical aspects of Colored Petri Net are introduced mathematically. Based on the mathematical presentation and the process of fasteners assembly operation, a Colored Petri Net model is constructed for the simulation of assembly operation in virtual environment. With CPN Tools software package, the simulation for evaluating the feasibility of modeling is implemented. It is demonstrated that the modeling approach can support the early stage design of virtual assembly system.
Experimental Investigation on Brittle-Ductile Transition in Electroplated Diamond Wire Saw Machining Single Crystal Silicon
Authors: Gao Yu Fei , Ge Pei Qi
Published: March 2010

Based on reciprocating electroplated diamond wire saw (REDWS) slicing experiments, a study on REDWS machining brittle-ductile transition of single crystal silicon was introduced. The machined surfaces and chips were observed by using Scanning Electron Microscope (SEM), and some experimental evidences of the change of material removal mode had been obtained. The experimental results indicate there is a close relationship between material removal mode and the ratio r value of ingot feed speed and wire speed, through controlling and adjusting the r value, the material removal mode can be complete brittle, partial ductile and near-ductile removal.
Experimental Study on the Laser Rapid Forming Repairing of 45 Steel and 2Cr12 Components
Authors: Song Jian Li , Li Yong Tang , Deng Qi Lin , Hu De Jin
Published: March 2010

Laser rapid forming is a kind of new developed technology combining laser surface modification and rapid prototyping technology. It provides a powerful tool for the manufacturing and repairing of metal components. Laser rapid forming repairing experiments of 45 and 2Cr12 steel have been carried out with 316L stainless steel powder. Microstructure and properties of the repaired components are analyzed and tested with optical microscopy (OM), scanning electron microscopy (SEM) and electronic tensile experimental machine etc. Repaired components of different materials have been metallurgically bonded with the deposited layers, with fine microstructure, better mechanical properties and free of defects.
Finite Element Simulation of Residual Stress on the Surface in the Cutting Considering Tool Flank Wear
Authors: Liu Hai Tao , Sun Ya Zhou , Lu Ze Sheng
Published: March 2010

Deformation caused by residual stress has been one of the main reasons influencing the machining accuracy, studies on machining residual stress should be performed. The tool flank wear on the cutting process has great influence on cutting heat which will infulence the distribution of residual stress, therefore,we should do the finite element simulation of cutting tool flank wear on the heat-affected firstly,then simulate and forecast the surface residual stress, studies on the effect of tool flank wear on the distribution of machined surface residual stress Johnson-Cook’s coupled thermal-mechanical model is used as workpiece material model, thermal-displacement coupled brick are used to mesh, while friction between tool and work piece uses modified Coulomb's law whose slide friction area is combined with sticking friction. By means of FEA, residual stress on the machined surface and cutting temperature under different tool flank wear conditions are obtained. The results are compared and analyzed, and then we can get the fundamental influencing law on machined surface residual stress of tool flank wear.
Modeling and Micro-Milling Experiments on Complex 3D Micro-Mould Parts
Authors: Bai Qing Shun , Liang Ying Chun , Yang Kai , Luo Zhi , Fang Xiao Yan
Published: March 2010

Micro-mould is a necessary and productive component for the development of MEMS. However, the machining of micro-mould parts with complex 3D surfaces becomes the key problem for the development of micro machinery. In the paper, a new machining technique was introduced to manufacture micro-mould parts. With a reverse engineering technique, point cloud data were acquired and reconstructed into a 3D model of micro mould part in a computer. The numeral control code for micro-machining was also processed with the help of micro-machining simulation. The machining experiment on micro-parts with complex 3D surfaces was conducted on self-developed micro machine tools with micro-diameter ball-end cutter. High quality micro mould parts with complex 3D surfaces were obtained under these micro-milling experiments. The results will provide a perspective resolution on the manufacturing of micro-mould parts with complex surfaces.
Study on the Detection Techniques of Sheet-Metal Delamination Based on Laser Shock Wave
Authors: Luo Kai Yu , Song Guang Shan , Zhu Jin Lian , Zhang Lei , Zhang Yong Kang
Published: March 2010

The large area delaminated (two layers) and non-delaminated samples of 1mm-thick aluminium alloy 2024 were shocked by pulse laser, the restricted layer and the absorbing layer were coated on the surface of the samples, and the PVDF sensors were set on the facing of a quilt of the samples. The signs of laser shock waves were transmitted to the computer by the oscillograph. The results indicated that can be effective detected by laser shock waves, and the math model of hierarchical sheet-metal by laser shock wave was fundamentally developed. A new method to detect the large area delaminated samples was provided, which has the definite engineering importance.
Research of Complications Effected on Structure Angles of the Hyperboloid Twist Drill
Authors: Li Chao , Chen Ling
Published: March 2010

The complications that effected on key geometry parameters of the drill point had been searched in this paper by the result of 3D figuration simulation. The simulation result solved the quantificational change relations between the main structure angles of the hyperboloid drill and its figuration configuration parameters on numerical value relation. This method will give a theoretic basis and effectively optimize method for practically drill and grinding.
A Practical Algorithm for Compensating the Whole-Error of On-Machine Measurement
Authors: Bao Sheng , Feng Ping Fa
Published: March 2010

The On-machine measurement is usually based on the data of points. When data come from the CNC machine tools, the information they carry may be invalid. Therefore, it is unsuitable to compensate the errors by rotating and translating all data. In this paper, a practical algorithm is proposed to compensate the errors. Firstly, the valid data are picked out and sorted according to their normal vectors. By using the least square method, an error reference frame is constructed. Then the relation between the compensation values and coordinates of the theoretical points is derived. Finally, an example of aircraft structural parts is presented to validate the design.
3D FEM Simulation and Experimental Research of Springback in Bending Process of Aluminum Alloy Sheet
Authors: Jin Xia , Lu Shi Hong
Published: March 2010

Bending of the aluminum alloy is one of the processes frequently applied during manufacture of aircraft sheet metal. The bending operation involves springback, which is defined as elastic recovery of the part during unloading. In manufacturing industry, it is still a practical and difficult problem to predict the final geometry of the part after springback and to design appropriate tools in order to compensate for springback. In this study, 3D commercially available finite element analysis (FEA) software-MARC is used to analyse bending and springback of different aluminium materials (LY12CZ) with different thickness. The amount of springback, total equivalent plastic strains and equivalent von mises stresses are obtained. Moreover, the relation between bent angle and springback angle, R/t ratio and springback angle are presented and discussed in detail.The comparison results of FEA result and experiment data indicate that the FEM (finite element analysis method) simulation is a power tool for the highly accurate prediction of springback behavior in sheet metal bending.
Thermal Shock Behaviors of Laser Cladding NiCoCrAlY Coatings Strengthened by Nanometric SiC Particles
Authors: Wang Hong Yu , Zuo Dun Wen , Li Xiang Feng , Chen Yong Jun
Published: March 2010

Three NiCoCrAlY coatings strengthened by different contents of nano-SiCp (nanometric SiC particles)were prepared on Ni-based superalloy substrates using crosscurrent CO2 laser, and the thermal shock test of these coatings was conducted by cycling between 1050°C and room temperature (10-15°C). The spalled area in the oxide scale of coatings after 10 thermal shock cycles and the thermal shock cracks in the cross-section of coatings after 100 thermal shock cycles were investigated using SEM, OM, and other means. The results show that the thermal shock resistances of NiCoCrAlY coatings are improved after adding nano-SiCp. Among nano-SiCp-added coatings, the coating added with 1.0 wt% nano-SiCp performs best. After 10 thermal shock cycles, there is a slight spallation whose area is only 2.65% in the oxide scale of the coating; after 100 thermal shock cycles, no internal crack is observed in the cross-section, and the amount and size of propagating cracks are slight.
Aircraft Assembly Simulation Path Planning Based on Engineering Semantics
Authors: Li Ying Guang , Song Cheng Zhi , Song Wen Juan , Wang Lei
Published: March 2010

A technique of assembly simulation path planning based on engineering semantics is proposed. This method classifies the assembly paths and then describes them as templates based on engineering semantics. A fast assembly simulation path planning is realized by reusing the templates of the assembly path, which improves the efficiency of aircraft assembly simulation path planning.
Study on the Fabrication and Cutting Performance of HFCVD Diamond Coated Silicon Nitride Inserts
Authors: Yang Guo Dong , Shen Bin , Sun Fang Hong , Zhang Zhi Ming , Chen Ming
Published: March 2010

Microcrystalline diamond (MCD) and fine-grained diamond (FGD) films are deposited on silicon nitride (Si3N4) inserts using the hot filament chemical vapor deposition (HFCVD) method. Scanning electron microscope (SEM), X –ray diffraction (XRD) and Raman spectrum are employed to characterize these as-deposited diamond films. Cutting performance of as-fabricated CVD diamond coated Si3N4 inserts is examined in dry turning glass fiber reinforced plastics (GFRP) material, comparing with the uncoated Si3N4 inserts. The results indicate that the tool failure is mainly attributed to its severe flank wear, which is caused by continuous friction and impact brought by many hard SiO2 particles distributed in the GFPR work piece. The lifetime of Si3N4 inserts can be prolonged by depositing MCD or FGD films on them and the FGD coated insert shows better wear resistance than the MCD coated one.
Cutting Parameters Optimization by Fuzzy Synthetic Evaluation and BP Neural Network in Milling Aluminum Alloy
Authors: Zhang Xiao Hui , Guo Guo Giang , Chen Ming , Rong Bin , Han Bing , Liu Gang , Zhang Yun Shan
Published: March 2010

Aluminum alloy, as a kind of large-scaled structures, have been widely used in modern aerospace industry. In order to reduce its machining deformation, cutting parameter optimization is absolutely necessarily. By fuzzy synthetic evaluation, cutting parameters are optimized based on factors: surface roughness, residual stress, radial milling force and milling temperature. By maximal grade of membership rule, optimized values are obtained by different two methods. And by BP network with Bayesian regularization method the corresponding milling parameters are obtained too.
A Separated-Axis Interpolator with Variable Period for Stepping Systems
Authors: Chen Hao , You You Peng , He Jun , Yang Xue Feng
Published: March 2010

In motion systems driven by stepping motors, reference word interpolation is usually used with a constant period T, in which the existing position quantization errors will inevitably result in the trouble of velocity quantization errors. A separated-axis interpolator with variable period is proposed to deal with these troubles. The reassignment module of displacement and time is the key of the interpolator. In the module, the interpolation period of each axis can be separately adjusted upon its quantized displacement, thus resulting in almost ideal velocity profile and moving smoothness. Simulation and machining results are given and show that the proposed interpolator is effective in the improvement of motion stability and interpolation accuracy.
Equipments and Strategies of Machining 3D Meso-Scale Parts
Authors: Zhang Xiang , Han Zhen Yu , Sun Ya Zhou , Fu Hong Ya
Published: March 2010

Currently machine tools and strategies researched in micro-milling field universally cannot be applied to 3D meso-scale parts machining directly, so great importance should be attached to the research on 5-axis machine tools and the suitable strategies for 3D meso-scale machining. This paper introduced a self-made 5-axis machine tool and several micro-milling strategies which were applicable to 3D meso-scale parts machining. Using these strategies, a mini impeller was successfully machined on the 5-axis machine tool developed independently. The experiment result showed the machine tool and the strategies were suitable for machining meso-scale 3D parts.
Contact Stress Analysis of NCD Coating on Cemented Carbide
Authors: Yuan Jia Jing , Lu Wen Zhuang , Zuo Dun Wen , Xu Feng
Published: March 2010

The contact stress of cemented carbide with NCD coating in elastic contact was analyzed using ANSYS. Factors such as elastic modulus and thickness of NCD film and elastic modulus of interlayer which affect the shear stress distribution of NCD film on cemented carbide substrate were investigated. The results show that the maximum shear stress point moves towards the interface with the increase of film elastic modulus. Film thickness has a significant effect on shear stress distribution of NCD film. High shear stress develops in the film layer with the increase of film thickness. Interlayer with low elastic modulus will cause shear stress concentration in NCD film.
Adhesion of Ceramic Plates with Geopolymer
Authors: Do Rego Sóstenes Rodrigues , Gomes Kelly Cristiane , Leal Antonio Farias , Barbosa Normando Perazzo , Torres Sandro Marden , de Barros Silvio Romero
Published: March 2010

The detachment of ceramic tiles from buildings is a problem that still persists in several modern constructions. Although there are several specific techniques for the prevention of tiles from detaching this issue still requires in-depth research in order to be fully solved. These detachments happen commonly in facades that are submitted to the incidence of solar rays on the surfaces. In this work, the adhesion of porcelanate-adhesive-substrate was investigated through direct detachment tests according to Brazilian standards. Two types of adhesives were used: a commercial adhesive, classified by Brazilian standard as being of high adhesion (ACIII-E) and a geopolymer, developed through alkaline activation of metakaolin with sodium silicate. The bonded systems were submitted to two temperature exposure regimes. In general, geopolymeric adhesives had better adhesion than the systems bonded with ACIII-E adhesive mortar, especially with temperature increase.
Geopolymeric Adhesives for Aluminium Joints
Authors: de Barros Silvio Romero , Gomes Kelly Cristiane , De Souza João Regis , Barbosa Normando Perazzo , Torres Sandro Marden
Published: March 2010

Bonded joints have been used in substitution of more traditional techniques as screws, rivets and mainly welding. However, the applications in which the work temperatures are relatively high remain as an obstacle to the use of more common polymeric adhesives. In this sense, the study of adhesive properties of thermally stable materials as the geopolymers becomes a need. This work deals with the adhesion of aluminium sandwich beams using geopolymeric adhesives. Metakaolin-based geopolymers were used as adhesives, activated with sodium and potassium silicates. Shear mode adhesion tests were accomplished and the results indicate the possibility for use of these new adhesives.
Fatigue Life Curves of NiTi Alloys – The Z Effect
Authors: Figueiredo Ana Maria Gontijo , Gonzalez Berenice Mendonça , Buono Vicente Tadeu Lopes , Modenesi Paulo José
Published: March 2010

Superelasticity is closely related to shape memory effect. It refers to the property presented by some materials submitted to large strains (usually up to about 8%) to restore their original shape immediately after unloading without the need of heating. This phenomenon results directly from a diffusionless transformation of the material from an austenitic to a martensitic phase (martensitic transformation). The recovering mechanism is the reverse transformation, from martensite to austenite. This paper compares fatigue live curves obtained in bending-rotation fatigue tests carried out on wires of NiTi alloys with three different microstructures, stable austenite, unstable austenite (superelastic), and stable martensite. These curves are also compared to data from the literature. The tests were strain controlled and the wires were submitted to strain amplitudes from 0.6% to 12.0%. To minimize changes in material properties, the wire temperature was monitored using a thermocouple and controlled by its rotation speed. For strain amplitudes up to 4%, the εa-Nf curve for superelastic wires was consistent with those reported in the literature, closely approaching the curve of the stable austenite wire. For higher strain amplitudes, fatigue life of superelastic wires increased with strain until it approached the fatigue life curve of stable martensitic wire. This unusual behavior results in a “Z-shaped” curve for high strain values. It is possibly linked to the changes in microstructure and fatigue properties that occur when the superelastic material is deformed.
Elemental Analysis of a Heterogeneous Polymeric System by EDS: Detection of the Compatibilizer Agent Containing Si Atoms and Silver Nano-Particles (AgNP´s) in High Impact Polystyrene
Authors: Soriano F. , de Anda C. , Morales G. , Ponce Arturo
Published: March 2010

High impact polystyrene (HIPS) is considered a heterogeneous polymeric system and is constituted by a disperse phase of rubber particles within a continuous phase formed by a polystyrene (PS) matrix. During the synthesis of HIPS, PS is formed whereas some PS chains become chemically bonded to polybutadiene (PB) chains, resulting in a PB-g-PS copolymer, which decreases the interfacial tension between both incompatible phases, acting as a compatibilizer. In this study, 2 HIPS systems were evaluated by energy dispersive spectroscopy (EDS). In the first case, a HIPS composite was analyzed by EDS to locate the graft copolymer species containing Si atoms, which were previously synthesized by anionic polymerization using chloro-silane chemistry. The graft copolymer was incorporated to the HIPS synthesis from the beginning of the reaction in order to provide an improvement on the rubber phase stability. The graft copolymer was located at the interphase between the PS occlusions and the PB subdomains of the rubber particles. In the second case, HIPS was synthesized incorporating silver nanoparticles (AgNP´s) during the polymerization reaction, where the system can exhibit different types of morphology of the elastomeric phase (micelles, lamellas and core-shell). These structures overlapped the AgNP´s in the transmission electron microscopy (TEM) images, thus resulting this technique to be inadequate to establish the location of the AgNP´s. In this context EDS was used to evaluate the location and distribution of the AgNP´s by means of the elemental composition analysis. AgNP´s were preferentially detected in the PS phase as bigger clusters.
Obtaining NiHCF Nanoparticles Using a Reverse Micellar System
Authors: Gutiérrez Becerra Alberto , Vega Venegas Tanya , Bárcena Soto Maximiliano , Casillas Norberto , Escalante José Inés
Published: March 2010

The synthesis of metallic nanoparticles using a reverse microemulsion medium brings controlled size and shape. In this study, reverse micelar system was employed for the synthesis of nickel hexacyanoferrate nanoparticles, NiHCF, by direct encapsulation in the water pools of reverse micelles formed in a pseudoternary system that consist of a mixture of 95 %wt. cetyltrimetyl ammonium bromide (CTAB) and 5 %wt. of a novel modified surfactant cetyltrimetyl ammonium ferrocyanate (CTA[Fe(CN6)]4-, CTAFe)/n-butanol/Hexane/Water. These NiHCF nanoparticles were produced with particle size ranging with 20 – 60 nm.
Influence of Texture on Ridging and Formability of 16%Cr Ferritic Stainless Steel
Authors: Mola Javad , Chae D. , De Cooman Bruno C.
Published: March 2010

The influence of the texture on ridging and forming properties of transformable 16mass-%Cr steel was studied for two different specific processing routes. In the first route (HACA), hot strips were annealed prior to cold rolling, whereas in the second route (HCA), un-annealed hot strips were directly subjected to cold rolling. Results indicate that compared to HACA, HCA results in an improved surface smoothness, i.e. reduced roping, but a lower mean r-value, as a result of strengthening of the α-fiber texture components. Differences in the roping and forming properties could also be achieved by compositional differences resulting in differences in the fraction of austenite at hot rolling temperatures.
Microstructural Characterization of Friction Welded TiAl-Ti6Al4V Hybrid Joints
Authors: Ventzke Volker , Brokmeier Heinz Günter , Merhof Peter , Koçak Mustafa
Published: March 2010

This paper describes microstructure and microtexture development in dissimilar friction welded -TAB-Ti64 joints. The effect of friction welding parameters on microstructure and local properties are examined and discussed. It was found that the intermetallic -TiAl based alloy Ti-47Al-3.5(Mn+Cr+Nb)-0.8(B+Si) (denoted as -TAB) is more sensitive to the applied friction welding parameters used in this study. Furthermore, the bonding between these two alloys was controlled by a diffusion process during a very short process duration. Grain refinement as well microstructure transformation led to local improvement of the friction-welded joints.
Overexpression of CXC Chemokine Ligand 14 Exacerbates Collagen-Induced Arthritis
Authors: Chen Limo , Guo Linjie , Tian Jun , He Hongxia , Marinova Ekaterina , Zhang Pumin , Zheng Biao , Han Shuhua
Published: March 2010

CXCL14 is a relatively new chemokine with unidentified receptor and undefined function. Recently, we found that CXCL14 is upregulated in arthritic joints in a mouse model of autoimmune arthritis, collagen-induced arthritis. To examine the role of CXCL14 in the development and pathogenesis of autoimmune arthritis, we have generated transgenic (Tg) mice that overexpress CXCL14 under control of phosphoglycerate kinase promoter. The results showed that CXCL14-Tg mice developed more severe arthritis compared with wild-type controls. The draining lymph nodes of CXCL14-Tg mice were significantly enlarged and contained an increased number of activated T cells, particularly the CD44+CD62Llow effector memory cells. In addition, T cells from CXCL14-Tg mice exhibited an enhanced proliferative response against collagen II and produced higher levels of IFN-γ but not IL-4 or IL-17. CXCL14-Tg mice also had elevated levels of IgG2a autoantibodies. These findings indicated that CXCL14 plays an important role in the autoimmune arthritis, which may have an implication in understanding the pathogenic mechanisms of rheumatoid arthritis in humans and, ultimately, therapeutic interference.
Effect of Bone Marrow-Derived Mesenchymal Stem Cells on Endotoxin-Induced Oxidation of Plasma Cysteine and Glutathione in Mice
Authors: Iyer Smita S. , Torres-Gonzalez Edilson , Neujahr David C. , Kwon Mike , Brigham Kenneth L. , Jones Dean P. , Mora Ana L. , Rojas Mauricio
Published: March 2010

Bone marrow-derived mesenchymal stem cells (BMDMSC) are emerging as a therapeutic modality in various inflammatory disease states, including acute lung injury (ALI). A hallmark of inflammation, and a consistent observation in patients with ALI, is a perturbation in the systemic redox environment. However, little is known about the effects of BMDMSC on the systemic redox status. The objective of the present study was to determine whether exogenously infused BMDMSC protect against endotoxin-induced oxidation of plasma cysteine (Cys) and glutathione (GSH) redox states. To determine the effect on the redox state if BMDMSC, mice received endotoxin intraperitoneally (1 mg/kg), followed by intravenous infusion of either5×105BMDMSC or an equal volume of saline solution. Control mice received intraperitoneal endotoxin followed by5×105lung fibroblasts given intravenously. Cys, cystine (CySS), GSH, and glutathione disulfide (GSSG) concentrations were determined by HPLC. Results showed sequential preservation of plasma Cys and GSH levels in response to BMDMSC infusion. The data show that BMDMSC infusion leads to a more reducing Cys and GSH redox state. The findings are the first to demonstrate that BMDMSC have antioxidant effects in vivo, and add to our understanding of the systemic effects of BMDMSC in lung injury.
Associations Among Hip and Shoulder Range of Motion and Shoulder Injury in Professional Baseball Players
Authors: Scher Steve , Anderson Kyle , Weber Nick , Bajorek Jeff , Rand Kevin , Bey Michael J.
Published: March 2010

Context:

The overhead throwing motion is complex, and restrictions in range of motion (ROM) at the hip may place additional demands on the shoulder that lead to injury. However, the relationship between hip and shoulder ROM in athletes with and without a history of shoulder injury is unknown.

Objective:

To (1) determine if differences exist in hip and shoulder ROM between professional baseball players with a history of shoulder injury and those with no history of shoulder injury and (2) assess relationships between hip and shoulder ROM in these players.

Design:

Cross-sectional study.

Patients or Other Participants:

Fifty-seven professional baseball players.

Main Outcome Measure(s):

Outcome measures consisted of hip extension and internal rotation, shoulder internal and external rotation, glenohumeral internal-rotation deficit, and history of shoulder injury. Differences in shoulder and hip ROM were assessed with a 1-way analysis of variance. Associations between hip and shoulder ROM were assessed with linear regression.

Results:

Nonpitchers with a history of shoulder injury had more external rotation and less internal rotation of the shoulder than nonpitchers with no history of shoulder injury. Glenohumeral internal-rotation deficit was greater in both pitchers and nonpitchers with a history of shoulder injury. The relationship between dominant hip extension and shoulder external rotation was significant for pitchers with a history of shoulder injury and nonpitchers with a history of shoulder injury.

Conclusions:

Shoulder injury may be associated with specific measures of hip and shoulder ROM, and hip extension and shoulder external rotation may be related in baseball players with a history of shoulder injury. Additional research is necessary to understand the specific mechanisms of shoulder injury in the throwing athlete.
A Qualitative Examination of Professional Role Commitment Among Athletic Trainers Working in the Secondary School Setting
Authors: Pitney William A.
Published: March 2010

Context:

Work-related demands can challenge an athletic trainer's professional role commitment for an extended period throughout one's career.

Objective:

To explore how athletic trainers perceive the phenomenon of professional commitment and maintain this commitment while working in a professionally challenging environment.

Design:

Basic, interpretive qualitative study.

Setting:

Secondary school.

Patients or Other Participants:

A criterion sample was used. Each participant had a minimum of 10 years of experience as an athletic trainer and self-identified as having maintained his or her professional commitment. Seventeen individuals (14 men, 3 women) with a mean age of 44.3 ± 6.8 years and 19.0 ± 6.7 years of experience in the secondary school setting participated in the study.

Data Collection and Analysis:

Seventeen total interviews were conducted. Interviews were transcribed and an inductive analysis was performed. A peer debriefing and member checks with 7 participants were completed to enhance the trustworthiness of the findings.

Results:

Four themes emerged from the findings: 1) professional responsibility, 2) rewards, 3) respect, and 4) rejuvenation. Participants explained that a strong sense of responsibility to their patients was a prominent feature of maintaining their commitment. Their professional commitment was influenced by both intrinsic and extrinsic rewards and respect from others. The last emergent theme, rejuvenation, explained the necessity of having appropriate time away from the athletic training role to interact with peers and address personal needs.

Conclusions:

A strong sense of professional responsibility to both patients and the athletic training discipline is a central feature of professional commitment. Organizations, such as high school athletic programs, can play an influential role in helping an athletic trainer to maintain professional commitment by examining the intrinsic and extrinsic reward systems, assessing the work structure to ensure time to address personal needs, fostering effective communication, and addressing continuing education needs to maintain competence.
Behavior of Cubaris murina Brandt (Crustacea: Isopoda) in Soil Contaminated With Glyphosate: Avoidance Tests in Laboratory
Authors: Niemeyer Júlia Carina , Santos V. C. dos , Rodrigues J. M. L. , Da-Silva E. M.
Published: March 2010

Acute tests and avoidance tests were carried out using laboratory populations of Cubaris murina, to assess their sensibility to glyphosate. The contaminant solutions were prepared by herbicide Roundup®. In the acute tests, ten offspring were confined and exposed to each treatment: soil with different concentrations of glyphosate and soil without contaminant (control). Mortality was observed after 7 days. The Spearman-Karber test was used to calculate the LC50 . In the avoidance tests, ten juveniles were put on the center of each recipient-test, with four portions of soil: three portions with different concentrations of glyphosate and one control. The preference of the isopods was registered after 1.5, 2, 3, 4 and 24 hours. ANOVA was used to verify whether there were significant differences among the mean number of isopods in each treatment and the control. The 7-d-LC50 was 35.5 mg gli/g soil. In the avoidance tests, significant differences (p < 0.05) in relation to the control, which indicated avoidance, occurred in all treatments, including 5.12 mg gli/g soil, already at 1.5 hour. The avoidance behavior was a very sensitive endpoint, assessed in low cost experiments, showing a rapid response and having an important ecological role.
N. 6 Fuel Oil Effects on Antioxidant Enzymes and Immunological Responses in the Fish Thalassophryne maculosa (Pisces: Batrochoididae)
Authors: Marcano Leida , Nusetti O. , Zapata-Vívenes E. , Nusetti S. , Esclapés M. M.
Published: March 2010

With the aim of investigate the acute effects of two concentrations (25 and 100%) of N. 6 fuel oil-water-accommodated fraction (OWAF) on antioxidant enzyme activities and immunological responses, fishes Thalassophryne maculosa were sampled from the La Restiga Lagoon, Margarita island, in eastern Venezuela. The antioxidant enzymes, catalase (CAT), glutathione peroxidase (GPX), glutathione reductase (GR) and glutathione-S-transferase (GST) were measured in liver and gills. The macrophagic phagocytosis and antibacterial lysozyme activity of anterior kidney were the immune parameters examined. Increases in gill GST activity and hepatic GR activity were observed after the exposure to 25 and 100% OWAF, respectively. GPX, CAT and immune responses were not affected by the experimental treatments. Our results demonstrated that among the antioxidant enzymes tested, GR and GST activities were the most sensible to the acute treatment with fuel oil, indicating changes in the redox cellular state that may result in oxidative stress in T. maculosa.
Oreochromis niloticus and Pistia stratiotes Sensibility to Copper and Chromium
Authors: Masutti Mariana Beraldo , Espíndola E. L. G. , Nogueira A. de M. , Simões F. C. F.
Published: March 2010

A few works about aquatic organisms sensibility to environmental contaminants are conducted using species common to Brazilian ecosystems. Oreochromis niloticus is a widespread species in reservoirs, as Pistia stratiotes, being the fish and macrophyte species, respectively, most abundant in Lobo reservoir. The aim of this work was to determine the sensibility range to Cr and Cu to this species. The LC50 was calculated by the Trimmed Spearman-Karber method, after 96 h of exposition to fish, and the EC50 after 168 h to macrophytes. The follow characteristics were measured in P. stratiotes individuals: height, diameter, number of leaves and number of roots. The LC50 values range to Cr obtained with the individuals of O. niloticus was 107.2-164 mg/L, and the values to Cu ranged between 0.32 and 0.65 mg/L. The EC50 values to Cr determined in the P. stratiotes tests ranged from 22.4 to 33.7 mg/L, as to the leaves number estimation as to the roots number estimation. In the tests with Cu, these values ranged between 0.2-0.3 mg/L, considering the roots number. Both the species tested were more sensible to Cu than to Cr, and the LC50 values obtained to the fish and the EC50 values obtained to the macrophytes were higher than the values determined by other works to different trophic level organisms, suggesting that the species studied in this work are not indicate to use as test organism, at least considering the effect parameters evaluated.
Comparison of Particulate Suspended Matter (PSM) Effects From Different Pollution Sources on Chicken Egg Embryogenesis
Authors: Azevedo D. C. , Oliveira D. S. , Guimarães H. M. B. , Martins R. S. L. , Macchiore M. , Saldiva P. H. N.
Published: March 2010

Airborn particles are due to adverse effects on health and may cause adverse fetal outcomes. The present study compares the embryotoxicity of the PTS (Total Suspended Particulate) from three different emitting pollution sources: São Paulo, Capital; Cubatão; and Araraquara. Chicken fertilized eggs were divided on: nontreatment control, PTS treated and positive control. The eggs were opened and analyzed the mortality rates and weight of the embryos. The mortality rates of the PTS treated eggs were the highest on Cubatão (41.7%) followed by Araraquara (37.5%) and São Paulo (9.1%) at 0.3 μg/L PTS dose (p < 0.05). The mean weight from hatching embryos were lower at Cubatão PTS treated when compared with São Paulo and Araraquara. These observations are supportive of the concept that not only the concentration of PTS interferes on embryo development, but also their components, therefore the highest mortality and the lower mean weight belong to Cubatão sample.