bluuebunny/crossref_metadata_2025 huggingface dataset:
About the Effects of Residual Stress States Coming from Manufacturing Processes on the Behaviour of Riveted Joints
Authors: Caputo Francesco , Lamanna Giuseppe , Soprano Alessandro
Published: March 2009

A very large number of variables affect the response of bolted or riveted joints typically
used in aerospace applications: geometry of the joint, characteristics of the sheets, friction between
sheets, geometry of head and kind of fastener, amplitude of clearance before assembly, mounting
axial load, pressure effects after manufacture. It must be also recalled that these parameters
influence the many failure modes existing for such joints, among which a relevant importance is
attributed to bearing.
The present paper deals with the study of the influence of assembly parameters on the joint
operational behaviour and in particular with the analysis, performed through numerical simulations,
of the influence of the residual stress-strain state coming from the riveting operation on the bearing
resistance of an aluminium alloy joint.
This work has been developed within the FP6 research project called MUSCA (Non linear static
multiscale analysis of large aero-structures).
Research on Performance of Reduced Web Connections in Steel Frame
Authors: Shao Yong Song , Jin Lu , Liu Hong Bo , Xie Li Li
Published: March 2009

Following the Northridge earthquake, widespread damages in connections have been
discovered. Then the research on behavior of new beam-column connections has been being a hot
spot in recent several years. Non-linear analysis of reduced web connections with circular and
rectangular openings in concentrated loading was carried out with finite element method. The
parameters were conducted to study the effect of opening ratio, opening style and opening position on
bearing capacity. Results show that bearing capacity of reduced web connection reduces with the
increase of opening ratio. The opening ratio of reduced web connection takes little effect on bearing
capacity when opening ratio is less than 50%. The bearing capacity of reduced web connection with
circular opening is larger than rectangular opening if the opening area is equal.
Fatigue Crack Monitoring Using Image Correlation
Authors: Lopez-Crespo Pablo , Shterenlikht A. , Patterson Eann A , Yates J.R. , Withers Philip J.
Published: March 2009

A novel methodology based on a combination of experimental and analytical methods is
used for monitoring the stress intensity factor in fatigue cracks subjected to constant amplitude
loads. Full-field displacement information is fitted, following a multi-point over-deterministic
approach, to an analytical model. This is developed from Muskhelishvili’s complex formulation.
The methodology allowed accurate monitoring of the stress intensity factor during three fatigue
cycles when small-scale yielding conditions were achieved. Moreover for larger loads where
important plastic deformation occurs around the crack tip, Dugdale’s correction accounted for the
differences between theoretical and calculated stress intensity factors. Accordingly the tool provides
an indirect approach for measuring crack tip plasticity. Due to the fact that image correlation is
relatively simple to use and is a non-contacting technique, the approach pioneered in this work
seems ideal for monitoring fatigue cracks in industrial applications.
Numerical and Experimental Analysis of Crack Closure
Authors: Lopez-Crespo Pablo , Camas Daniel , González-Herrera Antonio , Yates J.R. , Patterson Eann A , Zapatero Jose
Published: March 2009

The fatigue life of metallic materials is strongly influenced by crack closure effects. Finite
element (FE) methods allow the study of crack closure with great detail and can provide valuable
information about phenomena occurring in the bulk of the material. In this work the distribution of
stresses through the thickness of a cracked specimen has been studied using 3D FE simulations. It
was found that the transition between the interior of the specimen (plane strain) and the surface
(plane stress) differs from that predicted by 2D plane stress models. In addition, an attempt is
presented to experimentally validate the results at the surface level. For this purpose full-field image
correlation technique was utilized. This allowed direct comparison between the displacement field
predicted by the numerical simulations and the experimental results measured by digital image
correlation.
Analysis for Mechanical Properties of Spiral Accumulating Core Used for Permanent Magnet Motor
Authors: Noda Naoaki , Zhang Biao , Yonemaru Kazuhiko , Higo Shota , Takamatu Yoshihiro
Published: March 2009

Recently, permanent magnet motors are widely used in many industrial fields because
they are suitable for compact mechanical system. The motor core is usually manufactured from
magnetic steel sheet with press machine. However, usually most parts of the plate are scraped, and
only small percent of the sheet is used for the core. The spiral accumulating core system is suitable
for manufacturing the core more ecologically because in this system more than 50% of the magnet
steel sheet can be used. In this study, therefore, the effective Young’s modulus of the spiral
accumulating core is considered in order to find out a good method to fix the core. In this analysis,
the finite element method is applied to 3D models, whose layers and slits are periodically arranged.
Stress and thickness distributions are also analyzed in the bending process. When the spiral core is
manufactured through spiral accumulating system with plate-bending process, the thickness change
should be minimized because that may deteriorate dimensional accuracy of the spiral core. Also
residual bending stress is investigated because that may cause an electric loss. The results indicate
that plastic zone is limited at localized regions and therefore an electric loss is not very large. The
effective Young’s modulus of the 3D dimensions model of the real spiral accumulating core is
estimated about 127.5 GPa.
Crack Size Dependency of Shear-Mode Fatigue Crack Threshold in Bearing Steel
Authors: Muramoto Satoshi , Matsunaga Hisao , Moriyama Shigeaki , Endo Masahiro
Published: March 2009

Semi-elliptical shear-mode fatigue cracks were promoted in the axial direction of round
specimens of SAE52100 bearing steel by fully-reversed cyclic torsion tests under a static axial
compressive stress. Non-propagating cracks smaller than 1 mm were obtained in two ways; (i)
stress amplitude decreasing tests of notched specimens, or (ii) constant stress amplitude tests of
smooth specimens. The threshold stress intensity factor ranges, (KIIth and (KIIIth, showed a crack
size dependency.
A Study of Crack Propagation in BCC Iron by Molecular Dynamics Method
Authors: Gao Yuan , Lu Cheng , Michal Guillaume , Tieu A. Kiet
Published: March 2009

In this paper, molecular dynamics method has been employed to model mode I crack propagation in body center cubic (BCC) single iron crystal. To maximize the simulation efficiency the parallel computing was performed. Six cases with different lattice orientations have been simulated to investigate the crack propagation behaviors at atomic level. The strain distributions have been calculated to indicate the density of dislocation. It has been found that the lattice orientation significantly affects the propagation behaviors. The crack in BCC iron propagates more readily along the direction <111> on the plane {1-10}.
The Analytical Trial Function Method (ATFM) for Finite Element Analysis of Plane Crack/Notch Problems
Authors: Fu Xiang Rong , Cen Song , Long Yu Qiu , Jiang Xiu Gen , Ju Jin San
Published: March 2009

A new technique, Analytical Trial Function Method (ATFM), is proposed to formulate
new finite element models for analysis of plane crack/notch problems. A new analytical finite
element, named ATFM-CN, is successfully constructed. Furthermore, in order to determine the
eigenvalues of the crack/notch problems, which utilized in above analytical trial functions, a modified
sub-region accelerated Müller method is also suggested. Numerical examples show the present
approach exhibits excellent performance in the analysis of stress-singularity problems.
Fatigue Life Evaluation of Automotive Engine Mount Insulator
Authors: Woo Chang Su , Kim Wan Doo , Hur Shin
Published: March 2009

Fatigue life of automotive engine mount insulator made of natural rubber was evaluated.
In order to develop an appropriate fatigue damage parameter of the rubber material, a series of
displacement controlled fatigue tests was conducted using 3-dimensional dumbbell specimens with
different levels of mean displacement. It was shown that the maximum Green-Lagrange strain was a
proper damage parameter, taking the mean displacement effects into account. Nonlinear finite
element analyses of the rubber engine mount insulator and 3D dumbbell specimen were performed
based on a hyper-elastic material model determined from the simple and equi-biaxial tension tests.
Fatigue life prediction of the engine mount insulator was made by incorporating the maximum
Green-Lagrange strain values, which was evaluated from the finite element analysis and fatigue
tests, respectively. Predicted fatigue lives of the engine mount insulator showed a fairly good
agreement with the experimental fatigue lives.
Dynamic Stability of Lateral Vibration of Bottom Hole Assemblies
Authors: Zhao Guang Hui , Liang Zheng
Published: March 2009

Bottom hole assemblies (BHA) of oil drilling engineering were simplified as simply
supported beam, and parametric resonances of BHA in mud drilling and air drilling were studied.
Lateral vibration of BHA, which was induced by bit/formation interaction, was described and
reduced into Mathieu equation by means of separation of variables and Galerkin method. Modified
strained parameter method was adopted in stability analysis. The parametric resonance zones
expressed by weight on bit (WOB) are presented here. It is found that drilling method, speed of
rotation (SOR), material properties, and length of compression drillstring all can influence
parametric resonance zones. So unstable responses can be avoided by adjusting these parameters.
A Viscoplastic Constitutive Model for Single Crystals and its Application in a Numerical Simulation of Creep-Plasticity Behaviors
Authors: Zeng Xiang Guo , Chen Hua Yan , Gao Zhan Hua
Published: March 2009

Founded on the energy storing characteristics of microstructure during irreversible
deformation, a viscoplastic constitutive model with no yielding surface introduced was developed for
single crystals by adopting a spring-dashpot mechanical system. Both plastic dashpots reflecting the
material time-independent responses and Newtonian dashpots mirroring the material time-dependent
viscous responses were introduced to describe the viscoplasticity of slip systems. The single crystal
constitutive model was established based on the thermodynamics of internal variables and the theory
of absolute reaction rate. By implementing the KBW self-consistent theory, a polycrystal viscoplastic
constitutive model was formed. The numerical analysis in corresponding algorithm was significantly
simplified as no searching process for the activation of the slip systems and slip directions was
required. The numerical simulation of creep-plasticity behaviors demonstrated excellent agreement
with the corresponding experimental data.
A Study on Shear Reinforcement of Exterior Joints for Flat Plate
Authors: Choi Hyun Ki , Beck S.W. , Baik Y.S. , Choi Chang Sik
Published: March 2009

The purpose of this research was to study the response of slab-column connections
containing various types of shear reinforcement when subjected to the combination of gravitational
and lateral cyclic loads. The three test specimens were full-scale representations of exterior slabcolumn
connections of a prototype apartment building in Korea. The control specimen had no shear
reinforcements, while the other specimens had CS-Bar and SS-Bar as shear reinforcements. The
control specimen failed due to the punching shear around the slab-column connection at 4.0% drift.
None of the specimens with shear reinforcement experienced punching shear failure up to 4.4%
drift. The two types of slab shear reinforcements proved to be equally effective in resisting
punching shear failure of these connections subjected to relatively low levels of gravity load. The
presence of shear reinforcements significantly increased the lateral load ductility of the connections.
The test results showed that the strength and ductility of the specimens with SS-Bar and CS-Bar
were improved by 23% and 15% compared to the specimen without shear reinforcements.
Influence of Hydrogen Atoms on Electrical Properties of BST Thin Film Capacitors
Authors: Morito Kentaro , Suzuki Toshimasa , Mizuno Youichi , Sakaguchi Isao , Ohashi Naoki , Haneda Hajime
Published: March 2009

The relationship between the distribution of hydrogen and the electrical properties of (Ba, Sr)TiO3
(BST) thin film capacitors was investigated using secondary ion mass spectroscopy (SIMS)
analyses. It has been clearly shown that there is a close relationship between the hydrogen
distribution in BST thin film and the frequency dependence of the complex impedance of the BST
thin film capacitors. It was confirmed that protons, the interstitial hydrogen impurity dissolved in
BST thin films annealed at 400oC, were produced by a thermal equilibrium reaction between the
hydrogen in the annealing atmosphere and the BST thin films.
Preparation of Epitaxial LiNbO3 Thin Film by MOCVD and its Properties
Authors: Morohashi Rintarou , Wakiya Naoki , Kiguchi Takanori , Yoshioka Tomohiko , Tanaka M. , Shinozaki Kazuo
Published: March 2009

Lithium niobate (LiNbO3) thin films were deposited on Al2O3(001) substrates using metal-organic
chemical vapor deposition (MOCVD), with Li(dpm) and Nb(C2H5)5 as precursors. By optimizing the
conditions of thin film deposition, the c-axis oriented and epitaxially grown LiNbO3 thin films with
stoichiometric composition were deposited on an Al2O3(001) substrate. The refractive index of the
stoichiometric LiNbO3 thin film was 2.24 at = 632.8 nm, which is close to that of bulk crystal.
Preparation of Transparent SBN Ceramics and their Opto-Electrical Properties
Authors: Kubota Teppei , Tanaka Nobuhiko , Kageyama Keisuke , Takagi Hiroshi , Sakabe Yukio
Published: March 2009

The electrooptic material of transparent (Sr,Ba)Nb2O6 (SBN) ceramics was prepared using the
conventional solid-phase reaction process with no special techniques such as hot-pressing or hot isostatic
pressing. The SBN ceramics were made transparent by substituting a small amount of Zn2+ ion for the B
site (Nb5+ ion site). The Curie temperature was increased by substituting a small amount of Na+ ion for
the A site (Sr2+ or Ba2+ site). Furthermore, the orientation of the SBN structure by the template grain
growth (TGG) method improved the electrooptic properties of the ceramics.
Synthesis and Lithium Ion Conductivity of MP2O7-Based Solid Electrolytes
Authors: Kato Akihiro , Saito Morihiro , Kuwano Jun
Published: March 2009

Phase studies and ac-conductivity measurements were carried out in the compositions M0.8In0.2Li0.2P2O7 [MILP] (M=Sn, Zr, Ti). The bulk conductivities were of the order of ~10-5 Scm-1 at 623 K and higher in the order of TiILP≥ZrILP>SnILP. The activation energies, as expected, became lower in the order of ZrILP<TiILPSnILP in bulk conductivities were not correlated with that of the activation energies probably because of the impureness of the ZrILP sample.
Measurement of High-NA Axisymmetric Aspherical Surface with Continuous Interference Method
Authors: Nagaike Y. , Kuriyagawa Tsunemoto , Gao Wei , Yan Ji Wang , Yoshihara Nobuhito
Published: March 2009

The measurement principle where in a high-NA (Numerical Aperture) surface, for which
the degree of the angle of surface inclination exceeds π/3 radians, could be evaluated with high
precision and high speed is proposed. This is based on the stitching method, where aspherical surface
measurement becomes possible by dividing the surface of the sample into a range so that
measurements can be made with an interferometer and finally combined. We examine the method of
applying an interferometer to the condition in which the sample is rotated on an air spindle at a
constant speed. It is not necessary in this method to make the sample static. Therefore, the vibration of
the servo motor and any location errors can be eliminated. Moreover, the measurement time does not
depend on the number of divided areas which are necessary for the stitching method, allowing for
high-speed measurement. The principle behind this technique is expanded first, and an experiment
system based on it was constructed. The principle proposed was evaluated, and its effectiveness was
confirmed.
Effects of Thermal Deformation of Multi-Wire Saw’s Wire Guides and Ingot on Slicing Accuracy
Authors: Abe Yoshinori , Ishikawa Ken Ichi , Suwabe Hitoshi
Published: March 2009

Warp accuracy and nanotopography in the silicon wafer slicing process influence the final
quality of the wafer. Therefore, methods to improve these factors are important. And this will require
the achievement of low costs and high quality processing – conflicting requirements – with larger
sized wafers than in previous generations. The present study was performed to assess mechanical
factors, such as machine static accuracy and thermal deformation, to improve the accuracy of
multi-wire saws. This report deals with the influence of thermal deformation of the ingot and wire
guides upon processing accuracy, and describes the assessment results.
Polishing Characteristics of CMP for Oxygen Free Copper with Manganese Oxide Abrasives
Authors: Sato Ryunosuke , Ichida Yoshio , Morimoto Yoshitaka , Shimizu Kenji
Published: March 2009

A series of polishing experiments have been carried out using Mn2O3 as abrasive grains to
examine the polishing characteristics of CMP for oxygen-free copper. It has been found that the
polishing rate increases as the polishing speed and/or polishing pressure increases, also the role of
polishing speed on the polishing rate is more significant than that of the polishing pressure. The
effects of the polishing conditions are however small, when polishing a finished surface roughness of
about Ra 5 nm. A long polishing time, with an approximately constant polishing rate, can be
achieved, without dressing, with a polishing pressure P = 9.4 kPa. It was found that higher polishing
pressures could achieve a higher polishing rate, however the polishing pressure would decrease as the
polishing time increased.
Silicate Consolidants for Stone
Authors: Scherer George W. , Wheeler George S.
Published: March 2009

Consolidants are sols or solutions that are used to restore the strength of weathered stone. The liquids are drawn into the pores of stone by capillary suction, then they harden by gelation and/or drying. In this chapter, we discuss the requirements that such a material must fulfill, and demonstrate the effectiveness of consolidants based on alkoxysilanes and alkylalkoxysilanes.
Finite Element Simulation on Face Milling of Austenitic Stainless Steel with Chamfered Tools
Authors: An Qing Long , Li Jun Li , Ming Wei Wei , Chen Ming
Published: March 2009

Due to the high strength of austenitic stainless steels, it is essential for cutting tool to keep with appropriate chamfered edges during the face milling process. In this paper, face milling mechanics with chamfered edge based on cutting force and chip formation were analyzed through finite element analysis (FEA). Three kinds of tools with different chamfered edges were studied on face milling of 1Cr18Ni9Ti austenitic stainless steel. The primary research results indicated that FEA results showed good consistency with experimental results. This can provide references for development and application of tools during face milling process.
An Intelligent Optimization Approach of Feedrate Scheduling Based on Hybrid Simulation Models
Authors: Zhang Li Qiang , Wang Yu Han , Chen Ming
Published: March 2009

In free-form surface machining, it is essential to optimize the feedrate in order to improve the machining efficiency. Conservative constant feedrate values have been mostly used since there was a lack of physical models and optimization tools for the machining processes. The overall goal of this research is the integration of geometric and mechanistic milling models for force prediction and feedrate scheduling for free-form surface machining. For each tool move a geometric model calculates the cutting geometry parameters, then a mechanistic model uses this information with the constraint force to calculate desired feedrates. The feedrate is written into the part program. When the integrated modeling approach was used, it was shown that the machining time can be decreased significantly along the tool path. Production time in machining propeller example was reduced to 35% compared to constant feedrate cases.
Experiment and Analysis on Near-Dry Cutting System in Titanium Alloy Deep-Hole Drilling
Authors: Peng H. , Wang Jiang Ping , Bao Ze Fu
Published: March 2009

This paper depicts a boring and trepanning association (BTA) deep-hole drilling system
with near-dry cutting technique. The cutting tests are carried out in view of the machining
performances under the condition of applying the compressed air and atomized cutting fluid for
drilling deep holes on titanium alloy which is difficult to cut. Several cutter materials have been
utilized in the tests. The reasonable material of the deep-hole drilling cutter has been determined by
analyzing the cutting force, the cutter wear and the surface finish. Environmental pollution decreases
owing to little cutting fluid consumption in near-dry cutting system.
Residual Stress Prediction by Adaptive Neuro-Fuzzy System in Milling Aluminum Alloy
Authors: Zhang X.H. , An Qing Long , Chen Ming
Published: March 2009

As a sort of large-scaled structural components in modern aircraft, aluminum part has
been widely used nowadays. Its residual stress measurement and prediction are necessary to reduce
machining deformation and keep machining precision. By Adaptive Neuro-Fuzzy Inference System
(ANFIS), residual stress prediction model is set up based on different cutting parameters. Due to
data sample scarcity, input selection and regression are analyzed comparatively to reduce input data
dimension. It shows that cutting speed and feed per tooth have major impacts on residual stress, but
they do not have better prediction ability in ANFIS model. The combination of cutting speed and
radial depth of cut can predict the residual stress better.
Study on the Web-Service Platform Architecture for Bio-Manufacturing
Authors: You Fei , Hu Qing Xi , Yao Yuan , Lu Qi
Published: March 2009

Based on RP, the web-service platform architecture of bionic manufacturing was proposed
to provide the service of networked bionic manufacturing with service publication. According to B/S
hierarchical structure model, the four-layer architecture was constructed. It includes user layer,
service layer, semantic layer and data layer. The description meta-model of web-service was
constructed based on the manufacturing ontological knowledge. The dynamic connection between
two collaborative enterprises and their manufacturing condition were described with enterprise class,
process class, resource class, enterprise-alliance class, project class and strategy class. The
information flow of web-service was detailedly described to show the service process of bionic
manufacturing.
Measurement of Temperature Field in Laser Molten Pool by CCD Based on DSP
Authors: Cao Z. , Yang Xi Chen
Published: March 2009

In this paper, a measurement system of temperature field in laser molten pool by CCD
based on DSP is presented. The paper also presents the system of hardware, software process, and the
method of image processing by DSP. To solve the real time problem in the processing of measuring
the temperature field, the system uses DSP as the main CPU, processing the image without a
computer. By this method, the system can become simple and efficient and measure the laser molten
pool temperature field quickly and exactly. Gradient image of temperature field is displayed on LCD
after real time processing by this system. The final picture of temperature field can be directly
analyzed.
Experimental Studies of Cutting Temperature during High-Speed Milling of Aerospace Aluminum
Authors: Bai W.J. , Ke Ying Lin , Wu H.B. , Dong Hui Yue
Published: March 2009

A semi-artificial thermocouple device is developed to explore the dynamic cutting
temperature variation rules in high-speed milling of Al7050-T7451 aluminum alloy. Both the
aluminum-constantan thermocouple calibration diagram and cutting temperature curves are
obtained. The cutting temperature empirical formula is constructed by means of orthogonal
experimental design and multivariate linear regression analyses. It shows a reasonable good match
between the theoretical predicted values and the measured temperatures. This allows for the
optimization of cutting parameters and the exploration of machining deformation induced by the
cutting heat in high-speed milling of aerospace aluminum monolithic constructions.
Research on Numerical Control Program Based on Fuzzy Neural Network
Authors: E Shi Ju , Li X.M. , Zhu Xi Lin
Published: March 2009

According to the processed materials, characteristics of their shapes, process precision and
other conditions, a fuzzy neural network (FNN) can be trained with experiment data. The trained
network can automatically select process parameters by using the fuzzy neural network (FNN)
technology, and the selected process parameters can be saved in the computer in file. In this way, the
selected process parameters can enter into the process program during the programming and the
automatic selection can be accomplished, so that full automatic achievement of NC process program
is feasible.
Research on Optimization and Emulate Planning of Automobile Assembly Process
Authors: Xie Tan Cheng , Zhao Q. , Nan X.
Published: March 2009

Assembly process planning automobile production line is the bridge between the design and large-scale production. It is extremely important. Not only it affects directly the assembly efficiency and the quality, moreover has decided the workshop building, the equipment investment, quantity of production personnel, goods in process quantity and so on. Whole optimization and the partial purification of the assembly craft will all have the huge economic efficiency, and obviously strengthen the emulative power of automobile production enterprise in the market. In order to optimize the result of craft planning, enhance the quality and efficiency of computer aided assembly process planning and reach expected output and efficiency, the optimizing of automobile ALB (Assembly Line Balancing) problem is deeply analyzed with linear programming theory. Besides, linear programming mathematical model of ALB problem is established. Based on the mathematical process modeling and the generation of assembly sequence and considered the relative factors between production line and process planning, basing chart of process for assembly line (PAL Chart) a modeling method is put forward. It includes the main parameters of the assembly process planning and displays the planning result directly.
Finite Element Analysis of the Effects of Coated Tool on High Speed Orthogonal Machining
Authors: Liu Hui Xia , Yan H. , Wang Xiao , Lu Shu Bin , Yang K. , Cai Lan
Published: March 2009

Two 3-D finite element models of coated tool and uncoated tool were established using
the finite element code DEFORM-2D based on the updated Lagrangian formula. And their
machinability on high speed orthogonal machining was simulated and compared. The investigation
results indicate that the coated tool has higher surface temperature and lower inside temperature
compared with the uncoated tool. Moreover, the cutting forces of the model using coated tool are
lower than that using uncoated tool.
Bone Regeneration at Cortical Bone Defect with Unidirectional Porous Hydroxyapatite In Vivo
Authors: Iwasashi Masashi , Sakane Masataka , Suetsugu Yasushi , Ochiai Naoyuki
Published: March 2009

Unidirectional porous hydroxyapatite (UDPHAp) was developed which has microstructure in that cross sectionally oval pores 100 ~ 300µm in diameter penetrate through the material, and that is suitable for osteogenesis and angiogenesis.The porosity of the UDPHAp was 75 % and the compression strength was 14 MPa. A cortical bone defect was made at proximal tibia of Japanese white rabbit, and a trapezoidal prisms shaped UDPHAp was implanted. By histlogical evaluation, 2 weeks after implantation, new bone and new capillary was observed inside UDPHAp. Twelve weeks after implantation, new bone formation was observed in 41.6 % of the porous area. The results of this study suggest a great possibility of utilizing it in actual clinical setting as a bone substitution.
Factors Affecting In Vitro Bioactivity of Glasses
Authors: Zhang Di , Ylänen Heimo O. , Hupa Mikko , Hupa Leena
Published: March 2009

In this work we summarize the most important findings of the influence of glass composition, sample shape and fluid circulation on in vitro behavior of bioactive glasses in the system Na2O-K2O-MgO-CaO-B2O3-P2O5-SiO2. The sample shapes included plates, particulates, powdered glasses, glass fibers and sintered cones with interconnected porosity. The in vitro bioactivity was measured as the changes observed in the immersion solution, SBF, and the formation of reaction layers on the samples at 4 to 168 h immersion. A lower surface area to volume ratio gave smaller changes on the ion concentrations and pH of the immersion solution but thicker reaction layers on the glass surfaces. In particulate systems with circulating fluid the pH gradients in SBF were lower but surface layers more even than in static systems. The influence of glass composition on reaction layer formation as suggested by glass plates correlated with the in vitro behavior of glass particulates larger than 250 µm, porous cones and fibers when using similar SA/V ratio.
Adhesion Characteristics of Base-Coated Single Crystal Brackets for Orthodontics
Authors: Lee Myung Hyun , Seo Won Seon , Kang Jong Ho , Choi H.Y. , Kim Y.K. , Yim H.B. , Oh Kyung Sik , Lee Deuk Yong , Choi J.Y. , Oh Nam Sik
Published: March 2009

Adhesion characteristics of base-coated single crystal brackets for orthodontics were investigated to evaluate the feasibility for the ceramic bracket applications. Sapphire single crystal ingot were machined, abraded and spray-coated with slurries containing 50 wt% of flux and 40µm, 80µm and 150µm of granules. Maximum adhesion to the base surface of the brackets was observed when the size of granule in the slurries was 80µm. It may be due to higher bonding area of adhesive to granule and to base as a result of interlocking structure which has moderate thickness and uniform distribution of granules. The one-way analysis of variance indicated that there were not significant differences in bond strength measurements between the once and twice coating condition in 80µm and 150µm granule groups. But ARI values exhibited large differences between once and twice coating groups and showed different median or ranges. Adhesive remnant of adhesive resin was minimized when the slurry of 80µm granule was coated once. Reduction in adhesive remnant is likely due to the higher bonding of adhesive resin to granules. No teeth and bracket damages were found in any teeth de-bonded by shear force. The base-coated brackets with higher strength (12.9 MPa) and no adhesive remnant were newly proposed for the orthodontics applications.
In Vitro Characterization of Porous Ceramic Based Calcium Phosphate Processing with Albumin
Authors: Ribeiro Christiane , Rojas-Cabrera W.I. , Marques M. , Bressiani José Carlos , Bressiani Ana Helena A.
Published: March 2009

In recent years, the processing of porous ceramic materials for implant applications has motivated the development and optimization of new technologies. To this purpose, a globular protein based (i.e. ovalbumin) consolidation approach has been proposed. In the present study, a porous hydroxyapatite:b-tricalcium phosphate - biphasic ceramics (BCP), was processed by consolidation using the protein-action technique. The processed ceramic materials exhibited appropriate pore configuration in terms of size, morphology and distribution. The in vitro reactivity and dissolution behavior of the ceramics was evaluated in SBF and biocompatibility in an osteoblasts culture, respectively. Overall, the materials tested showed biocompatibility and suitable properties for osteoconduction. A rough surface pattern displayed by the ceramics seemed to have improved both; cell adhesion and proliferation processes. In conclusion, this study revealed that the porous matrices obtained, promoted suitable development of cell metabolism without cellular death.
Coatings Containing Silica Nanoparticles and Glass Ceramic Particles Applied onto Surgical Grade Stainless Steel
Authors: Ballarre Josefina , Pellice Sergio A. , Schreiner Wido H. , Ceré Silvia M.
Published: March 2009

Metals are the most used materials as orthopaedic or dental implants for their excellent mechanical properties. However they are not able to create a natural bonding with the mineralized bone and they could release metallic particles that could finally end in the removal of the implant. A promising alternative to avoid those effects is to protect the implant with a biocompatible coating. In this work there are analyzed two kinds of protective organic-inorganic coatings made by sol gel technique with the adding of silica particles, in order to increase the barrier effect of the coating, and glass-ceramic (GC) particles with the aim of generating bioactivity. X-ray photoelectron spectroscopy (XPS) and electrochemical techniques were used to analyze the bioactive and protective response of this silica reinforced coatings with the adding GC particles applied on surgical grade stainless steel.
Corrosion Characterization of Titanium Alloys by Electrochemical Techniques in Artificial Saliva and SBF Solution
Authors: Mariano Neide A. , Oliveira Rafael G. , Braga E.I. , Rigo E.C.S.
Published: March 2009

The commercially pure titanium (cp Ti) biocompatibility is due to its chemical stability in organism because of the presence of a fine film and impermeable of titanium oxide over the metal surface that confirms its corrosion resistance, changing this material's surface has been the direction of many research groups, these modifications may have influence in corrosion resistance. In this work was investigated the electrochemical behavior of cp Ti, without and with coating of the hydroxyapatite, commonly used implant materials, in artificial saliva and simulated body fluid (SBF) solution at 25oC and pH=7.4. The potentiodynamic polarization curves, shows that there is a passive region with low current’ density, indicating that in the investigated conditions the formation of a surface protective film occurs. In the studied conditions it was observed that hydroxyapatite layer has influence on corrosion resistance properties.
Hydroxyapatite Coating Improves Bone Integration and Interface Strength of Polymer Implants in Bone
Authors: Brandt Joerg , Pfennig M. , Bieroegel Christian , Grellmann Wolfgang , Bernstein Anke
Published: March 2009

Many attempts had been made to improve the durability of artificial joint replacement and other orthopaedic implants by approaching the mechanical properties of bone and artificial material. The most joint prostheses used today are manufactured of metal alloys based on cobalt, chromium or titanium. The mechanical stiffness of these materials is much higher than that of natural bone resulting in adverse effects such as local overloading on one hand or stress shielding phenomena with the lack of adequate mechanical load on the other. Both mechanisms contribute to earl loosening and failure of implants. Polymer materials may deliver mechanical properties very similar to bone and their mechanical behaviour may be modified in a wide range during the process of manufacturing. First attempts to lower the stiffness of the implant material and to gain the stiffness range of natural bone were made in the seventies by R. Matthys with his concept of “isoelastic hip prosthesis”. In this prosthesis the femoral stem was manufactured of polyacetal, a thermoplastic polymer with very good biocompatibility and elastic properties which are much nearer to bone than common metal alloys. While the prosthesis showed good results during the mechanical testing the clinical use in vivo became a disaster. Shortly after implantation polyacetal was degraded in the body and broke down under the immense loading of the human hip joint. Later attempts to use polymer materials alone for load bearing implants also failed in clinical practice over a long time because the mechanical interlocking between bone and implant was not sufficient for the biological demand. To make the outstanding properties of polymer materials useable for load bearing implants they are backed with metal alloys (as polyethylene for hip joint cups) until the presence. Only recent developments of polymer science succeeded in the use of polymers for loaded implants. One of the most interesting materials seems to be the polyetheretherketone (PEEK) which is successfully used for spinal fusion cages [2] and computerdesigned individual implants for defect reconstruction in the skull [4] meanwhile. A pre-clinical study of a new anatomically shaped flexible acetabular cup reported satisfactory results recently [3].
Structure and Adhesion of Hydroxyapatite Films Electrochemically Deposited onto Titanium Substrates under Short-Pulse Current in Metastable Calcium Phosphate Solution
Authors: Masakazu Kawashita , Hayakawa Tomoyasu , Takaoka Gikan H. , Miyazaki Toshiki
Published: March 2009

Hydroxyapatite (HA) films were deposited onto titanium (Ti) metal substrates by an electrodeposition method under a short-pulse current. Metastable calcium phosphate solution was used as the electrolyte. The ion concentration of the solution was 1.5 times that of human body fluid, but the solution did not contain magnesium ions at 36.5°C. We used an average current density of 0.01 A/cm2 and current-on time (TON) equal to current-off time (TOFF) of 10 ms, 100 ms, 1 s, and 15 s. The adhesive strength between HA and Ti substrates were relatively high at TON = TOFF = 10 ms. It is considered that small calcium phosphate crystals with low crystallinity were deposited on the Ti surface without reacting with other calcium phosphate crystals, H2O, and HCO3– in the surrounding environment. This resulted in relaxation of the lattice mismatch and enhancement of the adhesive strength between the HA crystals and Ti substrates.
Surface and Electrochemical Analysis of Titanium Submitted to Alkaline Treatment by SEM, XRD and EIS
Authors: Szesz Eduardo Mioduski , Marino Cláudia E. B. , Ponte Haroldo A. , Nascimento Fabiana C. , Lepienski Carlos M. , Kuromoto Neide K.
Published: March 2009

Although titanium metal has been used intensively in the last years as biomaterial in the medical and dental areas its surface is not bioactive. In this work, titanium metal was submitted to an alkali treatment in order to make the metal surface bioactive. The samples were submitted to alkaline treatment (AT) using NaOH 5M aqueous solution at 60°C for 24 h and after that they were heated thermically to stabilize the layer obtained with AT. The bioactivity of the samples was evaluated soaking them into the simulated body fluid (SBF) at 36,5°C for 28 days. The morphological, structural changes and the electrochemical characterization were analyzed using scanning electron microscopy, x-ray diffraction and electrochemical impedance spectroscopy (EIS), respectively. It was verified that after AT plus heat treatment (HT) a sodium titanate layer was formed on the samples surface and after the bioactivity tests an apatite layer was formed. Impedance analysis show that the resistance of film on Ti is high and this value increases when the sample is soaked in SBF. It means that the apatite (HPA) film is occurring and the value of the capacitance with the presence of the HPA film (Cp) values indicate that the film maintain a compact and uniform characteristics.
Preparation and Characterization of Fe3O4/Poly (2-Hydroxyethyl Methacrylate) Magnetic Nanocomposite Films
Authors: Wang Wei , Li Zhen , Li Li
Published: March 2009

Magnetic nanocomposite films of the Fe3O4/pHEMA were prepared by dispersing the Fe3O4 nanoparticles into the HEMA monomer before they were polymerized. The resultant nanocomposite films were characterized by Fourier transform infrared (FT-IR) and the vibrating sample magnetometer (VSM). The swelling behavies and the hemolytic ratios of the filmes were also investigated in this work.The equilibrium swelling ratio decreased with the increase of the amount of nanoparticles. The nanocomposite films had a clear superparamagnetic behavior because of the addition of nanoparticles. The hemolytic ratios were all lower than 5%, which indicated that the nanocomposites films had the good blood compatibility and can be used in the biomedical field
Interest of High Shear Wet Granulation to Produce Drug Loaded Porous Calcium Phosphate Pellets for Bone Filling
Authors: Viana Marylène , Désiré Amelie , Chevalier Emilie , Champion Eric , Chotard-Ghodsnia Roxana , Chulia Dominique
Published: March 2009

Spherical porous calcium phosphate pellets were fabricated by high shear wet granulation using native starch as a binder. After a heat treatment to eliminate the organic template, pellets were loaded with ibuprofen by solvent evaporation method. In vitro drug release kinetics was determined using an USP II apparatus (Prolabo Dissolution Tester, France). Results showed the interest of the calcination and of the increase in the binder-porogen content, to improve the drug loading (higher drug content) and prolong the release of the drug substance.
Effect of Surface Treatments on Bonding Strength of Zirconia to Dental Cements
Authors: Hashiguchi Makiko , Sato Hideo , Nishi Y. , Ban Seiji , Krnel Kristoffer , Kocjan A. , Kosmač Tomaž
Published: March 2009

The aim of this study was to investigate the effect of surface treatments on bonding
strength of two kinds of zirconia to two kinds of dental cements. After thermal cycling, the shear
bonding strength of both zirconia with alumina coating increased in both cements. The shear
bonding strength of both zirconia with sandblasting decrease in Fuji plus after thermal cycling
(p<0.05). There was no significant difference between NANOZR and Y-TZP (p>0.05). The bonding
strengths of NANOZR with the alumina coating were higher than those with sandblasting after
thermal-cycling (p<0.05).
In Vivo Performance of an Injectable Biphasic Calcium Phosphate Bone Filler
Authors: Layrolle Pierre , Baroth Serge , Goyenvalle Eric , Aguado Eric , Moreau Françoise , Daculsi G.
Published: March 2009

An hydrated putty was prepared by mixing submicron particles, rounded particles and granules of Biphasic Calcium Phosphate (BCP) ceramics composed of HA and β-TCP phases. The material filled entirely critical sized defects in the femoral epiphysis of NZW rabbits. After 3, 6 and 12 weeks, histology revealed that submicron particles were rapidly degraded by multinucleated TRAP-positive cells. This osteoclastic resorption stimulated bone ingrowth while the large BCP particles served as scaffold supporting bone healing by osteoconduction.
Obtainment of α-Tricalcium Phosphate by Solution Combustion Synthesis Method Using Urea as Combustible
Authors: Volkmer Tiago M. , Bastos L.L. , Sousa V.C. , Santos L.A.
Published: March 2009

The aim of this work is the synthesis of α-tricalcium phosphate by solution combustion synthesis using urea as combustible in the stoichiometric ratio and with excess of combustible. The salts Ca(O3)2.4H2O and (H4)2HPO4 were used as reaction precursors with Ca/P ratio of 1.5. The pH adjustment was made adding nitric acid. A porous foam composed by β-tricalcium phosphate, hydroxyapatite and α or β-dicalcium pyrophosphate were obtained as reaction product. X-ray diffraction was used to identify the phases. The obtainment of α-TCP was possible after a heat treatment where the material was held at 1250°C for 15 hours followed by quenching. Smaller particle size was obtained when four times the stoichiometric ratio of combustible was used in the reaction. α-TCP samples were immersed in SBF in order to verify the biocompatibility.
Morphology and Mechanical Properties of Injectable Ceramic Microspheres
Authors: Oliveira S.M. , Barrias C.C. , Ribeiro C.C. , Almeida I.F. , Bahia M.F. , Barbosa Mario A.
Published: March 2009

The aim of this study was to analyze the effect of starting powder granulometry and sintering conditions on the morphological structure and mechanical properties of injectable hydroxyapaptite (HAp) microspheres. The mechanical properties of the microspheres were evaluated, to investigate if their integrity could be maintained during the injection process. To obtain microspheres, HAp powders were dispersed in a sodium alginate solution and spherical particles were prepared by droplet extrusion under a co-axial air stream, coupled with ionotropic gelation in the presence of Ca2+. This was followed by a sintering process at various temperatures and times. The morphology of microspheres was observed under SEM, diameter measurements were performed in an optical microscope and the compression strength was evaluated using a texture analyzer. Finally, microspheres prepared using lower granulometry HAp powders and sintered at 1200 °C for 1 hour presented the best properties and were selected as the most suitable for the envisaged application.
Investigations Regarding the Thermoplastic Resistance Evaluation with Simulated Imperfections
Authors: Murariu Alin Constantin , Safta Voicu Ioan , Fleşer Traian
Published: March 2009

The thermoplastic polymer components are used in new domains and the evaluation of their characteristics in specific conditions represents a new actuality domain. The experimental program realized on polyethylene sample pipes type PE 80, SDR 11 GAS, Æ160x15.5 mm had the objective to present the imperfection noxiousness of the geometric configuration, respectively the different dimensions and to define the influence of those to the safety in exploitation of the transport networks and to the industrial distribution of the fluids under pressure (water, natural gases, etc).
A hybrid TT-IRT test method is used, combining the tensile test (TT) and the Infrared Thermography (IRT) method. The temperature distribution of the material is monitored under loading conditions with different rates. The noxiousness of the geometric discontinuity is analyzed by the local losses of resistance following the local heating in the imperfection areas.
The results obtained are used in design calculus for the materials quality levels in specified safety conditions for the fluids transport networks.
Experimental and Numerical Analysis of the Behaviour of Ceramic Tiles under Impact
Authors: Constantinescu Dan Mihai , Sandu Marin , Volceanov Eniko , Găvan Mircea , Sorohan Ştefan
Published: March 2009

Static loading and impact tests of ceramic alumina tiles have shown a very interesting behaviour of a tough, brittle, and high energy absorbing material. Strain gauges techniques and data acquisition were used throughout this research. A static-dynamic equivalence is done through a calibration procedure of the measuring system. The experimental strain history is completely acquired till the failure of the ceramic tile. Numerical simulation of impact tests gives additional insight on the complicated phenomena. Low velocity impact testing revealed different patters of failure, depending on the conditions of impact, and the capacity of this material to be used in particular purpose designed applications.