bluuebunny/crossref_metadata_2025 huggingface dataset:
Damage Assessment of Composite Structures Subjected to Low Velocity Impact
Authors: Lee Ouk Sub , Han M.S. , Baek J.H. , Lee G.S.
Published: March 2009

To evaluate the damage of composite laminate structures which are consist of maraging steel, rubber and carbon fiber reinforced composite subjected to low velocity impact, the drop weight was used to impact the specimens and nondestructive evaluation using the C-scan was performed. After experiments, impact damages were compared with respect to various temperatures and impact
energies. In case of circular plate, the damage characteristics such as delamination, matrix cracking, and fiber breakage were observed at the interface of rubber and carbon fiber reinforced composite. These results were found to be correlated with the deflection of specimen.
Determination of Dynamic Fracture Toughness Using Strain Measurement
Authors: Kim Duck Hoi , Moon Soon Il , Kim Jae Hoon
Published: March 2009

By contrast with static fracture toughness determination, the methodology for dynamic fracture toughness characterization is not yet standardized and appropriate approaches must be devised. The accurate determination of the dynamic stress intensity factors must take into account inertial effects. Most methods for dynamic fracture toughness measurement are experimentally complex.
However, dynamic fracture toughness determination using strain measurement is extremely attractive in terms of experimental simplicity.
In this study, dynamic fracture toughness tests using strain measurement are performed. High rate tension and charpy impact tests are carried out for titanium alloy, maraging steel and Al alloys. In the case of evaluating the dynamic fracture toughness using high rate tension and charpy impact tests, load or energy methods are used commonly. The consideration about inertial effects is essential, because load or energy methods are influenced by inertia. In contrast, if the position for
optimum response of strain is provided, dynamic fracture toughness evaluation using strain near crack tip is more accurate. To obtain the position for optimum response of strain, a number of gages were attached at angles of 60°. Reliability for experimental results is evaluated by Weibull analysis. The method presented in this paper is easy to implement in a laboratory and it provides accurate results compared to results from load or energy methods influenced by inertia.
Experimental Measurement of Dynamical Young's Modulus and Shear Modulus of Low-Impedance Materials
Authors: Shih Shao Chiu , Wang Yong Zhong , Yu Bing , Wang Li Li
Published: March 2009

A new dynamical measurement technique that combines PVDF film piezoelectric gages with
resistor strain gages in conventional SHPB is developed to study the dynamical mechanical
behavior of low-impedance aluminum foam. The average value of the stresses measured by PVDF
gages from the front face and the back face of the specimen at each time is taken as the effective
stress history of the specimen. This effective stress history is combined with the measured axial
strain history in the specimen by eliminating time t. Then the initial part of the stress-strain
relationship of the material can be determined reliably. From its slope, the dynamical Young’s
modulus of low-impedance aluminum foam can be determined. For the aluminum foam with a
density of 1.2×103 Kg/cm3 at a given strain rate (ε& =814/s), we get: E =1.15 GPa, G=0.44GPa.
Mesoscopic Study of Ductile Fracture of Aluminium Alloy LY12CZ
Authors: Li T. , Wang Qing Yuan , Yuan X.M.
Published: March 2009

In the present paper, axisymmetric smooth and notched specimens of aluminium alloy
LY12CZ were monotonic tension tested to study the ductile fracture behavior and evaluate the suitability for the critical void growth ratio, VGC of the material, from the micro and macro points of view. It's found that the material would change fracture morphology from tensile to shear failure in the various stress states; the ductile fracture parameter VGC is sensitive to the fracture morphology which is applicable for the case of tensile failure while not suitable for the case of the shear failure, i.e. the case of smooth tensile specimens.
The Horizontally Polarized Shear Waves in Multilayered Piezo-Composites with 2-2 Connectivity
Authors: Qian Zheng Hua , Jin Feng , Wang Zi Kun , Kishimoto Kikuo
Published: March 2009

Following the advances in structural applications, composite structures are being used commonly in transducer applications to improve acoustic, mechanical and electrical performance of piezoelectric devices. Functional composite transducers for sensors and actuators generally consist of ceramics and polymers, the disadvantage of the brittleness nature of the piezoelectric ceramics can be overcome and the structures especially good for sensing can be allowed for building up. Propagation behavior of horizontally polarized shear waves (SH-waves) in piezoelectric ceramic-polymer composites with 2-2 connectivity is taken into account. The multilayer structures are consisted of piezoelectric thin films bonded perfectly with polymeric thin films alternately. The phase velocity equations of SH-waves propagation in the piezoelectric ceramic-polymer composites with 2-2 connectivity are obtained for the cases of wave propagation in the direction perpendicular to the layering and along the layering, respectively. Filter effect of this kind of structure and the effect of volume fraction and shear modulus ratio of piezoelectric layer to polymer layer on the phase velocity are discussed in detail, respectively. One practical combination of piezoelectric thin film-polymer thin film multilayer system is chosen to carry out the numerical simulation, some basic properties of SH-waves propagation in above multilayered structures are revealed.
A New Quadratic Membrane Element
Authors: Wang Shui Lin , Feng Xia Ting , Ge Xiu Run
Published: March 2009

In finite element method, the order of complete polynomial of the interpolation function is related to the number of nodes in the element. This paper presents a four-node quadrilateral element with quadratic function on it. The presented displacement functions maintain C0-continuity. Meanwhile, the element stiffness matrix is derived from the displacement functions. Test problems show that high accuracy can be achieved by the use of the new displacement function on the element.
Magnetostrictive Terfenol-D Material Linear Simulation Using a Coupled FE-BEM
Authors: Jarng Soon Suck , Lee Je Hyeng , Kwon Y.J.
Published: March 2009

This paper describes the application of the coupled FE-BEM (finite element-boundary element method) for the numerical harmonic analysis of the linear dynamic behaviour of a magnetostrictive Terfenol-D rod in water. The magnetostrictive rod is three-dimensionally modeled to transduce applied electric current in a helical coil around the rod to mechanical displacement. The steady-state
resonance response of the displacement is shown.
Analytical Solutions of Stresses in Functionally Graded Circular Hollow Cylinder with Finite Length
Authors: Shao Z.S. , Fan L.F. , Wang Tie Jun
Published: March 2009

Analytical solutions of stress fields in functionally graded circular hollow cylinder with finite length subjected to axisymmetric pressure loadings on inner and outer surfaces are presented in this paper. The cylinder is simply supported at its two ends. Young's modulus of the material is assumed to vary continuously in radial direction of the cylinder. Moreover, numerical results of stresses in functionally graded circular hollow cylinder are appeared.
Comparison of Global and Local Approaches to Predicting Warm Pre-Stress Effect on Cleavage Fracture of Ferritic Steels
Authors: Hadidi-Moud Saeid , Mirzaee-Sisan A. , Truman Christopher E. , Smith David John
Published: March 2009

Potentially both global and local approaches may be used to predicting the effect of loading history on cleavage fracture toughness distribution of ferritic steels. In this paper the dramatic increase in the apparent lower shelf fracture toughness of A533B steel following warm pre-stressing (WPS) has been predicted using these approaches. Extensive experimental evidence suggesting significant enhancement in fracture toughness of ferritic steels within the lower shelf temperatures following WPS are used to verify and compare the applicability and the extent of validity of the models. The global approach is based on the distribution of toughness data described by Wallin statistical model in conjunction with the Chell model for WPS effect. The local approach on the other hand is a Beremin type model that uses the Weibull stress to predict the WPS effect. Weibull stresses would essentially reflect the WPS effect on redistribution of stress-state around the crack tip. Predictions for apparent toughness using the two approaches are discussed in the light of the suggestion that residual stresses are the main cause of the enhancement, at least for the material and geometry used in this study.
Finite Element Analyses for Thickness Effects on J-Integral Testing using Non-Standard Testing Specimens
Authors: Kim J.S. , Kim Young Jin , Cho S.M.
Published: March 2009

This paper compiles solutions of plastic η factors for standard and non-standard fracture toughness testing specimens, via detailed three-dimensional (3-D) finite element (FE) analyses. Fracture toughness testing specimens include a middle cracked tension (M(T)) specimen, SE(B), single-edge cracked bar in tension (SE(T)) and C(T) specimen. The ligament-to-thickness ratio of the specimen is systematically varied. It is found that the use of the CMOD overall provides more robust experimental estimation than that of the LLD, for all cases considered in the present work. Moreover, the estimation based on the load- CMOD record is shown to be insensitive to the specimen thickness, and thus can be used for testing a specimen with any thickness.
2D Vector Cellular Automata Model for Simulating Fracture of Rock under Tensile Condition
Authors: Li Ming Tian , Feng Xia Ting , Zhou Hui
Published: March 2009

Based on the cellular automata of the plane truss structure, a 2D cellular automata model is presented to simulate the fracture of rock at meso-level. Cellular automata are made up of cell, states, lattice, neighbor and rule. Rock is divided into lattice in which each lattice point presents a cell. Each cell is assumed to connect with several cells, which are called as its neighbors, in virtue of truss elements. The truss elements can adopt some different simple local laws, i.e. constitutive law, which may be elastic or elastic-plastic and the simple fracture rule. It also can adopt different mechanical properties, which present their heterogeneity and anisotropy. This model can make full use of the advantages of cellular automata such as its intrinsic parallelism, localization and so on. In the meantime, as a powerful tool to analyze the nonlinear, complex system, cellular automata can be used to study the nonlinear, complex fracture process. The model is used to simulate the direct tensile of the rock plates, the complete fracture process and the stress-strain curves are attained which are accordance with the experiment.
Crack Driving Force in Anisotropic Media due to Non-Elastic Deformation
Authors: Nie G.H. , Xu H.
Published: March 2009

In this paper elastic stress field in an elliptic inhomogeneity embedded in orthotropic media due to non-elastic deformation is determined by the complex function method and the principle of minimum strain energy. Two complex parameters are expressed in a general form, which covers all characterizations of the degree of anisotropy for any ideal orthotropic elastic body. The stress acting on the long side of ellipse can be considered as a crack driving force and applied in failure and fatigue analysis of composites. For some special cases, the resulting solutions will reduce to the
known results.
Rational Reinforcing of the Honeycomb Facets Variable Thickness for Wind Turbine
Authors: Kim Yun Hae , Kim J.D. , Shuripa V.A. , Yim Cheolmun , Park Tae Gyu
Published: March 2009

Decreasing of wind turbine blade weight by using honeycomb sandwich collides with strength lack of the honeycomb facets at the high loaded places of the blade under heavy wind load. For providing tensile and compressive strength profiling of the variable thickness facets was made. By using response surface model based on design space the facets rational thickness distribution was performed by using optimization. The condition of evenly distributed stresses at narrow range of
values for reinforced facets was used like state variables for optimum designing. By combining finite element analysis and sequential programming the response of the thickness within the process integration framework on criteria the rationalization of the facets thickness was performed. The facets thickness variations are assigned by polynomial of fifth degree to provide small difference of stresses in the facets for blade. The angles of the glass fiber stacking relatively of the blade axis for mass minimization were selected on the similar stress reinforcement condition for outside and inside facets of the honeycomb sandwich. The structure of the reinforcing was built to coincide the principal stresses and strains of the facets to longitudinal and transversal direction of the blade. Calculation results were obtained for glass fiber -epoxy resin composite material having and shown that decreasing total mass of the blade 19% compare to shape optimization.
Effect of Boundary Conditions of Failure Pressure Models on Reliability Estimation of Buried Pipelines
Authors: Lee Ouk Sub , Pyun Jang Sik , Hwang Si Won , Cho Kyoo Sung
Published: March 2009

This paper presents the effect of boundary conditions of various failure pressure models published for the estimation of failure pressure. Furthermore, this approach is extended to the failure prediction with the help of a failure probability model. The first order Taylor series expansion of the limit state function is used in order to estimate the probability of failure associated with each corrosion defect in buried pipelines for long exposure periods with unit of years. The effects of random variables such as defect depth, pipe diameter, defect length, fluid pressure, corrosion rate, material yield stress, material ultimate tensile strength and pipe thickness on the failure probability of the buried pipelines are systematically investigated for the corrosion pipeline by using an adapted failure probability model and varying failure pressure model.
Shape Optimization in Laminated Composite Plates by Growth-Strain Method, Part One - Volume Control
Authors: Han Seok Yoon , Bae S.S. , Jung S.J.
Published: March 2009

The growth-strain method was applied to cutout optimization in laminated composite plates. Since the growth-strain method optimizes a shape by generating the bulk strain to make the distributed parameter uniform, the distributed parameter was chosen as Tsai-Hill value. In this study, of particular interest is to see whether the growth-strain method developed for shape optimization in isotropic media would work for laminated composite plates. In volume control of the growth-strain method, it makes Tsai-Hill value at each element uniform in laminated composite plates under the predetermined volume. The shapes optimized by Tsai-Hill fracture index were compared with those of the initial shapes for the various load conditions and predetermined volumes of laminated composite plates. As a result, it was verified that volume control of the growth-strain method worked very well for cutout optimization in laminated composite plates.
Shape Optimization in Laminated Composite Plates by Growth-Strain Method, Part Two - Stress Control
Authors: Han Seok Yoon , Park J.Y. , Ma Y.J.
Published: March 2009

Stress control of the growth-strain method was applied to shape optimization of multiple cutouts in laminated composite plates. Since the growth-strain method optimizes a shape by generating the bulk strain to make the distributed parameter uniform, the distributed parameter was chosen as Tsai-Hill value, as volume control of the growth-strain method. In this study, of particular interest is to see whether stress control of the growth-strain method developed for shape optimization in isotropic media would work for laminated composite plates. The shapes optimized by Tsai-Hill fracture index were compared with those of the initial shapes for the various load conditions. As a result, it was verified that stress control of the growth-strain method also worked very well for multiple cutouts optimization in laminated composite plates.
Effects of Dissolved Hydrogen on the Primary Water Stress Corrosion Cracking Behavior of Alloy 600 at 325 °C
Authors: Peng Q.J. , Shoji Tetsuo
Published: March 2009

Primary water stress corrosion cracking (PWSCC) of Alloy 600 has been a great concern to the nuclear power industry. Reliable PWSCC growth rate data, especially at temperatures in the range of 290-330°C, of the alloy are required in order to evaluate the lifetime of power plant components. In this study, three tests were carried out in simulated pressurized water reactor (PWR) primary water at 325°C at different dissolved hydrogen (DH) concentrations using standard one-inch compact tension (1T-CT) specimens. The initiation and growth of cracks as well as insights into the different PWSCC mechanisms proposed in the literature were discussed. The experimental results show that the detrimental effects of hydrogen on
crack initiation and growth reached a maximum at a certain level of DH in water. The
experimental results were explained in terms of changes in the stability of the surface oxide films under different DH levels. The experimental results also support the assumption that hydrogen absorption as a result of cathodic reactions within the metal plays a fundamental role in PWSCC.
Condition Monitoring of the Material Test Facility Using Vibration and Ultrasonic Measurements
Authors: Sato Hisashi , Tsujimoto Yousuke , Takahashi Makoto , Kitamura Masaharu
Published: March 2009

In the present study, the vibration and ultrasonic measurements have been applied to a high flow rate pump installed in the SSBF in order to develop the monitoring and diagnosis methods. The vibration of the casing of the canned pump is measured by using the laser vibration sensor. The frequency domain analyses have been applied to the measured signals. The measurement results showed the validity of the proposed method to monitor the state of the high flow rate pump.
Freeze Casting of Aqueous Al2O3/Y-TZP Slurries
Authors: Yang Tae Young , Yoon S.Y. , Lee Gun Dae , Wang Chang An , Stevens Ron , Huang Yong , Park Hong Chae
Published: March 2009

Freeze casting is a useful forming technique to produce complex-shaped ceramic parts. The colloidal processing stage is an essential step for preparation of freeze casting slurries. In order to optimize freeze casting slurries, several processing additives, such as dispersant, binder, surfactant, and cryo-protectant are usually employed. Dispersion and suspension rheology of aqueous alumina/ zirconia slurries with 55 and 60 vol.% solid loading have been characterized in terms of the effect of organic additives, and the resulting microstructures of the freeze cast green and sintered materials examined.
Dielectric Properties of TiO2-NiO Ceramics and Its Response Mechanism
Authors: Wang Jian Fei , Lin Yuan Hua , Chen Yu , Jiang Lei , Nan Ce Wen
Published: March 2009

NiO-NiTiO3 composite ceramics were prepared by the conventional solid state reaction process and dielectric properties were investigated as a function of frequency and temperature. The results indicate that all samples showed high dielectric constant ~103 at 0.1 kHz, but a remarkable decrease of the dielectric loss appeared when the volume fraction of NiTiO3 phase reached 42.4%. Relaxor-like peaks were observed in the temperature dependence of the dielectric constant with ceramics having low composition of NiTiO3 phase (≤21.2%). The possible response mechanism associated with the microstructure and the associated defects of the composites was discussed.
Gelcasting of Aqueous Silicon Carbide / Carbon Black Slurry
Authors: Chen Yu Feng , Wang Hua , Tang Jie , Liu Hai Lin , Fan Qi Sheng
Published: March 2009

This paper describes the investigation of gelcasting of silicon carbide/carbon black aqueous slurry. Aqueous slurries are prepared by using polyvinylpyrrolloidone and tetramethyl ammonium hydroxide as dispersants. Rheological behaviors of the slurries have been studied. Two initiator systems are used to initiate free-radical polymerization of acrylamide in silicon carbide/carbon black aqueous slurry. In order to reduce strong effect of carbon black on inhibiting polymerization of acrylamide, acetylacetone is added into the slurry. The experimental result shows that controllable free-radical polymerization of acrylamide in silicon carbide/carbon black aqueous slurry can be realized by adding small quantity of acetylacetone.
Effect of Grain Growth Inhibitor on the Microstructure and Mechanical Properties of Ti(C,N)-Based Cermet
Authors: Zheng Yong , Liu Wen Jun , Yuan Quan , Wen Lei , Xiong Wei Hao
Published: March 2009

Several Ti(C,N)-based cermets with different grain growth inhibitor were studied using scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive X-ray analysis (EDX). The microstructure and mechanical properties of a cermet as a function of the content of the typical grain growth inhibitors, such as vanadium carbide (VC) and chromium carbide
(Cr3C2), was revealed. VC addition could remarkably refine the grains, but it reduced the wetting of the ceramic grains by liquid metal during sintering. Thus it still reduced the performances of the cermet. Cr3C2 addition was found to inhibit grains from growing to lower extent during sintering. However it reduced the wetting of the ceramic grains by liquid metal slightly. Most of chromium element congregated in the rim phase and improved the plasticity of the rim. With Cr3C2 added properly, the performances of the cermets were improved remarkably.
Mechanical Properties of Macroporous Biphasic Calcium Phosphate Bioceramics Fabricated Using a Porogen
Authors: Castagné Jean François , Chamousset Jeanne , Minois Lise-Marie , Ponsinet Alexandre , Bouler Jean Michel , Tancret Franck
Published: March 2009

Macroporous biphasic calcium phosphate bioceramics, for use as bone substitutes, have been fabricated by cold isostatically pressing and conventional sintering, using naphtalen or saccharose particles to produce macropores. The resulting ceramics, composite materials made of hydroxyapatite and b-tricalcium phosphate containing ~ 45% macropores and ~ 25% micropores, have been submitted to compression and three-point bending tests, toughness tests by single-edge-notched-bending, and spherical indentation tests. A new model is established to describe mechanical properties as a function of the amount and morphology of porosity, and propositions are made to optimise the fabrication procedure. Finally, those highly porous ceramics, although very brittle, exhibit a damage-tolerant contact behaviour, due to the compaction of the porous body under the indenter.
Synthesis of Apatite Ceramics with Bimodal Pore Structure Using Mechanochemically Prepared Fine Apatite Powder
Authors: Zhang Yin , Yokogawa Yoshiyuki , Kameyama Tetsuya
Published: March 2009

Preparation of apatite ceramics with bimodal pore structure was studied. First fine
hydroxyapatite powder was obtained through mechanochemical method. The particle size of the product was around 0.64 µm. The slurry with the fine apatite powder content of 55-62.5wt% was prepared using defloculant, and foaming reagent. The organic form was immersed into the slurry, dried under vacuum,
and heated at 1100°C, 1200°C, 1300°C. Pore size distribution of the product measured by porosimeter showed that small pores of around 1 µm and large pores of 100 µm exist, and SEM observation confirmed. SEM observation showed that the large pores seemed to be interconnected through the openings of several dozens µm in size. The porosity of the products were found to be 48 – 58.5%, and the bending strength of the products obtained by heat-treatment at 1100°C for 3 hours was 5.6 MPa, and that at 1200°C was 10.5 MPa.
Colloidal Process of Magnesia-Carbon Refractory and Its Sintering Characteristic
Authors: Xu Li Hua , Cheng Zhi Fei , Lian Fang , Wang Ti Zhuang , Yao Yun
Published: March 2009

Carbon-containing refractories are widely used in metallurgical industry due to their excellent thermal property and resistance to corrosion by molten iron. In the present work, slip casting colloidal process, which is used to fabricate high performance structural ceramics, has been introduced into the preparation for magnesia-carbon refractory with selection of suitable dispersant. The results indicated that the curve of zeta-potential of magnesia was similar with that of carbon just containing dispersant and the homogenized mixtures were attained under a controlling of low pH value. Three kinds of preparing routes for green bodies were designed, and all of the final densities and the resultant hardness of sintered bodies using colloidal process were superior to these of the specimen using conventional dry pressing, whereas its high green density can be plausibly observed in dry pressing body because of high compaction pressure used.
Numerical Simulation of Temperature Field in Desulphurizing Lance
Authors: Li Jiang , Li Nan , Chen Feng Jun , Li Yuan Bing , Qi Jian Qiang
Published: March 2009

The paper shows a finite element method (FEM) model to calculate the temperature distribution of desulphurizing lance use in hot metal pretreatment by ANSYS program. The dynamic temperature distribution under non-linear thermal loads within lance in one or more duty cycles is obtained. The temperature distribution at important parts of the lance changes with time and is summed up according to the simulation. Some important instructional opinions offered by the conclusion benefit the improvement of temperature-based structure design and mend of desulphurizing lance. In addition, the conclusion provides research data for thermal stress analysis of lance.
Ni/Graphite/BaTiO3 PTCR Composites
Authors: Qu Yuan Fang , Du Juan , Ma Wei Bing , Li Xiao Lei
Published: March 2009

Nickel/graphite/BaTiO3 PTC composites with lower room-temperature resistivity and
higher resistance jump were fabricated by adding graphite and nickel powders into BaTiO3 PTC ceramics. Characteristics and conductive mechanism of the composites were discussed based on the experimental results.
Electronic Structure Calculations of Ba(Mg1/3Nb2/3)O3 and its Dielectric Properties Analysis
Authors: Lian Fang , Xu Li Hua , Fu Zhi , Chen Ning
Published: March 2009

The electronic structure of Ba(Mg1/3Nb2/3)O3 as a typical example of Ba(B¢1/3B¢¢2/3)O3 complex perovskites was investigated using the quantum chemical SCF- Xa-SW method. The calculations indicated that ionic bond strength plays the most important role in the structure stability of Ba(Mg1/3Nb2/3)O3 and BaTiO3. It was found that the bonding strength between oxygen and cations of B-site in Ba(Mg1/3Nb2/3)O3 is greater than that in BaTiO3, and the unbalance force in Ba(Mg1/3Nb2/3)O3 leads to the tendency of B-site ion arranging orderly. The more stable ordered structure of BMN phase can contribute to their better dielectric properties. The calculated results agree with the experimental observations, so it
is helpful to designing and synthesizing the microwave dielectric ceramic with high Q-factor.
Preparation and Characterization of Anisotropic Ammonium Titanium Phosphate Crystals via Hydrothermal Route
Authors: Li Yun Hua , Ling Yun Han , Bai Xin De
Published: March 2009

A series of ammonium titanium phosphate nanocrystals were prepared by hydrothermal synthesis method, and characterized by XRD, IR, XPS, SEM and DTA/TG. The results showed that themicrostructures of the materials could be rod- or sphere-like nanocrystals with aqueous pH values changing from 0 to 5, and could be flake like nanocrystals when a certainty of oxalic acid was added to the hydrothermal systems. The hydrothermal duration and temperature were not the main factors influencing the morphology of the products, but longer time and higher temperature would make the material more highly crystalline. The hydrothermal synthesizing mechanism on different experimental conditions was also discussed.
Low-Temperature Synthesis of PMnN-PZT Powders by Hybrid Method of Sol-Gel and Ultrasonic Atomization
Authors: Xu Zh.J. , Chu Rui Qing , Li Bao Shan , Li Guo Rong , Yin Qing Rui
Published: March 2009

Pb(Mn1/3Nb2/3)O3-Pb(Ti,Zr)O3 (PMnN-PZT) powders were synthesized by a hybrid method of sol-gel and ultrasonic atomization. The study shows that the resulting powder is pure, homogeneous and possesses a reasonably fine particle size. It is also believed to be applicable to other materials that can be processed via the technique.
Calcium Phosphate Bone Cement Preparation Using Mechano-Chemical Process
Authors: Tofighi Aliassghar , Palazzolo R.
Published: March 2009

ACP (amorphous calcium phosphate) and DCPD (dicalcium phosphate dihydrate, or Brushite) powders were high energy dry ball milled at a 1:1 ratio for 1, 2, 3, 4, 10, or 24 hours to produce a variety of powders for use as calcium phosphate cements (CPC). A 1:1 blend of powders not subjected to milling was used as baseline material (control). Physicochemical and mechanical characterization was performed on the powder or cement at each milling time point and compared to control. The following changes were noted after 24 hours
of milling: the crystallinity was reduced to a fully amorphous phase, the tap density increased by 89%, the specific surface area decreased by a factor of 7, and the total porosity of hardened cement decreased by 50%. Additionally, the compressive strength of hardened CPC increased from 2.6 MPa to a peak of 50 MPa after 10-h milling. The rate of paste hardening increased throughout the 24-h period. Full conversion of each milled material produced a similar composition low-crystalline calcium deficiency apatite with Ca/P atomic ratio of 1.45 and specific surface area around 195 m2/g. The specific structure of these CPC, with high surface area and reactivity of nano-crystals, is ideal for in vivo remodeling of new bone and
controlled release of protein and growth factors.
Investigations of the Mechanical Properties of an Alumina Toughened Zirconia Ceramic for an Application in Joint Prostheses
Authors: Begand Sabine , Oberbach Thomas , Glien Wilfried
Published: March 2009

The objectives of this study were to investigate the mechanical properties of a ZrO2-
Al2O3 composite ceramic. The mechanical strenght, wear behaviour and phase composition of the ceramic composite were analysed. The tested material showed a significantly higher bending strength compared to Al2O3- and ZrO2-Ceramic. According to the results of ring-on-disc, the wear rates were comparable to the Al2O3-Ceramic.
Surface Energies Acting at the Interfaces of Ceramics and Glasses while in Contact with Organic and Biological Liquids
Authors: Agathopoulos Simeon , Nedea M. , Ghiban Brandusa , Ferreira José Maria F. , Nikolopoulos P.
Published: March 2009

The surface energy components which govern the interfacial interactions between bioinert solid substrates of partial stabilized ZrO2 (with 3 mol% Y2O3) and a glass with a composition of 55SiO2×10Na2O×35MgO in contact with organic and biological liquids under equilibrium regime, were determined. The experimental results indicated that the interfacial bonding between zirconia and the polar liquids is result of interactions due to dispersion forces. In the case of the glass, polar
forces significantly contribute to solid/liquid interfacial interactions.
Clinical Outcome of Current Generation Hydroxyapatite Coated Acetabular Design
Authors: Hermida Juan C. , D'Lima Darryl D. , Steklov Nikolai , Colwell Clifford W.
Published: March 2009

Hydroxyapatite (HA) coatings for femoral stems have been successful in short- to intermediate-term follow up. However, the outcomes of HA-coated cups have not been as successful as comparable non-HA-coated designs. This has been attributed to component design and to poor quality HA-coating processes. This is a clinical outcome study of a newer generation acetabular design with an improved plasma-sprayed HA-coat. Ninety consecutive primary total hip replacements implanted with a HA-coated metal-backed cup were prospectively followed up for 2–5 years after surgery. Mean age was 69 years, male:female ratio was 36:47; mean-weight was 77 kg. Polyethylene wear was measured on digitized images. Component position, component migration, and implant-bone interface radiolucent lines were analyzed by computerized image analysis. Hip-scores improved from preoperative mean 59(±12) to a final follow-up mean of 91(±12). One hip
was revised for recurrent dislocation. No hips were revised for aseptic loosening. Mean acetabular abduction angle was 46°(±8.5) and anteversion was 18°(±8.7). Incomplete lucent lines were noted on early postoperative radiographs in 5% of the cases. With ongoing follow up radiolucent line thickness decreased by mean 13% and radiolucent line density increased by 11%. No cup had complete
continuous radiolucent lines or lysis. Mean polyethylene linear and volumetric wear rates were 0.14(± 0.15) mm/year and 73(± 70) mm3/year respectively. Wear rates were higher in males (p<0.03). No other factor (age, body weight, cup abduction or anteversion angle) correlated significantly with wear rate. This study presents encouraging short-term results. The improvement in radiolucent lines
suggests a beneficial effect of the HA-coat on bone ingrowth. None of the cups loosened or migrated. Wear rates were comparable to published reports of successful non-HA-coated cups. Long-term follow up is ongoing to corroborate these early findings.
Comparing Dynamic Hip Screw to External Fixation for Treatment of Osteoporotic Pertrochanteric Fractures: A Prospective Randomized Study
Authors: Moroni A. , Faldini C. , Pegreffi F. , Hoang-Kim A. , Vannini F. , Giannini S.
Published: March 2009

External fixation has proven to be a viable minimally invasive treatment option for
elderly patients with trochanteric fractures. Postoperative complications has limited external fixation in relation to inadequate pin fixation. We compared Orthofix pertrochanteric fixator (OPF) with hydroxyapatite-coated pins to dynamic hip screw (DHS) with AO/ASIF stainless-steel screws in osteoporotic trochanteric fractures. Methods: Forty patients were divided into two groups and randomized for treatment with 135° 4-hole DHS (Group A) or OPF with four hydroxyapatite-coated pins (Group B). Inclusion criteria was: female, age ≥ 65 years, AO fracture type A1 or A2 and BMD lower than -2.5 T-score. All fixators were removed at 3 months. Results: There were no differences in patient age, fracture type, BMD, ASA, hospital stay and reduction quality. Average number of blood transfusions was 2.0 ± 0.1 in Group A, whereas there were none in Group B (p < 0.0001).
Operative time was 64 ± 6 minutes in Group A and 34 ± 5 in Group B (p < 0.005). Post-operative femoral neck shaft angle was 134 ± 6° in Group A, and 132 ± 4° in Group B (ns). In Group A, fracture varization at 6 months was 6 ± 8°, in Group B 2 ± 1° (p = 0.002). Harris hip score was 62 ± 20 in Group A and 63 ± 17 in Group B. (n.s.) In Group B, no pin infection occurred. Pin fixation was maintained over time, as shown by no significant difference between pin extraction and
corresponding insertion torque. Discussion and Conclusion: In external fixation with
hydroxyapatite-coated pins there was no need for blood transfusions and fixation was superior, as confirmed by less varization at long-term.
Biological Behaviour of Bonelike® Graft Implanted in the Tibia of Humans
Authors: Gutierres M. , Sooraj Hussain Nandyala , Afonso A. , Almeida L. , Cabral T. , Lopes M.A. , Santos José D.
Published: March 2009

This paper reports the ability of Bonelike® to regenerate bone defected areas when
implanted in the tibia of 3 patients (average age of 59 years) during a high tibial osteotomy (HTO) to treat medial compartment osteoarthritis of the knee. Bonelike® is a synthetic bone graft designed to mimic the inorganic composition of bone using a patent process that consists of liquid sintering hydroxyapatite in the presence of CaO-P2O5 based glass. The preliminary clinical evaluation
performed showed that an intimate contact between new formed bone and Bonelike® was established (67±10 %), with no fibrous interface. Therefore, Bonelike® is a single-handedly viable osteoconductive synthetic grafting material as it has been demonstrated from the profiles of radiological, histological and scanning electron microscopy analyses for the six months implantation period.
New Calcium Carbonate-Based Cements for Bone Reconstruction
Authors: Fontaine Marie-Laure , Combes Christèle , Sillam Thierry , Dechambre Gérard , Rey Cristian
Published: March 2009

The feasibility of calcium carbonate-based cements involving the re-crystallization of
metastable calcium carbonate varieties has been demonstrated. Two cement compositions were obtained by mixing either calcium carbonate phases (cement A) or a calcium carbonate and a calcium phosphate phase (cement B) with an aqueous media. These cements set and hardened after 30 minutes and 90 minutes respectively. The final composition of cement A was calcite and aragonite whereas cement B lead to a carbonated apatite analogous to bone mineral. Despite poor
mechanical properties the presence of a high carbonate content in the final phase might be of interest to increase the cement resorption rate and to favour its replacement by bone tissue. First assays of implantation performed on fresh anatomical pieces (fresh cadavers) at 37°C revealed important advantages of such cement compositions: easiness of use, rapid setting, good adhesion to
bone, very good homogeneity and stability of the cement.
Treatment of Pseudoarthrosis Using Tissue-Engineered Bone Graft
Authors: Yoshikawa Takafumi , Ueda Y. , Ohmura Takahito , Iida Jin , Sen Yasunori , Koizumi M. , Miyazaki Kazuhide , Takakura Yoshinori , Nonomura Akitaka
Published: March 2009

Subjects were graft patients with pseudoarthrosis (average age, 60.3 years; range, 17-85 years). Pseudoarthrosis affected the thoracolumbar spine, the femur, the clavicle, the humerus and the metatarsal. From the ilium (tibia in one patient), 10-20 ml of bone marrow fluid was collected, and then, it was immediately transferred to the culture room and incubated in a flask containing MEM with 15% autologous or fetal bovine serum, etc.. After 2 weeks in primary culture, cells were released by trypsin treatment and were subsequently incubated with porous beta-TCP in order to prepare tissue-engineered artificial bone, according to the previously reported modified culturing technique. Tissue-engineered artificial bone was grafted around the non-union site of each affected long bone, while tissue-engineered artificial bone was grafted via the pedicle of each affected vertebral body. In all patients, favorable bone formation was seen at three months after surgery. In the patients with pseudoarthrosis of the spine, CT and MRI confirmed favorable vertebral body formation. In the patients with pseudoarthrosis of a long bone, the artificial bone was remodeled and favorable bone union was confirmed. In 2 patients in whom bone biopsy was performed during pin removal, bone
regeneration was confirmed histologically. With present type of tissue-engineered artificial bone, an artificial material with a high bone regeneration capacity can be prepared by aspiration, which is minimally invasive, and thus when compared to iliac bone grafts, it is possible to radically reduce postoperative pain without damage of autologous bone.
Hydroxyapatite Ceramic Hip Survey Alumina on Alumina Bearings
Authors: Buchanan James M.
Published: March 2009

To reduce osteolysis and loosening, alumina bearings in hip arthroplasty have been used in Sunderland since 1991. This consecutive series demonstrates the results which have been most rewarding. However, ceramic implant fractures have been encountered but these probably represent less than meticulous operative technique. The results are published and the complications discussed together with advice to reduce the incidence of implant failure.
Preliminary Investigation of Bone Cement Using Calcium Phosphate Glass
Authors: Lee Byung Hyun , Kim Min Chul , Kim Kyoung Nam , Kim Kwang Mahn , Choi Seong Ho , Kim Chong Kwan , LeGeros Racquel Z. , Lee Yong Keun
Published: March 2009

The mixed pastes of binary calcium phosphate glass with Ca/P ratio of 0.6 and distilled water were set after about 4 hr, while never set when calcium phosphate glass with Ca/P lower than 0.5. Their compressive strength was ranged from 16.0 to 23.3 MPa. When Na2HPO4 solution was used instead of distilled water as liquid phase, the setting time became drastically much shorter. As the mole concentration of Na2HPO4 solution increased from 0.25 M to 2 M, setting time was shortened to 35 min from almost 3 hr, but compressive strength decreased from 28.8 MPa to 13.2
MPa. At constant mole concentration, as the mass ratio of a powder to liquid ratio increased, setting time was shortened and maximum compressive strength was measured when a powder/liquid ratio was 2.5. However, no crystallized phases were detected either during setting or after complete setting.
The XRD , FT-IR and SEM examinations indicated that calcium phosphate glass dissolved and then glass phase precipitated again. We concluded, therefore, that Na2HPO4 just affected the kinetics of dissolution and precipitation of CPG. The mechanism of hardening has yet to be studied.
The Effects of Calcium Aluminate Cement According to Particle Sizes on Calvarial Bone Defects in Rats
Authors: Shin J.A. , Im S.U. , Song S.E. , Kim C.S. , Choi Se Young , Lee Yong Keun , Kim Kyoung Nam , Kim Chong Kwan , Choi Seong Ho
Published: March 2009

This present study was carried out to find out the effects of calcium aluminate
cement(CaO·Al203, CAC), which has been developed with biocompatibility and mechanical properties, in biological environments. Two different particle sizes of CAC - 3.5 µm vs. 212-250 µm which is recommended in periodontal bone grafting procedures – were filled in 8mm calvarial defects in Sprague-Dawley rats. The specimens were examined histologically, especially the bone-cement
interface and the response of surrounding tissues. The result of this study shows that when calvarial defects in white rats are filled with 212-250 µm calcium aluminate cement, the materials proved to be bio-compatible in growth and healing on the surrounding tissues. When further researches on direct bone adhesion and bone regeneration ability are fulfilled, CAC is expected to be applied to various fields of periodontology in the future.
Preparation of Bioactive Coatings on the Surface of Bioinert Polymers through an Innovative Auto-Catalytic Electroless Route
Authors: Oliveira J. Miguel , Leonor Isabel B. , Reis Rui L.
Published: March 2009

The aim of this research was to develop a new methodology to obtain bioactive coatings on bioinert and biodegradable polymers that are not intrinsically bioactive. In this study, three types of materials were used as substrates: (i) high molecular weight polyethylene (HMWPE) and two different types of starch based blends (ii) starch/ethylene vinyl alcohol blends, SEVA-C, and (iii)starch/cellulose acetate blends, SCA. These materials were obtained by injection moulding and by
extrusion with blowing agents in order to obtain compact/porous 3D architectures. Three types of baths were developed in order to produce the newly proposed auto-catalytic Ca-P coatings: (i)alkaline, (ii) acid, and (iii) oxidant bath. The obtained results indicated that it was possible to coat the materials surfaces with calcium phosphate (Ca-P) layer with only 60 min of immersion in the different types of auto-catalytic solutions. These innovative auto-catalytic electroless route allows for the production of an adherent bioactive film on the polymeric surfaces. Furthermore, it was possible observe by SEM/EDS the clear bioactive nature of the Ca-P coatings after different immersion periods, in a simulated body fluid (SBF).
Solution Deposition of Hydroxyapatite on a Highly Porous Titanium Surface Enhances Osseointegration
Authors: Hermida Juan C. , Patil Shantanu , Dimaano Fred , Hawkins Monica , Colwell Clifford W. , D'Lima Darryl D.
Published: March 2009

Implants with a highly porous coating of Tritanium Dimensionalized MetalÔ have the
advantage of simulating the trabecular structure of bone to provide maximum available porous space for bone ingrowth. Plasma-sprayed hydroxyapatite coatings work well on non-porous substrates but do not coat the inner surfaces of open-porous substrates. Solution deposition can produce a consistent bioceramic coating of precise thickness on porous surfaces. This report compares bone response to a
highly porous titanium surface with a solution deposited coating of hydroxyapatite. Ti6AL4V rods were implanted bilaterally in the intramedullary canals of 40 rabbit femurs. The implants had a 1.5 mm CPTi coating, which was >65% porous with pore sizes of 250-400 microns. (Tritanium Dimensionalized MetalÔ). Twenty implants (T-HA) were coated with hydroxyapatite by a solution deposition method (Peri-ApatiteÒ). The other 20 implants (T) had no hydroxyapatite coating. Implants were provided with a final diameter of 5 mm and length of 23 mm (Howmedica Osteonics, Mahwah, NJ). Rabbit femurs were harvested at 6 and 12 weeks after surgery sectioned at two levels: in the diaphyseal and metaphyseal portion of the femoral canal. Scanning electron images (SEM) in backscattered mode were digitally captured. Osseointegration was measured by automated computerized histomorphometry of the SEM images. Mean bone ingrowth at both time points was
significantly different between hydroxyapatite-coated and non-hydroxyapatite coated implants (p<0.01). The hydroxyapatite coating had a significant benefit on the bone growth into porous titanium surfaces. Bone ingrowth was substantially higher at all time points in the hydroxyapatite-coated surface relative to the uncoated surface and in both diaphyseal and metaphyseal cross-section levels. The finding of a higher percentage of bone growth deeper in the pores of the surface is encouraging. This signifies that the solution deposited Peri-Apatite coating is capable of depositing a bioactive coat of hydroxyapatite in the depths of the porous surface. This depth of penetration is not achievable by conventional plasma-sprayed deposition of hydroxyapatite. Implants with a Tritanium Dimensionalized MetalÔ surface and a solution deposited Peri-Apatite coating have the potential to develop into attractive alternatives for noncemented total hip
arthroplasty.
Fabrication of Microporous Apatite Coating on Titanium by a Novel Chemical Method
Authors: Feng Bo , Weng Jie , Qu Shao Xing , Zhang Xing Dong
Published: March 2009

A microporous apatite coating was fabricated by a heat-oxidation and chemical routine. The morphology, composition and structure were characterized by scanning electron microscopy with X-ray energy dispersion spectroscopy, X-ray photoelectron spectroscopy and X-ray diffraction. The components of the coating were predominantly apatite, next tri-calcium phosphate and octa-calcium phosphate. The pore size ranged from 1µm to5µm. The thickness of the coating was about 6µm ~ 10µm. The microporous coating was Ca-deficient carbonate apatite.