bluuebunny/crossref_metadata_2025 huggingface dataset:
Evaluation of Gamma Irradiated Human Bone in Nude Rats
Authors: Yu Y. , Chen Jin Biao , Yang J.L. , Morgan D.A.F. , Walsh W.R.
Published: March 2009

Deep-frozen morselized human bone grafts showed osteoconductivity and
osteoinductivity when implanted into tibial window defects of nude rats. The osteoconductivity was assessed by measuring the total area of newly formed bone bridged by the implanted bone grafts in the entire defect area. The osteoinductivity was evidenced by the presence of active osteoblast-like cells and new bone formation around the implanted bone grafts, which were surrounded by soft tissues distant from the host cortex. Gamma irradiation at the doses of 15 or 25 kGray reduced the osteoconductivity (ANOVA and LSD tests, p<0.05) at 3 weeks post
operation. The 25 kGray group had a significantly lower level of new bone formation compared with the 0 and 15 kGray groups. The evidences of osteoinductivity were only noted in the 0 and 15 kGray groups. Our data indicate that 25 kGray gamma irradiation reduces the osteoconductive and osteoinductive properties of the morselized human bone graft.
Attachment and Proliferation of Human Dermal Fibroblasts onto ECM-Immobilized PLGA Films
Authors: Son Hyun Joo , Han Dong Wook , Kim H.H. , Kim Hee Joong , Lee In Seop , Kim Jeong Koo , Park Jong Chul
Published: March 2009

In this study, human dermal fibroblast behaviors onto non-porous PLGA (75:25) films immobilized with 1, 10 and 100 µg/ml collagen (CN) or fibronectin (FN) were investigated according to different cell-seeding densities (1,000, 10,000 and 100,000 cells/ml). Cell attachment and proliferation were assessed using water soluble tetrazolium salt. The results indicated that 1 µg/ml of FN-immobilized PLGA film demonstrated significantly (p < 0.05) superior cellular attachment to the intact PLGA film after 4 hr of incubation. Moreover, the number of attached cells was shown to be directly proportional to that of initially seeded cells. After 48 hr, the cells showed significantly (p < 0.05) higher proliferation onto 1 or 10 µg/ml of FN-immobilized PLGA films than onto other PLGA films, regardless of the initial cell-seeding density. In terms of CN-immobilization, cell proliferation was appreciably increased but it was relatively lower than FN-immobilization. These results suggested that ECM-immobilization can enhance the cell affinity of hydrophobic scaffolds and be used to potential applications for tissue engineering by supporting
cell growth.
Physico-Chemical Modifications and Biological Improvements of Biomedical PET as a Consequence of Excimer LASER Irradiation
Authors: Mayer G. , Blanchemain N. , Dupas-Bruzek C. , Traisnel M. , Derozier D. , Laude L.D. , Hildebrand H.F.
Published: March 2009

LASER Excimer irradiation can modify surface properties for biocompatibility improvement of a medical device. The PETs from 3 different origins were used in this study. The samples have been irradiated by excimer LASER with 10 different energies. The surface profile, the surface energy and the materials crystallinity have been assessed. Biological characterizations were made with human embryonic epithelial cells L132: proliferation, vitality, viability, adhesion with the p-NPP, and morphology. - The profile measurements allowed to establish the ablation threshold, which was 36 mJ/cm². The surface hydrophilic state increased reciprocally with the irradiation intensity. The gain is 13 %. The irradiated and non-irradiated product has identical cristallinity. PET was shown not to be toxic for L132 cells. Cell proliferation and cell vitality showed dose-dependant increases reciprocal to the irradiation energy (from 88 to 138% with respect to control). The correlation was highly significant (R² = 0,8). SEM micrographs show that the cells are better spread on the surface of irradiated PET than on untreated PET.
The Mechanical Behavior of Water Vapor-Treated HA Coating Produced by Plasma Spraying Technique
Authors: Cao Y. , Zhang Bo , Wang Li Ping , Lin Qiang , Li Xu Dong , Bao C.Y. , Chen Ji Yong , Yang Bang Cheng , Yang L. , Zhang Xing Dong
Published: March 2009

Plasma-sprayed hydroxyapatite coating on metal substrate was prepared. Two kind of post-treatment methods were been applied to the coating, treatment in air at 650°C for 30 min and treatment in water vapor at 125°C with a pressure of 0.15MPa for 6 hours. XRD showed that the HA nanocrystals increased after water vapor treatment. The interfacial tensile bond strength between HA and substrate was 45.0±1.82MPa, 39.1±1.27MPa and 30.3±1.61MPa for as-received coatings, water
vapor treated coatings and heated in air coatings, respectively. 3 months after implantation in dogs limbs, the push-out strength between implants and bone was 11.27±2.71MPa, 11.63±3.11MPa, 23.92± 2.01MPa and 18.8± 1.82MPa for pure Ti implants, as-received coating implants, water vapor treated implants and heated in air implants, respectively. The results showed that the post-water vapor treated HA coating have better mechanical behavior in vitro and in vivo
Smooth Muscle Cell Ingrowth of a Surface-Modified ePTFE Vascular Graft
Authors: Noh In Sup , Edelman Elazer R.
Published: March 2009

A variety of attempts have been made to improve small diameter expanded
polytetrafluoroethylene (ePTFE) vascular grafts through cellular and tissue engineering. Some of these techniques have made their way into clinical trials. Coating of endothelial cells via surface modifications has increased graft patency in some hands but lack of firm adhesion of the seeded cells on the graft surface can lead to graft failures. We increased cell-graft and graft-tissue interactions by inducing smooth muscle cell growth into the pores of the graft wall through chemical modification of superficial surfaces, including those of the transmural pores. In contrast to non-modified surfaces seeded cells adhered on and proliferated into the modified pores and internodal surfaces. Cellular growth into these critical pores spaces seemed to arise from surface
modification including defluorination and oxygenation incorporation leading to changes in chemical composition, surface tension, cell-surface interaction and modified surface fibril aggregation.
Biological Behaviors of Keratinocytes Cultured on Chitosan-Gelatin Membrane
Authors: Yang G.H. , Yang J. , Wang Jian Mei , Cui Lei , Liu Wei , Cao Yi Lin
Published: March 2009

Chitin/Chitosan membrane has been used as wound dressing materials to facilitate clinical wound healing for many years. However, there are fewer articles studying the cell-biomaterial interaction in vitro or in vivo. In this study, the biological characteristics of human keratinocytes cultured on chitosan membrane that was mixed with gelatin in different ratio were investigated in vitro. Chitosan-gelatin membrane (CGM) in different ratio were prepared with N, N-(3 dimethylaminopropyl)-N'-ethyl carbodiimide (EDC). CGMs were divided into four groups: pure chitosan membrane, 7:3 (chitosan: gelatin), 5:5 and 3:7 groups. Human keratinocytes were isolated from foreskin by Dispase/Trypsin-EDTA digestion. Keratinocytes of passage3 were then seeded on the surface of CGM. Cloning forming efficiency (CFE) and migration distance of cultured
keratinocytes on CGM were measured. The CFE of keratinocytes cultured on the surface of pure chitosan membrane was 9.8±2.08%; cultured on 7:3 CGM was 14.33±1.53%, 5:5 CGM was 19.17±1.26%, 3:7 CGM was 18.33±2.08%. The migration distance of cultured keratinocytes on pure chitosan membrane was 61.47±2.70µm, 7:3 CGM was 66.22±9.39µm, 5:5 CGM was 120.31±15.82µm, 3:7 CGM was 225.38±10.48µm. This sutdy demonstrated that increasing contents
of gelatin in CGM could promote keratinocyte proliferation and migration. The results also suggested the membrane prepared from chitosan and gelatin can be utilized as a good keratinocyte delivery system.
The Influence of Different Base Materials on Marginal Adaptation of Direct Class II Composite Resin Restorations
Authors: Park Sung Ho , Cho Yon Sang , Jung I.Y. , Lee Kwon Yong , Jeon S.B.
Published: March 2009

The purpose of present study was to evaluate the influence of different base materials on the marginal integrity of posterior direct composite resin restorations. Conventional mesio-occluso-distal(MOD) cavity preparations, with margins in enamel and dentin, were prepared in 24 extracted human mandibular molars and randomly divided into four equal groups. One of three base materials (RMGI, compomer, flowable resin) was placed on the pulpal floors of the teeth of the groups. One group of teeth, which served as the control group, was not given any base material. Then, all teeth were restored with composite resin. The micromorphology of the tooth/restoration interfaces along the entire surfaces of the restorations was quantitatively analyzed using microscope at 150 magnifications immediately after finishing and after completion of thermo-mechanical stress. Marginal adaptation was assessed along the entire margin and % perfect margin (%PM) was calculated. The %PMs before and after thermo-mechanical stress in the groups were compared with Two- way ANOVA with Tukey test at the 95% confidence level. Before thermo-mechanical stress, there was no difference in marginal adaptation between groups. After the thermo-mechanical stress, the RMGI group showed the highest marginal adaptation rate among the tested groups. In compomer and flowable resin groups, the marginal adaptation was lower after thermomechanical stresses than before the stress (p<0.05).
Prefabricated Vascularized Bone Graft Using Autologous Tissue, Biomaterials, and Growth Factors: A New Technique for Bone Reconstruction
Authors: Hokugo A. , Mushimoto K. , Morita S. , Tabata Yasuhiko
Published: March 2009

Although clinically, grafting of vascularized autologous bone has been preferably performed, there are some disadvantages for this grafting therapy, such as the limited availability of donor site and the clinical difficulty to harvest the bone graft of desired shape and size. As one trial, we have designed a prefabricated vascularized bone graft by combining autologous vessels, particulate cancellous bone and marrow (PCBM), and β-tricalcium phosphate (β-TCP) with a biodegradable membrane. However, the volume of vascularized bone tissue newly formed was small and the density was low. In this study, the controlled system of basic fibroblast growth factor (bFGF) was combined with the conventional preparation method to improve the nature of vascularized bone graft. The femur vessels of rabbits were rolled with a membrane of L-lactide-ε-caploractone copolymer. Hydrogel microspheres of gelatin were prepared as the release carrier of bFGF. Autologous PCBM harvested from the beforehand tibia of rabbits was mixed with β-TCP granules with or without the microspheres incorporating bFGF and packed into the rolled membrane. When bone formation was assessed at different time intervals, additional mixing of bFGF significantly increased the volume of vascularized bone tissue compared to that without bFGF. It is concluded that combination of bFGF release system was a promising method to prefabricate the bone graft of large size with good blood circulation.
Effect of Macrophage on Degradation of β-TCP Ceramics
Authors: Li Shi Pu , Dai Hong Lian , Yan Yu Hua , Cao Xian Ying , Zheng Qi Xin
Published: March 2009

Mice macrophages which were mixed with β-tricalcium phosphate (β-TCP) ceramics powder were cultured, both calcium and phosphorus concentrations in the culture medium were evidently higher than that of β-TCP ceramics powder without cells. The microscope and SEM observation showed that macrophages wrapped β-TCP particles, and then phagocytized them into cytoplasm. The pH values inside and outside macrophage in β-TCP-bearing were tested. The histochemistry observation showed that there were many carbonic anhydrase positive grains in the cytochylema of macroghage after β-TCP ceramics powder being implanted. TEM investigation indicated that many β-TCP particles were phagocytized into the cytochylema of macroghage, and then vacuole was found after particles had degraded. The results showed that macrophages could take part in the degradation of calcium phosphate ceramics in two different ways.
Finite Element Analysis of a Stent Implantation in a Stenosed Artery
Authors: Liang Dongke , Yang Da Zhi , Qi Min , Wang Wei Qiang
Published: March 2009

Instent restenosis (ISR) has been a key factor that restricts the further use of
intraoronary stents. And the mechanical interaction between the stent and the artery has been indicated as one of the significant causes for the activation of stent-related restenosis. However, there is very little quantitative information about the interaction of stent with artery. In order to improve the general understanding of coronary stenting, finite element method (FEM) has been used to model the revascularization of a stenosed artery through the insertion of a balloon-expandable stent. Given a stent design, the deformed shape of the stent and possible areas
of the artery injury were presented. The fact that the distal end of stent penetrated into the artery wall may help to explain the phenomena that much restenosis occurs at the ends of stents. The recoil ratios of the stent model, the plaque-artery model and the stent-plaque-artery model were 2%, 26.7% and11.3%, respectively. They were well consistent with the experimental data. In conclusion, this work would be helpful for the general understanding of intraoronary stent implantation and stent design optimization.
The Studies on Biocompatibility of Self-Expanding NiTi Stent and Apoptosis of Smooth Muscle Cells after Stenting
Authors: Li Chun Jiang , Zheng Yu Feng , Li Chao , Zhao Lian Cheng
Published: March 2009

The biocompatibility of the NiTi alloy self-expanding stent, its dilating effect on the
vascular wall, and the apoptosis of smooth muscle cells (SMCs) were studied by implantation of stent into the rabbit’s abdominal aorta for different period. All the animals lived throughout the study. There was no detectable migration or dissection of the stent, and there were no acute closures or sub-acute thromboses in the vessels. The rates of patency were 100% both at the beginning when the stent was implanted and at the end when the animal was sacrificed. It may be concluded that the vascular intima covers the whole stent at the 8-week point. The atherosclerotic process existed in the vascular intima in contact with the stent surface, while the proliferation and apoptosis of SMCs occured simultaneously. After stent implantation, the apoptosis happened in both intima and media, which indicated that the stent might not only stimulate the intima but also compress the media, leading to proliferation and apoptosis. This might contribute to vessel remodeling after stenting.
Tribological Properties of UHMWPE Composites Filled with Nano-Powder of SiO2 Sliding against Ti-6Al-4V
Authors: Xiong Dang Sheng , Wang Na , Lin Jian Ming , Zhu He Guo , Fan Dong Li
Published: March 2009

Wear is the primary cause of the failure of joint replacement prostheses. In this paper, the ultra-high molecular weight polyethylene (UHMWPE) as an artificial joint acetabular material was filled with nano-powder of SiO2 of various mass fractions. The effect of SiO2 mass fraction on the tensile strength, tensile modulus, wetting property and tribological properties of the SiO2-UHMWPE composites were investigated when sliding against Ti-6Al-4V under lubrication of physiological saline water. The morphologies of the worn surfaces of composites were observed with optical microscope. As a result, the tensile strength, tensile modulus, wettability and wear resistance of the composites were all improved by filling with SiO2, and the composites had largely decreased friction coefficients under lubrication of physiological saline water compared with the unfilled UHMWPE. This was attributed to the reinforcing function of the nano-powder of SiO2 in the composites and the lubricating action of the water boundary film. The wear of pure UHMWPE was dominated by plowing, plastic deformation, while the SiO2-UHMWPE was characterized the mild fatigue wear.
Wear of Resin Composites Polymerized by Conventional Halogen Light Curing and Light Emitting Diodes Curing Units
Authors: Kim Hwan , Park Sung Ho , Jung I.Y. , Jeon S.B. , Lee Kwon Yong
Published: March 2009

In this study, the wear characteristics of five different dental composite resins cured by conventional halogen light and LED light sources were investigated. Five different dental composite resins of Surefil, Z100, Dyract AP, Fuji II LC and Compoglass were worn against a zirconia ceramic ball using a pin-on-disk type wear tester with 15 N contact force in a reciprocal sliding motion of sliding distance of 10 mm/cycle at 1Hz under the room temperature dry condition. The wear variations of dental composite resins were linearly increased as the number of cycles increased. It was observed that the wear resistances of these specimens were in the order of Dyract AP >
Surefil > Compoglass > Z100 > Fuji ı LC. On the morphological observations by SEM, the large crack formation on the sliding track of Fuji ıLC specimen was the greatest among all resin composites. Dyract AP showed less wear with few surface damage. There is no significant difference in wear performance between conventional halogen light curing and light emitting diodes curing sources. It indicates that a light emitting diodes (LED) source can replace a halogen light
source as curing unit for composite resin restorations.
Polyurethane Foam with a Negative Poisson's Ratio for Diabetic Shoes
Authors: Park K.O. , Park Jong Chul , Choi Jae Boong , Lee Sung Jae , Choi H.H. , Kim Jeong Koo
Published: March 2009

This study fabricated polyurethane foam after transforming the cell structure from a convex polyhedral shape to a concave shape. Polyurethane was synthesized and fabricated after changing the cellular structure of the foam using two methods. Scanning electron microscopy showed that the cellular structure was a more concave structure than in control foam. The Poisson’s ratio of the experimental foam was negative. The average range of the Poisson’s ratio was –3.4~0, versus
0.3~1.3 for the control foam.
Chitosan-Based Scaffolds for Hepatocyte Culture
Authors: Pan Ji Lun , Bao Zhi Ming , Li Ji Liang , Zhang Li Guo , Wu Chen , Yu Yao Ting
Published: March 2009

Chitosan is considered to be a very promising biopolymer for various biomedical and
pharmaceutical uses because of its nontoxic and biocompatible nature [1]. In this paper, we introduced and discussed chitosan-based biomaterials used for hepatocyte culture, including chitosan microcarriers, heparin and alginate modified chitosan scaffolds, collagen-chitosan complex and sugar-modified chitosan scaffold
Fracture and Fatigue Behaviour of Mullite/Molybdenum Composites
Authors: Torres Hernández Y. , Anglada Marc , Llanes Luis , Bartolomé J.F. , Díaz M. , Moya J.S.
Published: March 2009

The fracture and fatigue behaviour of a mullite/molybdenum composite is investigated. The attention is focused on the measurement of fracture toughness, KIc, on long through the thickness cracks by using SENB specimens, and on the growth of indentation cracks under static, monotonic and cyclic loads. Molybdenum was chosen to reinforce the mullite matrix because of the similar thermal expansion coefficients for both phases. It is essential to know and take into account the shape of the initial indentation cracks as well as the eccentricity change after extension under monotonic and cyclic stress. This study shows that, in mullite/molybdenum composites, static fatigue effects are negligible, but these composites are susceptible to mechanical degradation under cyclic loads. It is shown that the fatigue crack growth rate exhibits a high dependence on Kmax and that the fatigue sensitivity, defined as the ratio between fatigue crack growth rate threshold and KIc, is much lower than for other materials processed by powder metallurgy.
Fracture and Crystallographic Phase Correlation in Alumina Based Particulate Composites
Authors: Pędzich Zbigniew , Faryna Marek
Published: March 2009

The paper deals with the results of mechanical properties and microstructure
investigations performed in two composite systems: Al2O3/WC and Al2O3/W. The fracture toughness measurements were made for materials characteristics. Microstructure of composites was thoroughly investigated using transmission and scanning electron microscopy. Selected Area Electron Dffractions (SAEDs) as well as Electron Backscatter Diffractions (EBSDs) were applied to establish crystallographic relationships between neighboring grains of different phases both
in a local and global scale. Examples of orientation maps and stereographic projections for different crystallographic directions as well as orientation relationships between different phases (alumina and reinforcing inclusions) were shown and described.
Fracture Mechanisms in Laminates in the Alumina - Titania System
Authors: Bueno S. , Baudín Carmen
Published: March 2009

Alumina (Al2O3)-aluminium titanate (Al2TiO5) composites present higher toughness than alumina materials but rather low strength due to microcracking. Laminates in which a flaw tolerant material is located between high strength layers is one way to overcome this problem. In this work, the fracture behaviour of a laminated structure constituted by five layers, where low residual stresses are expected, is studied. In this system, external and central layers of monophase alumina with high strength were combined with intermediate layers of alumina with 10vol.% of aluminium titanate. In the monophase alumina layers, an additional "in situ" formed layer of about 200 µm, constituted by large (@10µm) grains was found, close to the composite layers. The laminated structure presented semistable behaviour during SENVB tests for conditions in which stable crack propagation is not predicted for small grain sized alumina materials. Toughening mechanisms related to thermal expansion mismatch between matrix and second phase in the composite layers and crack bridging in the large grain sized alumina layer were identified.
Fractographic Analysis of Surface Flaws in Glass
Authors: Kašiarová Monika , Rouxel Tanguy , Sanglebœuf J.-C. , Le Houérou V.
Published: March 2009

Biaxial testing was used to get insight into the incidence of the surface flaw properties (size, shape) on the strength of float glass specimens. Grinding grooves, Vickers' indentations and scratches as defects were introduced at the surface of annealed float glass specimens. The machined and fractured surfaces were observed using optical and confocal microscopes. The influence of the flaw characteristics on the strength of glass was evaluated and analyzed in the light of the fracture mechanics.
Low Cost SiAlON from Pyrophyllite with High Hardness and Good Corrosion Resistance
Authors: Křest'an J. , Šajgalík Pavol , Pánek Zdenĕk , Salamon David
Published: March 2009

Bulk ceramic materials on the base of β-sialon were prepared from hydrosilicates. Except of some mechanical properties (HV, KIC) also the corrosion resistance of β-sialon against Cl-, iron and steel was investigated. The results were compared with β-sialon of similar composition z = 3.8, which was prepared from commercial powders Si3N4, AlN and Al2O3. The differences in mechanical properties of β-sialons prepared from natural hydrosilicates and synthetic powders are discussed.
Mechanical Properties of Thermal Barrier Coatings at Room Temperature
Authors: Guidoni G. , Torres Hernández Y. , Anglada Marc
Published: March 2009

Four point bending tests have been carried out on a thermal barrier coating (TBC) system, at room temperature. The TBC system consisted of a plasma sprayed Y-TZP top coat with 8 % in weight of Yttria, a bond coat of NiCrAlY and a Ni-based superalloy Inconel 625 as substrate. The TBC coating was deposited on both sides of the prismatic specimens. Efforts have been done in detecting the damage of the coating by means of Maltzbender et al [1] model.
Effect of Oxidation at Elevated Temperature on Elastic and Interface Properties of Ceramic Matrix Composites
Authors: Brandstetter Johann , Glogar Petr , Loidl Dieter , Kromp Karl
Published: March 2009

Unidirectionally reinforced ceramic matrix composites (CMC) with matrix derived by pyrolysis of polymethylsiloxane or polymethylphenylsiloxane resins and reinforced with Nicalon or Nextel fibres were investigated. In order to assess and mutually compare their mechanical properties and stability when exposed to hot air up to 1200°C their elasticity moduli were measured prior to and after this exposure. The oxidation - induced damage of the material was monitored also in terms of microstructural features. Moreover, an attempt was undertaken to assess the bonding level by monitoring the push - through of macroscopic bundles of fibres using a flat indentor.
Mechanical and Fracture Properties of R-Glass Reinforced Composites with Pyrolysed Polysiloxane Resin as a Matrix
Authors: Černý Miroslav , Bednářová D. , Glogar Petr , Dusza Ján , Rudnayová Emőke
Published: March 2009

Mechanical and fracture properties of unidirectional composites reinforced with R-glass fibres and utilizing various commercially available polysiloxane resins as matrix precursors were investigated. As the matrix becomes more brittle after the pyrolysis the impact toughness and flexural strength of the composites fall. On the other hand, the shear modulus rises after the pyrolysis as the matrix becomes stiffer in shear. The appearance of fracture surfaces generated during the flexural strength at room temperature (RT) and elevated temperatures is discussed.
Thermography and Simulation as a Combined Method for Failure Analysis of PTCs
Authors: Platzer A. , Supancic Peter , Lembacher C. , Theiszl U. , Danzer Robert
Published: March 2009

PTCs are electrical resistors (thermistors) with a positive temperature coefficient. They change their resistivity up to seven orders of magnitude within a certain temperature range. Though these parts are only loaded electrically, they often fail due to thermo-mechanical stresses caused by Joule self heating. With the aid of an infrared camera system the temperature distributions of PTCs in service were investigated. They show a big variety in appearance, often strongly differing from the
temperature distribution predicted by a model-calculation using homogenous material properties. The temperature distributions measured with the infrared system give information about gradients in material properties. Performing destructive tests by high electrical loading lead to fractures, which are initiated in the most stressed regions. Fractography was used to identify fracture origins. With the information of the fractography and thermal analysis of the infrared camera the FEM-model could be modified in order to understand different kind of fracture modes.
An Adaptive Control of Machine Table Reciprocation Using a Hydrophone - A Method for Improving the System Efficiency and Reliability -
Authors: Okuyama Shigeki , Hayashi Makoto , Yui Akinori , Kitajima Takayuki
Published: March 2009

In order to eliminate unnecessary table-over-travel of a surface grinding machine, the
authors previously developed an adaptive table-reciprocation-control system using a hydrophone. The system eliminated the over-travel and reduced grinding time by 20-40%. However, during the stage of the grinding-wheel approach to a workpiece the system did not work. In order to improve the efficiency and reliability of the system, a fluid-flow stabilizer and a new coolant-supply nozzle have been developed and their performances were experimentally investigated. By using these devices, the reciprocation-control system showed its capability even during the stage of the grinding-wheel approach and this ability improved the system efficiency and reliability.
Reliability Prediction of Centerless Grinding Machine
Authors: Lee Seok Woo , Choi Hon Jong , Nam S.H. , Choi Young Jin
Published: March 2009

Along with the recent developments in the optical communication industry, the demand for optical communication components has increased. Ferrule is a significant element that determines transmission efficiency and quality of information in the optical communication area. Most ferrule machining entails grinding and this requires high processing precision. Therefore, the ultra precision centerless grinding machine for ferrule grinding was designed. The centerless grinding machine is composed of a high damping bed, grinding wheel spindle unit, regulating wheel spindle unit, feeding table and dressing unit. Reliability prediction is very important for the high quality design. In this study, reliability of the centerless grinding machine was predicted.
Effective Deburring of Micro Burr Using Magnetic Abrasive Finishing Method
Authors: Park Jung Il , Ko S.L. , Hanh Y.H. , Baron Yuri M.
Published: March 2009

Micro burrs formed in micro parts are not subject to be removed by the conventional
deburring method for marco parts. Magnetic abrasive deburring method which was proved to be effective for small burrs are applied for deburring the micro burr in electric gun parts used in TV monitor. A specific magnetic inductor is designed and manufactured for this part. To improve the deburring performance, vibration table is used for increasing the relative velocity. To evaluate the deburring capability and surface finishing, edge shape, surface roughness and composition of surface
material are measured precisely. It is verified the chemical composition of surface is not affected by the powder composition when the proper powder are used with coolant.
The Optimization of Technological Processes of Details Processing by Free Abrasives
Authors: Tamarkin M.A.
Published: March 2009

The purpose of the research is the development of theoretical foundation of
processing of details by free abrasives, the increase of efficiency of finishing processing of details on the base of creation of methodical principles of optimization of technological processes by means of CAD.
Corrosion Inhibiting Effect on Copper Chemical Mechanical Planarization (CMP) in Fe(NO3)3 Based Slurries
Authors: Guo Dong Ming , Li X.J. , Jin Zhu Ji , Kang Ren Ke
Published: March 2009

The slurry of Copper chemical mechanical planarization for ultra large-scale integrate
circuit (ULSI) usually contains oxidizer, etchant, complexing reagent and corrosive inhibitor. In planarization process, the corrosive inhibitor has an important effect on the planarization. Only if the concave surface of the wafer is properly protected from corrosion by the inhibitor, the process can obtain perfect surface planarity. In this paper, with Fe(NO3)3 as an oxidant and several corrosive
inhibitors selected, the corrosive efficiency of slurries are investigated. The static etching rate and the polishing material removal rate of wafer are obtained. The electrochemical behavior of the slurry is investigated by the potentiodynamic polarization studies. And the inhibitive efficiency of the related corrosive inhibitors is calculated from the polarization data. X-ray diffraction is applied to analyze the
composition modification of the copper surface. Atom force microscopy is applied to measure the surface topography of corrosive copper wafer and the value of surface roughness is measured by ZYGO surface analysis system. The result shows that the benzotriazole (BTA) is a perfect corrosive inhibitor. With addition of 0.1wt% BTA into 1.5wt% Fe(NO3)3 solution, the inhibitive efficiency can reach 99.1%. The polishing test shows that if only 1.5wt% Fe(NO3)3 is added as an oxidizer without any other additive, the surface roughness of the polished wafer is 26.9Å, while with 0.1wt%BTA added in the meantime, 5.2 Å of surface roughness can be obtained.
A New Architecture of Tool Path Generation for Five-Axis Control Machining
Authors: Nakamoto K. , Shirase K. , Morishita Akifumi , Arai E. , Moriwaki T.
Published: March 2009

NC machine tools, which are widely employed in manufacturing systems, are basically driven by NC programs. However, it requires extensive amount of time and efforts to generate high quality tool paths before a machining operation. An NC program for five-axis control machining is more difficult to generate because the motion of machine tool is more complicated. In this paper, a new architecture is proposed to autonomously control the machine tool without an NC program for more rapid and flexible machining. A technique called digital copy milling is developed to generate the tool paths in real time based on the principle of copy milling. It means that the cutting parameters can be adaptively controlled in order to maintain stable cutting process and to avoid the cutting troubles. In the experimental verification, the improved digital copy milling system for five-axis control milling successfully detected and avoided tool collision in real-time.
Calculating the Overcut in Electro-Discharge Machining
Authors: Zhao Fu Ling , Wang H. , Lu Z.Z.
Published: March 2009

The dimensional accuracy of electro-discharge machining (EDM) is greatly influenced by the overcut resulting from discharge gap and electrode wear. In order to achieve fine accuracy, it is necessary to estimate the overcut according to an empirical formula. In this paper, experiments in electro-discharge machining were carried out. The effects of parameters on the overcut, such as peak current, pulse duration, were analyzed. Then an empirical formula for the overcut in EDM was
established based on the experimental results using the least square method. Finally, reasonable agreement between calculated results and the further experimental results was obtained.
Attempt of Electrodischarge Grinding with an Electrically Conductive Diamond-Cutting-Edge Wheel
Authors: Suzuki Kiyoshi , Ninomiya Shinichi , Iwai Manabu , Tanaka Y. , Murakami Yoshihiko , Sano Sadao , Tanaka Katsutoshi , Uematsu Tetsutaro
Published: March 2009

Electro-discharge grinding (hereafter called ED-grinding) was carried out with a trial manufactured metal bond diamond wheel containing electrically conductive diamond grits (hereafter called EC-D-grits-wheel). In this research two effects i.e. removal action of workpiece by electrical discharge machining, and an in-process dressing action of the cutting edges on the grits are expected to take place. The results of ED-grinding with EC-D-grits-wheel (f100mm, SDE120Q80M) on tungsten carbide indicated a significant decrease of 21% in the grinding force, when the set discharge current was increased from 0A to 12A. It was also clarified from the alternative-grinding test with and without an electro-discharge action that stable grinding characteristics along with a reduced grinding force could be achieved in the case of the EC-D-grits-wheel with the electro-discharge action. High-speed camera photographs indicated that a stable discharge condition was achieved.
Features of Application of the Laser Method for Normalization of Accuracy of Resistors in Hybrid Integrated Circuits
Authors: Antonov Y.
Published: March 2009

Features of application of laser trimming for normalization of accuracy of resistance of resistive elements (REs) of hybrid integrated circuits (ICs) are considered. Limitations of the applied method are determined and decisions on its development are offered on the basis of application of means of the automated designing and modelling. Application of the method of the analysis of hierarchies (MAH) and the theory of indistinct sets for an estimation and optimization of projects of normalization is proved.
Ultraprecision Fabrication of Large-Scale SiC Spherical Mirror Using ELID Grinding Process
Authors: Dai Y. , Ohmori Hitoshi , Lin Wei Min , Eto H. , Ebizuka N.
Published: March 2009

Lightweight mirrors of SiC (Silicon Carbide) are currently used for numerous space telescopes. The most favorable characteristics of the material are high specific stiffness, high thermal conductivity and low thermal expansion (CTE). For large-scale SiC mirrors, however, the machining cost is very high using traditional polishing process. In this study, a large-scale SiC spherical mirror (φ360mm) was designed as reducing-weight structure with many open-back triangular cells. The ELID mirror grinding technique was conducted to finish the mirror. A unique jig composed of many hydrostatic actuators was developed for reducing the deformation resulted from the grinding force. By using an on-machine measurement system, the form error of the finished surface was measured. The surface roughness of the mirror was also examined with a mobile AFM. As result, a high quality mirror surface, which has form accuracy 0.8µm P-V and roughness of Ra 7.8nm, was achieved. This paper presents the experimental procedure and results.
Adaptive Table-Motion Control of a Surface Grinding Machine Using an AE Sensor
Authors: Yui Akinori , Okuyama Shigeki , Kitajima Takayuki
Published: March 2009

Improvement in grinding efficiency is very important to economically produce precision parts. This paper proposes a new table-motion control system for reducing non-machining time in the surface-grinding process and describes the results of performance tests of the system. The table-motion is adaptively controlled so that the table stroke is shifted along a workpiece shape. That is, an AE signal is emitted from the contact zone between a grinding wheel and a workpiece and is diminished when the wheel leaves the workpiece. When the signal level becomes less than a preset trigger level, a command is sent to a table controller to reverse the table-motion. By using the proposed system, unnecessary table over-travel is successfully eliminated and total machining time is reduced by 22 to 38 percent.
Identification of Impact Force for Base on Higher Order Wigner Distribution
Authors: Lee Sang Kwon , Hwang Sung-Ug , Gu Jinhoi
Published: March 2009

In mechanical structures, the impact force is related to the structural damage. To identify the location where impact force occurs, the triangle method has long been used. This method requires three acceleration signals or strain signals to be measured on the mechanical structure. Time delay among these signals is useful information to estimate the location of the impact force. It is very difficult to estimate time delay by using the raw data of three signals because the propagation wave of the structure is a dispersive wave. Therefore, three signals should be analyzed in the time and frequency domain in order to estimate the time delay at each frequency. For the time-frequency analysis of highly non-stationary signals like impulse signals, time-frequency methods or time scale methods have been used. These methods use the first or second order statistical characteristics of the signal. This paper outlines the higher order Wigner method to obtain time and frequency information of a signal. Since it uses the high order statistics of signals, this method is useful for identifying the impact signal embedded in the background. It has a better time-frequency resolution for a non-linear signal than other time-frequency and time scale methods. This method can be applied to estimate the location of an impact force, which becomes a cause of damage of mechanical plants. Finally, in order to prove this method, experimental work was conducted on an aluminum plate in the laboratory.
Comparison of Different Methods of Ritz Vectors Extraction
Authors: Mendrok Krzysztof , Uhl Tadeusz
Published: March 2009

Ritz vectors are parameters, which describe object dynamics in similar way as modal vectors. Their advantage with respect to modal vectors is a fact, that less number of them is required to estimate object response. It is also proofed, that Ritz vectors are more sensitive for damage detection then modal vectors. The problem which arises, when one wants to use Ritz vectors for damage assessment is that there are no many methods to extract Ritz vectors from operational data. In addition, the methods require knowledge of analytical mass matrix or state a space model matrix, which makes them rather complicated. In the paper two Ritz vectors extraction methods are taken into account. First bases on flexibility matrix and second is related with state space model. Both of them are evaluated with respect to analytical procedure of Ritz vectors calculation. For the vectors evaluation, a simulation data from theoretical model were used. In next step Ritz vectors were extracted from data measured on a real structure. On the structure damage was simulated. The Ritz vectors extracted with use of both tested methods were used to detect damage.
Impact Load Identification Based on Local Measurements
Authors: Wiklo Marcin , Holnicki-Szulc Jan
Published: March 2009

A new methodology for load identification is proposed. The global dynamic structural response is modeled using only pre-computed, time dependent, dynamic influence matrix, describing structural response to locally generated unit impulses. Then, the impact load identification procedure is based on distance minimization between the modeled and measured local dynamic responses in sensor locations. The theoretical background as well as numerical examples is presented.
A Combined Finite and Spectral Element Approach to Wave Scattering in a Cracked Beam: Modelling and Validation
Authors: Shone Simon P. , Mace Brian R. , Waters Tim P.
Published: March 2009

This paper concerns flexural and axial wave motion in a cracked beam. A combined
finite element (FE) and spectral element (SE) model of a cracked beam is presented. A portion of the beam, which contains the crack, is modelled using FE analysis and combined with semi-infinite SEs. From the combined model the reflection and transmission coefficients of the crack are estimated. To determine the accuracy of this approach, a beam with a mass discontinuity is considered in the first instance. The reflection coefficients are estimated numerically and compared with experimental results. Secondly, a slot-type transverse crack is cut along the width of the beam. The experimental results are compared with both an FE model and a conventional lumpedparameter spring model. The purpose of this work is to investigate further the use of audiofrequency wave propagation as a basis for crack assessment and provide a valid model to use in the development of an assessment procedure.
Predicting Failure in Multi-Bolt Composite Joints Using Finite Element Analysis and Bearing-Bypass Diagrams
Authors: McCarthy C.T. , McCarthy M.A. , Gilchrist Michael D.
Published: March 2009

A three-dimensional finite element model of a three-bolt, single-lap composite joint is
constructed using the non-linear finite element code MSC.Marc. The model is validated against an experiment where the load distribution in the joint is measured using instrumented bolts. Two different joint configurations are examined, one with neat-fit clearances at each bolt-hole and another with a 240 µm clearance at one hole with neat-fits at the others. Bearing and by-pass stresses are extracted from the model and used in conjunction with published bearing/by-pass diagrams to predict the failure load, mode and location for the joints. It is shown that the proposed model accurately predicts the failure behaviour of the joints, as determined from experiments on three-bolt joints loaded to failure. It is also shown that introducing a clearance into one hole significantly changes the failure sequence, but does not affect the ultimate failure load, mode or location. The proposed method demonstrates a simple approach to predicting damage in complex multi-bolt composite joints.
Effect of Residual Stresses on a Micromachined Z-Axis Vibrating Rate Gyroscope
Authors: Qiu A.P. , Su Y. , Wang S.R. , Zhou B.L.
Published: March 2009

The design of mechanical structures depends upon characterizing the stress/strain state in these devices under the combined influence of both loading and residual stresses. The performance of the dynamic structures is strongly influenced by residual stresses. Understanding of the behavior of gyroscopes in presence of residual stresses and ability to relieve the stresses are essential for improving the performance. In this paper, we briefly analyze the cause of residual stresses. The effect of residual stresses on natural frequencies of the drive mode and sense mode is theoretically analyzed. The FE model of the z-axis gyroscope is built to investigate the relation between the frequencies and the residual stress by model analysis. Methods for residual stress relief are presented. The results of the simulation demonstrate that the performance of the gyroscopes with serpentine beams and stress relief slots can be improved significantly.
A Measurement System for Step Imprint Lithography
Authors: Liu H.Z. , Lu Bing Heng , Ding Y.C. , Li D.C. , Tang Yi Ping , Jin T.
Published: March 2009

A precision 6-degree-of-freedom measurement system has been developed for simultaneous on-line measurements of imprint lithography stage. To successfully accomplish nanometer-scale pattern transfer from mold to resist film on the wafer, two types of positioning methods, static and dynamic, are used in this system. Two laser interferometers, two optical reflection mirrors and special structure on the stage with 3 elastic tracks are employed in this system to detect the positions and rotations of the stage. Through an algorithm, measurements of pitch, yaw and roll motions can be achieved. This system can realize on-line position detecting. Based on adjusting of PZTs, the detecting precision can reach 10nm and ±3 milli-arcsec, respectively. The measuring range can reach 100mm and ±10 arcsec, respectively.
Detection and Control of Synchro-Operation of Long-Stroke Cylinders in a Deep Ocean Mining Heave Compensation System
Authors: Wu B.H. , Xiao T.B. , Zou D.P. , Long J.J.
Published: March 2009

A relative detecting method is proposed to detect the synchronous error of several long stroke hydraulic cylinders by using a short stroke displacement sensor, which has the advantages of low cost, easy to install and convenient in operation compared with an absolute detecting one. A synchronous model test system is established and on-line detection and control is realized by utilizing computer technology. A strategy named as Fuzzy-PID control and a program developed for this system are used for compensation of the synchronous errors. An effective new method for detection and control of synchro operation of hydraulic cylinders is presented for a deep ocean mining heave compensation system.
Web-Based Virtual Measurement, Analysis and Evaluation Software Development for 3D Surface Topography
Authors: Anthony C. , Ma L. , Zhou J.
Published: March 2009

This paper is aimed to develop and implement a web-based 3D surface evaluation, analysis and simulation software. The software can provide users from all around the world with a means to conduct surface study through the Internet. The software automatically calculates all 3D surface roughness parameters and has options for the user to view various 2D and 3D graphical representations of the entire surface. All outputs calculated are viewed through a web browser or can be downloaded to a user computer, giving the user a complete numerical and graphical representation of any surface for which they have measured the surface data.
Instantaneous Measurement of 3D Profiles by Projecting Coded Grating
Authors: Tian A.L. , Li B. , Huang M.T. , Jiang Zhuang De
Published: March 2009

A three-dimensional profile measurement system based on a projection coded grating technique is presented. The system uses a designing and decoding technique for grey coded gratings. The coded grating has black, white and grey stripes. The period triples a conventional grating. It greatly increases the height measuring range without any decrease in stripe separation. The shape of object can be obtained from only one grating image. The system is suitable for instantaneous measurement of moving objects including human face. The technique proposed permits rapid 3D measurement and no moving parts are involved in the system. The hardware is relatively simple. Special data processing software is developed. Results of a practical example confirm the effectiveness of the proposed method.