bluuebunny/crossref_metadata_2025 huggingface dataset:
The Effect of Bovine Serum Albumin on the Crystalline Characteristics of the CaP Biomimetic Coating
Authors: Wu Yao , Chen Ji Yong , Xiao Yu Mei , Yang Bang Cheng , Zhang Xing Dong
Published: March 2009

It is very necessary to develop a real biomimetic compound coating of CaP with
organic component and investigate quantitatively the effects of different bovine serum albumin (BSA) concentration on the crystallite properties of the coprecipitated CaP layer. Bioactivated Ti was immersed in Ca-P solution with different BSA contents to obtain different biomimetic coating. The coatings were analyzed with scanning electron microscopy (SEM) and X-ray diffraction (XRD). With the increase of BSA, the crystals on the coating grew more slowly but packed more closely. The preferential crystallographic direction of 002 of hydroxyapatite became less distinguishable and the crystallinity of the deposited hydroxyapatite decreased gradually. The crystallite sizes reduced with the addition of BSA proteins. Accordingly, when a certain content of BSA protein was added to
the Ca-P solution, Ti surface would form a real biomimetic coating with the crystal size and crystallinity similar to the natural bone.
Preparation and Characterization of Three Dimensions Chitosan Rods with Biomimetic Layered Structure Similar to Annual Ring
Authors: Hu Qiao Ling , Li Bao Qiang , Zhang Zhong Ming , Shen Jia Cong
Published: March 2009

Inspired by the annual ring structure of wood, a cylindrical semi-permeable chitosan gel membrane was chosen as a template to separate chitosan solution from NaOH coagulation solution. Three dimensions (3D) chitosan (CS) rods (Φ5×80 mm) with layered structure similar to annual ring of wood were prepared via a novel and simple in-situ intermittently precipitating method. These chitosan rods presented quite good mechanical properties with bending strength and shear strength of 102MPa and 31MPa respectively. The concentric circles layered structure was approved by SEM characterization, the mechanism of preparation and the relationship between structure and properties of chitosan rods were also discussed.
Research on Platelet Adsorption Behavior Using Enzyme Immunoassays and LDH Testing
Authors: Zhao An Sha , Yang Ping , Leng Yong Xiang , Sun H. , Wang Jin , Wan Guo Jiang , Huang Nan
Published: March 2009

Platelet adhesion and activation restrict the clinical applicability of blood-contacting
biomaterial because platelet-biomaterial interaction can result in the formation of a haemostatic plug or thrombus. In this study we used LDH (lactate dehydrogenase) tests to evaluate the adsorption behavior of platelets on material surfaces. Enzyme immunoassay (EIA) was applied to evaluate platelet activation using a special monoclonal antibody directly binding to the Pselectin on the activated platelet membrane. The results show compared with the conventional detecting tools of platelet adhesion / activation such as optical microscopy. LDH (lactate dehydrogenase) testing and EIA (enzyme immunoassay) are surface-sensitive methods for the investigation of various aspects of platelet adsorption and activation on different biomaterials.
The Study of a New Injectable Root Canal Filling Material
Authors: Teng Li Zhao , Fan Hong Song , Yang Xiu Dong , Wu Dayi , Zhang Xing Dong
Published: March 2009

The new-style injectable root canal filling material was prepared by hydroxyl apatite (HA), calcium hydroxide (Ca (OH) 2), iodoform (CHI3) and silicon oil. The material was injected into the isolate teeth to observe the sealing effect through marinating the isolate teeth in SBF and 1% methylblue solution. The practical effect of this material through clinical trials ten patients including fourteen teeth was also evaluated. After six months follow-up, patients have no any uncomfortable. This root canal filling material has good injectability, good biocompatibility, and is very convenient to manipulate. The relevant results suggest that it has good prospect of clinical application.
Fabrication of Porous Titanium with Biomechanical Compatibility
Authors: Li Hu , Fan Hong Song , Zhang Xing Dong
Published: March 2009

Porous titanium with good strength and three-dimension pore structure was fabricated by using H2O2 as vesicant foaming titanium powder. The compressive strength, bending strength and Young’s modulus of porous titanium with the porosity of 58vol% are 190.7Mpa, 159Mpa and 4.15Gpa, respectively, similar to that of the nature bone. This kind of porous titanium with good bio-mechanical compatibility may be potential to alleviate the problems caused by the mismatch of
the strength and Young's modulus between implant (110 GPa for Ti) and bone. Moreover, the pores (mainly in 100-700µm) are all interconnected and there are many microspores (about 10µm) in the wall of the macrospores. This porous structure would endow the materials with better activity.
Research on the Parallel Arrangement of Aragonite Sheets in Clam's Shell
Authors: Chen Bin , Peng Xiang He , Fan Jing Hong
Published: March 2009

Molluscan shell is a typical biocomposite in nature. It possesses excellent strength,
stiffness and fracture toughness, which are closely related to its exquisite microstructure. SEM observation on clam’ shell shows that the shell is a kind of layered ceramic composite consisting of aragonite sheets and protein matrix. The aragonite sheets have long and thin shape and are arranged in a parallel manner. The higher fracture toughness of the shell is analyzed based on its representative model and the concept of maximal pullout energy. Analysis shows that the long and
thin shape as well as the parallel arrangement of these sheets will substantially improve the maximal pullout energy of the sheets and the fracture toughness of the shell.
Poly-N-Acetyl Glucosamine-SO4 for Repairing Osteochondral Defect in Rabbits
Authors: Kang Qian K. , Hill Christopher M. , Demcheva Marina V. , Vournakis John , An Yuehuei H.
Published: March 2009

Repair of osteochondral defects created in rabbit femoral trochlea were studied using a water-soluble sulfated p-GlcNAc formulation, (Marine Polymer Technologies, Danvers, MA, USA). After 12 weeks of healing empty defects were compared to defects filled with sulfated p-GlcNAc sponge alone and sulfated p-GlcNAc sponge seeded with autologous chondrocytes. The chondrocyte seeded sponge provided the best healing of both cartilage and subchondral bone. The sulfated p-GlcNAc sponge alone did not provide as good healing as the chondrocyte seeded sponge, but healing was still superior to that of the empty defect. This study supports the use of p-GlcNAc sponge to augment healing of osteochondral defects in animal models.
Contact Strength of the RE-Oxynitride Glasses
Authors: Lofaj František , Dorčáková Františka
Published: March 2009

Effects of the rare-earth additives (RE = Sc, Y, La, Nd, Gd, Sm, Yb and Lu) and nitrogen on contact strength of the oxide and oxynitride glasses were investigated at room temperature. The advantage of this relatively new technique is its experimental simplicity and using of miniature samples, however, a relatively complex stress distribution around the contact points reduces Weibull parameter in comparison with the conventional bending strength. Contact strength of the tested glasses is also strongly influenced by surface finish. The differences in the effects of REmodifiers in oxide and oxynitride glasses suggest that the contributions from RE and nitrogen may not be simply additive, as observed earlier for various thermo-mechanical properties. However, additional study is necessary to eliminate the effects of surface defects to support this assumption.
Quantitative Surface Fractography of Alumina and Alumina-SiC Composites during Diamond Grinding
Authors: Ortiz Merino J.L. , Cock A. , Roberts Steve G. , Todd Richard I.
Published: March 2009

It has recently been shown that small additions of SiC to alumina can significantly improve both the surface finish for a given grinding treatment, and the resistance to severe wear. This paper describes experiments designed to obtain a clearer understanding of the mechanisms involved by correlating quantitative measurements of surface fracture during a standard abrasive wear test with the wear rate for a range of microstructures. The surface fracture parameters measured were (i) the proportion of the surface in which pieces of material had been removed by brittle fracture, and (ii) the size (equivalent circular diameter and depth) of the individual pullouts. Microstructures with systematic variations in grain size, SiC volume fraction, SiC particle size, SiC position (inter- or intra-granular) and sintering aids were tested. The results indicate that the reduction in wear rate on adding SiC or reducing the grain size is caused by a reduction in the area fraction of surface pullout by brittle fracture. For low SiC contents (~2vol%), this reduction in surface pullout is a consequence of the reduction in size of the individual pullouts. For higher SiC contents (10vol%), there is evidence that the nucleation of surface cracking is also inhibited. The underlying micromechanisms responsible for these effects are discussed.
Effect of Carbon and Nitrogen Implantation on the Properties of Silicon Nitrides
Authors: Arató Péter , Balázsi Csaba , Kövér Zsuzsanna , Wéber Ferenc , Richter E. , Gyulai J.
Published: March 2009

This study focused on the effect of ion implantation on the mechanical properties of silicon nitride based ceramics. The examined materials contained 4% Al2O3, 6% Y2O3 and, in some cases, graphite or black carbon additives. Fully densified bodies were manufactured by two-step hot isostatic pressing, in other experiments pressureless sintering gave porous ceramics. Nitrogen or carbon ions with 190 keV or 350 keV were implanted, a part of samples obtained laser treatments for comparison. Measurements of elastic modulus, four point and three point bending strength were carried out at room temperature on sintered samples, partially sintered samples and sintered and oxidised samples. Carbon or nitrogen implantation influenced the strength of partially sintered samples only if the density was over 80%. Both the implantation of carbon or nitrogen ions and the laser treatment affected the bend strength of sintered samples, enlarging the power introduced its value first increased than decreased. Implantation slightly decreased the strength of samples oxidised at 1400 °C. Comparison of different mechanical characteristics may support a better understanding of phenomena during ion beam implantation or laser irradiation.
Effect of Ion-Implantation on the Microstructure of Si3N4 Based Ceramics
Authors: Babcsán J.K. , Maros Maria Berkes , Wanderka N. , Klaffke D. , Schubert Helmut
Published: March 2009

Si3N4 based ceramics that made by hot isostatic press, were implanted at room temperature with N+ - and C+ - ions with energy of 500 keV and 2 MeV, respectively. The specimens were irradiated at a fluence of 1017 ion/cm2. The microstructure changes after ionimplantation in the surface layer were investigated by transmission electron microscopy (TEM). The effect of ion-implantation on the tribological properties was also studied. After N+ and C+ ionimplantation an amorphous layer near to the surface has been formed which was observed by electron diffraction measurement. The wear tests were performed by means of a ball-on-disk configuration using commercially available Si3N4 ball. The friction coefficient was measured online, the wear coefficient was determined on the base of the wear scar sizes. The specific wear rate was reduced by N+-implantation and the coefficient of friction was lower in the initial stage in both cases.
Influence of Alumina Platelets on the Mechanical Strength of Porous Zirconia Tape
Authors: Rak Z.S.
Published: March 2009

The improvement of the mechanical strength of a porous anode support (NiO/8YSZ) induced by the addition of 5 to 10v% of alumina platelets to the basic composition was studied. The results obtained proved that the addition of 10v% alumina platelets, Placor 6, to the NiO/8YSZ composition improved the bending strength of the sintered material by nearly 20%, without any significant effect on the electrochemical performance. Changes in the processing procedure also had a strong influence on the mechanical strength, which resulted in the mechanical strength being increased to more than 100 MPa.
Determination of Dynamic Fracture Toughness of Si3N4 Ceramics by Instrumented Impact Test
Authors: Maros Maria Berkes , Helmeczi Nikoletta Kaulics , Lenkey B.Gy. , Arató Péter
Published: March 2009

The current paper give a brief overview over the principle and information content of the instrumented impact test completed by electro-emission measurement. Introducing over experiences taken by applying these test on a high-tech SiAlON ceramic a novel method for the determination of the dynamic fracture toughness of silicon nitride ceramics is suggested.
Eco- and Energy-Efficient Grinding Processes
Authors: Denkena Berend , Reichstein M. , Kramer Niklas , Jacobsen J. , Jung M.
Published: March 2009

Eco-efficiency of manufacturing processes is increasingly important. Here grinding is
supposed to be unfavorable because of the need for coolant and a high energy consumption per removed material volume. Nevertheless, it can be not be substituted by an alternative process due to the superior quality of ground parts. The overall eco-efficiency of grinding can be improved by different approaches. A better understanding of grinding processes and a modified setup of the process chain minimizes the material to be removed by grinding. Design changes of the machine tool can significantly reduce the energy consumption of additional devices as coolant supply units without a loss of flexibility. Adapted process parameters increase eco-efficiency and can also improve cost effectiveness while maintaining part quality.
Nano Mechanical Processing of Silicon by Atomic Force Microscopy
Authors: Miyake S. , Wang M. , Kim J.
Published: March 2009

Nanometer-scale protuberance and groove processing was performed on a silicon (Si) surface by diamond tip sliding using atomic force microscopy (AFM). The protuberances of 0-5 nm height were obtained the silicon surface by using the diamond tip of approximately 200 nm radius and the grooves of 0-2 nm depth were processed by the tip of about 50 nm radius. It was observed that both protuberance and groove were produced using the tip of about 100 nm radius. Indentation measurements show the hardness of processed parts was greater than that of unprocessed parts. Potassium hydroxide (KOH) solution etching was performed on the mechanochemically processed sample. The processed areas were prevented from etching due to the formation of a dense oxide layer. This may be because the processed parts were oxidized by tip sliding due to the effect of mechanochemical oxidation.
Drilling Assisted by Ultrasonic Elliptical Vibration
Authors: Ma Chun Xiang , Shamoto Eiji , Moriwaki T.
Published: March 2009

The drilling assisted by ultrasonic elliptical vibration (UEV) is proposed in present paper. The drilling system assisted by UEV was developed. The characteristics of the drilling process assisted by UEV are analyzed. The effect of ultrasonic elliptical vibration on the axial drilling force, the radial drilling force and the chip thickness are investigated experimentally. The experimental results show that the axial drilling force, the variation of the radial drilling force and the chip thickness of drilling assisted by UEV can be reduced.
Study on Ultrasonic Vibration Drilling of Particulate Reinforced Aluminum Matrix Composites
Authors: Liu C.S. , Zhao Bo , Gao G.F. , Zhang X.H.
Published: March 2009

Metal matrix composites（MMCs）is applied widely in recent years because of its
excellent performances, but the machining is very difficult due to the rigidity of reinforced-phase in it, so, the application of MMCs is restricted much. In this paper the experiment of common and ultrasonic vibration drilling is performed to SiC particulate reinforced Al matrix composites （SiCp/Al）by use of carbide-alloy-twist-drill, and the surface roughness of hole is compared, furthermore, the wearing of twist drill and the feature of chips are analyzed by scanning electron microscope (SEM). From above, we can draw aconclusion that ultrasonic vibration drilling may
meliorate the mechanism of drilling to some extent and it takes on much superiority that the common drilling is unmatched, so this method could provide a certain foundation for the posterior study and application.
The Effect of Secondary Piezoelectric Effect on the Measuring Precision of Quartz Dynamometers
Authors: Shi L.P. , Sun Bao Yuan , Qian Min
Published: March 2009

People apply quartz dynamometers to measure of milling force extensively. It is mainly made from piezoelectric quartz sensor. In this paper, the theory of the secondary piezoelectric effect is deduced by four kinds of piezoelectric equations. With the measuring the quartz stack secondary piezoelectric effect is verified. By theory and experiment we can show that the secondary piezoelectric effect makes elastic compliance constant of piezoelectric quartz smaller and do elastic stiffness constant of piezoelectric quartz bigger. Obviously, the secondary piezoelectric effect will have direct effect on the measuring precision of quartz dynamometers. So the investigations of secondary piezoelectric effect contribute to improving measuring precision of piezoelectric dynamometers.
Effect of Tool Segmentation in Ultrasonic Machining - Studies of Ultrasonic Die Sinking -
Authors: Saito O. , Kuriyagawa Tsunemoto
Published: March 2009

If a circular section tool is used for ultrasonic machining, cavitation occurs at its center. This cavitation suppresses the penetration of abrasive grains and leaves a projection at the center of a machined hole. On a square section tool, a cavitation vortex appears symmetrically on a diagonal line to promote the penetration of abrasive grains and makes the machining rate greater than that for a circular section tool. If the aspect ratio (ratio of vertical and horizontal dimensions) of the tool section is changed, the cavitation vortex changes the machining rate even when the sectional area is the same. For confirmation in detail, square section tools of different aspect ratios were created and used for SiC ultrasonic bottom die sinking to survey the machining characteristics. At the same time, tools having segmented square sections were checked for the occurrence of cavitation, and the influence on the
height of the projection generated by machining was studied. Consequently, a 4-segmented tool of 3 × 4.2 mm minimized the cavitation in each element and produced the greatest machining rate of 2.26 µm/s. In every machined hole, the tool suppressed the projection height within 50 µm.
Graph-Analytic Modification of the Method of Upper Estimation (Method of Energetic Geometry)
Authors: Alexandrov A.A. , Evstifeev V.V.
Published: March 2009

Graph-analytic modification of the known method of upper estimation is presented here. This method gives possibility to get easily and quickly the result of graphic design of process and speed godograph (locus). The given modification allows realize graphic calculation of speeds and efforts of deformation through ratio l/h excluding design of speed godograph. This process does not only simplify and formalize all solutions but also gives possibility to optimize results and find
defined parameters. Depending on the type of presented ratio l/h the given modification of this method attracts different kinds of graphic and analytic solutions. The results of calculation according to specific efforts coincide with known graph-analytic solution attained by the method of upper estimation with identical representation of the center of deformation. The usage of graphanalytic method in solution of energy expenses on the bases of geometric ratio allows find ways to
the definition of conformity deformation processes applying to as forging as other fields of mechanics. The given method of defining energetic expenditure during the process of deformation gives the possibility of seeing interaction between some parts of deformed body, caused by selforganization of the process. Stating laws of self-organization of deforming processes is the necessary task of mechanic as a whole, mechanics of a solid deformed body and its appliances.
Wavelet Transform Based 3D Scattered Data Processing in Binocular Micro Stereovision System
Authors: Liu C. , Pei W. , Xia Z.Y. , Niyokindi S. , Song J.C. , Wang Li Ding
Published: March 2009

In micro stereovision system, false matching due to the randomicity of image signal makes 3D reconstruction data contain a large amount of abnormal data in the form of noise (pulse noise, Gauss noise). In order to obtain a more accurate 3D reconstruction shape, a novel method of 3D scattered data processing, which is a combination of wavelet transform and extended Vector Median Filters, is proposed to use wavelet transform to realize primary denosing, and use extended Vector Median Filters to further denoise thereby achieving higher precision 3D measurement. In wavelet based denosing, wavelet based edge detector in vector space removes edge abnormal points effectively, moreover, boundary tracking is used to prune out the image background from the matching area to remove exterior abnormal points. Then the local areas determined by edges are filtered by extended vector median filter. Experimental results indicate that the method proposed is
effective to removing abnormal data from the 3D reconstructed data and enables 3D measurement position accuracy to reach 3 m µ .
Studies on CCD On-Line Measurement System for Grinding Wheel Wear
Authors: Zhang Yong Hong , Tang Hui Qiang , Hu De Jin
Published: March 2009

A CCD on-line image measurement system for curve grinding was schemed out according to the working process. Real-time images of work piece and wheel grinding can be gathered while using synchronal control and outer trigger technology. For the purpose of increasing the measurement precision, we presented a new method for locating edges in digital images to sub-pixel values based on local interpolation and spline fitting. An application of its validity and the comparison results of grinding wheel wear are also given. Experiments show that the proposed method in this paper is effective, and its detection precision and results are reasonable.
Detection of Fatigue Crack Growth in Aircraft Landing Gear, 4 Point Bend Test Specimens
Authors: Baxter M.G. , Pullin Rhys , Holford Karen M. , Evans S.L.
Published: March 2009

This investigation considers the identification of fatigue crack growth in aerospace grade steel using Acoustic Emission (AE) techniques. Four specimens with small radius crack initiation sites were investigated under four-point bending (SENB4). A linear array of 4 resonant AE sensors was utilised to locate the crack growth. Detection and location of fatigue crack growth in aerospace grade steel SENB4 specimens using appropriate AE techniques was successful. Time of arrival (TOA) linear location has provided an invaluable tool for separating AE signals arising from fatigue crack growth from the notch from those emanating from the loading points. Analysis of the AE feature data from the notch has allowed initial categorisation of AE from fatigue crack growth. AE data from this research was found to correspond with that reported in previous studies [1] examining Compact Tension (CT) specimens.
Assessment of Materials and Operational Imperfections in Rotating Machinery
Authors: Kiciński Jan
Published: March 2009

Presented have been the methods of modelling of the selected materials and operational imperfections (defects) like rotor cracks and hydrodynamic instability in rotating machines. Despite abundant information on this topic, there are still numerous problems to be solved. This regards primarily to the analysis of characteristic symptoms of such defects in the form of e.g. nonlinear vibrations and coupled forms of lateral, axial and torsional vibrations. The paper presents also author’s opinions concerning the one of the most intriguing operational imperfections, namely the formation of oil whirls and oil whips in slide bearings of a rotating machine. Coupled forms of vibration are generally a result of different kinds of couplings taking place in the system and interactions between construction and material imperfections.
Modeling and Analyzing of Vibration in Working Crankshaft with Cracks
Authors: Lei Xuan Yang , Zhang Gui Cai , Song Xi Geng , Chen Jin , Dong Guang Ming
Published: March 2009

In this paper, a simplified finite element model of the cracked crankshaft is proposed, and a new method for simulating the nonlinear vibration of operating crankshaft with several cracks is presented. For crankshaft, cracks occur frequently in the parts of crankpin-web fillet region and the edge of oil aperture because of fatigue or damage. According to the characteristic of those cracks, the cracked parts are modeled by the corresponding cracked spatial finite elements respectively, and two cracked elements are discussed in this study. The other, un-cracked, crankshaft parts are modeled by spatial Timoshenko beam elements. Flywheel and front pulley are simplified as lumped mass elements, and main bearings are simulated by equivalent linear springs and dashpots. In order to find the dynamic response of crankshaft-bearing system, a right-handed rotating coordinate system attached to crankshaft is applied. Based on the proposed finite element model, the breathing behavior of cracks in operating crankshaft is studied, and the nonlinear motion equation with variational stiffness is formed. Finally, a four-in-line crankshaft is taken as an example, and its vibration response corresponding to different kinds of crack are calculated and analyzed. Some conclusions are drawn, and a foundation is laid for diagnosing crack fault of crankshaft.
Acceptable Dislocation of Bearings of the Turbine Set Considering Permissible Vibration and Load of the Bearings
Authors: Rybczynski Jozef
Published: March 2009

The paper presents the procedure and the results of determination of acceptable dislocation for particular bearings of the large power turbine set. The ranges have been evaluated by numerical analysis of the turbine set model. Acceptable dislocations of the bearings were calculated in horizontal and vertical direction separately in regard to criterion of permissible bearing vibration and in regard to permissible bearing load. The results have been presented graphically in the form of areas of acceptable dislocations, which allow the comparison considering both criteria. The paper contains exemplary trajectory graphs for all bearings corresponding to maximum acceptable dislocations. The investigations revealed asymmetry of areas of acceptable dislocations, which suggests that the constructional kinetostatic line of rotors is not optimal.
Vibration Behaviour of a Disc Assembly with a Cracked Lacing Wire
Authors: Szwedowicz Dariusz , Acosta Carlos , Bedolla Jorge , Martinez Eladio
Published: March 2009

In this paper, mathematical descriptions of the static and dynamic behaviour of the bladed disc with the undamaged and damaged lacing wire are briefly explained. For a steam turbine disc with 70 axial blades coupled by the lacing wire, the centrifugal static analysis is performed. Then, the free and forced vibrations are computed to find differences in vibrations of the bladed disc with and without a failure in the lacing wire. The tip timing measurement is considered as an experimental tool for identifications of possible failures. According to the obtained FE results, a failure of the lacing wire in the rotating disc assembly can be identified by monitoring the centrifugal deformations of the blade tips, resonance frequencies and response amplitudes of the whole bladed disc. The dynamic behaviours of the failure-free disc and with cracked wire connection are compared to each other to outline differences in the known nodal diameter and dispersion curve definition.
Application of Statistical Energy Analysis for Damage Detection in Spacecraft Structures
Authors: López-Díez J. , Torrealba M. , Güemes A. , Cuerno-Rejado C.
Published: March 2009

This paper analyses the applicability of the Statistical Energy Analysis (SEA) for detecting incipient damages in a typical spacecraft structure, as a stiffened panel. The damage on attachment element is investigated by analyzing its influence on the system characteristics. Because of incipient damage affects mainly on highest modes, rather than on lowest, the coupling loss factor between sub-elements can be used to detect and localize the damage.
Health Monitoring: New Techniques Based on Vibrations Measurements and Identification Algorithms on an Aeronautical Composite Panel
Authors: Bovio Igor , Della Ragione M. , Lecce Leonardo
Published: March 2009

Purpose of the paper is to present a new application of a Non Destructive Test based on vibrations measurements, developed by the authors and already tested for analysing damage of many structural elements. The proposed new method is based on the acquisition and comparison of Frequency Response Functions (FRFs) of the monitored structure before and after an occurred damage. Structural damage modify the dynamical behaviour of the structure such as mass, stiffened and damping, and consequently its FRFs, making possible to identify and quantify a structural damage. The activities, presented in the paper, mostly focused on a new FRFs processing technique based on a dedicated neural network algorithm aimed at obtaining a “recognition-based learning”; this kind of learning methodology permits to train the neural network in order to let it recognise only “positive” examples discarding, as a consequence, the “negative” ones. Within the structural NDT a “positive” example means “healthy” state of the analysed structural component and, obviously, a “negative” one means a “damaged” or perturbed state. The developed NDT has been tested for identifying and analysing damage on an aeronautical composite panel to validate the method and calibrate the neural network algorithm. These tests have permitted to understand the influence of environmental parameters on the neural network training capability. Thanks to these new techniques it is possible to carry out a smart Health Monitoring system which is going to lead to the reduction of time and maintenance cost and to the increase of the aeronautical structure safety and reliability.
A Uniplanar Capacitive Approach for Subsurface Damage Detection of Nonmetallic Materials
Authors: Dong Ensheng , Dong Yong Gui , Lv Wener , Jia Huibo , Li Jun
Published: March 2009

The detection and characterisation of subsurface flaws in nonmetallic materials are very important for people’s health, lives, and environment. Possible damage must be detected early and reliably. A capacitive approach for detecting the subsurface cracks is discussed. A uniplanar capacitive sensor with multi-electrodes for obtaining the corresponding electrical capacitance information of the measured slab is presented. An experimental rig, which is composed of a uniplanar capacitive sensor of 8-electrodes and two engineering plastic samples, has been built for damage detection of nonmetallic material. Principal component analysis is used to extract relevant features from capacitance values for damage detection and identification. The simulated, as well as the preliminary experimental results show that the current approach is capable of detecting subsurface damages of nonmetallic materials and discriminating the flaws. The proposed approach is feasible and effective for damage detection and health monitoring.
Identification of Crack Damage with Wavelet Finite Element
Authors: Chen Xue Feng , He Zheng Jia , Gao Qiang , Zi Yanyang
Published: March 2009

An improved method to identify the crack location and size is presented which takes advantages of wavelet finite element (WFE). The important property of wavelet analysis is the capability to represent functions in a dynamic multiscale manner, so solution with WFE enables a hierarchical approximation to the exact solution. WFE has good ability in modal analysis for singularity problems like a cracked beam. The crack in a beam is modeled with WFE and represented as a rotational spring. The additional flexibility caused by crack in its vicinity is evaluated according to linear and elastic fracture mechanics theory. The WFE stiffness matrix of the crack is constructed and the algorithm for crack identification through the use of vibration-based inspection (VBI) is developed. With the accurate natural frequencies obtained from the transient signal measured, graphs of crack equivalent stiffness versus crack location are plotted, by providing the first three natural frequencies as an input. The intersection of the three curves gives the crack location and size. Experimental studies of cracked shafts are presented to demonstrate the accuracy of the method. The error in identification of crack location and size are both less than 2%. This study provides the new method for the diagnosis of incipient small crack.
Modal Analysis of a Reinforced Concrete Frame in Various States of Damage
Authors: Zembaty Zbigniew , Kowalski Marcin
Published: March 2009

The purpose of this paper is to report selected results of an experiment in which two,
natural size r/c frames were put on shaking table and subjected to a sequence of seismic excitations with increasing intensity interlaced with low level, diagnostic tests. The shaking table experiment aimed at working out new methodology for monitoring vibrations of r/c structures to assess their state. Characteristic decrease of natural frequencies and increase of structural damping was observed and analyzed in detail. It was interesting to note 20 per cent drop in natural frequencies prior to visual detection of any cracks.
A Resonant Frequency Measurement System for Osseointegration Trans-Femoral Implant
Authors: Xu W. , Shao F. , Ewins D.
Published: March 2009

The osseointegration trans-femoral implant is a new orthopedic anchoring method to
attach prosthetic limb. The success of this technique depends on how healthy the osseointegration between implant and bone can be achieved and how the post-surgical rehabilitation is progressed. The current clinical practice is based on patient fitness feeling. To achieve a high success rate of osseointegration and an optimal rehabilitation process, a quantitative measurement of the degree of osseointegration is required. In this paper, the authors present a non-invasive method to determine the stability of an osseointegration trans-femoral implant system. It uses resonant frequency of implant system to observe the integration between the implant and bone. The vibration signals of a trans-femoral implant system were collected using an accelerometer attached to the implant abutment and analyzed using Fast Fourier Transform (FFT). The results of in vitro tests are presented to demonstrate that the developed instrument system can be used in future in vivo clinical research.
Influence of the Size of Round Objects on the Output Signal of Laser Measuring Scanner
Authors: Jabłoński Ryszard
Published: March 2009

In laser measuring scanners, in addition to the ideal output signal, interfering signals occur. They are due to superimposition of diffracted, reflected, scattered, incident, transmitted and interfering light. The proportions between the mentioned components vary in time and also the total intensity distribution changes. Having the above in view, a close analysis of detector signal was carried out. It was proved that for certain beam parameters the intensity distribution pattern depends on the geometry of object and the real dimension of an object can be calculated by introduction of the size dependent correction.
Process Analysis and Characterization of ASNSS Using Automatic On-Line Measurement
Authors: Chen Liang Chia , Sun J.Y. , Tsung Tsing Tshih , Chang H. , Lin Hong Ming
Published: March 2009

This article presents the development of an automatic on-line measurement system for characterizing a nanoparticle manufacturing process known as Arc Spray Nanoparticle Synthesis System (ASNSS). The ASNSS has been developed to generate metal nanoparticles and to explore the optimum system parameters for producing the desired nanopowders. Preliminary experimental results indicate that the size of nanoparticles, widely ranging from 10nm to 300nm, is significantly affected by the process parameters such as operating pressure, temperature, electrical current and type of dielectric liquid used. The on-line measurement system was developed to provide an effective multi-solution for characterizing the nanoparticle synthesis process and for monitoring the manufacturing quality of the ASNSS. Experiments were conducted to identify the optimum sampling period and volume of the particle suspension for accurate sampling and data acquisition. Experimental results revealed that a sampling duration of 20 minutes and a dielectric volume of 40 c.c. can achieve effective data representation while maximizing the sampling efficiency.
A Fast Search Coil Sensing Method for Tracking Systems
Authors: Cai Z.J. , Zeng Li Jiang
Published: March 2009

It is important to track a free flying insect to investigate its flight performance. Conventional video tracking systems are difficult to track a highly maneuverable insect, because the capture frequency of the camera is limited and it can hardly get the position of the insect in real time. We proposed a fast sensing method for insect tracking based on magnetic search coil sensors. It can simultaneously determine the orientation and position of the sensors. We constructed a system, calibrated the magnetic device. We developed a set of calculating methods and measured several positions and angles of coil sensors. The results show that it can rapidly provide the tracking feedback information to meet the requirement for insect tracking.
Prediction of the Fatigue Life of Tires Using CED and VCCT
Authors: Kim T.W. , Jeong H.Y. , Choe J.H. , Kim Y.H.
Published: March 2009

A new simulation methodology using the finite element method (FEM) was proposed to predict the fatigue life of tires. In the FEM simulation the cracking energy density (CED) was calculated, and the virtual crack closure technique (VCCT) was used to calculate the strain energy release rate (SERR) for a crack. First, a plane in an element on which CED had its maximum was determined, and a crack was created on the plane. Once a crack was introduced, another plane on which CED had its maximum was again determined, and the crack was further elongated along the plane. In addition, SERR was calculated for every crack increment by using VCCT, and it was represented as a function of the crack length. Then, the fatigue life of a tire was determined using Paris law. For Paris law, the initial crack length and the final crack length as well as the material constants
should be known. In this paper, the initial crack length was set in a way that the fatigue life predicted by using Paris law became the same as the test data for a tire model (Tire A), and the final crack length was determined from the cross-section views of failed tires which showed cracks grown about halfway toward the carcass from the carcass turn-up edge. Finally, the fatigue life for another tire model (Tire B) was predicted by using Paris law, and the predicted fatigue life was compared with the test data.
Yield Criterion and Constitutive Model for Ductile Materials with Hydrogen and Deformation Induced Voids
Authors: Zhang Jian Ping , Shi Hui Ji , Yin Ya Jun
Published: March 2009

Using the method of mesomechanics, a represent volume element (RVE) with internal pressure acted on the inner wall of the void is suggested to simulate the hydrogen induced cracking (HIC) in porous ductile materials. Based on this RVE, yield criterion is derived and constitutive model is constructed. Simulations show that the hydrogen pressure intensively reduces the yield stress for porous ductile materials
Crack Growth Simulation of Arbitrarily Shaped 3D Cracks Using Finite Element Alternating Method
Authors: Kim Tae Soon , Park Sang Yun , Park Jai Hak
Published: March 2009

In order to simulate the growth of arbitrarily shaped three dimensional cracks, the finite element alternating method is extended. As the required analytical solution for a crack in an infinite body, the symmetric Galerkin boundary element method formulated by Li and Mear is used. In the study, a crack is modeled as distribution of displacement discontinuities, and the governing equation is formulated as singularity-reduced integral equations. With the proposed method several example problems for three dimensional cracks in an infinite solid, as well as their growth under fatigue, are
solved and the accuracy and efficiency of the method are demonstrated.
Microstructure and Creep Behavior of BN/Al (-Mg) Metal Matrix Composite
Authors: Lee Dong Bok , Woo Seung Wan , Bae Si Yon , Lim Byeong Soo
Published: March 2009

Metal matrix composites (MMC) that consisted of Al (-Mg) matrix reinforced with initially added BN particles were fabricated using the pressureless infiltration technique. Initially added BN particles were partly consumed to make AlN, as new reinforcing particles. The other reaction product was MgAlB2 dispersoids. The creep behavior was investigated between 225- 275oC in air. Despite of the presence of the reinforcing particles, the creep resistance was found to be unsatisfactory due to the weak Al (-Mg) matrix.
3-D Micromechanics Model for Progressive Failure Analysis of Laminated Cylindrical Composite Shell
Authors: Liang Zheng Zhao , Tang Chun An , Zhao De Shen , Zhang Yong Bin , Xu Tao , Zhang Hou Quan
Published: March 2009

A newly developed numerical code MFPA3D is applied to simulate the progressive
damage and failure process of laminated cylindrical composite shell. Heterogeneities in meso-scale are taken into account by randomly distributing the material properties throughout the model by following a Weibull statistical distribution. The cylindrical composite shell is discretized into 3-D block elements with the fixed size and is subjected to a lateral compressive loading, applied with a constant displacement control manner. The numerical simulation results show that not only the process of crack initiation, propagation and coalescence but also the failure process can be numerically obtained in three dimensional. The MFPA3D modeling demonstrates that the code can simulate non-linear behavior of brittle materials with a simple mesoscopic constitutive law with a strength and elastic modulus reduction of the weaken elements.
Tensile Pre-Strain Effects on Torsional Fatigue Properties of Medium Carbon Steels
Authors: Zhou Cong Ling , Nishida Shinichi , Hattori Nobusuke , Sun Wen Xian
Published: March 2009

This study was focused on the effects of pre-strain on the torsional fatigue properties of three kinds of medium carbon steels, including the fatigue strength, surface hardness, microstructure, and the crack initiation and propagation behaviors. The effect of pre-strain on the non-propagating cracks was also discussed. The main results obtained in this test are as follows: 1) the fatigue limits
increase with the increasing of tensile pre-strain ratio for all kinds of the test materials; 2) under certain stress amplitude, with the increasing of tensile pre-strain ratio, the fatigue crack initiates a little earlier and propagates faster; 3) the length of non-propagating crack decreases with the increasing of tensile pre-strain ratio.
Influence of Hydrogen on Tensile Property of Ti-6Al-4V
Authors: Sun Dong Li , Li Zhong Hua , Han X. , Wang Qing
Published: March 2009

The influence of hydrogen content on the microstructure and the tensile property of
Ti-6Al-4V alloy was studied, and the phenomenon of minimum yield stress at certain hydrogen content was discussed. The results show that Ti-6Al-4V alloy can absorb hydrogen above 600°C and the different hydrogen contents can be achieved by changing the flow rate of hydrogen. With increase of hydrogen contents, the microstructure gradually transforms from the original near basket-type to the α clusters which consist of α plates and hydrides distributed in α plates, and then to the mixture of α, β and the large amount of hydrides. When the specimens tensioned at 600°C, their strength first decreases and then increases, but their ductility changes quite the contrary as increasing hydrogen contents. There is optimum hydrogen content at which the strength is the lowest and the plasticity is the highest for the specimens tensioned at 600°C. Ti-6Al-4V alloy may gain the higher tensile strength or better ductility at 600°C through appropriate hydrogenation treatment in comparison with samples untreated. With increase of hydrogen contents, the fracture type transforms from microvoid coalescence type to “cleavage like” type for specimens tensioned at 600°C.
Influence of Microstructure on Small Crack Behavior
Authors: Kamaya Masayuki , Kitamura Takayuki
Published: March 2009

Averaging the anisotropy of each crystal, the macroscopic behavior of polycrystalline materials is isotropic and homogenous in terms of elastic deformation. However, the anisotropic property of each crystal influences on the local stress field ahead of a crack tip if the crack size is not large enough in comparison with the grain diameter. This brings about the change in the crack driving force (CDF) such as stress intensity factors. In the present study, in order to investigate the cause and magnitude of the change in the CDF, the finite element analysis is performed. The calculations are carried out for a single crystal model, a bi-crystal model, and a polycrystal model containing a transgranular or an intergranular semi-circular crack. The results implied that the magnitude of CDF is dependent not only on the crystal orientation but also on the deformation-constraint caused by the difference in elastic modulus of grains near the crack tip. The statistical scatter of CDF due to the random crystal orientation in a polycrystal is examined by a Monte Carlo simulation. The variation in the SIF becomes small as the crack size increases.
Fatigue Properties of Smart Electrorheological Materials
Authors: Choi Seung Bok , Kim Kyung Su
Published: March 2009

In this study, both mechanical and electrical fatigue properties of electrorheological (ER) materials whose global characteristics can be controlled by an external electric field are experimentally evaluated. In order to investigate the mechanical fatigue property, a linear reciprocating apparatus is devised and operated by the hydraulic unit. Two important characteristics of methylcellulose based ER material: the field-dependent yield stress and current density are investigated as a function of the operating cycle. The electrical fatigue property is investigated by applying high voltage to the ER material domain through the electrode gap. The voltage is imposed in on-off manner for the specific cycles by changing the field intensity. The yield stress and current density of the ER material are evaluated at each specified cycle and surface roughness of the electrode is observed as well.