bluuebunny/crossref_metadata_2025 huggingface dataset:
Machining Cracks in Finished Ceramics
Authors: Quinn George D. , Ives Lewis K. , Jahanmir S.
Published: March 2009

Grinding may create flaws that control strength and limit the performance of finished ceramics. Machining cracks sometimes have been difficult or impossible to find especially in toughened ceramics with interlocking grain microstructures that create rough fracture surfaces. Our fractographic examinations show that machining damage leaves telltale markings on fracture surfaces that may be easily detected using common fractographic techniques. A comprehensive study with over 400 ground rods and rectangular bars was conducted on several commercial silicon nitrides to study the effects of various machining conditions. Similarities and differences in behavior were observed. A paradoxical finding was that tougher silicon nitrides developed deeper grinding cracks. Machining crack size and shape strongly depended on the grinding wheel grit size.
Development of Preparation Processes for CNT/Si3N4 Composites
Authors: Balázsi Csaba , Wéber Ferenc , Kövér Zsuzsanna , Kónya Zoltán , Kiricsi Imre , Biró L.P. , Arató Péter
Published: March 2009

Silicon nitride based composites with different amount (1, 3 and 5 wt%) of carbon
nanotubes have been prepared. Optimisation of the manufacturing processes has been conducted to preserve the carbon nanotubes in composites and to avoid damaging during high temperature processing. The first results show that carbon nanotubes have a good contact to the surface of silicon nitride grains. With increasing the carbon nanotube content a lower densification rate was obtained together with the deterioration of the mechanical characteristics of composites. In the case of 1wt% and 3 wt% carbon nanotube addition the increase of pressure resulted in increase of bending strength. It was found that microstructure features achieved by properly designed sintering parameters are the main responsible factors for the strength improvements.
Thermal Shock Behavior of an Al2O3/ZrO2 Multilayered Ceramic with Residual Stresses due to Phase Transformations
Authors: Bermejo Raúl , Llanes Luis , Anglada Marc , Supancic Peter , Lube Tanja
Published: March 2009

In this work, the thermal shock behavior of an Al2O3-5%tZrO2/Al2O3-30%mZrO2 multilayer ceramic is studied. On these materials, a tetragonal to monoclinic phase transformation within the Al2O3-30%mZrO2 layers takes place when cooling down from sintering. The latter induces an increase in volume and therefore compressive residual stresses arise in these layers. The residual stress distribution profile in the laminate influences the thermal shock response of the material. A finite element model has been developed to estimate both the thermal strain effects during the sintering process as well as the temperature distribution and stress profile within the laminate during thermal shock testing. Experimental tests on the monoliths and laminates were carried out and compared to the model. It is observed that the presence of the compressive layers within the laminate inhibits the penetration of thermal shock cracks into the body at even more severe conditions than in the monolithic material.
Residual Stresses in Al2O3-ZrO2 Laminar System
Authors: Zimovčák Peter , Köves Tibor , Dusza Ján , Chalvet Francis , de Portu Goffredo
Published: March 2009

The aim of the paper is to present an analytical model of thermal stresses in a
laminar system, and consequently to verify the model validity by comparing calculated thermal stresses with measured ones by indentation method. Analytical models of thermal stresses acting in anisotropic and isotropic laminar plane systems are presented, and consequently applied to the thermal-stress-strengthened Al2O3-ZrO2 laminar ceramics.
Fracture Toughness of Ceramic Materials and Its Relationship to Chipping Formation
Authors: Jonšta Zdenĕk , Horváthová Jana , Blažková Kateřina , Mazanec Karel
Published: March 2009

The work is devoted to the evaluation of indentation fracture toughness in ceramic materials and to the comparison of these data with the results of this characterisation obtained by the application of fracture mechanics method (chevron notched beam specimen – CVNB). The indentation fracture toughness measurement is realized using the indentation load lying in the loading extent between 50-300 N. The evaluation of basic parameters of lateral crack initiation resulting in chipping formation in the vicinity of indent is performed. This measuring is based on the finding of relationship between the indent load level and the number of loading cycles leading to chips formation. The geometry of lateral cracks and chipping morphology are described. This evaluation is complemented with the analysis of chip fracture surfaces.
Failure Analysis on a De-NOx Catalyst of a Large Waste Burner
Authors: Kübler Jakob , Baechtold R. , Blugan Gurdial , Lemster K. , Fuso S.
Published: March 2009

Modern waste burners are equipped with catalysts to reduce NOX. During operation the catalysts and their performance are influenced by, for example rapid temperature changes, facility vibrations, cleaning procedures and unwashed exhaust gas (when the catalyst is installed before the washer). The catalyst discussed in this paper comprised over 2’500 extruded elements of 150 x 150 x 770 mm3. During commissioning the catalyst elements exhibited a tendency to spall off pieces, thus preventing acceptance of the plant. For the failure analysis, one element from the catalyst was removed and two spare elements were selected. The investigation comprised a visual check, fractography, measurement of the most important physical, mechanical and chemical properties, and a microstructural analysis. It could be shown that:
− Processing defects, such as extrusion defects, were the source of cracks which led to pieces spalling off;
− Hot steam, used for periodic cleaning, reduced the structural strength by half;
− The elements were exposed to higher mechanical loads than expected during transport;
− The cleaning process, in combination with particles transported by the exhaust gas, has an erosive effect on the catalyst material;
− Blockages, caused by catalyst material among other things, could be found at different depths;
− The chemical composition did not significantly differ between used and unused elements.
In summary, the failure analysis led to an understanding of the failure mechanism and to a set of recommendations for improvements whose implementation ultimately led to the plant being cleared for operation.
Energy-Mode Adjustment in Laser Processing a Small Vitrified CBN Grinding Wheel
Authors: Wang Xu Yue , Wu Yong Bo , Kang Ren Ke , Wang Jun , Xu Wen Ji , Kato M.
Published: March 2009

A study of the energy-mode adjustment and application was presented to investigate the effects of adjustable methods on energy mode. Three methods of energy-mode adjustment were used: by circular profile itself, by an optical scanning expander and deformable mirror. The circular profile naturally modifies energy density with the changes of incident angle. The optical scanning expander was used to turn a Gaussian beam into a uniform beam. Also a novel technique of deformable mirror was designed to obtain a more controllable energy mode for laser selective processing. Moreover, the models describing energy modes were developed to improve laser-processing performance. An experiment was arranged to simulate single-tip diamond truing and produced a result, as shown in the SEM photo, quite similar to a fine thread. The results were discussed to reveal the mechanism of laser processing.
Development on Micro Precision Truing Method of ELID-Grinding Wheel (2nd Report: Application to Edge Sharpening of Large Wheel)
Authors: Yin Shao Hui , Lin Wei Min , Uehara Yoshihiro , MORITA Shinya , Ohmori Hitoshi , Asami Muneaki , Ohmori M.
Published: March 2009

In V-groove ELID grinding process, to achieve optimal grinding performance and
satisfactory surface quality and profile accuracy, metal bonded diamond grinding wheels need to be carefully sharpened. In this paper, we applied the proposed new micro-truing method consisting of electro-discharge truing and electrolysis-assisted mechanical truing to sharpen the edge of large grinding wheels. The minimum wheel tip radiuses of 6.3 and 8.5µm were achieved for the #4000 and #20000 grinding wheels. The truing mechanisms and sharpening performance are also discussed.
Study on Lubricating and Cooling Effects of Several Cooling Systems Used in Face Grinding
Authors: Tanaka Takeshi , Kobayashi T.
Published: March 2009

We observed that the lubrication effect is greater than the cooling effect for decreasing the friction heat in face grinding. It was clarified that cool-air grinding is difficult to apply to face grinding under the present grinding conditions. We could obtain the minimum ground surface roughness (hereafter noted as surface roughness) at a mist suppｌy volume of 15 to 30ml/h in mist grinding. The largest stock removal rate (hereafter noted as grinding efficiency) is obtained in mist grinding. However, grinding efficient was small in cool-air mist grinding, by which a large cooling effect of cool air was expected. Though mist and cool-air mist grinding perform similar to wet grinding in few grinding passes, wet grinding is properly applied by large chip removal action in many grinding passes.
Effects of Actively Cooled Coolant for Grinding Brittle Materials
Authors: Gao Y. , Lai H. , Tse S.
Published: March 2009

To solve the problem associated with the cryogenic cooling approach and the one with the chilled air approach, an actively cooled coolant approach is proposed and examined. The proposed cooling system is also able to reduce the time period to reach the equilibrium state to enhance productivity. An active cooling prototype was developed that utilizes a compact air conditioner design, which is easy to use, movable, and can be easily fitted into different type of machine designs with relatively low costs. The system is based on the use of forced convection of the heat generated during the machining process. Experimental and computational studies of the effects of actively cooled coolant for grinding brittle materials are carried out. The experimental results show that the use of actively cooled coolant is able to improve surface quality for up to 13.1% on average in terms of surface roughness Ra. The results of optical and SEM examinations confirmed that the proposed approach is advantageous. Computational testing results show that the heat can be taken away more effectively by using the proposed approach.
Development of New Device for Form-Grinding and Research on the Profile-Accuracy
Authors: Yan Qiu Sheng , Kong Ling Ye , Wu N.Q. , Chen Shao Bo , Zhang Zi Qiang , Zheng Zhi Dan
Published: March 2009

The profile accuracy of the workpiece is mainly determined by the accuracy of abrasive wheel in the form-grinding process. Thus, the shaped wheel dressing becomes one of the key points in the form-grinding process. In order to grind the revolving curved surfaces grooves whose cross-sectional profiles are steep and smooth, a new NC dresser with three NC axes is developed by adding a swing axis on the basis of NC external cylindrical grinding machine. A wheel of any desired convex profile can be dressed when using the Diaform single-diamond dresser and the possible geometrical interference between the single-diamond dresser and wheel can be eliminated. By analyzing the influence of installation accuracy on the profile accuracy, a method of comprehensive error compensation is presented. The comprehensive errors can be diminished greatly to improve the profile accuracy by means of error compensation. It is proved in the experiments that the precision requirements of grinding the formed surfaces grooves can be met.
Quality of Deburring and Surface Finishing (DSF) in Russia
Authors: Babichev Anatoly P.
Published: March 2009

The examination of deburring and surface finishing (DSF) quality was held at the
enterprises of Russia. Here are the results of the examination. It was held on the base of general conclusion from the Scientific Research Institute “V and T” investigation results. The practical use of DSF at the engineering plants was also taken into account.
Lapping Machining of High-Speed and High-Precision Ceramic Bearing Balls
Authors: Wu Yu Hou , Li Song Hua , Zhang Ke
Published: March 2009

In resent years, ceramic balls have been applied into precision bearings and other parts far and wide because of its advantages in light weight, high hardness, abrasive resistance, high-temperature resistance, corrosion resistance, little heat expansion coefficient and so on. The high-precision ceramic balls are machined by lapping usually, and the method of lapping has an important influence on the machining precision and efficiency of ceramic balls. In order to improve the precision and efficiency of ceramic ball machining, in the paper, a new cone lapping method is
researched by the lapping experiment. The research result shows that the cone method is the optimal lapping method with high precision, high efficiency and the very simple machine. Furthermore, the mechanics characteristic of the cone lapping method have been analyzed and summarized, which will provide the basic principle and theoretical basis for the choice of primary geometry and mechanics parameter in the process of ceramic balls lapping.
Improvement of Machined Surface Flatness in Ultra-Precision Plane Honing
Authors: Suzuki Shinya , Yoshihara Nobuhito , Kuriyagawa Tsunemoto
Published: March 2009

In recent years, there has been a great demand for large-diameter wafers with high
flatness of hard and brittle materials that are used as optical and sensor elements. To meet these demands, we have developed an ultra-precision plane honing method as a highly efficient surface finishing technique using a fixed abrasive. This technique offers good finish surface roughness, shallow subsurface damage and high machining efficiency. However, there is a need to improve the surface flatness, which is dependent on the grinding wheel surface flatness and the tilt of the spindles. In this paper, the relationship between grinding wheel surface flatness and the shape of a truer is investigated by calculating the contact length of a point on the grinding wheel with the truer. It was found that there is an optimum shape of the truer to make the grinding wheel surface flat, and the machined 3-inch glass wafer is controlled to a flatness of less than 1µm by using the optimum truer.
Thinning Technology of Patterned Silicon Wafer for Micro Pressure Sensor
Authors: Nagano T. , Touge Mutsumi , Watanabe Junji
Published: March 2009

Recently, the research of the gene using the transgenic mouse has been performed for the development of new medicines. However, 600,000 kinds of mice are produced for the elucidation of each gene function. For this reason, the intelligent microchips have been developed to obtain an individual identification and biological information. The ventricular rate of a mouse can be monitored by the micro pressure sensor mounted on the intelligent microchip. In this research, the detailed structure and functions of the micro pressure sensor were investigated by the FEM analysis, and the sensor-chips were manufactured on 6-inch silicon wafer. The wafer thickness had to be reduced owing to the size restriction of the intelligent microchip. The grinding of the 6-inch silicon wafer with 560 µm in thickness with 19200 sensor-chips was carried out by the newly developed thinning technology. After the basic characteristics of a sensor-chip were evaluated, the output profile containing small peaks corresponding to the heartbeat of a transgenic mouse was finally detected
using a mounted sensor-chip.
Mathematical Models for the Hydrodynamic Characteristics of Abrasive Waterjets
Authors: Wang Jun , Liu H.
Published: March 2009

Predictive models for the particle velocity in an abrasive waterjet (AWJ) are developed following a CFD (computational fluid dynamics) study. A numerical study is then carried out to assess the models. It is shown that the predictive models can adequately predict this particle characteristic in an AWJ.
Studies on NC Machining for Cylindrical Cams
Authors: Gao Wei Qiang , Yan Qiu Sheng , Liang J. , Liu Z.Y.
Published: March 2009

Cylindrical cam mechanisms have many merits, such as compact configuration, low cost, high reliability, better performance of kinematics and dynamics, and they have been widely used in fields of automatization and mechanization. Cylindrical cam mechanisms are the spatial mechanisms. Traditional methods of design and machining for cylindrical cam were complex, and it was difficult to ensure the precision of machining cylindrical cams, so it is impossible to meet the requirement of the development of high-speed automatic equipments. The better method of machining for cylindrical cams is to use the NC milling machine with 3 moving coordinates and 1 revolving coordinate. The key to realize the machining method is to resolve the problem of calculating tool’s paths for NC machining from the motion rule of followers of cam mechanisms. In this paper, the programming principle and technology of NC machining for cylindrical cams were analyzed, the compensation of
cutting-tool radius for NC machining was discussed, the method of calculation for motion rule of cam followers and method of programming of NC machining with 4-coordinates were proposed, through which perfect effect have been gained in practice.
A New Application of PCD as a Very Low Wear Electrode Material for EDM
Authors: Suzuki Kiyoshi , Sharma Anurag , Sano Sadao , Iwai Manabu , Uematsu Tetsutaro
Published: March 2009

Electrically conductive CVD diamond having a high thermal diffusivity, when used as an electrode for micro EDM, revealed very low wear compared to copper and Cu-W electrodes in the case of finish EDM condition, where the short pulse duration is adopted. In this research work polycrystalline diamond (PCD), which has a thermal conductivity similar to that of the electrically conductive CVD diamond, is introduced as a new composite electrode material for EDM. Various properties of PCD with respect to EDM of die-steel (SKD11) and tungsten carbide (G5) have been studied and compared with those of the electrically conductive CVD diamond, copper and copper-tungsten electrode materials. It is found that electrode wear and material removal rate decreased with an increase in thermal conductivity depending on the type of the PCD material when very short pulse duration of te=1µs is applied. Extremely low wear, 1/20~1/50 times of the Cu-W electrode in the case of EDM of tungsten carbide workpiece at short pulse duration and zero wear in the case of EDM at short and long pulse duration of SKD11 can be realized.
A Study of Surface Integrity in WEDM-HS with Air Medium
Authors: Guo Zhong Ning , Liu Jiang Wen , Zeng F.Z.
Published: March 2009

In wire electro-discharge machining with high traveling speed(WEDM-HS), the emulsion is used as working liquid. Because there exists a functional electrolyte, this affects the surface quality of workpiece machined. An investigation has been made into the machining feasibility when the gas or air is employed as processing medium. The first cut on workpiece is done with emulsion, and then air or distilled water is used for the second cut and multi-cuts. After machining, the surface quality and mechanical performance of the specimen under different conditions are compared. The experimental results show that air and distilled water have little influence on the surface roughness, but they can improve the mechanical performance such as the increase of hardness and the decrease of surface cracks. An orthogonal design is adopted to optimize the electric parameters and cutting passes so as to obtain the best integrative result. The experiment with air as medium reveals that it is a feasible and effective way for eliminating the electrolytic layer and improving the surface integrity of workpiece.
A New Diamond Wheel Containing Boron Doped Diamond Abrasives Enabling Electrically Conductive Cutting Edge and High Thermal Stability
Authors: Suzuki Kiyoshi , Iwai Manabu , Ninomiya Shinichi , Takeuchi Keizo , Tanaka Katsutoshi , Tanaka Y. , Uematsu Tetsutaro
Published: March 2009

Electrically conductive cutting edges diamond grinding wheels (EC-cutting edges D
wheels) have properties such as, 1) convenient precise forming by EDM, 2) realization of high cutting edge density, 3) sufficiently large chip pockets along with fine cutting edges on large diamond grits, 4) contact sensing of the cutting edges with workpiece due to electrical conductivity, 5) expected application to the grinding of various types of steels due to high thermal resistance. Until now, the
grinding ability of the sharp edges generated on the electrically conductive CVD diamond thick film wheel by electrodischarge trueing (ED trueing) was confirmed by grinding experiments using a small diameter lapping wheel and a small diameter disk wheel. In this research work, metal bonded diamond wheels containing boron doped electrically conductive diamond (EC diamond) grits, which possess high oxidation temperature, were trial manufactured. From the results of grinding test for an optical glass (BK7), it was found that the wear and grinding force for the EC diamond grits wheel were significantly low compared to a conventional diamond grits wheel. Furthermore, from the results of the investigation on ED trueing performance, a high trueing efficiency along with the possibility of cutting edge tip formation was confirmed.
Signal Analysis of Acoustic Emission for Laser Imitating Grinding Burn
Authors: Chen Xun , Liu Q.S. , Gindy Nabil
Published: March 2009

Grinding burn is a common phenomenon of thermal damage that has been one of the main constraints in grinding in respect of high efficiency and quality. Use of acoustic emission technique for identifying grinding burn was reported before. However, the AE features of grinding burn are relatively weak and easily merged by other AE sources. This paper presents an investigation of the AE features of the thermal expansion induced by laser irradiation, which was designed to simulate grinding thermal behaviour. By means of the wavelet packet transforms, AE features at the grinding burn temperature can successfully be extracted without other mechanical interferential factors. These clean features can provide a firm foundation for analysing the real grinding burn AE features and for monitoring grinding burn.
Damage Identification of a Mechanical Structure with a Non-Minimum Phase Based on Singular Value Decomposition
Authors: Lee Sang Kwon , Rho Kyung-Rae , Gu Jinhoi
Published: March 2009

This paper presents experimental results of source identification for a non-minimum phase system. Generally, a causal linear system may be described by matrix form. The inverse problem is considered as a matrix inversion. Direct inverse method cannot be applied for a non-minimum phase system, because the system has ill-conditioning. Therefore, in this study the SVD inverse technique is introduced to execute an effective inversion. In a non-minimum phase system, its system matrix may be singular or near-singular and has very small singular values. These very small singular values have information about a phase of the system and ill-conditioning. Using this property we could solve the ill-conditioned problem of the system and then verify it for the practical system (cantilever beam). The experimental results show that the SVD inverse technique works well for a non-minimum phase system. This inverse technique can be applied to the estimation of the magnitude of impact force, which becomes often a cause of damage to a mechanical system.
Classification Using Radial Basis Function Networks with Uncertain Weights
Authors: Manson Graeme , Pierce Gareth , Worden Keith , Chetwynd Daley
Published: March 2009

This paper considers the performance of radial basis function neural networks for the purpose of data classification. The methods are illustrated using a simple two class problem. Two techniques for reducing the rate of misclassifications, via the introduction of an “unable to classify” label, are presented. The first of these considers the imposition of a threshold value on the classifier outputs whilst the second considers the replacement of the crisp network weights with interval ranges. Two network training techniques are investigated and it is found that, although thresholding and uncertain weights give similar results, the level of variability of network performance is dependent upon the training approach
Strip Yield Model for a Crack in a Plate of Arbitrary Thickness
Authors: Kotousov Andrei G.
Published: March 2009

This paper presents new analytical results on the crack tip opening displacement (CTOD) for a through-the-thickness crack in an infinite plate of arbitrary thickness. These results are based on a new fundamental solution for an edge dislocation obtained earlier and published elsewhere. The analytical predictions of CTOD for various ratios of the crack length to the plate thickness are compared with an independent three-dimensional elasto-plastic finite element (FE) study. It is shown that both analytical and numerical results are in a good agreement when the numerical calculations are not affected by the size of the FE mesh and finite boundaries of the FE model.
Computation Tool for Rotor's Life Consumption in Steam Turbines According to Industrial Specifications
Authors: Lucifredi A. , Poldi M.E. , Silvestri P. , Foglino E.
Published: March 2009

Life consumption evaluation presently represents a high priority topic for Industry and University. In the specific work of this paper, we performed an analysis about the effects of thermal transients on life consumption of steam turbine rotors and an optimization of the thermal transient during runups. This kind of operation, more and more recurrent in power generation, produces a stress in the mechanical elements that could compromise their integrity. The work was developed in its larger part in the MGMV laboratory of the University of Genova, using the equipment (hardware and software) present in this structure, in cooperation with industry. The study moves from a classification of the damage mechanism and from a description of the most important manufacturing technologies of turbine rotors. Then, after a glance at the most important commercial software for estimating life consumption, a classification is given referring to the checks that Ansaldo, the industrial collaborator, performs during its service interventions. Finally, the paper reports the calculation module developed according to the specifications given by the industrial collaborator; the software was developed in Matlab and needs as input the characteristic constants of the rotor and the temperature measurements (with high precision transducers) at the inlet of the HP and IP sections of the turbine. This study confirms that thermal transients are very important to define the rotor’s residual life; the results could help the manufacturer, who designed the machines, and the operators, who run the power plant, to ensure a correct use of the installation, without unexpected failures that could create an economical damage connected with a missed production.
Finite Element Model Updating for Damage Localisation and Quantification Using Experimental Modal Data
Authors: Kompalka A.S. , Reese S.
Published: March 2009

In this contribution we present a validation of an identification procedure and a modeling method with regard to detection, localisation and quantification of damage in a structure. Vibration measurements of an excited experimental structure are used as input for a stochastic subspace system identification algorithm. The identified experimental modal data (eigenvalues and mode shapes) serve to update the underlying finite element model. The experimental setup consists of a cantilever beam and an additional equipment to damage the structure locally and progressively. In contrast to earlier contributions the evolution of damage is quantified in order to estimate the lifetime of the structure.
Benchmark of Damage Localisation Algorithms Using Mode Shape Data
Authors: Morlier Joseph , Bos F. , Castera P.
Published: March 2009

This paper presents a comparative study of three enhanced signal processing methods to locate damage on mode shape data. The first method called curvature mode shape is used as a reference. The second tool uses wavelet transform and singularity detection theory to locate damage. Finally we introduce the windowed fractal dimension of a signal as a tool to easily measure the local complexity of a signal. Our benchmark aims at comparing the crack detection using optimal spatial sampling under different severity, beam boundary conditions (BCs) and added noise measurements.
Example of Application of Experimental Modal Model for Damage Detection for a Rotating Shaft
Authors: Uhl Tadeusz , Lisowski Wojciech
Published: March 2009

Structural properties of machinery elements and sub-assemblies are often used for diagnostic purpose. Occasionally in engineering practice for some technical objects there is no description of distribution of structural parameter values available. Results of experimental evaluation of this distribution are difficult to be applied for diagnostic purpose as a result of lack of a reference distribution for comparison purposes. Nevertheless, for some technical objects, the inherent properties of the structural parameter values distribution may be used in such a case. In the paper an example of a rotating shaft is considered for which the axial symmetry of structural parameter values distribution is expected. Application of impact testing for the purpose of identification of the modal model is an easy way to check this symmetry and to use the results for diagnostic purpose. The technique applied to an example shaft indicated its failure but proved to be inefficient in localization of the failure.
Hybrid Model Based Identification of Local Rubbing Fault in Rotor Systems
Authors: Han Qing Kai , Yu Tao , Li He , Qin Zhao Ye , Zhang Zhi Wei , Wen Bang Chun
Published: March 2009

A quantitative identification procedure for local rubbing fault in rotor systems based on a hybrid model is proposed. The hybrid model combines finite element model of rotor and rigid discs, online identified oil film stiffness and elastic supports. The identification algorithm of oil film parameters is stated in detail. The hybrid model based diagnosis process for local rubbing fault is described with assumption of periodic rubbing forces. With the help of modal expansion technique, the estimated rubbing forces at each node along rotor are checked for the rubbing position. The estimated rubbing forces at ascertained position are then used in fault severity assessing quantitatively next. These approaches have been tested successfully on a test rig with single rotor double discs.
Time-Frequency Feature Extraction without Cross-Terms Based on Acoustic Signal in Rotor Malfunctions
Authors: Wu F.Q. , Meng Guang
Published: March 2009

An effective approach is presented to eliminate the cross-terms in Wigner distribution by ICA (independent component analysis) and EMD (empirical mode decomposition), through which the cross-terms caused by the uncorrelated mixing signals can be removed successfully. This method is used for time-varying signal analysis and is powerful in signal feature extraction, especially for joint time frequency resolution, which is demonstrated by numerical examples. To further understand the method and its application, a detailed analysis about abrupt unbalance experimental example is shown to explain the cause of malfunction as well as its occurrence and phenomenon. In addition, the proposed approach based upon independent component analysis, empirical mode decomposition method and wigner distribution allows the separation and analysis of the sources with nonlinear and non-stationary properties. In this method, the main conceptual innovations are the associated introduction of ‘source separation’ and ‘intrinsic mode functions’ based on the local properties of the mixed signals, which makes the instantaneous frequency meaningful; the method serves to illustrate the roles played by the nonlinear and non-stationary effects in the energy-time-frequency distribution. At the same time, the method can also be expanded and applied in other fields.
Strain-Based Damage Tolerance of Cylindrical Shells Subjected to Transient Loading and Its Application
Authors: Gao C.Y. , Fang Y.T.
Published: March 2009

In this paper, a new approach to damage tolerance determination, which is related to the critical rupture strain, is proposed for cylindrical shells subjected to inner transient high-pressure loading. The relation of damage variable and circumferential plastic strain is deduced on the basis of a damage evolution equation as well as a simplified dynamic viscoplastic constitutive equation. The value of damage variable can be obtained then if the strain is known by strain measurement, and the damage tolerance just corresponds to the rupture strain of the structure. Further, the damage tolerance has been applied as the strain-based rupture criterion in the FE simulation of the dynamic fracture process for transient-pressurized cylindrical shells. Especially for the notched shells, the strain concentration effect of notches on the rupture criterion is analyzed quantitatively.
Identification of Damage in Composite Structures Using Thermoelastic Stress Analysis
Authors: Emery T.R. , Dulieu-Barton Janice M. , Cunningham P.R.
Published: March 2009

The application of a cyclic load on a composite material containing damage has the effect of heating due to the material viscoelasticity. This is exaggerated in the proximity of interlaminar failure because of friction between plies. Quantitatively studying a stressed component subject to these conditions using Thermoelastic Stress Analysis (TSA) has been inaccurate, as the localised heating has an effect on the thermoelastic response. Hence the thermoelastic signal from damaging composites will contain a stress-induced component and a temperature-induced component. In this paper a process is described that allows the thermoelastic signal to be de-coupled into a stress component and a temperature component. This is achieved using a combination of infra-red thermography and TSA. The process is based on the use of a special calibration device. The paper provides an experimental verification of the de-coupling using actual damaged composite components.
Non-Linear Vibration of a Delaminated Composite Beam
Authors: Żak Arkadiusz J.
Published: March 2009

Certain results have been presented in this work on damped non-linear vibration of a delaminated composite beam. In order to investigate this problem the finite element method has been applied while for beam modelling higher order shear deformation beam finite elements have been used. The vibration of the beam has been investigated in the time domain and next the time series obtained from solving the non-linear equation of motion have been analysed in the frequency domain by using FFT. The vibration responses of the beam due to various harmonic excitations, at different delamination locations, and for different delamination lengths, together with changes in the dissipation of damping energy due to the delamination, have all been considered in the work.
Health Monitoring of Electric Circuits
Authors: Kokot M. , Holnicki-Szulc Jan
Published: March 2009

A methodology of defect identification in linear DC circuits based on so called Virtual Distortion Method (VDM) will be presented. The proposed approach takes adventage of the analogy linking mechanical models of truss structures and electric circuits. In this paper we cover the issue of modelling defects in electric circuits by compatible state of distortions, next we introduce the concept of influence matrix Dij, which describes global sensitivity of the circuit and enables fast recalculation of system response, and we formulate a gradient method of defect identification (inverse problem) based on local current and voltage measurements. In the following analysis we focus on so-called impotent states of distortions, which are the source of ambiguity of solution. We show that these difficulties can be overcome by a proper measuring strategy.
A Biological Immunity-Inspired Novelty Detection Algorithm for Rotor System Monitoring
Authors: Dong Yong Gui , Dong Ensheng , Jia Huibo , Lv Wener
Published: March 2009

In case of mechanical system health monitoring, a need to develop normal-knowledge
based novelty detection techniques is increasing. The negative selection algorithm, which is inspired from the operation mechanism of human immune system, is one of such approaches. Our approach is to apply the idea for the anomaly detection in the vibration time series of the rotor system. A real-valued negative selection algorithm based on Euclidean distance, as well as cosine similarity, has been implemented. By means of adding the corresponding coverage radius to each antibody elements, the detection efficiency of each antibody element is increased. The detection efficiency is evaluated with simulated data as well as vibration signal sampled from one rotor system. The results indicate that the algorithm can efficiently detect the anomaly in time series data. Moreover, the number of detectors in antibody set is less enough for potential application in online signal monitoring.
Local and Global Damages of Quasi-Brittle Material in Uniaxial Compression Based on Gradient-Dependent Plasticity
Authors: Wang X.B.
Published: March 2009

Theoretical relations among local and nonlocal damage variables in localized band as well as global damage variable according to the measured stress-strain curve of quasi-brittle material subjected to shear and tensile failures in uniaxial compression and in three-point bending were presented. The nolocal damage variable depends on the local counterpart and its second spatial gradient based on nonlocal theory. Analytical solution for the local damage variable was derived by substitution of the nonlocal damage variable for averaged damage variable in shear band and by using boundary condition as well as by resorting to the assumption that the actual thickness of shear band corresponds to the maximum local damage variable. It is found that local damage variable depends on the internal length parameter, coordinate, flow shear stress, shear strength, shear elastic and softening moduli. Assuming that the shear localization is initiated just at the peak strength, and that afterwards the strain-softening behavior of specimen occurs. The relation among shear strength, uniaxial compressive strength, flow shear and compressive stresses was established. The global damage variable was defined according to the measured stress-strain curve whether the post-peak response is snap-back or snap-through, which depends on the uniaxial compressive strength and flow compressive stress. A relation among local, nonlocal, and global damage variables in uniaxial compression was proposed analytically, and then a relation applicable to three-point bending was directly presented. The latter relation can be simplified for uniaxial tension condition if tensile stress is assumed to be uniform. Two examples were presented to investigate the two- and three-dimensional distributions of local damage variable in shear and tensile localized bands. The present analytical solutions for the distributed damage in shear and tensile localized bands qualitatively agree with the previous numerical predictions.
A Correlative Method of Machine Condition Monitoring Based on the Choi-Williams Distribution
Authors: Yang Guoan , Wu Zhenhuan , Gao Jin Ji
Published: March 2009

In this paper, a new method for time-varying machine condition monitoring is proposed. By Choi-Williams distribution, the interference terms produced by the bilinear time-frequency transform are reduced and the fault signal is processed by the correlation analysis of the Choi-Williams distribution. For machine fault diagnosis, both the feature extractor and classifier are combined to make a decision. It is particularly suited to those who are not experts in the field. Satisfactory results have been obtained from a real example and the effectiveness of the proposed method is demonstrated.
Micro Angle Measurement for a Scanning Stage
Authors: Liu Qing Gang , Li M. , Li D.C. , Li Z.G. , Hu X.T.
Published: March 2009

Long range scanning stages with very small positioning errors are the key elements in the nano-CMM that is used to determine the sizes and coordinates of micromachines and parts in three dimensions to realize MEMS/nano technology. A transmission stage needs six degree-of-freedom precision motion controls. A compact critical angle sensor (CAS) can be mounted on the base or frame to be used to monitor the orientation parameters of the scanning/transmission stage along the 3 axes and feedback the error signal of the sensor output to maintain the stage moving performance. By calibration with an autocollimator, the resolution is better than 0.1 arcsec with a measurement range above 600 arcsec.
A High Precision Circuit Based on Digital Techniques for Roundness Measurement
Authors: Zhao W.Q. , Tan Jiu Bin , Xue Z. , Feng Z.D.
Published: March 2009

In ultra high precision roundness measurement, a high accuracy and high integrated measuring circuit system equipped with inductive sensor are a developing trend. In order to meet the demand, a novel method to improve the accuracy of measuring circuit of amplitude modulation sensor using digital synthesizing, digital phase sensitivity detection (PSD), and digital set average techniques, is presented. The measuring circuit system based on the method is easy to realize and to operate. It can be plugged directly into an ISA Bus slot for use. Experimental results show that the stability of the sensor measuring system that consists of the measuring circuit system and a Taylor inductive sensor reaches nanometer accuracy. The digital measuring circuit of amplitude modulation can not only be applied widely in amplitude modulation measuring circuit for use of inductive sensors to improve the accuracy of the sensor measuring circuit system but also used in the one for use of capacitance sensors and magnetic grating sensors.
Laser Scattering Measurement of Microdefects on Silicon Oxide Wafer
Authors: Ha Taeho , Miyoshi Takashi , Takaya Yasuhiro , Takahashi S.
Published: March 2009

Laser scattering characteristics of typical CMP-induced defects such as particles and microscratches with the size of sub-micron order are investigated using a developed automated scattered light measurement system. The measurement system has an ability to detect three-dimensional distribution of scattered light from the defects with high sensitivity. The angular distributions of scattered light from the standard PSL (Polystyrene latex) spheres and microscratches reveal that scattering characteristics of microscratches are quite different from those of Particles. The scattered light from the PSL sphere is detected mainly ahead. In contrast, the scattered light from the microscratches only exists in the direction perpendicular to its length dimension at an oblique incidence maintaining the sheet-shaped pattern, even if its orientation relative to the incident direction is changed. Optical arrangement for defect detection and classification is suggested based on the experimental results.
A Multi-Range Fiber-Optical Non-Contact Displacement Micrometer
Authors: Hwang G.J. , Ko W.H.
Published: March 2009

A multi-fiber reflection displacement micrometer is developed. The device consists of a light source and a receiving fiber-array of identical fibers and photo detectors that detect the light reflected from the surface being measured. The differential output of each neighboring fiber pair is proportional to the surface displacement in a section of the total range. The light intensity variation of the source and the reflectance change of the surface are compensated when the differential output is divided by the summation output. A scale voltage is given to each output of neighboring fibers in order to shift each output to correspond to the actual displacement within the total range, which can be varied by selecting the number of fibers in the receiving fiber array. The micrometer offers the advantages of wide range, non-contact, no electrical interference, simplicity, and low cost. It can be used in medical experiments and laboratory instruments.
A Displacement Sensor Based on Differential Frequency Measurement
Authors: Peng Dong Lin , Zhang Xing Hong , Liu Xiao Kang
Published: March 2009

For many reasons, the study of differential frequency measurement had disappeared for some years. This paper applies the differential frequency measurement previously used to measure transmission error to static differential frequency measurement. A new method called method of duality for gear and electric wave is proposed to explain the differential frequency measurement in a new way to discover its essence. A novel angular displacement sensor is designed. The composite error is ±17″ based on the static differential frequency measurement.
Development of a Sensitive Probe for Coordinate Measuring Machines
Authors: Watanabe M. , Furutani Ryoshu
Published: March 2009

Requirement for precision measurement becomes extremely advanced as industrial needs advances. CMM (Coordinate Measuring Machine) is one of the most adequate measuring machines to meet the requirement. As the precision of CMM becomes higher, it is important to improve the sensitivity of probe. We developed a contact type probe which consisted of a QPD (quadratic photo
diode), a ball lens, and a laser diode to detect the displacement of stylus. The probe system has a resolution of 31nm.
A Portable 3D Vision Coordinate Measurement System Using a Light Pen
Authors: Liu S.G. , Peng K. , Huang F.S. , Zhang Guo Xiong , Li P.
Published: March 2009

A portable three-dimensional vision coordinate measuring system is proposed in this paper. It consists of a light pen, a CCD camera and a laptop computer. The light pen is a hand-held probe with three point light sources using LEDs and a spherical touch stylus arranged in one line. The CCD camera takes the image of LEDs on the light pen and the 3D coordinates of measured point at the center of touch stylus are obtained by computing the positions of LEDs in the image when the probe contacts the object surface. The equations of the vision measurement system are derived by using perspective of three collinear points and spatial analytic geometry. The measuring device can be set up easily on an industrial site and the measurement is convenient. The object surface can be simple, complex, or hidden from the view of camera. The effectiveness of the mathematical model and validity of the measuring system are confirmed by experiments.
A Plastic Film Thickness On-Line Detecting System
Authors: Ma Yu Zhen , Ye S.H. , Duan F. , Zheng Y.
Published: March 2009

In this paper, the main new point is the use of a non-contact combinational system with a capacitive sensor and eddy current sensors to acquire measurement signals and the use of LabVIEW software platform for real time data processing of plastic film thickness. Using a combinational measurement system to replace a traditional micrometer, the thickness of plastic film can be measured intelligently, real time, and in non-contact mode with high precision. The whole system consists of a test unit, a data acquisition unit, a motor driving unit, and a data processing unit. The test unit does measurement by means of capacitive sensor and eddy current sensors. The system is operated on the LabVIEW software platform for automatic control of the whole process. The measurement process is faster. The test results from the combinational measurement system are compared with the results from a micrometer. It shows that this measurement system has higher precision and better repeatability, reliability and feasibility.