bluuebunny/crossref_metadata_2025 huggingface dataset:
Highly Porous Silica Nanoaerogels for Ultrafast Nonlinear Optical Applications
Authors: Seo Jae Tae , Ma S.M. , Lee K. , Brown H. , Jackson A. , Skyles T. , Cubbage N.M. , Tabibi B. , Yoo K.P. , Kim Suk Young , Jung S.S. , Namkung M.
Published: March 2009

Highly porous silica nanoaerogels with low apparent density of ~0.1 g/cm3 and
~0.07 g/cm3 were synthesized through two-step sol-gel processing and low temperature supercritical fluid drying. The nonlinear refraction (γ) of silica nanoaerogels was estimated to be ~ -3.4 x 10-16 m2/W for ~0.1 g/cm3 and ~0.07 g/cm3 apparent densities with a signal-beam femtosecond z-scan spectroscopy. The third-order nonlinear refraction coefficient of nanostructure silica nanoaerogels was almost four orders larger than that of bulk silica materials. The large nonlinearrefraction with high nonlinear figure of merit (γ/βλ, β~2×10-10 m/W for 0.07 g/cm3 apparent density, β~6×10-10 m/W for 0.1 g/cm3 apparent density, λ~0.775 µm) is an ideal optical property for nonlinear applications of homeland security, battlefield enhancement, and industrial uses.
Creep Behavior of Improved High Temperature Silicon Nitride
Authors: Wiederhorn Sheldon M. , Krause Ralph F. , Lofaj František , Täffner U.
Published: March 2009

New data are presented on the tensile creep behavior of silicon nitride sintered with Lu2O3. The data are compared with two earlier sets of data collected on the same material. The older sets gave results that are difficult to explain theoretically: a high value for the stress exponent, n=5.33, and no cavitation. The new set of data also gave no cavitation, but gave a stress exponent, n=1.81, that can be rationalized theoretically in terms of solution-precipitation creep of the silicon nitride grains. An analysis of variance showed that one of the earlier sets of data was statistically consistent with the newer set, whereas the other set of data was not. Combining the two sets of data that agreed statistically yields a consistent picture of creep with a low value of the stress exponent and no cavitation. The stress exponent for the combined set of data is n=1.87±0.48 (95 % confidence limits). The tensile creep mechanism of the silicon nitride containing Lu2O3, solution-precipitation, differs from those of other silicon nitrides, for which tensile creep has been attributed to cavitation. Enhancement of the creep resistance of the silicon nitride sintered with Lu2O3 may be a consequence of the fact that Lu2O3 produces a more deformation resistant amorphous phase at the two grain junctions, than do Y2O3 or Yb2O3. In parallel, reducing the amount of secondary phase below a critical limit, or increasing the viscosity of the two grain boundaries relative to three-grain junctions reduces the ability of the material to cavitate during creep, and forces the creep mechanism to change from cavitation to solution-precipitation.
Characterization of Mechanical Reliability of Silicon Nitride Microturbine Rotors
Authors: Lin Hua Tay , Ferber Mattison K.
Published: March 2009

This paper summarizes the recent results on component characterization efforts
carried out to verify the mechanical reliability of SN237 and SN281 silicon nitride
microturbine rotors manufactured by Kyocera. Mechanical properties of biaxial discs
machined from airfoils of microturbine rotors were evaluated by a ball-on-ring test technique. Results showed that the mechanical properties of samples from airfoils with as–processed surfaces exhibited lower characteristic strength than those machined from the hub region with as-machined surfaces. The differences in mechanical performance and reliability between asprocessed components and simple-shaped test coupons appear to arise mainly from differences in strength limiting flaw type and population.
Static and Dynamic Indentation Damage in SiC and Si3N4
Authors: Kim Jong Ho , Kim Young Gu , Kim Do Kyung , Lee Kee Sung , Chang Soon Nam
Published: March 2009

Hertzian and explosive indentations were used to determine the damage behavior of SiC and Si3N4 ceramics. Specimens were selected with different microstructures. In order to observe the subsurface damaged zone, the bonded interface technique was adopted. It was found that the damage response depends strongly on the microstructure of ceramics. Examination of subsurface damage reveals a competition between brittle and quasiplastic damage mode: brittle fracture mode is dominant in fine grain microstructure; quasiplastic deformation occurs in coarse grain. Dynamic indentation induces subsurface yield zone which contains extensive micro-cracks. The role of microstructure on static and dynamic damage behavior are discussed in terms of the weakness of grain boundary and grain size.
In Vitro Bioactivity of Composite of Nanophase Titania/Bioactive Glass-Ceramic in Simulated Body Fluid
Authors: Wang Hui , Yang Bang Cheng , Yu Qi Feng , Wu Dayi , Zhang Xing Dong
Published: March 2009

Titania ceramics is lack of bone-bonding ability even if it has excellent biocompatibility. Recently, it is even found that the nanophase titania ceramics could enhance the proliferation of osteoblasts. If the bone-bonding ability of this material is improved, it would be a potential bone replacement material. Bioactive glass-ceramic (BGC) is provided with the best bioactivity in biomaterials. In this study, the apatite formation ability and the mechanic properties of titania ceramic were investigated by the accession of BGC. Four samples: TiO2 ceramic, TiO2 +10%BGC, TiO2 +20%BGC and BGC were prepared respectively. These ceramics were exposed to a simulated body fluid (SBF) for 7, 14 and 21d. Scanning electron microscopy (SEM), energy dispersive X-ray detector (EDX) and thin film X-ray diffraction (TF-XRD) results showed that the apatite formation of the ceramics was improved by adding BGC into nanophase titania ceramic. The mechanical analysis showed the biomechanical compatibility was also improved by adding BGC into nanophase titania ceramic.
Manufacturing Porous Blocks of Nano-Composite of Needle-Like Hydroxyapatite Crystallites and Chitin for Tissue Engineering
Authors: Peng Qian , Weng Jie , Li Xiao Hong , Gu Zong Wei
Published: March 2009

A porous composite scaffold for tissue engineering had been developed through a novel gel-casting approach with needle-like nano hydroxyapatite (HA) crystallites and chitin. The freeze-dried nano-HA powder was firstly dispersed in the chitin solvent before chitin dissolves in its solvent completely. The composite solution was evenly mixed with a selected porosifier and poured into a mold in which it became a composite gel under the reaction of water molecules in atmosphere. Subsequently, the composite gel was subjected to the simultaneous extraction of the porosifier and
chitin solvent in distilled water. After the drying process the porous composite scaffold was obtained. The morphological analysis showed that the manufactured scaffold had uniform and isotropic porous structure with controlled, fully interconnected pores. In vitro experiments indicated that the bone-like apatite layer formed easily on the walls of the porous n-HA/chitin composite scaffold.
Surface Modification of Titanium Implant and In Vitro Biocompatibility Evaluation
Authors: Zeng Quan , Chen Zhi Qing , Li Quan Li , Li Gang , Darvell Brian W.
Published: March 2009

The improvement of the amount of OH functional groups and bioactivity of titanium
metal was attempted by chemical treatment and subsequent hot water treatments. The surface morphology, chemical composition and crystal structure were used to characterize the Ti surfaces and their biocompatibility was evaluated by culturing with osteoblasts. Porous network bioactive anatase were prepared by immersion in the 5 M NaOH at 80ı for 24 h, followed by soaking in the water at 80ı for 48 h. The treatment with H2O2/HCl solution at 80ı for 30 min followed by hot water aging also produced an anatase titania gel layer. Percentage of surface OH groups was
determined by XPS analysis. After chemical treatment and subsequent aging in hot water, the amount of surface OH groups increased. The modified Ti surface promoted the proliferation and the ALP activities of osteoblasts. These results indicate that the NaOH or H2O2/HCl treatment and subsequent hot water immersion improve the biocompatibility of Ti samples. On the other hand, a high OH group concentration is very important as functional groups for the apatite nucleation or
biochemical modification via an organometallic interface of immobilizing biomolecules.
Round-Hole-Fiber Distribution in Hydrophilidae Cuticle and Biomimetic Research
Authors: Chen Bin , Peng Xiang He , Fan Jing Hong
Published: March 2009

Insect cuticle possesses excellent mechanical properties, such as strength, stiffness and fracture toughness, which are closely related to its elaborate microstructures optimized through centuries’ evolution. SEM observation on Hydrophilidae cuticle shows a kind of biocomposite consisting of chitin-fiber plies and protein matrix, and the chitin-fiber plies are composed of several special arrangements. The observation also shows that there are many holes in the cuticle and the fibers passing along the brims of the holes round the holes continuously. Making use of such microstructure, a kind of biomimetic composite laminate with round-hole-fiber distribution is fabricated with preformed-hole method. The ultimate strength of the composite laminate is investigated and compared with that of the composite laminate with a hole drilled. It shows that the ultimate strength of the former is distinctly higher than that of the latter.
Application of Microbial Polyesters-Polyhydroxyalkanoates as Tissue Engineering Materials
Authors: Chen Guo Qiang , Wu Qiong , Wang Ya Wu , Zheng Zhong
Published: March 2009

Poly(hydroxybutyrate-co-hydroxyhexanoate) (PHBHHx) has improved mechanical properties over the existing PHA and our results have shown that PHBHHx has better biocompatibility over polyhydroxybutyrate (PHB) and polylactic acid (PLA). Surface treatment with lipases dramatically changed the material surface properties and increased the biocompatibility of the PHBHHx. PHBHHx and its PHB blends had been used to make three dimensional structures
and it has been found that cartilage, osteoblast, and fibroblasts all showed strong growth on the PHBHHx scaffolds. The growth was much better compared with PLA. The molecular studies also showed that mRNA encoding cartilages were strongly expressed when cartilage cells were grown on the PHBHHx. As PHBHHx has strong mechanical properties, easily processible and biodegradable, this material can be used to develop a new class of tissue engineering materials.
Control Release of Paclitexel-Coated 316L Cardiovascular Stent In Vitro
Authors: Dong Heyan , Li Xin Yue , Guo Ming , Liu Xing Jiang
Published: March 2009

Now the Cardio vascular restenosis in the clinic is still an unsolved question. The fact is that, if the 316L stent is without coating, it will harm the blood vessel wall and the inflammatory reaction of eye winker. This research is about the Paclitexel-drug coating stent that can be adapted to avoid restenosis. The drug control released by different methods, and also the nano-material releasing after the coating formation are investigated.
Improving Wear Resistance by Heat-Treatment in Different Atmospheres
Authors: Feng Bo , Weng Jie , Qu Shao Xing , Leng Yong Xiang , Zhou Zhong Rong
Published: March 2009

Influence of heat-treatment conditions on wear resistance of titanium was investigated. Titanium plates were subjected to heat-treatment in air and water vapor respectively. Heat-treatments increased micro-hardness of titanium. The plate heat-treated in air (H) has the highest roughness and the plate treated in water vapor (W) lowest. After heat-treatment surface oxide was rutile. The friction coefficient of W was the lowest and almost stable at about 0.18. Non-heat--treated titanium plate (S) had a highest coefficient up to 1.1. Wear resistance of heat--treated titanium, especially W was significantly superior to non-treated titanium. The wear of
S resulted mainly from adhesion failure, H involved with abrasive wear and fatigue failure. For W, a complex wear mechanism was probably existed.
Study on Bio-Tribological Properties of Nitrogen Ion Implanted UHMWPE
Authors: Xiong Dang Sheng
Published: March 2009

As the aseptic loosening induced by polyethylene wear debris is the main cause of
long-term failure of total joint replacements, increasing the wear resistance of ultrahigh molecular weight polyethylene (UHMWPE) will be very important to obtain long-life artificial joint. In this paper the UHMWPE was implanted with 450 keV N+ ions to three doses of 5×1014/cm2, 2.5×1015/cm2 and 1.25×1016/cm2. The friction and wear behaviors of UHMWPE were studied under lubrication of distilled water and blood plasma using a ball-on-disk tribometer with a ZrO2 ceramic ball as a counterface. Experimental results showed that the friction coefficient of ions implanted UHMWPE are higher than un-implanted UHMWPE. Under blood plasma lubrication condition, the wear rate of implanted UHMWPE was lower than un-implanted UHMWPE, and the wear rate decreased with increasing implantation dose. The plow, plastic deformation and fatigue were wearing mechanism for un-implanted UHMWPE and the abrasive wear for implanted UHMWPE.
3D Finite Element Analysis of Bone Stress around Distally Osteointegrated Implant for Artificial Limb Attachment
Authors: Zheng L. , Luo J.M. , Yang Bang Cheng , Chen Ji Yong , Zhang Xing Dong
Published: March 2009

Stress shielding, which occurred always around traditional one part implant applied for prosthetic artificial lower limb attachment, would cause osteoporosis and thus result in the loose and extrusion, and then the malfunction of the implant. To improve the structure of the implant, a new type of implant—multi-part implant was developed in this article. Based on CT data and under the maximal load during a normal walking cycle, 3D finite element analysis (FEA) was carried out to analyze the stress of bone around the new implant in three cases of distally truncated femur at high position、middle-position and low-position. Results reveal that stress shielding and stress concentration under the new type of implant reduced effectively compared with the traditional one-part implant, and the stress distribution is much close to the natural bone. Application for distally truncated femur at middle-position and low-position was much better, while stress concentration was marked at high-position. Meanwhile, the stability in vivo can also be maintained with the multi-part implant. The new implant is promising applied for prosthetic limb.
Fracture Resistance Evaluation of Fibre Reinforced Brittle Matrix Composites
Authors: Dlouhý Ivo , Chlup Zdeněk
Published: March 2009

Determination of the fracture toughness using a specimens with straight and/or chevron notch in the three (four) point bend test for monolithic ceramic materials can be taken as standardized techniques. In case of composite materials, mainly of brittle matrix reinforced by unidirectional fibres the crack growth resistance increases as the crack propagates. In addition, the long fibres stimulate delaminations along fibre – matrix interface perpendicularly to the major crack. Fracture toughness determination (in the loading mode I) in cases when delaminations take place is difficult. The chevron notch technique could be the right way to overcome this difficulty and obtain exact fracture toughness characteristics by its natural ability to “keep” the direction of major crack. Based on fractographic analyses some examples are described to show potential of the chevron notch technique for fracture resistance characterisation of the studied composite including comparison of data from chevron and straight notch technique etc.
A Contribution of Fractal Geometry to Characterization of Wear Process
Authors: Kupková Miriam , Kupka Martin , Rudnayová Emőke , Dusza Ján
Published: March 2009

Irregular evolution of friction coefficient, recorded during the ball-on-disc test on Si3N4 based ceramic materials, was analysed by means of fractal geometry methods. Tests were carried out at room temperature, in air and without any lubricant. It was proven that the friction coefficient trace, considered as a geometric object, has the property of a fractal curve. The fractal dimension of this curve increased with increasing wear rate measured in a corresponding wear test. This could indicate the possible correlation between the wear rate and the fractal dimension of friction coefficient as a function of sliding distance (time).
Precision Abrasive Jet Finishing of Cemented Carbide
Authors: Saito T. , Ito S. , Mizukami Y. , Horiuchi O.
Published: March 2009

Recently a technique has been developed to mold aspheric glass lenses by using cemented carbide dies at elevated temperature. The dies are precisely ground by an ultraprecision grinding machine. However the obtained form accuracy is generally around 100nm and is not enough high. In this study, to investigate a possibility of corrective figuring of the dies, a series of experiments of abrasive jet machining of cemented carbide was conducted and fundamental machining characteristics were examined. The used abrasives were fine grains of silicon carbide and aluminum oxide. The silicon carbide abrasives could accomplish a sufficient material removal. Both the material removal rate and the surface roughness increase as the collision angle increases up to 90 degrees. Therefore, in order to obtain a smooth surface finish, it was necessary to take a smaller collision angle and to slow down the material removal rate.
Microstructure of Ni-Al-Diamond Composite Fabricated by Self-Propagating High Temperature Synthesis
Authors: Zhang Feng Lin , Yuan Hui , Wang Cheng Yong , Fu K.X. , Zhou Y.M.
Published: March 2009

Diamond tool based on Ni-Al self-propagating high temperature synthesis (SHS) was introduced in this paper. Different heating methods such as muffle furnace, vacuum furnace and induction were used to ignite the Ni-Al-diamond SHS system. The morphology and microstructure of the Ni-Al-diamond composite were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM). It was found that SHS Ni-Al-diamond composite ignited by induction heating owned the best morphology and microstructure to work as diamond tool.
FGM Mould with Fine Veins Rapidly Manufactured by Plasma Spraying
Authors: Fang Jian Cheng , Xu Wen Ji , Zhao Zhi Yu , Wang L.
Published: March 2009

There is the advantage of continuity in organic structure and mechanical property for
functionally gradient materials (FGMs), but it is unable to be used in the mould industry for the difficulty of the second machining up to now. In this study, a novel technology of FGM mould with fine veins fabricated by plasma spraying has been developed, which can easily realize the integration of FGM forming and deep machining of the mould. According to applied characteristic of plastic injection mould, WC-12%Co/NiCrAl powders are selected and the reasonable FGM coating has been prepared. Spraying processes have been investigated, such as fabrication of spray mould with fine veins, FGM forming, backing and demoulding, etc. At the same time, the metallography, porosity and microhardness of the spraying layer have been analyzed. The results show that the service performance of the FGM mould is much more excellent than that of the traditional mould, and the life span can also be greatly improved. The research will have a significant influence on the material development in the mould industry.
Vibration Based Modal Parameters Identification and Wear Fault Diagnosis Using Laplace Wavelet
Authors: Zi Yanyang , Chen Xue Feng , He Zheng Jia , Chen Peng
Published: March 2009

Wavelet transform is a powerful technique well suited to non-stationary signal processing. The properties of wavelet are determined by its basis function. In the fields of modal analysis, mechanical condition monitoring and fault diagnosis, impulse responses or transient responses are very common signals to be analyzed. The Laplace wavelet is a single-sided damped exponential wavelet and is a desirable wavelet basis to analyze signals of impulse response. A correlation filtering approach is introduced using the Laplace wavelet to identify the impulse response from vibration signals. Successful results are obtained in identifying the natural frequency of a hydro-generator shaft, and diagnosing the wear fault of intake valve of an internal combustion engine.
Detection of Cracks Using Piezoelectric Wafer Active Sensors
Authors: Blazewicz Antoni , Kotousov Andrei G. , Wornle Frank
Published: March 2009

The capability of piezoelectric wafer active sensors to identifying cracks which are common to metallic structural elements subjected to fatigue loading were explored. A number of laboratory tests were performed to investigate Lamb wave transmission and reception characteristics as well as the sensitivity of the transmitted and reflected signals to the presence of a through-the-thickness crack of various length and orientation in a thin plate. Based on the laboratory tests an optimum strategy for crack detection with the pulse-echo method was investigated. The method can be used for large areas scanning with a small amount of sensors and is favoured for embedded and leave-in-place sensor applications.
An Embedded FBG Sensor for Dynamic Strain Measurement for a Clamped-Clamped Composite Structure
Authors: Ling Hang Yin , Lau Alan Kin Tak , Cheng Li , Wei J. , Thomson R.S. , Scott M.L.
Published: March 2009

A comparison of strain measurement results, from an embedded fibre-optic Bragg grating (FBG) sensor and surface mounted strain gauge, at different vibration frequency ranges and using a clamped-clamped glass fibre composite beam, is presented. It is shown that the FBG sensor is able to precisely measure the peaks at the first-two natural frequency modes compared with the spectrum captured from the strain gauge. The results also demonstrate that the strains measured from the FBG sensor agreed well with the strain gauge at frequencies below 100 Hz. Beyond this value, the actual strain on the beam surface was less than 3µe, and the data extracted from the strain gauge are no longer valid. For a clamped-clamped structure, the longitudinal strain of the beam correlates to its vibration amplitude and excitation frequency. Increasing the frequency results in decreasing the longitudinal strain of the beam and erroneous measurements from the strain gauge resulted. This study provides important information on the feasibility of using embedded FBG sensors as vibration monitoring devices to measure mechanical performance of composite structures.
A Study on the Multi-Wavelength Drop Analysis Technology
Authors: Hao G. , Qiu Zu Rong , Zhang Guo Xiong , Zhang A.P.
Published: March 2009

An instrumental method for measuring the properties of liquids has been developed. The instrument, called the fiber-capacitive drop analyzer (FCDA), is based on a specially designed drop sensor by means of the fiber drop analyzing technology and the capacitive drop analyzing technology, and produces a volume-based fiber drop trace (VFDT), which shows the relation between the light intensity passing through the liquid drop and the instant drop volume. Preliminary experiments have been carried out and these prove that VFDT externalizes the overall properties of tested liquids and is suitable for fine discrimination among different kinds of liquids. In this paper, a multi-wavelength drop analysis (MWDA) method is described. In this case, the light source of the FCDA is developed from a single wavelength to a multi-wavelength. A special filter is employed to sort out the signals from the mixed multi-wavelength signals and it becomes possible to get two or three VFDT with different light wavelength at the same time. As one knows, a material will absorb the light on certain wavelengths. It means that, for a mixed liquid, one can get different VFDTs by MWDA at the same time. By this way, the resolution capability of a FCDA is enhanced very much due to more information including in those VFDTs. A special signal process circuit, the key technology of the MWDA, is described in this paper. The test results show that the new circuit had satisfied the MWDA method well and will be very useful to an instrument of the FCDA with MWDA.
Accurate Estimation of Phase Distribution on Reference Plane in Grating Projection Measurement
Authors: Zhao M.R. , Lin Yu Cheng , Niu X.B. , Cheng D.M.
Published: March 2009

A binary second order rational polynomial is adopted to simulate and extend the phase distribution on reference plane. In order to get the coefficients of the polynomial accurately, iterative least-square method based on the first order Taylor series expansion is used. The effect of the real reference plane profile error on measuring result is reduced by using extended unwrapped phase to substitute the original unwrapped phase. The effects of the random phase error and the system geometrical parameter error are decreased. The measuring accuracy of the system is improved. The principle of the 3D profile measuring system based on grating projection, the theoretic analysis for accurate estimate of phase distribution on reference plane, and the experimental results are presented.
Damage Detection of Composite Structures Using Dynamic Analysis
Authors: Yam L.H. , Cheng Li , Wei Z. , Yan Y.J.
Published: March 2009

A study on the use of modal parameter analysis for damage detection of structures made of composites is conducted. The damage-induced variations of modal parameters are investigated both numerically and experimentally. An appropriate finite element model is proposed to analyze the dynamic characteristics of different types of structures made of composites, such as honeycomb sandwich plates and multi-layer composite plates, with internal cracks and delamination. The numerical results are in good agreement with experimental results available in the literature. Natural frequencies, modal displacements, strains and energy are analyzed for the determination of damage severity and location. Vibration measurements are carried out using piezoelectric patch actuators and sensors for comparison and verification of the FEM model proposed in this study. Energy spectrum for wavelet packets decomposition of structural dynamic responses is used to highlight the features of damaged samples. The mechanism of mode-dependent energy dissipation of composite plates due to delamination is revealed for the first time. Experimental results clearly show the dependence of changes of modal parameters on damage size and location. The results obtained in this study show that the measured modal damping change combined with the computed modal strain energy distribution can be used to determine the location of delamination in composite structures. Both numerical and experimental findings in this study are significant to the establishment of guideline for size and location identification of damage in composite structures.
Investigation of Nonisothermal Crystallization Behaviors of Poly and Silica Nanocomposites Using Differential Scanning Calorimetry
Authors: Kong Ling Xue , Peng Z.
Published: March 2009

Nonisothermal crystallization behaviors of PVA and poly (vinyl alcohol) and Silica (PVA/SiO2) nanocomposites prepared via a self-assembly monolayer (SAM) technique are investigated in this study. Differential scanning calorimetry (DSC) is used to measure the crystallization temperature and enthalpy of PVA and nanocomposites in nitrogen at various cooling rate. The results show that the degree of crystallinity of PVA and nanocomposites decreases when
the SiO2 content increases but increases with an increasing cooling rate. The peak crystallization temperature decreases with an increasing cooling rate.
Effects of Key Parameters on the Performance of a New In-Process Optical Measurement Method
Authors: Tao Z. , Gao Y.
Published: March 2009

A new in-process optical measurement method has been developed for measuring surface profiles of workpieces under the coolant condition. In this method, a laser beam passes through two additional layers. This paper presents an error analysis for the new method. The effects of key parameters on performance of the new method are examined. The theoretical analysis and experimental results show that the measurement error in this new method can be controlled within an acceptable range.
Application of Wavelet Analysis for Online Measurement of Crude Oils
Authors: Li X. , Ding Z.L. , Yuan F.
Published: March 2009

The correlation method had once been considered as one of the best methods for the measurement of multiphase flow. However, if the behavior of flow does not fit the ergodic random process, the measured cross correlation plot will have a gross distortion when the different components of flow do not pervade within one another to the full extent. We measured a variety of parameters of three phase oil/water/gas flow in an oil pipeline. The change of flow pattern is so complex that the measured signals are always contaminated by stochastic noises. The weak signals are very easily covered by the noise so that it will result in great deviation. Wavelet transformation is an analytical method of both time and frequency domain. The method can achieve signal decomposition and location in time and frequency domain through adjustment and translation of scale. An LMS algorithm in wavelet transform is studied for denoising the signals based on the use of a novel smart capacitive sensor to measure three phase oil/water/gas flow in oil pipeline. The results of simulation and data processing by MATLAB reveal that wavelet analysis has better denoising effects for online measurement of crude oils with high measurement precision and a wide application range.
A Least Square Method for Measurement and Optimisation in Selected Physical Experiments
Authors: Frollo I. , Andris P. , Strolka I. , Bačiak L.
Published: March 2009

The scope of this paper is to demonstrate a least square method for optimisation of basic parameters for selected physical experiment design where large input parameter measurement and adjustment is needed. The speed of calculation and experimentally verified results are promising to use this method in many physical projects. We have demonstrated this method for computation of feeding currents of correcting coils for stationary magnetic field used in NMR imaging. A set of linear equation definition and determination of a target function and optimisation computations are presented with procedures that provide optimal values of currents for shim coils. The proposed method, because of its simplicity and speed of computation, is convenient for basic adjustment of the magnetic field homogeneity by the first magnet installation. It is also suitable for periodic testing and magnet inhomogeneity correction for MRI magnets.
A Study on the Low Cycle Fatigue Behavior of the Steel for Shipbuilding Industry
Authors: Kim Kyung Su , Kim Byung Ok , Kim Young Kwan , Lee Chang Hwan , Lee Sung Won
Published: March 2009

Recently, most of fatigue cracks in ship structures are reported within a few years after delivery. This type of fatigue characteristics cannot be explained adequately by the S-N curve based on high cycle fatigue. Calculation results under critical loading conditions reveal that stress magnitude higher than three times the yield stress occurs at some critical locations. It shows the fatigue cracks are related to low cycle fatigue. But the existing recommended design procedures in maritime industry do not properly cover low cycle fatigue problems. This work represents the first step in an effort to develop a design code that addresses low cycle fatigue problems. Low cycle fatigue test for uniform round specimen made of base/weld metal and for cruciform welded joint are carried out under constant amplitude alternating load, controlled by strain. Strain-cycle curves for the base metal and weld joints show good agreement with published data as well as some code recommended design curves.
Investigation on Fatigue Behavior of Zircaloy -4 Alloy in Room Temperature and 380°C Condition
Authors: Sun Wei Ming , Zhang Kangda , Ren Xing
Published: March 2009

Zr-4 alloy is the material of nuclear fuel shell in nuclear power plant’s PWR. This paper presents this material’s general mechanical property and fatigue behavior that are tested in accordance with ASTM in room temperature and 380°C condition. The test results show that there is no cyclic hardening or cyclic softening phenomena for Zr-4 alloy applied by cyclic loading in room temperature condition. The fatigue design curve is obtained by processing fatigue test results with adopting ASME Sec.Ⅲ based on the test results of strain fatigue property. The research result shows the fatigue design data at different temperature may be corrected by elastic modulus with room temperature curve. This paper’s result may be used in PWR component design.
Finite Element Modeling of Damage Formation in Rubber-Toughened Polymer
Authors: Todo Mitsugu , Fukuya Yoshihiro , Hagihara Seiya , Arakawa Kazuo
Published: March 2009

Microscopic studies on the toughening mechanism of rubber-toughened PMMA (RTPMMA) were carried out using a polarizing optical microscope (POM) and a transmission electron microscope (TEM). POM result showed that in a typical RT-PMMA, a damage zone was developed in the vicinity of crack-tip, and therefore, it was considered that energy dissipation due to the damage zone development was the primary toughening mechanism. TEM result exhibited that the damage zone was a crowd of micro-crazes generated around rubber particles in the vicinity of notch-tip. Finite element analysis was then performed to simulate such damage formations in crack-tip region. Macro-scale and micro-scale models were developed to simulate damage zone formation and micro-crazing, respectively, with use of a damage model. It was shown that the damage model introduced was successfully applied to predict such kind of macro-damage and micro-craze formations.
Applied Research of Fracture for Brass in Extra-Low Cycle Inverse Rotating Bending Fatigue
Authors: Li You Tang , Yan Chang Feng , Ma Ping
Published: March 2009

Rotating bending and inverse rotating bending are the two different forms of fatigue. The application of regular blanking for brass under extra-low cycle inverse rotating bending fatigue was investigated. The principle of inverse rotating bending fatigue was explained at first. And then the experiment of inverse rotating bending fatigue was made in special equipment designed by the authors. Several problems, i.e. the relations of the quantities such as cycle times of fracture, the strain amplitude near the notch tip and fracture toughness of fatigue to the presetting deflection, the effects of depth and tip radius of notch on the cycle times of fracture, were discussed with the helps of experiment. Finally, The relation of depth of crack propagation to cycle times were discussed also. The suitable parameters of inverse rotating bending fatigue for blanking of brass were obtained.
Fatigue Life Evaluation of Press-Fitted Specimens by Using Multiaxial Fatigue Theory at Contact Edge
Authors: Lee Dong Hyung , Goo Byeong Choon , Lee Chan Woo , Choi Jae Boong , Kim Young Jin
Published: March 2009

In the shrink or press-fitted shafts such as railway axles, fretting can occur by cyclic stress and micro-slippage due to local movement between shaft and boss. When the fretting occurs in the press-fitted shaft, the fatigue strength remarkably decreases compared with that of without fretting. In this paper fretting fatigue life of press-fitted specimens was evaluated using multiaxial fatigue criteria based on critical plane approaches. An elastic-plastic analysis of contact stresses in a press-fitted shaft in contact with a boss was conducted by finite element method and micro-slip due to the bending load was analyzed. The number of cycles of fretting fatigue and the crack orientation were compared with the experimental results obtained by rotating bending tests. It is found that the crack initiation of fretting fatigue between shaft and boss occurs at the contact edge and the normal stress on the critical
plane of contact interface was an important parameter for fretting fatigue crack initiation. Furthermore, the results indicated that a critical plane parameter could predict the orientation of crack initiation in the press-fitted shaft.
Research on Microstructures of Alloyed Layer by Plasma Surface Alloying with Tungsten and Molybdenum
Authors: Yuan Gao , Xu Jin Yong , Liu Yan Ping , Wang Jian Zhong , Kui Xiaoyun , Xu Zhong
Published: March 2009

The alloying elements W-Mo cementation is carried out on the surfaces of low carbon steels by the technique of plasma metallurgy. Then by using the plasma-supersaturated carbonization, the composition of surface alloying layer reaches or approaches that of low-alloy HSS. In the end the surface alloying layer possesses high hardness, favorable red hardness and a significant improvement in properties after high temperature quenching and high temperature tempering. The surface cementation structure and phase structure of alloying layer were analyzed using metallographic microscope and X-ray diffraction (XRD), respectively; the distribution of surface composition and hardness of the layer were investigated by Glow Discharge Analytical Instrument (GDA) and micro hardness instrument, respectively; the resistance to wear was tested by a abrasion machine. The experimental results indicated that the layer consisted of W-Mo solid solution in Fe, the depth of the layer could reach 100µm and the content of tungsten exceeded 10% after ion W-Mo cementation. The carbon content of carburized layer was 1.3% above, which was composed of M6C carbide containing a lot of elements of W-Mo. The surface hardness of the alloying layer attained the HV1000 or so and appeared graded distribution after quenching and tempering. The application study showed that alloying elements W-Mo cementation was an appropriate technique to enhance surface resistance to wear and prolong operating life of accessories.
Study on Temper Embrittlement of Phosphorus in Steel 12Cr1MoV
Authors: Li Li , Li Qing Fen , Guo Er Jun , Liu Er Bao , Cui Xin Fang , Xu Xiao Xue
Published: March 2009

According to the non-equilibrium grain-boundary segregation (NGS) kinetics curve of phosphorus, a series of Charpy impact tests was performed in an industrial steel 12Cr1MoV, at solution temperature 1050oC, with isothermal holding temperature 540oC, on specimens of different holding time (at the segregation process, the critical time, and the desegregation process respectively). The DBTT values were measured and a temper embrittlement kinetics curve was given. The reverse temper embrittlement NGS mechanism for steel 12Cr1MoV was proposed.
Principal Stress Separation Using a Combination of Photoelasticity and Thermoelastic Stress Analysis under Biaxial Stress
Authors: Shimamoto Akira , Ohkawara Hiroshi , Yang Sung Mo
Published: March 2009

Today, stress measurement methods by thermography and by photoelasticity are widely used to make stress distribution visible. However, it is difficult to separate principal stresses using only one of these methods because only the difference of principal stresses is measured in photoelasticity, and only the sum of the principal stresses is measured in thermograpy. Therefore, the inverse analysis problem must be solved to separate the principal stress in the thermoelastic method and the shear difference integration method must be used for the photoelastic method. Although there are some reports separation of the principal stresses under uniaxial stress by combining the two methods, little research under the biaxial stress has been reported due to the difficulty of experimentation. In this research, the principal stresses under biaxial stress are separated by a combined method. Moreover, it is verified that the thermoelastic stress measurement method is effective to evaluate the stress concentration factor.
Development of Damage Assessment Method for Steel Structures Using Material-Structure Coupling Analysis
Authors: Lee Jae Myung , Paik Jeom Kee , Kim Myung Hyun , Toi Yutaka
Published: March 2009

Once assessment of material failure characteristics is captured precisely in a unified way, it can be directly incorporated to the structural failure assessment under various loading environments, based on the theoretical backgrounds so called Local Approach to Fracture. The aim of this study is the development of an expert system applicable for the assessment of structural integrity throughout
crack initiation and structural failure based on the Local Approach to Fracture. The generalized elasto-visco-plastic constitutive equation, which can consider the internal damage evolution behavior, was developed and employed in the 3-D FEA code in order to numerically evaluate the material and/or structural responses. Explicit information of the relationships between the mechanical properties and material constants, which are required for the mechanical constitutive and damage
evolution equations for each material, was implemented in an automatic system using genetic algorithm based on an inference system. The material constants selected from genetic search and constitutive equations are used directly in the failure assessment of material and/or structures. The performance of the developed system has been evaluated for the S-N relationship assessment of several materials as well as the crack initiation assessment of various weldments in steel structures.
Effect of Heat Treatment on the Properties of Inconel X-750
Authors: Cheng Shi Chang , Lin Zhao Jie , Yang Gang , Liu Zheng Dong
Published: March 2009

The authors experimentally investigated the change of mechanical properties of Inconel X-750 alloy under various heat treatments. For the selected specimens, solid solution treatment under different temperatures was carried out, followed air cooling or furnace cooling. Results show that suitable solid solution treatment and air cooling enhances the strength, plasticity, impact toughness at room temperature of the alloy and lowers the hardness of the alloy at room temperature.
Effect of the Elastic Restraint by Adjacent Plate Component on the Local Buckling of Orthotropic Box-Shape Flexural Members
Authors: Jung Jae Ho , Yoon Soon Jong , You Sung Kun , Youn Seok Goo
Published: March 2009

The local buckling analysis of thin walled member is generally conducted by modeling
each plate component as an isolated plate with elastically restrained boundaries. When this analytical model is used for the orthotropic flexural members, it is necessary to obtain the degree of elastic restraint provided by adjacent plate. In this study, the equation to find the coefficient of elastic restraint by adjacent plate components of an orthotropic box-shape flexural member was derived by employing the energy approach, and the factors affecting the elastic restraint were briefly discussed. Using the suggested equation, the coefficient of elastic restraint was calculated, and the local buckling analysis was conducted according to the stepwise analytical procedure published by the authors. The theoretical predictions were in good agreement with results obtained by the closed-form solution. The local buckling strength of an orthotropic box-shape flexural member can be easily obtained through stepwise analytical procedure with the proposed equation that accounts for the effect of elastic restraint imposed by adjacent plate components.
Buckling Behavior of Pultruded Monosymmetric Members
Authors: Lee Seung Sik , Yoon Soon Jong , Cho S.K. , Park Jong Myen
Published: March 2009

Pultruded fiber reinforced polymer (FRP) structural members have been used in various civil engineering applications. T-shapes are commonly used for chord members in trusses and for bracing members. In these cases, T-shapes are mainly subjected to axial forces, and stability of a member is one of the major concerns in the design. Due to the monosymmetry existing in the cross-section of T-shapes, T-shapes are likely to buckle in a flexural-torsional mode. An energy solution, using the Ritz method, to the buckling problem of a pulturuded T-shape under uniform compression is derived based on a composite thin-walled beam theory developed by Bauld and Tzeng. The solution accounts for the bending-twisting and bending-extension coupling effects. The derived energy solutions are compared to the experimental results of buckling tests conducted on seventeen pultruded T-shapes. It is found that the ratios of the experimental to analytical results are in the range of 1.00 to 1.32.
Determination of Singular Residual Stresses in Epoxy Layer Deposited on Concrete Substrate
Authors: Lee Sang Soon
Published: March 2009

This paper deals with the hygrothermal stress singularity induced at the interface corner between the epoxy coating layer and the concrete substrate as the coating layer absorbs hot moisture from the ambient environment. The epoxy layer is assumed to be a linear viscoelastic material and to be theromorheologically simple. It is further assumed that moisture effects are analogous to thermal effects. The viscoelastic boundary element method is employed to investigate the behavior of interface stresses. The order of the singularity is obtained numerically for a given viscoelastic model. The numerical results exhibit the relaxation of interface stresses and large stress gradients are observed in the vicinity of the free surface. Since the exceedingly large stresses cannot be borne by the epoxy coating layer, local yielding or the delamination can occur at the interface corner.
Fatigue Behavior of Impacted Plain-Weave Glass/Epoxy Composites under Tensile Fatigue Loading
Authors: Kang Ki Weon , Kim Jung Kyu , Kim Heung Seob
Published: March 2009

The goals of this paper are to identify the impact damage behavior of plain-weave
E-glass/epoxy composites and predict the fatigue life of the composites with impact-induced damage under constant amplitude loading. To identify these behaviors, the low velocity impact and fatigue after impact tests are performed for glass/epoxy composites having two types of fiber orientations. The impact damage behavior is dependent on the fiber orientation of the composites. The fatigue life of the impacted composites can be identified through the prediction model, which was proposed on
the carbon/epoxy laminates by authors regardless of fiber orientations.
Impact Behavior Analysis of PC/ABS (50/50) Blends
Authors: Nizar Machmud M. , Omiya Masaki , Inoue Hirotsugu , Kishimoto Kikuo
Published: March 2009

Impact behavior of simply-supported circular thin plates made of PC/ABS (50/50) blends tested at room temperature by use of instrumented drop weight impact apparatus under different speeds: 2, 3, and 4m/sec has been studied. The blends have 10wt% content of rubber with rubber particle diameter of 270nm and of 150-170nm distributed in ABS. Features of the target are viewed to describe definite alteration of the plates induced by a hemispherical tip-ended cylindrical impactor
and effect of rubber particle size distributed in the blends. It was found that the blends with a rubber particle diameter of 150-170nm were not in shattering and exhibited a unique crack shape at speed of 3m/sec. Simulation of the impact test was also performed using dynamic explicit finite element code of MSC. Dytran. In the simulation, the material was assumed isotropic and mass served as a rigid
surface and an available material model in the finite element system, called piecewise linear plasticity, referring to a yield model of the von Mises was applied in the simulation for describing the large strain, non-linear behavior of the polymeric materials. Maximum plastic strain failure criterion was then used to simulate the impact failure. Contact between the impactor and the plate was applied and friction coefficient µ between the impactor and the plate was neglected. In order to study effect of friction coefficient value, additional simulation of the impact test has also been performed using µ = 0.3. Impact force-time histories of the blends obtained from the simulation were then verified to the impact test results and pointed out an evaluation of the use of the finite element analysis for predicting behavior of the blends under the impact loading.