bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of Element Size on Rock Shear Strength and Failure Pattern by Rock Failure Progress Analysis (RFPA2D)
Authors: Song Li , Zhang Hou Quan , Liang Zheng Zhao , Jiao Ming Ruo , Ma Tian Hui , Zhang Juan Xia , Tang Liexian
Published: March 2009

Six types of numerical specimens containing two notches are set up to numerically
investigate the effect of element size on rock shear strength and failure pattern using RFPA2D (rock failure process analysis) code. These specimens are of the same geometrical dimension 180 mm×180 mm and have been discretized into 61×61, 122×122, 183×183, 244×244, 305×305, and 366×366 elements.The width of notches is about 2.95 (180/61) mm and the length is 45mm. The specimens are placed in a direct shear box. A lateral confining pressure with a value of 0.15MPa is invariably loaded in the vertical direction and an increasing horizontal displacement with 0.002mm/step is applied in the horizontal direction. The whole shear failure progress and associated stress field for the specimens are visually represented. Results show that the crack propagation is mostly influenced by the stress field in the vicinity of the notch tip, the required element size would be necessary in order to obtain good results. In general, for a coarse mesh, the stress field close to the notch tip can’t be represented accurately and shear strength obtained by such discretisation is slightly higher than the accurate value. For a fine mesh, the notch tip spreads through a relatively large number of elements and the stress field in vicinity of notch tip is well represented by the finite element approximation, therefore the failure pattern is consistent with real physical fracture mode.
A Numerical Study of Pillar Failure Based on a Cusp-Type Catastrophe Model
Authors: Wang Shan Yong , Au S.K. , Lam K.C. , Tang Chun An
Published: March 2009

Based on cusp-type catastrophe theory, a sample rock-rock (hypocenter surrounding the rock) model for studying the pillar rockburst mechanism is presented in this paper. It is expounded theoretically that the stiffness ratio, K, of the roof and floor to the pillar plays an important role in the outbreak of instability. Using a newly developed numerical code, RFPA2D, the progressive failure process and associated microseismic behavior of the twin rock samples are simulated. The numerically simulated results also confirm that a soft roof and floor promotes an unstable failure or collapse of pillars. Additionally, the simulated results reproduced the deformation jump and the energy release that occur during a pillar rockburst. It is demonstrated that the proposed model properly simulates the pillar failure process.
Development of Integrated Materials Database System for Plant Facilities Maintenance & Optimization
Authors: Jang Dong Sik , Jung Jine Sung , Kim Eui Hyun
Published: March 2009

Features of the materials database system for plant facilities management are discussed here. Korea Electric Power Research Institute (KEPRI) has developed web-based materials database system for power plant engineers with an aim to give them the integrated materials information which is needed in solving material-related problems frequently occurred in plant maintenance activities. The materials database system contains more than twenty thousands material standard data of eight countries including chemical composition, mechanical properties, and their applications in the power plant facilities. Using the system, users can find useful information of equivalent material standards and physical or chemical environments where the material is applied. Integration of material data with facility data is expected to give more valuable information to plant engineers in solving their material related problems. The database system also adopted state-of-arts extensible markup language (XML) technology and was designed to share its data easily with other information systems such as plant engineering expert system, materials management system, enterprise resource planning (ERP) system and so on.
Development of Web Based Power Plant Maintenance Management System
Authors: Kim Bum Shin , Song Gee Wook
Published: March 2009

For prevention of failure and extension of maintenance interval, many Asian power
companies have continuously tried to apply Condition Based Maintenance system to their plants. However, only few companies succeed to change their maintenance system from fixed time based to equipment condition based, although there are many brand new ITs, such as high speed computing system, huge storage device, and advanced development software tools. This paper describes the reasons why they failed to change and proposes the solutions to construct maintenance management system based on equipment condition. The solutions were also applied practically to power plant in Korea.
Shape Optimization of Cutouts in Laminated Composite Plates Using Solid Element
Authors: Han Seok Yoon , Ma Y.J. , Park J.Y.
Published: March 2009

Shape optimization was performed to obtain the precise shape of cutouts including the internal shape of cutouts in laminated composite plates by three dimensional modeling using solid element. The volume control of the growth-strain method was implemented and the distributed parameter was chosen as Tsai-Hill failure index for shape optimization. In order to verify the validity of the obtained optimal shapes, the changes of the maximum Tsai-Hill failure index were examined for each load condition and cutouts. The following conclusions were obtained in this study; 1) It was found that growth-strain method was applied efficiently to shape optimization of three dimensional cutouts in anisotropic laminate composite, 2) The optimal three dimensional shapes of the various load conditions and cutouts were obtained, 3) The maximum Tsai-Hill failure index was reduced up to 68% when shape optimization was performed under the initial volume by volume control of growth-strain method.
Design of Transversely Isotropic Tapered Plate Element in FRP Flexural Members
Authors: Jeong Sang Kyoon , Yoon Soon Jong , Jang Won Sup
Published: March 2009

The structural shapes or plates with varying thickness are often adopted in aerospace industries such as a skin structure of an airplane and civil engineering fields where the load effects are varied along the longitudinal axis of the member. Specially, the structural steel tapered plate, so called LP (longitudinally profiled) plate, has been used in many countries as a part of main member of bridges, buildings, etc. This paper presents the result of an analytical study pertaining to the local buckling behavior of FRP (Fiber Reinforced Plastic) flexural member. The flexural member is consisted with uniform thickness web and flange tapered in thickness. The boundary conditions of flange plate in its unloaded edges are elastically restrained, but they are assumed to be either fixed-free or simple-free for simplicity. In the analysis, the Galerkin form of Rayleigh-Ritz method is adopted. The buckling equation of isolated unstiffened tapered plate elements having fixed-free or
simple-free boundary condition in its unloaded edges is derived. The plate buckling coefficients with respect to the thickness ratios and plate aspect ratios are calculated and presented in a graphical form. Unlike the buckling of plate with uniform thickness, discontinuous changes of buckling mode are not exist. In addition, the critical slenderness ratio of such an unstiffened tapered plate element is
suggested to prevent buckling.
Fatigue Life Evaluation for a Reaping Knife of Combine
Authors: Noh Byeong Wook , Choi Young Woo , Song Jung Il , Bae Sung In
Published: March 2009

The Combine is necessary equipment in the agricultural industry. The components of the Combine are worked for a long time under inferior environmental condition. Especially reaping knife is worked in high frequency domain, and submit fatigue load while use. So, fatigue test was performed to obtain the S-N curve of real component, and load history is measured through field test. The local stresses due to these loads have been calculated by FEM. These results have been used as the input values for the multi-axial fatigue analysis of real components. For the assessment of
multi-axial fatigue damage, the critical plane methods have been employed. The used parameters of critical plane methods are Morrow’s, Smith-Waston-Topper’s, and Brown-Miller’s, those were modified for the high cycle fatigue region within elastic behavior. In addition, design improvement is performed about shape of reaping knife to increase the endurance limit, and durability test for
improved knife is performed. It is found that the fatigue life of improved reaping knife is increased, and durability test result show that life of reaping knife is increased enough.
Automated Fatigue Life Assessment for Welded Cruciform Joint Considering Welding Residual Stress
Authors: Lee Tak Kee , Rim Chae Whan , Han Seung Ho , Lee Jong Han
Published: March 2009

For a rational design of a welded joint, it is necessary to repeatedly assess the fatigue life of the joint with various dimensions and welding conditions. In this paper, an automated, repeatable/repetitive fatigue life assessment process for a welded cruciform joint was studied. The process consists of a structural analysis to obtain the stress distribution in the vicinity of the weldtoe, a thermal elasto-plastic analysis to determine the welding residual stress, and a fatigue life assessment based on the analyzed stress distribution and welding residual stress. With changes in design conditions including dimensions and/or welding heat input, the aforementioned tasks have to be performed. Using a commercial tool for system integration, automation of a repeated process for a welded cruciform joint based on 2D modeling was achieved. In this automated system, data exchanges between programs, regardless of whether they are commercial or in-house, work well, and parametric studies for optimal design can be performed.
Effect of Process Variables on Microstructure and Mechanical Properties of Wide-Gap Brazed IN738 Superalloy
Authors: Kim Yong Hwan , Kim Il Ho , Kim C.S.
Published: March 2009

This study investigated the microstructure and mechanical properties of a wide-gap region brazed with various process variables. The IN738 and DF 4B alloy powders were used as additive and filler metal powder for the brazing process. The wide-gap brazing process was carried out in a vacuum of 2×10-5 torr. The wide-gap region brazed with 60wt.% IN738 additive powder had a microstructure consisting of IN738 additive and (Cr, W)2B. The fracture strength of the wide-gap region (60 wt.%
additive and 40 wt.% filler metal powder) brazed at 1230°C for 30hr was as high as 862MPa (93% of base material strength). It was observed that the brazing temperature was the main process variable affecting the mechanical properties of the wide-gap brazed region. The creep rupture life of the region brazed with 60wt.% additive and 40 wt.% was longer than that of other brazed samples. The Cracks in
the wide-gap brazed region initiated at the (Cr, W)2B and propagated through them. It was found that the (Cr, W)2B and the pore in the brazed region are important microstructural factors affecting the mechanical properties of the wide-gap brazed region.
Evaluation of Fatigue Strength and Spot Weldability of High Strength Steel Sheet for Light Weight Automobile Body
Authors: Bae Dong Ho , Jung Won Seok , Heo J.B.
Published: March 2009

An effective way to reduce the weight of vehicle body seems to be application of new
materials, and such trend is remarkable. Among the various materials for vehicle body, stainless steel sheets and cold rolled steel sheets are under the interests. However, in order to guarantee reliability of new material and to establish the long life fatigue design criteria for body structure, it is necessary to assess spot weldability and fatigue strength of spot welded lap joints fabricated under optimized spot welding condition. In this paper, spot weldability of stainless steel sheets, STS304L and STS316L, and cold rolled steel sheets, SPCC and SPCD. Fatigue strength of lap joints spot welded between similar and dissimilar materials were also assessed.
Fracture Toughness Measurement of a Micro-Sized Single Crystal Silicon
Authors: Koyama Satoru , Takashima Kazuki , Higo Yakichi
Published: March 2009

Reliability is one of the most critical issues for designing practical MEMS devices. In
particular, the fracture toughness of micro-sized MEMS elements is important, as micro/nano-sized flaws can act as a crack initiation sites to cause failure of such devices. Existing MEMS devices commonly use single crystal silicon. Fracture toughness testing upon micro-sized single crystal silicon was therefore carried out to examine whether a fracture toughness measurement technique, based upon the ASTM standard, is applicable to 1/1000th sized silicon specimens. Notched cantilever beam type specimens were prepared by focused ion beam machining. Two specimens types with different notch orientations were prepared. The notch plane/direction were (100)/[010], and (110)/[ ＿ ,110], respectively. Fracture toughness tests were carried out using a mechanical testing machine for micro-sized specimens. Fracture has been seen to occur in a brittle manner in both
orientations. The provisional fracture toughness values (KQ) are 1.05MPam1/2 and 0.96MPam1/2, respectively. These values meet the micro-yielding criteria for plane strain fracture toughness values (KIC). Fracture toughness values for the orientations tested are of the same order as values in the literature. The results obtained in this investigation indicate that the fracture toughness measurement
method used is applicable for micro-sized components of single crystal silicon in MEMS devices.
The Thermal Analysis of Brake Disc with 3-D Coupled Analysis
Authors: Hwang Jung Ho , Kim Heung Seob , Choi Young , Kim Byeong Soo , Kang Ki Weon
Published: March 2009

As the automobile industry develops, the demand for automobiles that provide more
comfortable ride and safety is also increasing. In the conventional braking analysis, frictional heat generation is only related to wheel speed, friction material, and the interface pressure. However, under the dynamic braking conditions, the frictional heat causes the thermo-elastic distortion that leads to more concentrated distribution of contact pressure and hence more and more non-uniform temperature. This paper describes the thermo-elastic instability arising from friction heat generation in braking and proposes the finite element methods to predict the variation of temperature and thermal deformation.
Design of Compound CVT with 2K-H II Type Differential Gear
Authors: Kim Yeon Su , Park Jae Min , Choi Sang Hoon
Published: March 2009

We designed the compound CVT (Continuously Variable Transmissions) by combining power circulation mode and power split mode, which have been proposed for connecting 2K-H II differential gear to the V- belt type CVU (Continuously Variable Unit), as an input coupled type. With the designed compound CVT, we carried out theoretical analysis and performance experiments. We proved that the compound CVT had a better performance than either of the power circulation mode or power split mode.
Image Processing Techniques Applied to Automatic Measurement of the Fatigue-Crack
Authors: Ryu Dae Hyun , Nahm Seung Hoon
Published: March 2009

A crack detection system was developed to observe growth behavior of fatigue crack using the digital image processing techniques. The crack propagation behavior was observed successfully by combining block matching method and inclination threshold value method. The data obtained with this new system agreed with the existent data and the standard deviation was 0.03%. If the proposed
method is utilized to develop a crack monitoring system to observe the crack growth behavior automatically, the time and effort needed for a fatigue test could be dramatically reduced. And also it will be easier to estimate and to manage efficiently the safety and residual life of industrial facilities.
Structural Assessment for Bogie Frame of 180km/h Korean Tilting Train
Authors: Kim Jung Seok , Kim Nam Po
Published: March 2009

This paper has performed the fatigue strength evaluation for the bogie frame of Korean tilting train. In order to verify the structural safety of the bogie frame, we firstly investigated the loading condition imposed on the bogie frame. The bogie frame of the tilting train is exposed to the more severe loadings compared with the conventional one because of the tilting of the carbody and the high-speed curve negotiation. We have conducted some multi-body dynamic analyses to extract the load condition by tilting on curve. The finite element analysis is used to obtain the stress distribution. Through this study, we could make sure the safety of the tilting bogie frame.
Analytical Study on Biaxial Strength of Structural Ceramics under Tension-Compression Condition
Authors: Hanawa Satoshi , Ishihara Masahiro , Motohashi Yoshinobu
Published: March 2009

In the structural design of ceramics components especially for graphite materials, it is important to apply the realistic fracture model in the design method so as to reduce the large safety margin. In this study, we proposed the multiaxial strength model by expanding the microstructure based brittle fracture model applicable to both uniaxial tensile and compressive stress conditions. The advantage of the model is a treatment of the microstructural information such as grain size, pore size
and pore size distribution. The proposed model was applied to biaxial strength prediction of near isotropic nuclear graphite using grain/pore related microstructure parameters. Predicted results were compared with biaxial strength data, and it was found that the proposed fracture model showed fairly good strength prediction.
A Study of Nitrogen Effect on the Characteristics of Creep-Rupture in 18Cr-9Ni Austenitic Steels
Authors: Shin Jae Kyoung , Nam Soo Woo , Lee Soo Chan
Published: March 2009

To understand the effects of nitrogen on high temperature, creep-rupture tests have been conducted at 973 and 1073K for 18Cr-9Ni austenitic stainless steels with 0.14 and 0.08wt% nitrogen contents. It is observed that creep-rupture life of 18Cr-9Ni-0.14N steel is longer than that of 18Cr-9Ni-0.08N steel. To verify the difference in creep-rupture life between two alloys, scanning electron microscope and transmission electron microscopy are used to observe the microstructure. From the observations, it is known that the Cr-rich carbides are precipitated mainly at the grain boundary. Comparing the ratio of the linear density of the precipitate particles, the higher nitrogen content is, the less carbide is precipitated. Nitrogen might retard the formation of carbides at the grain boundary and reduce the density of cavity sites which are one of the main grain boundary damages.
Effects of Forming Processing on Mechanical Properties of Ti-48Al-2Mn-2Nb Intermetallics
Authors: Chen Wen Zhe , Peng Kai Ping , Qian Kuang Wu , Gu Hai Cheng
Published: March 2009

Ti-48Al-2Mn-2Nb alloy was produced by “centrifugal spray deposition” (CSD), and then hot isostatic pressing (HIP) was employed to remove the porosity formed by CSD. The effects of CSD and HIP processing on the mechanical properties and microstructure of the TiAl alloy were investigated. The results show that the CSD and HIP processing can both improve the strength, plasticity of the TiAl alloy, and the tensile elongation values of the CSD or HIP samples are around
3%, which are better than those of as-cast TiAl alloys in room temperature. Especially, they show more excellent compressive properties at ambient temperature with a compressive ratio of 33.8% and compressive strength of 2210MPa for the CSD samples, and a compressive ratio of 37.8% and compressive strength of 2348MPa for the HIP samples. The CSD processing also improves the
fracture toughness of TiAl alloy, which is much higher than that of the HIP processing, while the HIP processing seems to be beneficial the ductility and plasticity as having a duplex structure. The effects of CSD and HIP processing on microstructure and properties of TiAl alloys are discussed to understand the deformation and fracture process of the alloy.
Effects of Melt-Treatment Technique on the Metallurgical Quality and Mechanical Properties of Al Sheet Used for Can Manufacture
Authors: Fu Gao Sheng , Chen Wen Zhe , Qian Kuang Wu
Published: March 2009

The Al sheet used for pressure can manufacture (or called Al piece) was prepared by different melt-treatment techniques and using the lower grade commercial purity raw Al (Al99.5). And the influence laws of melt-treatment techniques on the metallurgical quality and mechanical properties of Al piece were investigated. It is found that high-efficient melt-treatment technique improves the metallurgical quality of Al piece remarkably, that is, the rate of removing inclusions and the extent of lowering porosity amount to about 66.6% and 87.0%, respectively, and as-cast mean grain diameter decrease to a great extent, and the coarse and long needle/flake Fe-rich impurity phases transform into complex compounds of tiny, sphere/short stick form, which makes fracture mechanism of the material be transformed into the congregation of transgranular micro-hole, thus raising mechanical properties of this material remarkably. Its metallurgical quality and mechanical properties have reached or exceeded the level of present products. It is feasible that Al piece is made by using the lower grade commercial purity raw Al. The viewpoint that the purification is the fundamental and key process, i.e., the basic of modification and grain refinement processes, has been also further tested and verified.
Simple Estimation of Deformation-Induced Martensite in Stainless Steel
Authors: Date Hidefumi
Published: March 2009

To estimate the volume fraction of martensite induced in 304ss type austenitic stainless steel during tensile deformation, the electric resistance of the specimen was measured using the four-point-probes method at the temperatures of 77, 196 and 293K during the deformation. The magnetic force of the deformed specimen was also measured using a permanent magnet to determine the strain at which the martensite was induced initially in the specimen. The parallelepiped model was
suggested to separate the effects of the deformation and transformation on the electric resistivity because the resistivity was influenced by the evolution of the martensite and the growth of the defect in the matrix at a constant temperature. The parallelepiped model consisted of m columns with n pieces of the cubic element and was assumed to be a group of small electric resistors. The volume fraction of the martensite estimated using the measured resistivity and the model was compared with the experimental results reported by other researchers and then it was clarified that the volume fraction of the martensite estimated by the model was in agreement with the volume fraction measured by the experiment.
Tensile and Fracture Behavior of NbSS/Nb5Si3 In Situ Composites Prepared by Arc Melting
Authors: Kim Jin Hak , Tabaru Tatsuo , Sakamoto Michiru , Hanada Shuji
Published: March 2009

Nb-base in-situ composites, which have the base composition of Nb-18Si-5Mo-5Hf, have been investigated in microstructure, hardness (Hv*), Young’s modulus (E), tensile properties and fracture behavior. The microstructures of all composites examined consist of NbSS matrix and Nb5Si3 secondary phases. No secondary phase such as Nb2C appeared. The crystal structure of Nb5Si3 is Mn5Si3-type when C replaces 2mol%-Nb, though typical structures of a (Cr5B3-type) and b (W5Si3-type) as in the base composition when W replaces. W addition is effective in increasing Hv* and E of both phases as expected. However, C alloying is somewhat beneficial only in Nb5Si3 with a noticeable negative effect in NbSS. Furthermore, the composite exhibits the highest strength at 1473 K, while the base composite exhibits the highest at room temperature. The fracture behavior is
independent of the compositions and it is controlled by cleavage fractures of Nb5Si3, decohesion of NbSS/Nb5Si3 interface and ductile rupture of NbSS depending on the testing temperatures.
Mechanical Properties and Process of ZnO Deposited Various Substrates
Authors: Jung Hun Chae , Yoon Han Ki , Yu Yun Sik
Published: March 2009

ZnO is an n-type semiconductor having a hexagonal wurzite structure. ZnO exhibits good piezoelectric, photoelectric and optical properties and might be a good candidate for an electroluminescence device like an UV laser diode. But the important problems, such as substrate kinds and substrate temperature are raised its head, so they need to optimize deposit condition. Because these devices are very small and films are very thin, those are often prepared in limited quantities and
shapes unsuitable for the extensive mechanical test. In this present work, ZnO thin films are prepared on the glass, GaAs (100), Si (111) and Si (100) substrates at different temperatures by the pulsed laser deposition (PLD) method. ZnO was evaluated in term of crystalline through X-ray diffraction (XRD),
mechanical properties such as hardness, elastic modulus through nano-indenter. XRD measurements indicate that the substrate temperature of 200-500, 200-500, 300-500, and 300-500oC was the optimized conditions of crystalline for the glass, GaAs (100), Si (111), and Si (100) substrates, respectively. In spite of the films deposited on the different substrates, the films always show (002) orientation at the optimized conditions. Mechanical properties such as hardness and elastic modulus are influenced substrate crystallization. In case of Si (111) substrate, hardness and elastic modulus are about 10, 150GPa, respectively.
Preparation of Solid Polymer Actuator Based on PEDOT/NBR/Ionic Liquid
Authors: Cho Mi Suk , Nam Jae Do , Choi Hyouk Ryeol , Koo Ja Choon , Lee Young Kwan
Published: March 2009

The fabrication of dry type conducting polymer actuator was presented. In the preparation of actuator system, nitrile rubber (NBR) was used as a base material of the solid polymer electrolyte. Thin films of NBR (150-200μ m) were prepared by compression molding process. The conducting polymer, poly (3,4- ethylenedioxythiophene) (PEDOT) was synthesized on the surface of NBR by
chemical oxidation polymerization technique, and the room temperature ionic liquid, 1-ethyl-3- methylimidazolium bis (trifluoromethyl sulfonyl) imide (EMITFSI) was introduced into the composite film. The ionic conductivity of new type solid polymer electrolyte as a function of the immersion time and the cyclic voltammetry responses and the redox switching dynamics of PEDOT in NBR/ionic liquid solid polymer electrolyte were studied. The displacement of actuator was measured by laser beam radiation.
Development of Smart Composite Panel with Optical Fiber Sensors
Authors: Murayama Hideaki , Kageyama Kazuro , Ohsawa Isamu , Kanai Makoto , Uzawa Kiyhoshi , Matsuo Tsuyoshi
Published: March 2009

We have developed a novel fiber-optic vibration sensors and applied commercially
available strain and temperature sensors to health monitoring of composite structures. In this study, we constructed an optical fiber network integrating four types of optical fiber sensor into a carbon reinforced plastic (CFRP) panel. These four sensors were the vibration sensor developed by our laboratory, two distributed sensors based on Brillouin and Raman backscattering and Fiber Bragg
Grating (FBG) sensors. By dealing the data obtained from the measurement systems corresponding to these four sensors, strain/stress and temperature distributions throughout the panel can be monitored. Vibration and elastic waves transmitting on the panel are also detected at several sensing points. Furthermore, we will be able to determine damage locations and modes by processing the wave signals. To make the panel with the optical fiber sensor network more sensitive and smarter, we are developing some techniques that can improve the performance of the sensors and can assess the structural integrity by analyzing measurement results. In this paper, the development of the first generation of our smart composite panel with the optical fiber sensors is described and the techniques making the panel more sensitive and smarter are also described.
Design and Control of Three-DOF Dielectric Polymer Actuator
Authors: Koo Ja Choon , Choi Hyouk Ryeol , Jung Min Young , Jung Kwang Mok , Nam Jae Do , Lee Young Kwan
Published: March 2009

Smart polymer based actuators have demonstrated various benefits over the traditional electromagnetic or piezoelectric-material actuators. One of the most significant contributions of the polymers is its soft actuation mechanisms. Hence morphological freedom for actuator construction benefits production of either small scale complex mechanisms or human-like applications. Although many actuation paradigms of polymer actuators are presented in various publications, no significant
contributions are made for investigation of modeling and control methods of the material. In the present work, a smart polymer based actuator is constructed. It is then modeled and analyzed for feasible control scheme selection.
Analysis of Failure Criterion for Combustion Chamber with Notch Using Effective Distance
Authors: Kim Duck Hoi , Kim Jae Hoon , Moon Soon Il
Published: March 2009

In this study, the intrinsic static/dynamic fracture toughness of Al 7175-T74 is evaluated from the apparent static/dynamic fracture toughness of a notched specimen. A critical average stress fracture model is suggested to establish the relationship for predicting the intrinsic fracture toughness from the apparent fracture toughness of a notched specimen. The critical average stress fracture model is established using the relationship between the notch root radius and the effective distance calculated by finite element analysis. The effective distance is the major characteristic describing stress distributions ahead of the notch tip. Therefore, the effective distance can be used to evaluate the behavior of structures containing notches. In this study, effective distance is applied to estimate the failure criterion for the combustion chamber with a notch. It is concluded that the true fracture toughness can be estimated from test results of apparent fracture toughness measured by using a notched specimen. Also, the effective distance can be used to evaluate the failure criterion of structures with notches.
Fatigue Crack Initiation and Propagation Life of Welded Joints
Authors: Han Jeong Woo , Han Seung Ho , Shin Byung Chun , Kim Jae Hoon
Published: March 2009

The fatigue life of welded joints is associated with crack initiation and propagation life.
Theses cannot be easily separated, since the definition of crack initiation is vague due to the initiation of multiple cracks that are distributed randomly along the weld toes. In this paper a method involving a notch strain and fracture mechanical approach, which considers the characteristics of welded joints, e.g. welding residual stress and statistical characteristics of multiple cracks, is proposed, in an attempt
to reasonably estimate these fatigue lives. The fatigue crack initiation life was evaluated statistically, e.g. the probability of occurrence in 2.3, 50 and 97.7%, in which the cyclic response of the local stress/strain in the vicinity of the weld toes and notch factors derived by the irregular shape of the weld bead are taken into account. The fatigue crack propagation life was simulated in consideration of the Mk-factor and the mechanical behavior of mutual interaction/coalescence between two
adjacent cracks. The estimated total fatigue life as a sum of crack initiation and propagation life was found to be in good agreement with the experimental results.
Geometry Sensitivity Analyses of Microstructures of IC Packages on Passivation Cracking
Authors: He Yu Ting , Li F. , Shi Rong , Zhang G.Q. , Ernst L.J. , Zhang Jack , Song Zhi Tang
Published: March 2009

Passivation crack is one of the main failures of micro-electronics. And the IC interconnect has a large varying range values comparing with its geometry size. In this paper, the influence of geometry values of micro-structures of IC packages on passivation cracking is studied by maximum principal stress theory using a certain 2D FEM model with different design geometry parameters, pitch of lines, width of line, thickness of epoxy, thickness of dielectric layer and the Aluminum yielding stress (following as “d”, “w”, “t_epo”, “t_Teos” and “sy_al” respectively). For different critical process step, here the final process temperature is acted as a representative parameter to analyze its impact. Furthermore, Response Surface Model (RSM) of principal stress is established
using any two design parameters. Results show that width of line, thickness of dielectric layer and the Aluminium yielding stress will have great influence on passivation cracking while other parameters having little impact.
A Comparative Study of The Fatigue Behavior of SnAgCu and SnPb Solder Joints
Authors: Kim Il Ho , Park Tae Sang , Yang Se Young , Lee Soon Bok
Published: March 2009

Fatigue behaviors of 63Sn37Pb and two types of lead-free solder joints were compared using pseudo-power cycling testing method, which provides more realistic load cycling to solder joints than chamber cycling method does. Pseudo-power cycling test was performed in various temperature ranges to evaluate the shear strain effect. A nonlinear finite element model was used to simulate the thermally induced visco-plastic deformation of solder joint in BGA packages. The results revealed that lead free solder joints have a good fatigue property in the low temperature condition, where a small strain was induced. In the high temperature condition where a large strain was induced, however, lead contained solder joints have a longer fatigue life.
Diagram of Electromigration Pattern in Eutectic Pb-Sn and Pb-Free Solders
Authors: Hasegawa Takashi , Saka Masumi
Published: March 2009

Solder is the most frequently used alloy, which serves as the bonding metal for electronics components. Recently, the interconnected bump is distinctly downsizing its bulk along with the integration of high-density packaging. The evaluation of electromigration damage for solder bumps is indispensable. Hence, it is fairly urgent to understand the mechanism of the electromigration damage to be capable of securing reliability of the solder bump and ultimately predicting its failure lifetime.
Electromigration pattern in multi-phase material is determined by the combination of current density, temperature and current-applying time. In this paper, diagram of electromigration pattern (DEP) in solders is presented, where both of eutectic Pb-Sn and Pb-free solders are treated. DEP gives the basis for discussing and predicting the electromigration damage in solders.
Fracture Mechanic Analysis for Package Delamination
Authors: Azid Ishak Abdul , Tan C.P. , Lee Boon Leong , Seetharamu K.N. , Ratnam Manimaran , Murthy M.V.V.
Published: March 2009

Delamination and crack were considered as significant failures in electronic packaging. For these circumstances, Modified Crack Closure Integral method was tested and applied to determine crack growth rate and for the purpose to understand failures. TQFP package was successfully verified by using the method. A PBGA package was modeled for thermal distribution and moisture concentration in order to calculate vapor pressure acted on crack. The energy release rate was the main concern among fracture parameters, which had been proven fully related with vapor pressure and crack length ratio in popcorn cracking.
Metal Leadframe Surface Cleaning Prior to Electroplating by Atmospheric Pressure Glow Discharge Plasma
Authors: Cho Jung Hee , Kang Bang Kwon , Kim Kyung Soo , Jin Kyoung Bog , Kim Sae Hoon , Choi Won Youl
Published: March 2009

Metal leadframes (Alloy 42) were cleaned using atmospheric pressure glow discharge plasma. Atmospheric pressure glow plasma was generated by a RF source of 13.56MHz with a matching network (300W power) on to the leadframes free from streamers and arc. Argon (Ar) and oxygen (O2) were used as the carrier gas and reactive gas, respectively. The addition of O2 gas to Ar decreased the contact angle of water and increased the surface cleaning rate due to the ncrease of oxygen radicals in the plasma. The chemical characteristics and morphologies of leadframe surface after the plama treatment were analyzed using X-ray photoelectron spectroscopy (XPS) and atomic force microscope (AFM), respectively. The contact angle of 82° before the plasma treatment was decreased to 5° in the processing condition with oxygen flow rate of 50sccm, treatment speed of
100mm/sec, and input power of 300W. These surface cleaning effect will be very useful in the replacement many steps of wet cleaning before electroplating.
Tensile Stress-Strain Curves Modeling of Four Kinds of Solders with Temperature and Rate Dependence
Authors: Chen Xu , Zhang Li , Sakane Masao , Nose Haruo
Published: March 2009

A series of tensile tests at constant strain rate were conducted on tin-lead based solders with different Sn content under wide ranges of temperatures and strain rates. It was shown that the stress-strain relationships had strong temperature- and strain rate- dependence. The parameters of Anand model for four solders were determined. The four solders were 60Sn-40Pb, 40Sn-60Pb, 10Sn-90Pb and 5Sn-95Pb. Anand constitutive model was employed to simulate the stress-strain behaviors of the solders for the temperature range from 313K to 398K and the strain rate range from 0.001%sP -1 P to 2%sP -1 P. The results showed that Anand model can adequately predict the rate- and temperature- related constitutive behaviors at all test temperatures and strain rates.
Susceptibility of Automobile Spring Steels to Wet-Dry Cyclic Corrosion Induced Environmental Embrittlement
Authors: Kobayashi K. , Komazaki Shinichi , Misawa Toshihei , Fukuzumi T.
Published: March 2009

The susceptibility to environmental embrittlement (EE) of automobile spring steels was investigated using six different steels. A SSRT test and TDS analysis were applied to specimens subjected to wet-dry cyclic corrosion tests in a NaCl solution. Experimental results revealed that the reduction in ductility after the corrosion tests was pronounced with increasing strength level. This degradation was closely associated with the resistance to pitting corrosion. Consequently, the hydrogen absorbed in steel and the corrosion pit as a geometric damage were responsible for the EE of spring steels. The hydrogen in rust layer had no significant influence on the EE.
Chemical Solution Deposition of PZT/Oxide Electrode Thin Film Capacitors with Preferred Orientation on Si Substrate
Authors: Suzuki Hisao , Miwa Yuki , Ohno Tomoya , Fujimoto Masayuki
Published: March 2009

This paper describes the deposition of PZT/oxide electrode thin film capacitors on Si(100) substrate with a CSD (Chemical Solution Deposition). Highly (100)&(001)-oriented SRO/LNO electrode films with a perovskite structure were obtained by the annealing at 700 °C from a precursor solution of Sr and RuCl3·2H2O for SRO and from a precursor solution of La(NO3)3 and Ni(CH3COO)2 for LNO. In addition, highly (100)&(001)-oriented PZT/oxide electrode capacitor were deposited on SRO/LNO/Si substrate by annealing at 650 °C, showing a good ferroelectricity of Pr=22μC/cm2 and Ec=55 kV/cm. In addition, the resultant PZT/oxide electrode thin film capacitors exhibited no fatigue up to 108 switching cycles.
Development of Lead-Free Piezoelectric Thick Films with a/b-Axis-Oriented Bi4-xPrxTi3O12
Authors: Matsuda Hirofumi , Iijima Takashi
Published: March 2009

Pr-substituted Bi4Ti3O12 (BPT, Bi4-xPrxTi3O12, x=0.1-0.4) polycrystalline thick films with a-/b-axes orientations and thickness of 2-3 μm were grown on sputter-grown IrO2 layers by chemical solution deposition method for developing lead-free piezoelectric film microdevices. Electric-field-induced strains measurements were performed by double-beam laser displacement meter and longitudinal strain of e=0.25 % under 400 kV/cm and piezoelectric coefficient d33=63 pm/V at 10 Hz were observed in BPT thick film of x=0.1 with a-/b-axes mixed orientations. The value of strain closely related to spontaneous polarization and monotonously decreased with increasing x. Microstructures of 3 μm-thick BPT films were fabricated by photolithography and dry etching processes with several tens micrometers in size.
Synthesis of Thin Film by Self-Assembly of Perovskite Nanosheets
Authors: Sugawara Akira , Uematsu Kazuyoshi , Toda Kenji , Sato Mineo
Published: March 2009

Layered perovskite, K2NbO3F, includes rock-salt type KF blocks in a K2NiF4 type structure. After the KF blocks are dissolved selectively in water at room temperature, the resultant colloidal suspension consists of nanosheet forms. Positively charged K+ ions in colloidal suspension act as an inorganic binder in electrostatic self-assembly with an exfoliated perovskite nanosheet. In the present study, we synthesized a KNbO3 thin film on a quartz substrate using a self-assembly process. The thin film on a quartz substrate was characterized using XRD analysis. The molar extinction coefficient of the colloidal suspension and absorbance of the thin film were examined using UV-vis absorption spectra. Respective thicknesses of perovskite nanosheet aggregate thin films were examined using AFM. The UV-vis absorption spectra of the films showed an increase in absorbance with increasing immersion time, suggesting growth of a self-assembled multilayer comprising perovskite nanosheets and K+ ions.
Dry Shrinkage, Frost Resistance and Permeability of Rubber Included Concrete
Authors: Zhang Ya Mei , Chen Shen-Xia , Chen Bo , Sun Wei
Published: March 2009

This paper presents a preliminary investigation on dry shrinkage, frost resistance and permeability of rubber included concrete. The results show that rubber particles from waste tires are beneficial to reduction of dry shrinkage of cement mortars due to their soft characteristics. The addition of rubber powder in cement concrete can greatly improve frost resistance of concrete. However, coarse rubber particles (3~4 mm in diameter) seem to have little positive effect to frost resistance. The addition of proper amount of rubber in concrete can reduce permeability of concrete,
but excessive rubber can have negative effect.
On Electrorheological Effect Instantaneous Tiny Grinding Wheel for Fine Machining
Authors: Bi F.F. , Yan Qiu Sheng , Wu N.Q.
Published: March 2009

As a special instantaneous bond, particle-dispersed Electrorheological-fluid (ER fluid) is used to cohere abrasive particles in the ER fluid so as to form dynamical tiny grinding wheel in grinding. This technique eliminates the dimension restriction of traditional concretion abrasive grinding wheel and is applicable in optics glass polishing to meet machining demands for micro-apparatus within millimeter or sub-millimeter microstructure. By regulating some parameters such as voltage, ingredient, volume rate of ER fluid, machining time, as well as distance between
cone-tool and workpiece etc, the size, rigidity, and abrasive mutual combine-intensity of the micro grinding wheel can be controlled in order to achieve an expected machining effect. Experiments have been carried out by using SEM to analyze the characteristics in applying this technique.
Study on Precision Grinding Technique of PCD Tool's Cutting Edge
Authors: Liu Xian Li , Li Y.F. , Yan Fu Gang , Wang Yang , Hu Jing Shu , Wang Yan Jun
Published: March 2009

Polycrystalline diamond (PCD) composite sheet is a kind of material for cutter blank, which is formed by uniformly mixing micron diamond particles and metal binder powder such as Co and Ni, then sintered on WC under high pressure and high temperature. PCD tools have broad application and very high commercial value. However, compared with other materials, PCD tools’ service life relies greatly on blade sharpening quality. This paper just experimented on preparing
precision blade of CTB002 PCD composite sheet on grinding machine of high precision diamond tools and with different performance parameters of TYROLIT diamond grinding wheel. Rotational speed of grinding wheel, grain size of grinding wheel and grinding pressure were researched in the orthogonal test method, which have the largest influence on grinding process, and influencing rules
and the best combination of the three parameters are obtained.
Molecular Dynamics Analyze on Effects of Abrasive Size and Cut Depth on the Monocrystal Silicon Grinding
Authors: Guo Xiao Guang , Guo Dong Ming , Kang Ren Ke , Jin Zhu Ji
Published: March 2009

Molecular dynamics (MD) simulation is carried out to analyze the effects of abrasive ngrain size and cut depth on monocrystal silicon grinding process. Tersoff potential is used to describe the interactions of diamond and silicon atoms. Based on classical Newtonian mechanics law, the motion equations of atoms are established and the trajectory of each atom in phase space is obtained with the aid of Velocity Verlet algorithm. Debye model is introduced to convert between kinetic energy and temperature of an atom. The grinding processes of by single grain with different
size and different cut depth are investigated in atomic space. Through comparing shearing force and potential energy in the single grain grinding process, the effects of cut depth and grain size on the grinding process are discussed. From the results of MD simulation, it is revealed that when the cut depth increases, both the shearing force in silicon crystal and potential energy between the silicon atoms rise, deformation and dislocations in the silicon lattices increase. As a result, all theses lead to^more severe surface and subsurface damage. With the decreasing of grain size in the same cut-depth nanometric grinding processes, the shearing force in silicon crystal and potential energy between the silicon atoms become larger, deformation and dislocations in the silicon lattices increase.
Simulation Study on the Developed Eccentric V-Grooves Lapping Mode for Precise Ball
Authors: Yuan Ju Long , Wang Z.W. , Lv Bing Hai , Dai Yong , Zheng Jia Jin , Zhao Ping , Lou Fei Yan , Tao B.C.
Published: March 2009

A novel lapping mode is developed on the base of present eccentric v-grooves lapping mode for precise balls. The kinematics analysis shows that the ball spin axis can wiggle up to 180° under the developed mode, so the lapping trace will be dispersed onto the whole surface of the ball. The effect of offsetting and groove radius on the lapping uniformity in the developed eccentric v-grooves, the present eccentric v-grooves and the traditional v-grooves lapping mode are compared,
and the advantage of the developed mode is that the impact offsetting is less while the groove radius has no impact.
Wear Mechanism of Diamond Saw Blades for Dry Cutting Concrete
Authors: Hu Ying Ning , Wang Cheng Yong , Ding H.N. , Wang Z.W.
Published: March 2009

The wear mechanism of several kinds of diamond circular saw blades was studied in the different sawing parameters during dry cutting of cement concrete, ferroconcrete and steel fiber reinforced concrete. Seven wear forms of diamond grits were obtained in the sawing experiments. The cobalt based bond shown the best wear resistance. It showed that the damage of blade body was caused by thermal damage and the scratching action of concrete chips. The result indicates that the wear of diamond saw blades arises mostly from the difficult chips removing, high cutting temperature and drastic impacting in dry sawing.