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Transactions of the Korean Society of Mechanical Engineers A
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Journal DOI :
The Korean Society of Mechanical Engineers
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Volume & Issues
Volume 27, Issue 12 - Dec 2003
Volume 27, Issue 11 - Nov 2003
Volume 27, Issue 10 - Oct 2003
Volume 27, Issue 9 - Sep 2003
Volume 27, Issue 8 - Aug 2003
Volume 27, Issue 7 - Jul 2003
Volume 27, Issue 6 - Jun 2003
Volume 27, Issue 5 - May 2003
Volume 27, Issue 4 - Apr 2003
Volume 27, Issue 3 - Mar 2003
Volume 27, Issue 2 - Feb 2003
Volume 27, Issue 1 - Jan 2003
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The Shape Optimization of MIL-S-46119 Ring Obturator Under the High Pressure
Chae, Je-Wook ; Lee, Young-Shin ; Park, Tae-Kyu ;
Transactions of the Korean Society of Mechanical Engineers A, volume 27, issue 1, 2003, Pages 1~7
DOI : 10.3795/KSME-A.2003.27.1.001
The optimal design for the shape of MIL-S-46119 ring obturator under the high pressure using parameter stud:』 on the stress analysis considering effects of design variable is presented, and it is compared to experimental results. The trends of parametric study are in good agreement with the experimental results. The more thickness the higher stress. The more taper the higher stress. And maximum stress of circumferential surface is larger than maximum stress of forward surface. The design variable!; are such as thickness, taper, radius of shape of the obturator. In order to optimize the shape of obturation ring, the weight is maximized subject to maximum stress of the obturator within allowable stress. The design constraints are geometric elements of design variables.
Failure Mode and Fracture Behavior Evaluation of Pipes with Local Wall Thinning Subjected to Bending Load
Ahn, Seok-Hwan ; Nam, Ki-Woo ; Kim, Seon-Jin ; Kim, Jin-Hwan ; Kim, Hyun-Soo ; Do, Jae-Yoon ;
Transactions of the Korean Society of Mechanical Engineers A, volume 27, issue 1, 2003, Pages 8~17
DOI : 10.3795/KSME-A.2003.27.1.008
Fracture behaviors of pipes with local wall thinning are very important for the integrity of nuclear Power Plant. In Pipes of energy Plants, sometimes, the local wall thinning may result from severe erosion-corrosion (E/C) damage. However, the effects of local wall thinning on strength and fracture behaviors of piping system were not well studied. In this paper, the monotonic bending tests were performed of full-scale carbon steel pipes with local wall thinning. A monotonic bending load was applied to straight pipe specimens by four-point loading at ambient temperature without internal pressure. From the tests, fracture behaviors and fracture strength of locally thinned pipe were manifested systematically. The observed failure modes were divided into four types; ovalization. crack initiation/growth after ovalization, local buckling and crack initiation/growth after local buckling. Also, the strength and the allowable limit of piping system with local wall thinning were evaluated.
Design of a 6-DOF Parallel Haptic Rand Controller Consisting of 5-Bar Linkages and Gimbal Mechanisms
Ryu, Dong-Seok ; Sohn, Won-Sun ; Song, Jae-Bok ;
Transactions of the Korean Society of Mechanical Engineers A, volume 27, issue 1, 2003, Pages 18~25
DOI : 10.3795/KSME-A.2003.27.1.018
A haptic hand controller (HHC) operated by the user’s hand can receive information on position and orientation of the hand and display force and moment generated in the virtual environment to the hand. In this paper, a 3-DOF hand controller is first presented, in which all the actuators are mounted on the fixed base by combining a 5-bar linkage and a gimbal mechanism. The 6-DOF HHC is then designed by connecting these two 3-DOF devices through a handle which consists of a screw and nut. Analysis using performance index is carried out to determine the dimensions of the device. The HHC control system consists of the high-level controller for kinematic and static analysis and the low-level controller for position sensing and motor control. The HHC used as a user interface to control the mobile robot in the virtual environment is given as a simple application.
Plastic Limit Pressure Solutions for Cracked Pipes Using 3-D Finite Element Method
Shim, Do-Jun ; Huh, Nam-Su ; Kim, Yun-Jae ; Kim, Young-Jin ;
Transactions of the Korean Society of Mechanical Engineers A, volume 27, issue 1, 2003, Pages 26~33
DOI : 10.3795/KSME-A.2003.27.1.026
Based on detailed FE limit analyses, the present paper provides tractable approximations fer plastic limit pressure solutions fur axially through-wall-cracked pipe; axially (inner) surface-cracked pipe; circumferentially through-wall-cracked pipe; and circumferentially (inner) surface-cracked pipe. In particular, for surface crack problems, the effect of the crack shape, the semi-elliptical shape or the rectangular shape, on the limit pressure is quantified. Comparisons with existing analytical and empirical solutions show a large discrepancy in circumferential short through-wall cracks and in surface cracks (both axial and circumferential). Being based on detailed 3-D FE limit analysis, the present solutions are believed to be the most accurate, and thus to be valuable information not only for plastic collapse analysis of pressurised piping but also for estimating non-linear fracture mechanics parameters based on the reference stress approach.
The study for Compliance Mismatch in the End-to-End Anastomosis of Coronary Artery and PTFE
Shim,, Jae-Joon ; Han, Geun-Jo ; Ahn, Sung-Chan ;
Transactions of the Korean Society of Mechanical Engineers A, volume 27, issue 1, 2003, Pages 34~41
DOI : 10.3795/KSME-A.2003.27.1.034
Finite element analysis of end-to-end artery/PTFE anastomosis recently have been researched. But, these studies were carried out without the compensation for the error of finite element analysis and assumed the artery and PTFE as the simple cylindrical shape in spite of being the fatty tissue which covers the heart. Therefore, we performed the convergency study with respect to increasing the element numbers and considered the fatty tissue as the elastic foundation in the finite element analysis. The results are as fallow ： 1. An anastomosis with the thinner thickness and larger diameter PTFE than artery could reduce the compliance disagreement. 2. A fatty tissue was affected to reduce the compliance mismatch in the vicinity of anastomosis of different material. Therefore a hypercompliant zone become narrorw and a compliance discrepancy decrease between the artery and the PTFE about 70%. And radial displacement with respect to longitudinal direction of an artery and the PTFE anastomosis was similar to a sectional compliance.
Nonlinear Modelling for the Vibration Analysis of a Rotating Ring with the In-Plane/Out-of-Plane Deformations
Kim, Won-Suk ; Chung, Jin-Tai ;
Transactions of the Korean Society of Mechanical Engineers A, volume 27, issue 1, 2003, Pages 42~47
DOI : 10.3795/KSME-A.2003.27.1.042
Nonlinear models for a thin ring rotating at a constant speed are developed. The geometric nonlinearity of displacements is considered by adopting the Lagrange strain theory for the circumferential strain. By using Hamilton’s principle, the coupled nonlinear partial differential equations are derived, which describe the out-of-plane and in-plane bending, extensional and torsional motions. The natural frequencies are calculated from the linearized equations at various rotational speeds. Finally, the computation results from the nonlinear models are compared with those from a linear model. Based on the comparison, this study recommends which model is appropriate to describe the behavior of the rotating ring.
Nonlinear Vibration of a Cantilever Beam Subjected to Electromagnetic Forces
Choi, Yeon-Sun ; Seo, Kyung-Seo ; Woo, Young-Joo ;
Transactions of the Korean Society of Mechanical Engineers A, volume 27, issue 1, 2003, Pages 48~57
DOI : 10.3795/KSME-A.2003.27.1.048
This study presents nonlinear vibration of a cantilever beam subjected to electromagnetic forces. The dynamic responses of the beam show various nonlinear phenomena with the variation of the system parameters, such as the jump phenomenon, multiple solutions, and the movement of the natural frequency. In this study the nonlinear stiffness due to electromagnetic forces which depends on air gap size is measured experimentally, and the system is modeled by a single degree of freedom nonlinear dynamic system and solutions are solved numerically. The numerical results show good agreements with the experimental results, which demonstrate the nonlinearity of electromagnetic force. Finally the occurrences of the jump phenomenon and the first, second and fourth harmonic components are confirmed in using the method of multiple scales.
Fatigue Crack and Delamination Behavior in the Composite Material Containing n Saw-cut and Circular Hole (I) - Aramid Fiber Reinforced Metal Laminates -
Song, Sam-Hong ; Kim, Cheol-Woong ;
Transactions of the Korean Society of Mechanical Engineers A, volume 27, issue 1, 2003, Pages 58~65
DOI : 10.3795/KSME-A.2003.27.1.058
The aramid fiber reinforced metal laminates(AFRMLs) used for the wing part fair flight suffer the cyclic bending moment of variable amplitude during service. The fatigue crack propagation and delamination behavior in AFRMLs containing a saw-cut and circular hole was investigated using the average stress criterion(ASC) model. Mechanical tests were carried out using the cyclic bending moment of 4.9 N . m and delamination was observed by ultrasonic C-scan images. In case of AFRMLs containing a saw-cut fatigue crack propagated in aluminum matrix, inducing delamination. However, in case of AFRMLs containing a circular hole, delamination formed with two types under cyclic bending moment of 4.9 N . m. First, delamination formed along the fatigue crack in aluminum matrix. Second, delamination formed without any fatigue crack around the circular hole. Therefore, delamination was formed depending on the stress distribution near the circular hole.
Stress Fields for the V-notched Crack and Fracture Parameters by Boundary Collocation Method
Pae, Jung-Pae ; Choi, Sung-Ryul ;
Transactions of the Korean Society of Mechanical Engineers A, volume 27, issue 1, 2003, Pages 66~76
DOI : 10.3795/KSME-A.2003.27.1.066
The arbitrary V-notched crack problem is considered. The general expressions for the stress components on this problem are obtained as explicit series forms composed of independent unknown coefficients which are denoted by coefficients of eigenvector. For this results eigenvalue equation is performed first through introducing complex stress functions and applying the traction free boundary conditions. Next solving this equation, eigenvalues and corresponding eigenvectors are obtained respectively, and finally inserting these results into stress components, the general equations are obtained. These results are also shown to be applicable to the symmetric V-notched crack or straight crack. It can be shown that this solutions are composed of the linear combination of Mode I and Mode II solutions which are obtained from different characteristic equations, respectively. Through performing asymptotic analysis for stresses, the stress intensity factor is given as a closed form equipped with the unknown coefficients of eigenvector. In order to calculate the unknown coefficients. based on these general explicit equations, numerical programming using the overdetermined boundary collocation method which is algorithmed originally by Carpenter is also worked out. As this programming requires the input data, the commercial FE analysis for stresses is performed. From this study, for some V-notched problems, unknown coefficients can be calculated numerically and also fracture parameters are determined.
A Study on the Prediction of Thermally-Induced Residual Stress and Birefringence in Quenched Polystyrene Plate Including Free Volume Theory
Kim, Jong-Sun ; Yoon, Kyung-Hwan ;
Transactions of the Korean Society of Mechanical Engineers A, volume 27, issue 1, 2003, Pages 77~87
DOI : 10.3795/KSME-A.2003.27.1.077
The residual stress and birefringence in injection-molded plastic parts can be divided into the flow-induced residual stress and birefringence produced in flowing stage, the thermally-induced residual stress and birefringence produced in cooling stage. However, the physics involved in the generation of the thermally-induced residual stress and birefringence still remains to be understood. Because polymer experiences viscoelastic history near the glass-transition temperature it is hard to model the entire process. Volume relaxation phenomenon was included to predict the final thermally-induced residual stress and birefringence in quenched plastic parts more accurately. The present study focused on comparing the predicted values far thermally-induced residual stress and birefringence with and without volume relaxation behavior (or free volume theory) under free and constrained quenching conditions. As a result, tile residual stress remained as a tensile stress at the center and as a compressible stress near the surface for the free quenching cases. In contract the residual stress remained as a compressible stress at the center and as a tensile stress near the surface fur the constrained quenching cases. The residual birefringence remained as minus values at the center and as plus values near the surface for the free quenching cases. Interestingly the residual birefringence showed minus values in entire zone for the constrained quenching cases. In the prediction of birefringence only the case including free volume theory showed the correct result for the distribution of birefringence in thickness direction.
Friction Characteristics of Piston Assembly (II) -Experiment-
Cho, Myung-Rae ; Ha, Kyoung-Pyo ; Kim, Joong-Soo ; Oh, Dae-Yoon ; Han, Dong-Chul ;
Transactions of the Korean Society of Mechanical Engineers A, volume 27, issue 1, 2003, Pages 88~93
DOI : 10.3795/KSME-A.2003.27.1.088
The aim of this paper is to investigate the friction characteristics of piston assembly, which composed of ring pack and piston skirt. The friction force of piston assembly was measured by using the movable liner in the single cylinder engine, and the various parameters were tested. The friction force was suddenly increased at the expansion stroke due to higher cylinder pressure. The viscous friction was dominant at the mid stroke, but the boundary friction was dominant at the top and bottom dead centers. Through the experiment, we could validate previous theoretical study, and confirm that th e radial clearance and ring tension were very effective to reduce friction loss of piston assembly.
A Study on Applicability of SP Creep Testing for Measurement of Creep Properties of Zr-2.5Nb Alloy
Park, Tae-Gyu ; Ma, Young-Wha ; Jeong, Ill-Seok ; Yoon, Kee-Bong ;
Transactions of the Korean Society of Mechanical Engineers A, volume 27, issue 1, 2003, Pages 94~101
DOI : 10.3795/KSME-A.2003.27.1.094
The pressure tubes made of cold-worked Zr-2.5Nb alloy are subjected to creep deformation during service period resulting in changes to their geometry such as longitudinal elongation, diameter increase and sagging. To evaluate integrity of them, information on the material creep property of the serviced tubes is essential. As one of the methods with which the creep property is directly measured from the serviced components, small punch(SP) creep testing has been considered as a substitute for the conventional uniaxial creep testing. In this study, applicability of the SP creep testing to Zr-2.5Nb pressure tube alloy was studied particularly by measuring the power law creep constants, A, n. The SP creep test has been successfully applied fur other high temperature materials which have isotropic behavior. Since the Zr-2.5Nb alloy has anisotropic property, applicability of the SP creep testing can be limited. Uniaxial creep tests and small punch creep tests were conducted with Zr-2.5Nb pressure tube alloy along with finite element analyses. Creep constants obtained by each test method are compared. It was argued that the SP creep test result gave results reflecting material properties of both directions. But the equations derived in the previous study for isotropic materials need to be modified. Discussions were made fur future research directions for application of the SP creep testing to Zr-2.5Nb tube alloy.
Method for Measuring Mechanical Behaviors of Thin Films at High Temperature
Lim, Sang-Chai ; Joo, Jae-Hwang ; Kang, Ki-Ju ;
Transactions of the Korean Society of Mechanical Engineers A, volume 27, issue 1, 2003, Pages 102~108
DOI : 10.3795/KSME-A.2003.27.1.102
Recently, the authors have developed a new material test system fur thin film at the high temperature. It is so compact and precise with sub micron resolution that it seems to be a useful tool fur research of the oxide film growth, its mechanical behavior and failure mechanism. To this end. in this paper three methologies are described for in-situ monitoring of the displacement & strain and the temperature, the oxide thickness. These are the Laser Speckle analysis with digital image correlation technique, the two-color infra-red thermometer and the laser reflection interferometry respectively. The calibration results and some issues which should be addressed for practical application are presented.
FE Analysis and Experiments of Milli-fart forming Using Grain and Grain Boundary Element
Ku, Tae-Wan ; Kang, Beom-Soo ;
Transactions of the Korean Society of Mechanical Engineers A, volume 27, issue 1, 2003, Pages 109~118
DOI : 10.3795/KSME-A.2003.27.1.109
The recent trend towards miniaturization causes an increased demand for parts with very small dimensions. Milli-structure components are classified as a component group whose size is between macro- and micro-scale. The manufacturing process of these components of thin sheet metal forming has a microscopic properties in addition to a typical phenomenon of bulk deformation because of the forming size. Also, the material properties and the deformation behavior change with miniaturization, which means that, a coarse grained materials show a higher resistance against deformation, when the grain size is in the range of the sheet thickness. In this study, a new numerical approach is proposed to simulate intergranular milli-structure in forming by the finite element method. The grain element and grain boundary element are introduced to simulate the milli-structure in the bending. The grain element is used to analyze the deformation of individual grain while the grain boundary element is for the investigation on the movement of the grain boundary. Also, the result of the finite element analysis is confirmed by a series of milli-sized forming experiments.
Variation of A
with Crack Propagation in a Ductile Metal； Experimental Evaluation
Kim, Heon-Joong ; Kim, Dong-Hak ; Yang, Kyeong-Jin ; Kang, Ki-Ju ;
Transactions of the Korean Society of Mechanical Engineers A, volume 27, issue 1, 2003, Pages 119~125
DOI : 10.3795/KSME-A.2003.27.1.119
A way to measure the second parameter
of CT specimens is described. The displacement
which is measured continuously from visual images of the lateral surface during crack growth is used to calculate the A, as a function of crack growth. The crack length is measured by DCPD(Direct Current Potential Drop) method and the J-resistance curve is determined according to ASTM standard E1737-96. To prove the validity of this method, three dimensional finite element analyses were performed, and variations of the displacements
along the thickness were explored. As the result, it has been shown that the
measured from the visual images of the lateral surface and the corresponding
can be regarded as the average through the thickness for 1T and 1/2T specimens of SA106Gr.C steel.steel.
Stress Fields Along Semi-Elliptical Interfacial Crack Front with Yield-Strength-Mismatch
Choi, Ho-Seung ; Lee, Hyung-Yil ;
Transactions of the Korean Society of Mechanical Engineers A, volume 27, issue 1, 2003, Pages 126~137
DOI : 10.3795/KSME-A.2003.27.1.126
Many research works have been performed on the J-T approach for elastic-plastic crack-tip stress fields in a variety of plane strain specimens. To generalize the validity of J-T method, further investigations are however needed fur more practical 3D structures than the idealized plane strain specimens. The present study deals mainly with 3D finite element (FE) modeling of welded plate and straight pipe, and accompanying elastic, elastic-plastic FE analyses. Manual 3D modeling is almost prohibitive, since the models contain semi-elliptical interfacial cracks which require singular elements. To overcome this kind of barrier, we develop a program generating the meshes fur semi-elliptical interfacial cracks. We then compare the detailed 3D FE stress fields to those predicted with J-T two parameters. The validity of J-T approach is thereby extended to 3D yield-strength-mismatched weld joints, and useful information is inferred fur the design or assessment of pipe welds.
Study on the Development of Ultrasonic Gas Flowmeter
Hwang, Won-Ho ; Park, Sang-Gug ; Jhang, Kyung-Young ;
Transactions of the Korean Society of Mechanical Engineers A, volume 27, issue 1, 2003, Pages 138~143
DOI : 10.3795/KSME-A.2003.27.1.138
Ultrasonic flowmeters have more advantages than the conventional method using pressure-difference. In these reasons, many advanced nations are already selling the commercial model. In RIST, we have been developed ultrasonic gas flow meter for the localization since a project was been contracted with POSCO in 1997. This paper describes a new ultrasonic gas flowmeter. This ultrasonic gas flowmeter is developed for accurate measurement of gases in a harsh environmental conditions. It is especially suited for measuring LDG. COG, BFG gases produced in iron & steel making process. In this study, we had developed the commercial model about the first tested model and applied a completed system to the POSCO gas line. Its performance has been proven by extensive field tests for several months in POSCO, iron & steel making company.
Optimum Design of Endosseous Implant in Dentistry by Multilevel Optimization Method
Han, Jung-Suk ; Seo, Ki-Youl ; Choi, Joo-Ho ;
Transactions of the Korean Society of Mechanical Engineers A, volume 27, issue 1, 2003, Pages 144~151
DOI : 10.3795/KSME-A.2003.27.1.144
In this paper, an optimum design problem for endosseous implant in dentistry is studied to find best implant design. An optimum design problem is formulated to reduce stresses arising at the cortical as well as cancellous bones, in which sufficient design parameters are chosen fur design definition that encompasses major implants in popular use. Optimization at once (OAO) with the large number of design variables, however, causes too costly solution or even failure to converge. A concept of multilevel optimization (MLO) is employed to this end, which is to group the design variables of similar nature, solve the sub-problem of smaller size fur each group in sequence, and this is iterated until convergence. Each sub-problem is solved based on the response surface method (RSM) due to its efficiency for small sized problem. Favorable solution is obtained by the MLO, which is compared to both solutions made by RSM and sequential quadratic programming (SQP) in the OAO problem.
Process Design for Hot Forging of Asymmetric to Symmetric Rib-Well Shape Steel
Cho, Hae-Yong ; Lee, Ki-Joung ; Choi, Jong-Ung ; Jo, Chang-Yong ; Lee, Hak-Kyu ;
Transactions of the Korean Society of Mechanical Engineers A, volume 27, issue 1, 2003, Pages 152~157
DOI : 10.3795/KSME-A.2003.27.1.152
Process design of hot forging, asymmetric to symmetric rib-web shape steel, which is used for the turnout of railway express has been investigated. Owing to the big difference in shape between the initial billet and the final forged product, it is impossible to hot forge the rail in a single step. Therefore, multi step forging as well as die design for each step are necessary for the production. The deformation behavior during hot forging has been analyzed by the numerical simulation through commercial FEA software,
-2D. Modification of the design and repeated simulation have been carried out on the basis of the simulation result. For comparison with the simulation results. flow analysis experiment using plasticine has been also carried out. The results of the flow analysis experiment showed good agreement with those of the simulation. Therefore, the developed process design could be applied to the actual production.
Applications of Micro Genetic Algorithms to Engineering Design Optimization
Kim, Jong-Hun ; Lee, Jong-Soo ; Lee, Hyung-Joo ; Koo, Bon-Heung ;
Transactions of the Korean Society of Mechanical Engineers A, volume 27, issue 1, 2003, Pages 158~166
DOI : 10.3795/KSME-A.2003.27.1.158
The paper describes the development and application of advanced evolutionary computing techniques referred to as micro genetic algorithms (
GA) in the context of engineering design optimization. The basic concept behind
GA draws from the use of small size of population irrespective of the bit string length in the representation of design variable. Such strategies also demonstrate the faster convergence capability and more savings in computational resource requirements than simple genetic algorithms (SGA). The paper first explores ten-bar truss design problems to see the optimization performance between
GA and SGA. Subsequently,
GA is applied to a realistic engineering design problem in the injection molding process optimization.
Correlation Between Fatigue Life of 2.2Ni-0.1Cr-0.5Mo Steel Accompanying Mean Stresses with Cyclic Strain Energy Density
Koh, Seung-Kee ; Ha, Jeong-Soo ;
Transactions of the Korean Society of Mechanical Engineers A, volume 27, issue 1, 2003, Pages 167~174
DOI : 10.3795/KSME-A.2003.27.1.167
Fatigue damage of 2.2Ni-1Cr-0.5Mo steel used fir high strength pressure tubes and vessels was evaluated using uniaxial specimens subjected to strain-controlled fatigue loading. Based on the fatigue test results from different strain ratios of -2. -i 0, 0.5, 0.75, the fatigue damage of the steel was represented by using a cyclic strain energy density. Mean stress relaxation depended on the magnitude of the applied strain amplitude. The high pressure vessel steel exhibited the cyclic softening behavior. Total strain energy density consisting of the plastic strain energy density and the elastic tensile strain energy density described fairly well the fatigue life of the steel, taking the mean stress effects into account. Compared to other fatigue damage parameters, fatigue life prediction by the cyclic strain energy density showed a good correlation with the experimental fatigue lift within a factor of 3.
Fatigue Life Estimation of Welded Components Considering Welding Residual Stress Relaxation and Its Mean Stress Effect
Han, Seung-Ho ; Han, Jeong-Woo ; Shin, Byung-Chun ; Kim, Jae-Hoon ;
Transactions of the Korean Society of Mechanical Engineers A, volume 27, issue 1, 2003, Pages 175~182
DOI : 10.3795/KSME-A.2003.27.1.175
The fatigue life of welded joints is sensitive to welding residual stress and complexity of their geometric shapes. To predict the fatigue life more reasonably. the effects of welding residual stress and its relaxation on their fatigue strengths should be considered quantitatively, which are often regarded to be equivalent to the effects of mean stresses by external loads. The hot-spot stress concept should be also adopted which can reduce the dependence of fatigue strengths for various welding details. Considering the factors mentioned above, a fatigue life prediction model using the modified Goodman's diagram was proposed. In this model, an equivalent stress was introduced which is composed of the mean stress based on the hot-spot stress concept and the relaxed welding residual stress. From the verification of the proposed model to real welding details, it is proved that this model can be applied to predict reasonably their fatigue lives.
Mechanism Design of the Micro Weighing Device by Using Null Balance Method
Choi, In-Mook ; Woo, Sam-Yong ; Kim, Boo-Shik ; Kim, Soo-Hyun ;
Transactions of the Korean Society of Mechanical Engineers A, volume 27, issue 1, 2003, Pages 183~193
DOI : 10.3795/KSME-A.2003.27.1.183
Micro-weighing device by using null balance method is being essential part in fields of high-technology industries such as precision semiconductor industry, precision chemistry, biotechnology and genetics etc. Also, requirements for high resolution and for large measurement range increase more and more. The performance of the micro-weighing device can be determined by the mechanism design and analysis. The analytical design method has been proposed for the performance improvement such as resolution, measurement range and fast response. The 2-stage displacement amplification is designed to overcome the limit of conventional force transmitting lever. The parallel spring is designed for the measurement result independent of the input force position variation. Also, the natural frequency of mechanism is analyzed for the fast response. After each analysis, optimal design has been carried out. To verify the analysis and design result, characteristics experiments had been carried out after construction. Finally, the system had been controlled.
Deformation Characteristics of Gear System with a Profile Shift Coefficient Preserving Center Distance
Park, Su-Jin ; Yoo, Wan-Suk ;
Transactions of the Korean Society of Mechanical Engineers A, volume 27, issue 1, 2003, Pages 194~199
DOI : 10.3795/KSME-A.2003.27.1.194
In this paper, elastic deformations of several gear teeth are analyzed. The contact between a gear and pinion is modeled as a contact problem. The deformation overlap, which is defined as the interference due to deformation of gear teeth, is defined to represent the deformation characteristics of profile shifted spur sear system. The calculated deformation overlap shows teeth interference in the deformed state of a Rear system.
A Study on The Effect of Compressive Residual Stress on fatigue Crack Propagation Behavior of Spying Steel
Park, Keyoung-Dong ; Jung, Chan-Gi ;
Transactions of the Korean Society of Mechanical Engineers A, volume 27, issue 1, 2003, Pages 200~207
DOI : 10.3795/KSME-A.2003.27.1.200
In this paper, the effect of the compressive residual stresses which were obtained under the various shot velocities of shot balls on the fatigue behaviors of a spring steel, were investigated. The examination of CT specimen test were executed with the materials(JISG SUP9) which are being commonly used for the springs of automotive vehicles. As a result, the optimal shot velocity of shot balls were acquired considering the peak values of the compressive residual stresses on the surface of specimen and effect on the speed of the fatigue crack propagation da/dN in stage II and the threshold stress intensity factor range Δ
in stage I. Also the material constant C and the crack propagation index m in the formula of paris law da/dN= C
were suggested in this work to estimate the dependency on the shot velocity.