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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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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 29, Issue 12 - Dec 2005
Volume 29, Issue 11 - Nov 2005
Volume 29, Issue 10 - Oct 2005
Volume 29, Issue 9 - Sep 2005
Volume 29, Issue 8 - Aug 2005
Volume 29, Issue 7 - Jul 2005
Volume 29, Issue 6 - Jun 2005
Volume 29, Issue 5 - May 2005
Volume 29, Issue 4 - Apr 2005
Volume 29, Issue 3 - Mar 2005
Volume 29, Issue 2 - Feb 2005
Volume 29, Issue 1 - Jan 2005
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On the Contact Behavior Analysis of the O-ring Depending on the Contact Surface Profiles
Kim Chung Kyun ;
Transactions of the Korean Society of Mechanical Engineers A, volume 29, issue 2, 2005, Pages 169~175
DOI : 10.3795/KSME-A.2005.29.2.169
In this paper, the contact stress and strain distributions in elastomer O-ring seals have been analyzed using a non-linear finite element method. The stress behavior of PTFE materials is assumed as Odgen model because the sealing clearance between the flange and the surface of the O-ring is not small and the sealing pressure of working fluids covers from the atmospheric pressure to high pressure of 15MPa. The contact normal force and stress in wavy O-rings in which is developed for this analysis are uniformly distributed along the flange and the wall of the rectangular groove. And the normal sealing forces are also kept high compared to other contact sealing models such as the conventional O-ring and X-ring, Thus, the FEM computed results indicate that the sealing characteristic of wavy O-rings is food compared with other contact seals.
Evaluation and Design for Joint Configurations Based on Kinematic Analysis
Hwang Chang-Soon ;
Transactions of the Korean Society of Mechanical Engineers A, volume 29, issue 2, 2005, Pages 176~187
DOI : 10.3795/KSME-A.2005.29.2.176
This paper presents an evaluation of joint configurations of a robotic finger based on kinematic analysis. The evaluation is based on an assumption that the current control methods for the fingers require that the contact state specified by the motion planner be maintained during manipulation. Various finger-joint configurations have been evaluated for different contact motions. In the kinematic analysis, the surface of the manipulated object was represented by B-spline surface and the surface of the finger was represented by cylinders and a half ellipsoid. Three types of contact motion, namely, 1) pure rolling, 2) twist-roiling, and 3) slide-twist-rolling are assumed in this analysis. The finger-joint configuration best suited for manipulative motion is determined by the dimension of manipulation workspace. The evaluation has shown that the human-like fingers are suitable for maintaining twist-rolling and slide-twist-rolling but not for pure rolling. A finger with roll joint at its fingertip link, which is different from human fingers, proved to be better for pure rolling motion because it can accommodate sideway motions of the object. Several kinds of useful finger-joint configurations suited for manipulating objects by fingertip surface are proposed
Estimation Method for Kinematic Constraint of Unknown Object by Active Sensing
Hwang Chang-Soon ;
Transactions of the Korean Society of Mechanical Engineers A, volume 29, issue 2, 2005, Pages 188~200
DOI : 10.3795/KSME-A.2005.29.2.188
Control of a multi-fingered robotic hand is usually based on the theoretical analysis for kinematics and dynamics of fingers and of object. However, the implementation of such analyses to robotic hands is difficult because of errors and uncertainties in the real situations. This article presents the control method for estimating the kinematic constraint of an unknown object by active sensing. The experimental system has a two-fingered robotic hand suspended vertically for manipulation in the vertical plane. The fingers with three degrees-of-freedom are driven by wires directly connected to voice-coil motors without reduction gears. The fingers are equipped with three-axis force sensors and with dynamic tactile sensors that detect slippage between the fingertip surfaces and the object. In order to make an accurate estimation for the kinematic constraint of the unknown object, i.e. the constraint direction and the constraint center, four kinds of the active sensing and feedback control algorithm were developed: two position-based algorithms and two force-based algorithms. Furthermore, the compound and effective algorithm was also developed by combining two algorithms. Force sensors are mainly used to adapt errors and uncertainties encountered during the constraint estimation. Several experimental results involving the motion of lifting a finger off an unknown object are presented.
Multidisciplinary Optimization of Automotive Door
Park Gyung Jin ; Song Se Il ;
Transactions of the Korean Society of Mechanical Engineers A, volume 29, issue 2, 2005, Pages 201~213
DOI : 10.3795/KSME-A.2005.29.2.201
The automotive door has a large finite element model in analysis and many design requirements such as stiffness, natural frequency, side intrusion, etc. Thus, various related governing equations should be solved for systematic analysis and design. Because each governing equation has different characteristics, it is almost impossible to solve them simultaneously. Instead, they are separately handled and the analysis results are incorporated into the design separately. Currently, the design is usually conducted by trials and errors with engineering intuition in design practice. In this research, MDO methods are proposed to solve the problems that share design variables in disciplines. The idea is from the Gauss-Seidel type method for multi-discipline analysis. The developed methods show stable convergence and the weight of the door is reduced by fifteen percent.
Evaluation of Internal Stress and Dislocation Velocity in Creep with Austenite Stainless Steels
Kim Hyun Soo ; Nam Ki Woo ; Park In Duck ;
Transactions of the Korean Society of Mechanical Engineers A, volume 29, issue 2, 2005, Pages 214~219
DOI : 10.3795/KSME-A.2005.29.2.214
To investigate the change of internal stress and mobile dislocation density in the creep, stress relaxation test was examined from each strain range. Mobile dislocation density increased until it reached minimum creep rate but after that, it decreased. Internal stress did not change until it reached minimum creep rate but after that, it decreased. The stress relaxation rate is fast and approached zero later 1.5 seconds, which were begun in the stress relaxation. When the applied stress is large, the internal stress is large. It is cleared that dislocations glide viscously which N passes by cutting Cr atom rather than typical viscosity movement by the evaluation of mobility of dislocation in STS310J1TB.
Load Transfer Behaviors of the Splice-Jointed Fiber Metal Laminates
Roh Hee Seok ; Choi Won Jong ; Ha Min Su ; Choi Heung Soap ;
Transactions of the Korean Society of Mechanical Engineers A, volume 29, issue 2, 2005, Pages 220~227
DOI : 10.3795/KSME-A.2005.29.2.220
In this study, stress-displacement analytic solutions are obtained by a shear lag modeling method constructed for the spliced joint area with a splicing gap in the fiber metal laminate (FML). This gap can be empty or be filled with an adhesive material of elastic modulus
. Two splicing types are considered for spliced shear models, one for spliced in the center metal layer, the other for spliced in the outer metal layer. It is shown that from the viewpoint of the load transfer efficiency and the avoidability of disbond generation due to the shear and axial stresses at the interface between metal layer and composite layer of the gap-front in the spliced area, the center spliced type (k=2) is much preferable to the outer spliced type (k=1).
Fabrication of Nanoscale Reusable Quartz Master for Nano Injection Molding Process
Choi Doo-Sun ; Lee Joon-Hyoung ; Yoo Yeong-Eun ; Je Tae-Jin ; Whang Kyung-Hyun ; Seo Young Ho ;
Transactions of the Korean Society of Mechanical Engineers A, volume 29, issue 2, 2005, Pages 228~231
DOI : 10.3795/KSME-A.2005.29.2.228
In this paper, we present reusable quartz master fabricated by electron-beam lithography and dry etching process of quartz, and results of injection molding based on the reusable quartz master for the manufacturing of nano-scale information media. Since patterned structures of photoresist can be easily damaged by separation (demolding) process of nickel stamper and master, a master with photoresist cannot be reused in stamper fabrication process. In this work, we have made it possible of the repeated use of master by directly patterning on quart in nickel stamper fabrication process. We have designed and fabricated four different specimens including 100nm, 140nm 200nm and 400nm pit patterns. In addition, both intaglio and embossed carving patterns are fabricated for each specimen. In the preliminary test of injection molding, we have fabricated polycarbonate patterns with varying mold temperature. We have experimentally verified the fabrication process of the reusable quart master and possibility of quartz master as direct stamper.
A Study on the Correlations Between Ultrasonic Parameters and Fracture Toughness
Kim Jeong-Pyo ; Park Jae-Sil ; Bae Bong-Kook ; Seok Chang-Sung ;
Transactions of the Korean Society of Mechanical Engineers A, volume 29, issue 2, 2005, Pages 232~238
DOI : 10.3795/KSME-A.2005.29.2.232
In this study the four classes of the thermally aged 1Cr-1Mo-0.25V specimens were prepared using an artificially accelerated aging method. Ultrasonic tests were performed to get the correlation with fracture toughness. The modified theoretical Vary's equation, considering nonlinear response due to material degradation, was proposed for the correlations between ultrasonic parameters and fracture toughness. Experimental results indicate that ultrasonic attenuation coefficient, velocity and nonlinear parameters produce the correlations with fracture toughness and yield strength.
Rotor Dynamic Design of the Centrifugal Chiller Using Offset Bearing
Lee Chang-Joong ; Park Yong Suk ; Lee Joonkeun ;
Transactions of the Korean Society of Mechanical Engineers A, volume 29, issue 2, 2005, Pages 239~246
DOI : 10.3795/KSME-A.2005.29.2.239
A rotor dynamic analysis is implemented to confirm the vibration stability of the high speed centrifugal chiller coupled with gear system. As the rotating speed of the centrifugal chiller under investigation is increased up to 17605rpm at the pinion rotating part, the bearing instability is getting higher and, furthermore, the rotor-bearing system might experience a few critical speed which lead to system failure due to the excessive vibration. In this study, considering the loading capacity and stability conditions, offset journal bearings are adopted for the pinion rotating system and general cylindrical bearings are used for motor part. From the modal analysis, the system is found to be stable as the critical damping ratio which shows the damping characteristics of the system are positive over all operating ranges, and in addition, the synchronous rotating frequency does not come across with any whirl natural frequency. From these results the authors confirm the vibration stability of the rotor-bearing system suggested in this study.
Three-Dimensional Sheet Modeling Using Relative Coordinate
Cho Heui Je ; Bae Dae Sung ;
Transactions of the Korean Society of Mechanical Engineers A, volume 29, issue 2, 2005, Pages 247~252
DOI : 10.3795/KSME-A.2005.29.2.247
This research presents a three-dimensional modeling technique for a flexible sheet. A relative coordinate formulation is used to represent the kinematics of the sheet. The three-dimensional flexible sheet is modeled by multi-rigid bodies interconnected by out-of-plane joints and plate force elements. A parent node is designated as a master body and is connected to the ground by a floating joint to cover the rigid motion of the flexible sheet in space. Since the in-plane deformation of a sheet such as a paper and a film is relatively small, compared to out-of-plane deformation, only the out-of-plane deformation is accounted for in this research. The recursive formulation has been adopted to solve the equations of motion efficiently. An example is presented to show the validity of the proposed method.
Analysis of Damaged Material Response Using Unified Viscoplastic Constitutive Equations
Ha Sang Yul ; Kim Ki Tae ;
Transactions of the Korean Society of Mechanical Engineers A, volume 29, issue 2, 2005, Pages 253~261
DOI : 10.3795/KSME-A.2005.29.2.253
In decades, a substantial body of work on a unified viscoplastic model which considers the mechanism of plastic deformation and creep deformation has developed. The systematic scheme for numerical analysis of unified model is necessary because the dominant failure mechanism is the defect growth and coalescence in materials. In the present study, the unified viscoplastic model for materials with defects suggested by Suquet and Michel was employed for numerical analysis. The constitutive equations are integrated based on the generalized mid-point rule and implemented into a finite element program (ABAQUS) by means of user-defined subroutine (UMAT). To evaluate the validity of the developed UMAT code and the assessment of the adopted viscoplastic model, the results obtained from the UMAT code was compared with the numerical reference solution and experimental data. The unit cell analysis also has been investigated to study the effect of strain rate, temperature, stress triaxiality and initial defect volume fraction on the growth and coalescence of the defect.
Optimization of Satellite Structures by Simulated Annealing
Im Jongbin ; Ji Sang-Hyun ; Park Jungsun ;
Transactions of the Korean Society of Mechanical Engineers A, volume 29, issue 2, 2005, Pages 262~269
DOI : 10.3795/KSME-A.2005.29.2.262
Optimization of a satellite structure under severe space launching environments is performed considering various design constraints. Simulate annealing, one of combinatorial optimization techniques, is used to optimize the satellite. The optimization results by the simulated annealing are compared to those by the method of modified feasible direction and genetic algorithm. Ten bar truss structure is optimized for feasibility study of the simulated annealing. Finally, the satellite structure is optimized by the simulated annealing algorithm under space environment. Weights of the satellite upper platform and propulsion module are minimized with consideration of several static and dynamic constraints. MSC/NASTRAN is used to find the static and dynamic responses. Simulated annealing has been programmed and integrated with the finite element analysis program for optimization. It is shown that the simulated annealing algorithm can be extended to the optimization of space structures.
Comparison of Vibration Characteristics of a Multi-leaf Spring and a Tapered Leaf Spring of a Heavy Truck
Oh Chae-Youn ; Moon Il-Dong ;
Transactions of the Korean Society of Mechanical Engineers A, volume 29, issue 2, 2005, Pages 270~276
DOI : 10.3795/KSME-A.2005.29.2.270
This paper develops the flexible computational model of a heavy truck by interfacing the frame modeled as a flexible body to the heavy truck's computational model composed of rigid bodies. The frame is modeled by the finite element method. Three torsional modes and three bending modes of the frame are considered for the interface of the heavy truck's computational model. The actual vehicle test is conducted off road with a velocity of 20km/h. The vertical accelerations at the cab and front axle are measured in the test. For the verification of the developed computational model, the measured vertical acceleration profiles are compared with the simulation results of the heavy truck's flexible computational model. E grade irregular road profile of ISO is used as an excitation input in the simulation. The verified flexible computational model is used to compare the vibration characteristics of a front suspension system having a multi-leaf spring and that having a tapered leaf spring. The comparison results show that the front suspension having a tapered leaf spring has a higher vertical acceleration at the front axle but a lower vertical acceleration at the cab than the suspension system having a multi-leaf spring.
Generalized Kriging Model for Interpolation and Regression
Jung Jae Jun ; Lee Tae Hee ;
Transactions of the Korean Society of Mechanical Engineers A, volume 29, issue 2, 2005, Pages 277~283
DOI : 10.3795/KSME-A.2005.29.2.277
Kriging model is widely used as design analysis and computer experiment (DACE) model in the field of engineering design to accomplish computationally feasible design optimization. In general, kriging model has been applied to many engineering applications as an interpolation model because it is usually constructed from deterministic simulation responses. However, when the responses include not only global nonlinearity but also numerical error, it is not suitable to use Kriging model that can distort global behavior. In this research, generalized kriging model that can represent both interpolation and regression is proposed. The performances of generalized kriging model are compared with those of interpolating kriging model for numerical function with error of normal distribution type and trigonometric function type. As an application of the proposed approach, the response of a simple dynamic model with numerical integration error is predicted based on sampling data. It is verified that the generalized kriging model can predict a noisy response without distortion of its global behavior. In addition, the influences of maximum likelihood estimation to prediction performance are discussed for the dynamic model.
Stress Distribution and Crack Initiation Behavior due to the Defect Locations in Monolithic Aluminum and Al/Glass Fiber Laminates
Song Sam-Hong ; Kim Jong-Sung ; Oh Dong-Joon ; Yoon Kwang-Joon ; Kim Cheol-Woong ;
Transactions of the Korean Society of Mechanical Engineers A, volume 29, issue 2, 2005, Pages 284~292
DOI : 10.3795/KSME-A.2005.29.2.284
Material flaws in the from of pre-existing defects can severely affect the crack initiation. Stress distribution and crack initiation life of engineering materials such as monolithic aluminum alloy and Al/Glass fiber laminate may be different according to the defect location. The aim of this study is to evaluate effects of relative location of defects around the circular hole in monolithic aluminum and Al/Glass fiber laminates under cyclic bending moment. Stress distribution and crack initiation behavior near a circular hole are considered. Results of Finite Element (FE) model indicated the features of different stress field due to the relative defects positions. Especially, the defects positions at
was strongly effective in stress concentration factor (
) and crack initiation behavior.
Numerical Solutions for Thick-Welled Laminated Composite Spheres under Impact Pressure
Oh Guen ; Sim Woo-Jin ;
Transactions of the Korean Society of Mechanical Engineers A, volume 29, issue 2, 2005, Pages 293~302
DOI : 10.3795/KSME-A.2005.29.2.293
In this paper, the thick-walled laminated, orthotropic as well as bimaterial, composite hollow spheres under impact pressure are analyzed in detail by using the semi-discrete finite element method with the Houbolt time-integration scheme which results in unconditionally stable transient numerical results. Numerical results are obtained by using the self-constructed spherically symmetric (one-dimensional) and axially symmetric (two-dimensional) finite element programs, and compared with the previous solutions by other researchers, being shown some of which are incorrect. The finite element package Nastran is also adopted for numerical comparison.
Design Optimization of the Air Bearing Surface for the Optical Flying Bead
Lee Jongsoo ; Kim Jiwon ;
Transactions of the Korean Society of Mechanical Engineers A, volume 29, issue 2, 2005, Pages 303~310
DOI : 10.3795/KSME-A.2005.29.2.303
The systems with probe and SIL(Solid Immersion Lens) mechanisms have been researched as the technology to perform NFR(Near Field Recording). Most of them use the flying head mechanism to accomplish high recording density and fast data transfer rate. In this paper, ABS shape of flying head was optimized with the object of securing the maximum compliance ability of OFH. We suggest low different optimization processes to predict the static flying characteristics for the OFH. Two different approximation methods, regression analysis and back propagation neural network were used. And we compared the result of directly connected(between CAE and optimizer) method and two approximated optimization results. Design Optimization Tool(DOT) and
were used as the optimizers.
Measurement and Analysis for Positioning Control Characteristics using Encoder Signal of NC Machine Controller
Kim Jong-Gil ; Lee Eung-Suk ;
Transactions of the Korean Society of Mechanical Engineers A, volume 29, issue 2, 2005, Pages 311~317
DOI : 10.3795/KSME-A.2005.29.2.311
NC controller parameters are fixed when the controller is combined with a machine. However, the characteristics of controller could be changed as it has being used by the machine or other environmental conditions. Ultimately, it results in tool positioning accuracy changing. The loading torque in servo motor also influences on the positioning accuracy. This study focus on a measuring and analysing method for verifying the angular positioning accuracy of NC servo motor. We used a high resolution A/D converter for acquiring analogue signal of rotary encoder in servo motor. Generating tool path by the combination of axial movements (X,Y,Z) is compared with the encoder signals with the servo motor torque. The current variation signal is also read from the servo motor power using a hall sensor and converted to the motor torque. The method of analysing proposed in this study will be used for determining the gains (tuning) of parameter in NC controller, when the controller is set up at a machine initially or the controller condition is changed during the work.
A Study on the Prediction of Elastic Modulus in Short Fiber Composite Materials
Kim Hong Gun ;
Transactions of the Korean Society of Mechanical Engineers A, volume 29, issue 2, 2005, Pages 318~324
DOI : 10.3795/KSME-A.2005.29.2.318
Theoretical efforts are performed to extend the formulation of NSLT(New Shear Lag Theory) for the prediction of the elastic modulus in short fiber composite. The formulation is based on the elastic stress transfer considering the stress concentration effects influenced by elastic modulus ratio between fiber and matrix. The composite modulus, thus far, is calculated by changing the fiber aspect ratio and volume fraction. It is found that the comparison with FEA(Finite Element Analysis) results gives a good agreement with the present theory (NSLT). It is also found that the NSLT is more accurate than the SLT(Shear Lag Theory) in short fiber regime when compared by FEA results. However, The modulus predicted by NSLT becomes similar values that of SLT when the fiber aspect ratio increases. Finally, It is shown that the present model has the capability to predict the composite modulus correctly in elastic regime.
FEM analysis of Pearlite Lamella Structure of High Carbon Steel on Drawing Process Conditions
Kim Hyun-soo ; Bae Chul-min ; Lee Choong-yeol ; Kim Byung-min ;
Transactions of the Korean Society of Mechanical Engineers A, volume 29, issue 2, 2005, Pages 325~332
DOI : 10.3795/KSME-A.2005.29.2.325
This paper presents a study on defects in pearlite lamella structure of high carbon steel by means of finite-element method(FEM) simulation. High carbon pearlite steel wire is characterized by its nano-sized microstructure feature of alternation ferrite and cementite. FEM simulation was performed based on a suitable FE model describing the boundary conditions and the exact material behavior. Due to the lamella structure in high carbon pearlite steel wire, material plastic behavior was taken into account on deformation of ferrite and cementite. The effects of many important parameters(reduction in area, semi-die angle, lamella spacing, cementite thickness) on wire drawing process can be predicted by DEFORM-2D. It is possible to obtain the important basic data which can be guaranteed in the ductility of high carbon steel wire by using FEM simulation.
Cutting Power Based Feedrate Optimization for High-Efficient Machining
Cho Jaewan ; Kim Seokil ;
Transactions of the Korean Society of Mechanical Engineers A, volume 29, issue 2, 2005, Pages 333~340
DOI : 10.3795/KSME-A.2005.29.2.333
Feedrate is one of the factors that have the significant effects on the productivity, qualify and tool life in the cutting mechanism as well as cutting velocity, depth of cut and width of cut. In this study, in order to realize the high-efficient machining, a new feedrate optimization method is proposed based on the concept that the optimum feedrate can be derived from the allowable cutting power since the cutting power can be predicted from the cutting parameters as feedrate, depth of cut, width of cut, chip thickness, engagement angle, rake angle, specific cutting force and so on. Tool paths are extracted from the original NC program via the reverse post-processing process and converted into the infinitesimal tool paths via the interpolation process. And the novel NC program is reconstructed by optimizing the feedrate of infinitesimal tool paths. Especially, the fast feedrate optimization is realized by using the Boolean operation based on the Goldfeather CSG rendering algorithm, and the simulation results reveal the availability of the proposed optimization method dramatically reducing the cutting time and/or the optimization time. As a result, the proposed optimization method will go far toward improving the productivity and qualify.
Effect of Metal Removal and Initial Residual Stress on Contact Fatigue Life
Hur Hun-Mu ; Goo Byeong-Choon ; Choi Jae-Boong ; Kim Young-Jin ; Seo Jung-Won ;
Transactions of the Korean Society of Mechanical Engineers A, volume 29, issue 2, 2005, Pages 341~349
DOI : 10.3795/KSME-A.2005.29.2.341
Damage often occurs on the surface of railway wheel by wheel-rail contact fatigue. It should be removed before reaching wheel failure, because wheel failure can cause derailment with loss of life and property. The increase or decrease of the contact fatigue life by the metal removal of the contact surface were shown by many researchers, but it has not explained precisely why fatigue life increases or decreases. In this study, the effect of metal removal depth on the contact fatigue life for railway wheel has been evaluated by applying finite element analysis. It has been revealed that the residual stress and the plastic flow are the main factors determining the fatigue life. The railway wheel has the initial residual stress formed during the manufacturing process, and the residual stress is changed by thermal stress induced by braking. It has been found that the initial residual stress determines the amount of metal removal depth. Also, the effects of the initial residual stress and metal removal on the contact fatigue lift has been estimated, and an equation is proposed to decide the optimal metal removal depth for maximizing the contact fatigue life.
A Study of Developing Stamping Die by Using One-Step Form Method in Auto-Body Panel Stamping Process
Hwang Jae Sin ; Jung Dong Won ;
Transactions of the Korean Society of Mechanical Engineers A, volume 29, issue 2, 2005, Pages 350~359
DOI : 10.3795/KSME-A.2005.29.2.350
Finite element method is a very effective method to simulate the forming processes with good prediction of the deformation behaviour. For the finite element modeling of sheet mental forming the accurate die model is required. Among finite element method, the static-implicit finite element method is applied effectively to analyze real-size auto-body panel stamping processes, which include the forming stage. This study is about analyzing the stamping process problems by using AutoForm commercial software which used static-implicit method. According to this study, the results of simulation will give engineers good information to access the die design of optimization.