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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
Journal Basic Information
Journal DOI :
The Korean Society of Mechanical Engineers
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Volume & Issues
Volume 20, Issue 12 - Dec 1996
Volume 20, Issue 11 - Nov 1996
Volume 20, Issue 10 - Oct 1996
Volume 20, Issue 9 - Sep 1996
Volume 20, Issue 8 - Aug 1996
Volume 20, Issue 7 - Jul 1996
Volume 20, Issue 6 - Jun 1996
Volume 20, Issue 5 - May 1996
Volume 20, Issue 4 - Apr 1996
Volume 20, Issue 3 - Mar 1996
Volume 20, Issue 2 - Feb 1996
Volume 20, Issue 1 - Jan 1996
Selecting the target year
An Experimental Study on the Measurement of Radial Directional Natural Frequency in a Passenger Car Tire Roboting under the Load
Kim, Byoung-Sam ; Hong, Dong-Pyo ; Chi, Chang-Heon ;
Transactions of the Korean Society of Mechanical Engineers A, volume 20, issue 1, 1996, Pages 1~13
DOI : 10.22634/KSME-A.1918.104.22.168
The measurement of radial directional natural frequency ina passenger car tire rotating under the load is studied. In order to obtain theoretical matural frequency and mode shape, the ploane vibration of a tire is modeled to that of circular beam. By esing the Tieking method based on Hamiltons's principle, theoretical results are determined by considering tension horce due to tire inflation pressure, retational velocity and tangential, radial stiffness. Radial directional modal parameters varying with the inflation pressure, load, rotational velocity are experimentally determined by using frequency response function method. The results show that experimental conditions canbe considered as the parameters which shift the natural frequency.
A Blackboard-Based Scheduling Expert System
Park, Ji-Hyeong ; Gang, Mu-Jin ; Lee, Gyo-Il ;
Transactions of the Korean Society of Mechanical Engineers A, volume 20, issue 1, 1996, Pages 14~23
DOI : 10.22634/KSME-A.1922.214.171.124
Scheduling jobs effectively under consideration of actual loads on machines is one of the most complicated tasks in production control. The complexity of the finite capacity scheduling often makes the conventional methods of industrial engineering fail. As an alternative, Knowledge-based approaches to job-shop scheduling have been evolved recently. This paper presents a blackboard- based scheduling expert system which combines knowledge-based scheduling with interactive scheduling. It is shown to be possible to generate the feasible schedule within a reasonable time. Flexible reaction management is also possible while keeping the changes in the generated schedule to the minimal and adjusting the schedule to tardy operations or working environmental changes. The system is equipped with a rule base with heuristics for handling conflicted event. A case study applying the implemented system is described.
Symbolic Generation of Dynamic Equations and Modeling of a Parallel Robot
Song, Sung-Jae ; Cho, Byung-Kwan ; Lee, Jang-Moo ;
Transactions of the Korean Society of Mechanical Engineers A, volume 20, issue 1, 1996, Pages 35~43
DOI : 10.22634/KSME-A.19126.96.36.199
A computer program for automatic deriving the symbolic equations of motion for robots using the programming language MATHEMATICA has been developed. The program, developed based on the Lagrange formalism, is applicable to the closed chain robots as well as the open chain robots. The closed chains are virtually cut open, and the kinematics and dynamics of the virtual open chain robot are analyzed. The constraints are applied to the virtually cut joints. As a result, the spatial closed chain robot can be considered as a tree structured open chain robot with kinematic constraints. The topology of tree structured open chain robot is described by a FATHER array. The FATHER array of a link indicates the link that is connected in the direction of base link. The constraints are represented by Lagrange multipliers. The parallel robot, DELTA, having three-dimensional closed chains is modeled and simulated to illustrate the approach.
Influence of Graphite Content and Shape on the Cu-Based Sintered Friction Materials
Choe, Byeong-Ho ; Lee, Jong-Hyeong ; Song, Gyeong-Tae ;
Transactions of the Korean Society of Mechanical Engineers A, volume 20, issue 1, 1996, Pages 44~52
DOI : 10.22634/KSME-A.19188.8.131.52
Influence of frictional and mechanical properties was studied with the content(8-18 wt.%) and shapes(flake of irregular) of graphite that was used as lubricant components of copper-based sintered materials. The density, hardness and bending strength of friction materials with the shape of flake graphite were lower and decreased rapidly than that of irregular, as the content of graphite increases up to 18 wt.%. In friction test, wear rate was about 2.0-
/kgf.m and coefficient of friction was 0.30-0.37, independent on graphite content and shape. As the temperature of friction materials increased, wear rate decreased rapidly because oxides such as
in the surface of friction material were formed.
Dynamic Parameter Analysis of Bolted Joint
Baek, Sung-Nam ; Ji, Tae-Han ; Park, Young-Pil ;
Transactions of the Korean Society of Mechanical Engineers A, volume 20, issue 1, 1996, Pages 53~67
DOI : 10.22634/KSME-A.19184.108.40.206
The dynamic characteristics of mechanical structure are strongly affected by the properties of joint parameters. In this study, the test structures are constructed with two beams which are clamped by bolts, and a bolted joint which is modelled as a lumped stiffness element. To idientify the dynamic joint parameters with variance of clamping torque of bolts, the sensitivity analysis and the mode energy analysis methods are investigated experimentally. As a reult of these two methods, stiffnesses of bolted joint are experimentally found to increase as the clamping torque increases. These stiffnesses identified from the sensitivity analysis and the mode energy analysis method have some difference.
A Study of Vibration Characteristic Analysis of Beams with Laminar Tear
Han, Byoung-Kee ; Lee, Sung-Hee ;
Transactions of the Korean Society of Mechanical Engineers A, volume 20, issue 1, 1996, Pages 68~78
DOI : 10.22634/KSME-A.19220.127.116.11
A study of the natural vibraion of Timoshenko beam with a laminar tear is presented. An analytic model, based on the transverse and longitudinal vibration of beams is employed to determine the natural frequencies. A specific example are given to show the effects of rotary inertia, and shear deformation on the natural frequencies of the beam with a laminar tear. the variations of matural frequencies of beam with the changes of size and location of laminar tear are plotted for several thickness ratio.
Finite Element Simulation of Material Flow and Weld Line Formation in SMC Compression Molding
Hahn, Young-Won ; Im, Yong-Taek ;
Transactions of the Korean Society of Mechanical Engineers A, volume 20, issue 1, 1996, Pages 79~87
DOI : 10.22634/KSME-A.1918.104.22.168
SMC(Sheet Molding Compound) is made of unsaturated polyester resin and other additives reinforced with randomly distributed chopped fiberglass strands. Because of its higher stiffness per unit mass, SMC was used as a substitute for steel for automotive steel outer panels. Thus, understanding of flow characteristics during fabrication of SMC is of importance since the formation of weld line depends on material flow. In the present study, SMC compression molding simulations in the flat and T-shape molds were accomplished. During simulations, the preferential the preferential flow occurred at the low mold closing speed while plug flow was observed for the higher mold closing speed. When the preferential flow was observed, the weld line was seen at the final stage. For simulations, rigid-viscoplastic finite element method was applied. Self-contact algorithm was also applied in order to predict the formation of the weld line. Simulation results were compared to the experimental results available in the literature.
Rigid-Plastic Explicit Finite Element Formulation for Two-Dimensional Analysis of Sheet Metal Forming Processes
An, Dong-Gyu ; Jeong, Dong-Won ; Jeong, Wan-Jin ;
Transactions of the Korean Society of Mechanical Engineers A, volume 20, issue 1, 1996, Pages 88~99
DOI : 10.22634/KSME-A.1922.214.171.124
The explicit scheme for finite element analysis of sheet metal forming problems has been widely used for providing practical solutions since it improves the convergency problem, memory size and computational time especially for the case of complicated geometry and large element number. The explicit schemes in general use are based on the elastic-plastic modeling of material requiring large computataion time. In the present work, a basic formulation for rigid-plastic explicit finite element analysis of plain strain sheet metal forming problems has been proposed. The effect of some basic parameters involved in the dynamic analysis has been studied in detail. Thus, the effective ranges of parameters have been proposed for numerical simultion by the rigid-plastic explicit finite element method. A direct trial-and-error method is introduced to treat contact and friction. In computation, sheet material is assumed to possess normal anisotropy and rigid-plastic workhardening characteristics. In order to show the validity and effectiveness of the proposed explicit scheme, computations are carried out for cylindrical punch stretching and the computational results are compared with those by the implicit scheme as well as with a commercial code. The proposed rigid-plastic exlicit finite element method can be used as a robust and efficient computational method for analysis of sheet metal forming.
Finite Element Analysis of the Thin-Walled Beam with Arbitrary Cross Section
Yang, Woong-Pill ; Sin, Hyo-Chol ;
Transactions of the Korean Society of Mechanical Engineers A, volume 20, issue 1, 1996, Pages 100~114
DOI : 10.22634/KSME-A.19126.96.36.199
In this paper, a new thin-walled beam finite elcment is developed to overmome the difficulties in the analysis of real structures by existing beam elements. The element is formulated by extending Benscoter's assumption and also by adopting the concept of the curvature-based element. It is applicable to the analysis of the beams with arbitrary cross-sectional shapes. The results obtained show that the element is locking-free and the accuracy of the finite element solutions is remarkably improved.
Model-Following Control in Random Access Deviecs for Velocity Performance Enhancement
Lee, J.H ; Park, K.H ; Kim, S.H ; Kwak, Y.K ;
Transactions of the Korean Society of Mechanical Engineers A, volume 20, issue 1, 1996, Pages 115~126
DOI : 10.22634/KSME-A.19188.8.131.52
In the time optimal control problem, bang-bang control has been used becaese it is the theoretical time minimum solution. However, to improve tracking speed performance in the time optimal control, it is important to select a switching point accurately which makes the velocity zero near the target track. But it is not easy to select the swiching point accurately because of the damping coefficient variation and uncertainties of modeling an actual system. The Adaptive model following control(AMFC) is implemented to relieve the difficulty and inconvenience of this task. The AMFC and make the controlled plant follow as closely as possible to a desired reference model whose switching point can be calculated easily and accurately, assuring the error between the states of the reference model and those of the controlled plant appoaches zero. The hybrid control method composed of AMFC and PID is applied to a tracking actuator of the magneto optical disk drive(MODD) in random access devices to improve its slow tracking performance. According to the simulaion and experimental results, the average tracking time as small as 20ms is obtained for a 3.5 magneto-optical disk drive. The AMFC also can be applied for other random access devices to improve the average tracking performance.
Reduction of the Seismetic rRspocses by Using the Modified Hysteretic Bi-Linear Model of the Seismic Isolator
Koo, G.H ; Lee, J.H ; Kim, J.B ; Lee, H.Y ; Yoo, B ;
Transactions of the Korean Society of Mechanical Engineers A, volume 20, issue 1, 1996, Pages 127~134
DOI : 10.22634/KSME-A.19184.108.40.206
In general, seismic isolators which are made of laminated rubber and shim plate have characteristics of complex hysteretic behavior. When shear deformation of the seismic isolator is small, the isolator hassimple hysteretic almost bi-linear behabior. But on large shear deformation hardening effects may occur. This paper proposes a moldeling method of the seimic isolator with modified hysteretic bi-linear model which can consider the hardening effects. From the results of the seismic analyses of the isolated system it is shown that the responses are singificantly reduced compared with those of the non-isolated system. The modified hysteretic bi-linear model of the isolator gives larger ZPA(zero period acceleration) than those of the simple hysteretic bi-linear model and the equivalunt spring-damper model.
Order of Stress Singularities at Bonded Edge Corners with Two or Three Dissimilar Materials in the Eletronic Package
Choe, Seong-Ryeol ; Gwon, Yong-Su ; Park, Sang-Seon ; Park, Jae-Wan ;
Transactions of the Korean Society of Mechanical Engineers A, volume 20, issue 1, 1996, Pages 135~145
DOI : 10.22634/KSME-A.19220.127.116.11
Order of stress singularities at bonded Edge Corners with two or three dissimilar isotropic Materials is analyzed. The problem is formulated by Mellin transform and characteristic equation is obtained as a determinant of matrix considering boundary conditions. Roots of characterictic equation are determinde by numerical calculations with ward method, from which the order of stress sigularities is obtained. Applying the results to the electronic packaging, the order of stress singularities is obtained. Applying the results to the electronic packaging, the order of stress singularities at bounded edge corners is calculated as a various bouned edge angle with given material combinations. Comparing the results, the optimal material combinaitons of bounded edge corners and bouned edge angle to reduce stress singularity could be determined. It suggests that the results are used to the basic design of electronic packaging reducing the stress singularity.
Experimental Evaluation of Feedforward Control Based on the Dynamic Models of A Direct Drive SCARA Robot
Hong, Yun-Sik ; Kang, Bong-Su ; Kim, Su-Hyeon ; Park, Gi-Hwan ; Kwak, Yun-Geun ;
Transactions of the Korean Society of Mechanical Engineers A, volume 20, issue 1, 1996, Pages 146~153
DOI : 10.22634/KSME-A.1918.104.22.168
A SCARA type direct drive robot which can be used in the assembly operation was designed and manufactured. Graphite fiber epoxy composite material was used in the fabrication of the robot arm structure in order to improve the speed of the robot arm with a high damping effect. For model-based control and sensitivity analysis of system parameters, the dynamic model of robot arm and drive servo amplifier parameters such as equivalent gains of PWM driver and velocity gains of servo system were estimated from frequency response tests. The complete dynamic model for overall robot system was used in the simulation of the open-loop control. The simulation results agreed reasonably well to the experimental results. The feedforward control using the dynamic models improved the trajectory tracking performance, decreasing the tracking error by factor of three compared with PID control. This study found that the inverse dynamic model of the robot arm including the drive servo system showed better performances than the case of arm dynamic model only.
A Study on the Groove Design in Ball Screws
Park, Cheol-U ; Kim, Dae-Eun ; Lee, Sang-Jo ;
Transactions of the Korean Society of Mechanical Engineers A, volume 20, issue 1, 1996, Pages 154~162
DOI : 10.22634/KSME-A.1922.214.171.124
Ball screws are commonly used in linear motion feeding systems of various machine tools and automated systems. They are known to have relatively little backlash, high precision and efficiency compared to ordinary lead screws. Furthermore, the effectiveness of ball screw has made it the preferred choice of many newly developed high speed precision feeding units. The motivation of this work is to establish the groove edsigh basis of ball screws for the reduction of contact fatigue failure. In most instances, fatigue failure between ball and shaft groove is due to excessive contact pressure. Especially, the excessive load is causative of plastic flow below the contact surface, which can contribute to surface failure. But, in spite of small load, if groove conformity rate is large, contact pressure is increased and internal shear stress reach the yield value of the material. In such a point, the authors deal with design procedure for deciding the permissible conformity rate of a ball screw groove with the computational evaluation of contact pressure and maximum shear stress.
Trefftz Finite Element Method and Cavity Element Formulationfor Plane Elasticity Problems
Lim, Jangkeun ; Song, Kwansup ;
Transactions of the Korean Society of Mechanical Engineers A, volume 20, issue 1, 1996, Pages 163~171
DOI : 10.22634/KSME-A.19126.96.36.199
For the effective analysis of two dimensional plane problems, Treffiz finite elements and cavity elements have been proposed. These element matrix equaitons were formulated on the basis of hybrid variational principle and Treffiz function sets derived consitstently from the complex theoy of plane elasticity. In order to suggest the accuracy chatacteristics of the proposed Treffiz elements typical plane problems were analyzed and these results were compared with ones obtained by using the conveintional displacement type elements. The accuracy of the proposed elements is less sensitive to the element size and shape than the conventional displacement type elements. These elements, being able to be formed with multi-nodes, give the convenient modeling of an analytic domain. The cavity elements give the comparatively exact values of stress concentration factors of stress intensity factors and can be effectively used for the analysis of mechanical stuctures containing various cavities.
Effect of Thermophysical Properties on Stress Transfer Function ofr Thermal Fatigue Analysis
Kim, Yeong-Jin ; Seok, Chang-Seong ; Park, Jong-Ju ;
Transactions of the Korean Society of Mechanical Engineers A, volume 20, issue 1, 1996, Pages 172~179
DOI : 10.22634/KSME-A.19188.8.131.52
For mechanical systems operating at high tempertature, thermal fatigue phenomenon has been recognized as a major cause of mechanical component failures. To evaluate cumulative fatigue damage as a conesquence of thermal fatugue on real time, the stress tranfer function(Green's function) approach is popularly used. The objective of this paper is to investigate the effect of thermophsical properties on the stress tranfer function. For this purpose a modified Green's function approach considering temperature-dependent thermophysical properties is proposed. Two case studies were performed and the proposed approach agrees well with full finite element analysis.
Geometric Optimization Involving Contact Stress Singularities
Park, Jung-sun ; Lee, Soo-Yong ;
Transactions of the Korean Society of Mechanical Engineers A, volume 20, issue 1, 1996, Pages 180~188
DOI : 10.22634/KSME-A.19184.108.40.206
The stress singularity of a sharp wedge contacting a half plane can be avoided by changing the wedge shape. Shape optimization is accomplished with the geometric strain method (GSM), an optimality criterion method. Several numerical examples are provided for different materials in the wedge and half plane to avoid stress singularity neal the sharp corner of the wedge. Optimum wedge shapes are obtained and critical corner angles are compared with the angles from analytical contact mechanics. Numerical results are well matched to analytical and experimental results. It is shown that shape optimization by the geometric strain method is a useful tool to reshape the wedge and to avoid a stress singulatiry. The method applies to more general geometries where the singular behavior would be difficult to avoid by classical means.
Thermal Analysis on Twin-Roll Type Strip Continuous Casting Process Considering Contact Thermal Resistance between Molten Metal and Cooling Roll
Kim, Y.D ; Kim, C.G ;
Transactions of the Korean Society of Mechanical Engineers A, volume 20, issue 1, 1996, Pages 189~205
DOI : 10.22634/KSME-A.19220.127.116.11
The twin-roll type strip continuous casting process(or direct rolling process) of steel materials is characterized by two rotating water cooled rolls receiving a steady supply of molten metal which solidifies onto the rolls. A solidification analysis of molten metal considering phase transformation and thermofluid is performed using finite diffefence method with curvilinear coordinate to reduce computing time and molten region analysis with arbitrary shape. An enthalpy-specific heat method is used to determine the temperatures inthe roll and the steel. The temperature distribution of cooling roll is calculated using two dimensional finite element method, because of complex roll shape due to cooling hole in rolls and improvemnt accuracy of calculation result. The energy equaiton of cooling roll is solved simultanuously with the conservation equaiton of molten metal in order to consider heat transfer through the cooling roll. The calculated roll temperature is compared to experimental results and the heat transfer coefficient between cooling roll surface and rolling material(steel) is also determined from comparison of measured roll temperature and calculated temperature.
Acousto-Optical Third Order Correlator Using 2-D Ultrasonic Diffractor Cell
Jang, Gyeong-Yeong ; Sato, Takuso ;
Transactions of the Korean Society of Mechanical Engineers A, volume 20, issue 1, 1996, Pages 206~213
DOI : 10.22634/KSME-A.1918.104.22.168
Third order correlation funciton is to be advantageous to detect unique features embedded in various random signals that are undetectable with second order correlation or power spectrum. In this paper, we will introduce optical modulator which consists of a laser light source, 2-dimensional ultrasonic diffractor cell with signal controlling circuitry, and a CCD camera connected to personal computer for image processing. With this modulator, the third order correlaiton pattern of signal can be immediately obtained at the camera due to parallel nature of optical computing.
Geneation of Optimized Robotic Assembly Sequences Via Simulated Annealing Method
Hong, Dae-Sun ; Cho, Hyung-Suck ;
Transactions of the Korean Society of Mechanical Engineers A, volume 20, issue 1, 1996, Pages 213~221
DOI : 10.22634/KSME-A.1922.214.171.124
An assembly sequence is considered to be optimal when is minimizes assembly cost while satisfying assembly constraints. To derive such an optimal sequence for robotic assembly, this paper proposes a method using a simulated annealing algorithm. In this method, an energy funciton is derived inconsideration of both the assembly constraints and the assembly cost. The energy function thus derived is iteratively minimized until no further change in energy occurs. During the minimization, the energy is occationally perturbed probabilistically in order to escape from local minima. The minimized energy yields an optimal assembly sequence. To show the effectiveness of the proposed method, case studies are presented for industrial products such as an electrical relay and an automobil alternator. The performance is analyzed by comparing the results with those of a neural network-based method, based upon the optimal solutions of an expert system.
Prediction of Cutting Temperature in Flank Face at High Speed Steel in Orthogonal Turning
Jun, Tae-Ok ; Bae, Choon--Eak ;
Transactions of the Korean Society of Mechanical Engineers A, volume 20, issue 1, 1996, Pages 222~231
DOI : 10.22634/KSME-A.19126.96.36.199
Temperature distribution on the flank face in orthogonal turning with cutting tool of high speed steel is studied by using a finite element method and experiments. Experiments are carried out to verify the validity of the temperature measurement by using a thermoelectric couple junciton imbedded in a cutting tool of high speed steel. Good agreement is obtained between the analytical results and the experimental ones for the temperature distributions on flank face of cutting tool with igh speed steel. The analytical results show that the temperature on the top flank face of a tool is higher because of the difference of the friction velocity on each face of the tool.