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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 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
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A Compression Behavior of Semi-Solid Material and Finite Element Analysis Considering Flow of Liquid Phase
Gang, Chung-Gil ; Yun, Jong-Hun ;
Transactions of the Korean Society of Mechanical Engineers A, volume 20, issue 12, 1996, Pages 3715~3727
DOI : 10.22634/KSME-A.19188.8.131.5215
Compression behavior of semi-solid aluminum alloys with controlled solid fractions was investigated in the present study. The stress and strain relationships were obtained from the compression test. Variations of the solid fraction distribution and the material behaviour were investigated for various friction coeffieiants and die speedsd. For a finite element analysis, the semi-solid material was described by a compressible regid viscoplastic model for the solid region and darcy's law for the liquid region. The computed results were compared with experimental data for the validity of the yield criteria.
Study on the Hydromechanical Reverse Redrawing Pprocess Assisted by Separate Radial Pressure
Kim, Bong-Jong ; Lee, Dong-U ; Yang, Dong-Yeol ; Park, Chan-Seung ;
Transactions of the Korean Society of Mechanical Engineers A, volume 20, issue 12, 1996, Pages 3728~3740
DOI : 10.22634/KSME-A.19184.108.40.20628
High-quality cups of deep drawing ratio of more than four cannot be simply drawn by conventional drawing and redrawing processes. In the present study, after the first deep drawing process, subsequent hydromechanical reverse redrawing with controlled radial pressure is employed. In order to increase the deep drawing ratio up to muchmore than four, the radial pressure should be controlled independently of the chamber pressure and thus an optimum forming condition can be found easily by varying the radial pressure. The process has been subjected to finite element analysis by using the rigid-platic material modeling considering all the frictional conditions induced by the hydrostatic pressure. In order to consider the pressure effect on the sheet, the pressure distributions on the flange part and the side wall part are calculated mumerically from simplified Navier-stokes equation. The comparison of the computation with the experiment has shown that the finite element modeling can be conveniently emplyed for the design of the process with reliability from the viewpoint of formability.
Inverse Dynamic Analysis of Mechanical Systems Using the Velocity Transformation Technique
Lee, Byeong-Hun ; Yang, Jin-Saeng ; Jeon, U-Seong ;
Transactions of the Korean Society of Mechanical Engineers A, volume 20, issue 12, 1996, Pages 3741~3747
DOI : 10.22634/KSME-A.19220.127.116.1141
This paper presents a method for the inverse dynamic anlaysis of mechanical systems. Actuating forces(or torques) depending on the driving constraints are analyzed in the relative coordinate space using the velocity transformation technique. A systematic method to compose the inverse velocity transformation matrix, which is used to determine the joint reaction forces, is proposed. Two examples are taken to verify the method developed here.
Impact Damages and Residual Strength of CFRP Laminates under the Hygrothermal Environment
Jeong, Jong-An ; Yang, In-Yeong ;
Transactions of the Korean Society of Mechanical Engineers A, volume 20, issue 12, 1996, Pages 3748~3758
DOI : 10.22634/KSME-A.1918.104.22.16848
This study is to investigate experimentally relationships between the impact energy and moisture absorption characteristies vs.the residual bending strength with the variation of stacking seqences. When Carbon-fiber reinforced plastics(CFRP) impact-induced laminates are subjected to the high temperatures and hygrothermal effects, it is found that what CFRP laminates are impacted by a steel ball (5 mm in diametar) ; thus, the generated delamination is observed by the ultrasonic microscope. And the residual bending strength is evaluated by a three-point bending test. Also, a thermostat is used in test with the unimpacted and impacted specimens for the moisture experimentaiton. The percision electro lever scles is used to measure the moisture content(1/10, 000g).
Crater Wear Measurement Using Computer Vision and Automatic Focusing
Yang, Min-Yang ; Gwon, O-Dal ;
Transactions of the Korean Society of Mechanical Engineers A, volume 20, issue 12, 1996, Pages 3759~3766
DOI : 10.22634/KSME-A.1922.214.171.12459
In this paper a new gefchmique to measaure the creater wear using image processing and automatic focusing is presented. The contour detection algorithm, which can adopt ina noisy image, is suggested. It is suitable for eliminating high frequency noses with lower processing time and without blurring. An automatic focusing technique is applied to measure a createrwear depth with a one-dimensional search algorithm for finding the bestfocus. This method is implemented in the tool microscope driven by a servo motor. The results show that the countour and depth of crater wear can be measured reliably.
Transformation of a Dynamic Load into an Equivalent Static Load and Shape Optimization of the Road Arm in Self-Propelled Howitzer
Choe, U-Seok ; Gang, Sin-Cheon ; Sin, Min-Jae ; Park, Gyeong-Jin ;
Transactions of the Korean Society of Mechanical Engineers A, volume 20, issue 12, 1996, Pages 3767~3781
DOI : 10.22634/KSME-A.19126.96.36.19967
Generally, dynamic loads are applied to real structures. Since the analysis with the dynamic load is extremely difficult, static loads are utilized by proper conversions of the dynamic loads. The dynamic loads are usually converted ot static loads by safety foactors of experiences. However, it may increase weight and decrease reliability. In this study, a method is proposed for the conversion process. An equivalent static load is calculated ot generate a same maximum displacement. The method is verified through numerical tests on a spring-mass systems of one and multi degrees-of freedom. It has been found that the duration time of the loads and the natural frequencies of the structures are critical in the conversion process. A road arem is a self-propelled howizer is selected for the application of the proposed method. The shape of the road arm is optimized under the converted static loads.
Structural Dynamic Modification Using substructure Response Function Sensitivity Method(SRFSM)
Ji, Tae-Han ; Park, Yeong-Pil ;
Transactions of the Korean Society of Mechanical Engineers A, volume 20, issue 12, 1996, Pages 3782~3791
DOI : 10.22634/KSME-A.19188.8.131.5282
A great deal of effert has been invested in upgrading the performance and the efficiency of mechanical structures. Using experimental modal analysis(EMA) or finite element analysis(FEA) data of mechanical structures, this performance and efficiency can be effectively evaluated. In order to analyze complex structures such as automobiles and aircraft, for the sake of computing efficiency, the dynamic substructuring techniques that allow to predict the dynamic behavior of a structure based on that of the composing structures, are widely used. By llinking a modal model obtained from EMA and an analytical model obtained from FEA, the best conditioned structures can be desinged. In this paper, a new algorithm for structural dynamic modification-SRFSM (substructure response function sensitivity method) is proposed by linking frequency responce function synthesis and response function sensitivity. A mehtod to obtain response function sensitivity using direct derivative of mechanical impedance, is also used.
Reduced Minimization Theory in Skew Beam Element
Moon, Won-joo ; Kim, Yong-woo ; Min, Oak-key ; Lee, Kang-won ;
Transactions of the Korean Society of Mechanical Engineers A, volume 20, issue 12, 1996, Pages 3792~3803
DOI : 10.22634/KSME-A.19184.108.40.20692
Since the skew beam element has two curvatures which are a curvature and a torsion, spatial behavior of curved beam which cannot be included in one plane can be anlayzed by emploting the skew beam element. The
-continuous skew beam element shows the stiffness locking phenomenon when full integration is employed. The locking phenomenpn is characterized by two typical phenomena ; one is the much smaller displacement thant the exact one and theother is the undelation phenomenon is stress distribution. In this paper, we examine how unmatched coefficient in the constrained energy brings about the locking by Reduced Minimization theory. We perform the numerical ones. These comparisons show that uniformly full integration(UFI), which employs full integration for the constrained energy, entails the locking phenomenon. But the use of uniformly reduced integration(URI) of selectively reduced integration(SRI), which employs reduced integration for constrained energy, does not produce the significant errors of displacements of the undulation phenomenon in stress distribution since they do not entails the locking, Additionally, the error due to the approximated parameters for describing the geometry of skew beam is examined.d.
A Development of Two-Point Reciprocal Quadratic Approximation Mehtod for Configuration Optimization of Discrete Structures
Park, Yeong-Seon ; Im, Jae-Mun ; Yang, Cheol-Ho ; Park, Gyeong-Jin ;
Transactions of the Korean Society of Mechanical Engineers A, volume 20, issue 12, 1996, Pages 3804~3821
DOI : 10.22634/KSME-A.19220.127.116.1104
The configuration optimization is a structural optimization method which includes the coordinates of a structure as well as the sectional properties in the design variable set. Effective reduction of the weight of discrete structures can be obrained by changing the geometry while satisfying stress, Ei;er bickling, displacement, and frequency constraints, etc. However, the nonlinearity due to the configuration variables may cause the difficulties of the convergence and expensive computational cost. An efficient approximation method for the configuration optimization has been developed to overcome the difficulties. The method approximates the constraint functions based onthe second-order Taylor series expansion with reciprocal design variables. The Hessian matrix is approzimated from the information on previous design points. The developed algotithms are coded and the examples are solved.
A Study on the Efficiency of Ball Screws with Deduction of the Friction Coefficient
Kim, In-Joong ; Park, Cheol-Woo ; Lee, Sang-Jo ;
Transactions of the Korean Society of Mechanical Engineers A, volume 20, issue 12, 1996, Pages 3822~3827
DOI : 10.22634/KSME-A.1918.104.22.16822
In this study, the ways of calculating the efficiency of ball screws are presented to fix the design variables effectively. To calculate the efficiency of ball screws, the frection coefficient is needed to be deduced. Therefore it is deduced measuring the preload torque of double nut ball screws of which the preload can be varied by springs. The efficieny of ball screws and the mazimum efficiency condition are calculated with the deduced friction coefficient. In addition, the characteristic of friction and lubrication is considered.
Dynamic Mode III Crack Propagated with Constant Velocity at Interface Between Isotropic and Orthotropic Material
Lee, Gwang-Ho ; Hwang, Jae-Seok ; Yu, Jae-Yong ;
Transactions of the Korean Society of Mechanical Engineers A, volume 20, issue 12, 1996, Pages 3828~3837
DOI : 10.22634/KSME-A.1922.214.171.12428
The dynamic problems of interface crack propagated with constant velocity along the interface of bimateraial composed of isotropic and orthotropicmaterial under antiplane loading condition are studied in this paper. The general dynamic stress fields and displacement fields of mode III are derived when interface crack between isotropic and orthotropic material is propagating with constant velocity. The general dynamic stress fields and displacement fields in isotropic material. Finally, the characteristics of interface crack propagation are studied with various properties of isotropic and orthotropic material and crack propagarion velocities.
Analysis of an Isotropic Infinite Plate with Many Collinear Multiple Cracks by the Alternating Method
Park, Jai-Hak ;
Transactions of the Korean Society of Mechanical Engineers A, volume 20, issue 12, 1996, Pages 3838~3846
DOI : 10.22634/KSME-A.19126.96.36.19938
A method is proposed to obtain the stress intensity factors of multiple cracks lying on many straight llnes in an infinite isotropic plate. In this mehtod, analytical solutions for collinear multiple cracks subject to surface point forces are obrained and used as Green functions. For the multiple cracks lying onmany straight lines, the equivalent crack surface tractions are obtained by using the alternating method and the stress intensity factors are calculated. By using the proposed method several useful problems are solved and discussed.
Loading Rate Effects During Static Indentation and Impact on Silicon Carbide with Small Sphere
Shin, Hyung-Seop ;
Transactions of the Korean Society of Mechanical Engineers A, volume 20, issue 12, 1996, Pages 3847~3855
DOI : 10.22634/KSME-A.19188.8.131.5247
In order to study the relationship between static and cynamic behaviors of silion caride, both quasi-static indentaiton and impact experiments of spherical particle have been conducted. The difference inmaterial behavior when using the two mehtods suggests a loading rate difference in the damate pattrern and fracture strength of silicon carbide. This investigation showed some difference in damage pattern according to particla property, especially inthe case of particle impact. There was no differences in deformation behaviors according to the loading rate when the crater profiles were compared with each other at the same contact radius. From the result of residual strength evaluation, it was found that the strength degradation began at the initiation of ring crack and its behavior was colsely related to morphologies of the damage developed which was also dependent upon the extent of deformation atthe loaidng point. In the case of static indentation, there didnot exist the particle property effects onthe strength degradation behavior.
Evaluation of Heat Transfer Coefficient Distribution by Inverse Analysis
Kim, Heung-Gyu ; O, Su-Ik ;
Transactions of the Korean Society of Mechanical Engineers A, volume 20, issue 12, 1996, Pages 3856~3870
DOI : 10.22634/KSME-A.19184.108.40.20656
The objective of this study is to evaluate heat transfer coefficient distribution during heat treatment by inverse analysis. As a first procedure, the inverse heat transfer formulation by using two dimensional finite element method has been developed. The formulation can handlematerial nonlinearity and allow arbitrary placement and number of sensors. The formulation was verified through application to simulated exact and inexact measurements.
Kinematic Control of Redundant Robots in the Constrained Environment and Its Applicaiton to a Nozzle Dam Installation/Detachment Task in Nuclear Power Plants
Park, Ki-Cheol ; Chang, Pyung-Hun ; Kim, Seung-Ho ;
Transactions of the Korean Society of Mechanical Engineers A, volume 20, issue 12, 1996, Pages 3871~3882
DOI : 10.22634/KSME-A.19220.127.116.1171
In this paper, a closed-form formulation for inverse kinematics of robot manipulators with kinematic redundancy under the constrained environment has been derived using the Kuhn-Tucker condition, the extended Lagrange multiplier method and the working set method. The proposed algorithm satisfies the necessaryand sufficient conditions for optimization subject to equality and inequality constraints. In addition, computationally efficient kinematic control methods have been proposed using differential kinemetics and gradient projection mehtod. The effectiveness of the proposed methods has been demonstrated with a 4-dof planar robot, and then a 7-dof spatial robot as a practical application to the nozzle dam task in the Nuclear Power Plant.
Fuzzy Vibration Control of 3 DOF Robot Manipulator with Flexible Link
Kim, Jae-Won ; Yang, Yang, Hyun-Seok ; Park, Park, Young-Pil ;
Transactions of the Korean Society of Mechanical Engineers A, volume 20, issue 12, 1996, Pages 3883~3891
DOI : 10.22634/KSME-A.1918.104.22.16883
Performance and productivity of robot manipulator can be improved by increasing its working speed and extending its link length. But heavy weght of the commercial robot links, considered as "rigid body", limits its mazimum working speed and the weght of the links can be reduced for high speed operation. But this light-weight link or long link for special use cannot be consideredas "rigid" structure and vibration of the link due to its flexibility causes errors in end-effector position and orientation. Thus the elastic behaviro of the flexible link should be taken care of for increasing work speed and getting smaller error of end-effector position. In this paper, the fuzzy control theory is selected to design the controller which controlos the joint positions of the robot manipulator and suppress the vibration of flexible link. In the forst place, for the 1 DOF flexible link system, the fuzzy control theory is implemented. The contdroller for the 1 DOF flexible link system is designed. Experimental research is carried out to examine the controllability and the validity of the fuzzy control theory based controller. Next, using the extended desing schemes for the case of the 1 DOF flexible link system and usign the experimental phenomena of the 3 DOF flexible link system, the fuzzy controller for the 3 DOF flexible link system is desinged and experimented.ed and experimented.
The Fatigue Cumulative Damage and Life Prediction of GFRP under Random Loading
Kim, Jeong-Gyu ; Sim, Dong-Seok ;
Transactions of the Korean Society of Mechanical Engineers A, volume 20, issue 12, 1996, Pages 3892~3898
DOI : 10.22634/KSME-A.1922.214.171.12492
In this study, the prediction of the fatigue life as well as the extimation of the characteristics of fatigue cumulative damage on GFRP under random loading were performed. The constant amplitude tests and the ramdom loading test were carried on notched GFRP specimens with a circular hole. Random waves were generated with a micro-computer and had wide band spectra. Since it is useful that the prediction of fatigue life ot the given load sequences is based on S-N curves under constant amplitude loading, the estimation of equivalent stress is done on every random waves. The equivalent stress wasat first estimated by Miner's rule and then by the proposed model which was based on Hashin-Rotem's comulative damage theory regarding nonlinear fatigue cumulative damage behavior. The fatigue lives were predicted from each equivalent stress evaluated. And each predicted fatigue llife was compared with experimental results. The number of cycles of random loads were counted by mean-cross counting method. The reuslts showed that the fatigue life predicted by proposed model was correlated well with the experimental results in comparison with Miner's model.
A Study on the Machinability Charateristic of SM45C and SCM440
Kim, Nam-Hoon ; Lee, Yung-Sung ;
Transactions of the Korean Society of Mechanical Engineers A, volume 20, issue 12, 1996, Pages 3899~3908
DOI : 10.22634/KSME-A.19126.96.36.19999
In order to clarify the effects of nonmetallic inclusion contents insteels (SM45C & SCM440) on the tool life, cutting experiment was performed under various cutting conditions. Tool life, cutting force, roughness of machined surface and cutting mechanism are examined on these two kinds of steel. The following conclusions were obtained from the analysis (1) Cutting force of the steels was not affected by chemical component and nonmetallic inclusion. (2) If the rate of amount, Ca/S has a value grater than about 0.2 and addition of less amount of Al, Mn, tool wear of tips decreasesinturning. (3) It is also proved that higher contents of nonmetallic inclusion improve roughness of the surface. (4) Less amount of Ca, higher amount of S, Mn and Al improve the chip breakability.
The Influence of Assembling Errors on the Performance of the Rotor Supported by Active Magnetic Bearings
Kim, Dae-Gon ; Kim, Kyung-Woong ;
Transactions of the Korean Society of Mechanical Engineers A, volume 20, issue 12, 1996, Pages 3909~3916
DOI : 10.22634/KSME-A.19188.8.131.5209
Magnetic bearing is the machine element that supports the shaft without mechanical contact using the magnetic force induced by permanent magnet of electromagnet. Active magnetic bearing system is composed of sensor, controller, power amplifier, and electromagnet. If all the elements were dieal, shaft position could be controlled to sensor resolution, Because each elements inreal system have mechanical and electricla losses and nonlinearity, it is impossible to attain the desired performance using general control algorithm. So far it has been studied on improvement of the control algorithm of the electric characteristics of each elements. Another factors to affect shaft behavior are the manufacturing errors due to machine work, and assembling errors due to accumulate manufacturing errors of the radial magnetic bearing. This paper describes that the shaft behavior due to accumulate manufacturing errors and asymmetric bolting. This paper describes that the shaft behavior due to assembling errors of the radial bearings donot affect the rotaitonal accuracy of the shaft. But when the amplitude of the assembling errors increasees over the certain value, the bearing can not support the shaft properly.