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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
Editor in Chief :
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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Process Sequence Design in Cold Forged Part of Hub
Go, Dae-Cheol ; Kim, Byeong-Min ; O, Se-Uk ;
Transactions of the Korean Society of Mechanical Engineers A, volume 20, issue 11, 1996, Pages 3387~3397
DOI : 10.22634/KSME-A.19220.127.116.1187
The Hub is an auto mobile component used as aircon clutch. The important aspects in cold forging of the Hub with complex geometry are the design of an initial shape of the workpiece, the possibility of the forming by one-stage operation and the determination of number of performs, etc. Based on the systematic procedure of process sequence design, in this paper, the forming operation of cold forged part of the Hub is designed by the rigid-plastic finite element method. The two design criterion of geometrical filling without defect and an even distribution of effective strain in final product are investigated in controlling the initial shape of the workpiece and preform configuration. It is noted that one preforming operation is required in order to obtain final product of the Hub.
Inverse Kinematics of Complex Chain Robotic Mechanism Using Ralative Coordinates
Kim, Chang-Bu ; Kim, Hyo-Sik ;
Transactions of the Korean Society of Mechanical Engineers A, volume 20, issue 11, 1996, Pages 3398~3407
DOI : 10.22634/KSME-A.1918.104.22.16898
In this paper, we derive an algorithm and develope a computer program which analyze rapidly and precisely the inverse kinematics of robotic mechanism with spatial complex chain structure based on the relative coordinates. We represent the inverse kinematic problem as an optimization problem with the kinematic constraint equations. The inverse kinematic analysis algorithm, therefore, consists of two algorithms, the main, an optimization algorithm finding the motion of independent joints from that of an end-effector and the sub, a forward kinematic analysis algorithm computing the motion of dependent joints. We accomplish simulations for the investigation upon the accuracy and efficiency of the algorithm.
A Study on Elevated Temperature Fatigue Crack Growth Using Round Bar Specimen with a Surface Crack
So, Tae-Won ; Yun, Gi-Bong ;
Transactions of the Korean Society of Mechanical Engineers A, volume 20, issue 11, 1996, Pages 3415~3423
DOI : 10.22634/KSME-A.1922.214.171.12415
The compact tension specimen geometry has been widely used for measuring fatigue crack growth rates at elevated temperature when the fatigue load is under tension/tension condition. However, most of the elevated temperature components which have significant crack growth life experience fatigue load under tension/compression conditions. Thus test techniques are required since the compact tension specimen cannot be used for tension/compression loading. In this paper, a simplified test procedure for measureing fatigue crack growth rates is proposed, which employs a round bar specimen with a small surface crack. Fatigue crack growth rates under tension/ tension loading conditions at elevated temperature were measured according to the proposed procedure and compared with those previously measured by C/(T) specimens. Since both the measured crack growth rates were comparable, the fatigue crack growth rates under tension/ compression load can be reliably measured by the proposed procedure. For monitoring crack depth. DC electric potential method is employed and an optimal probe location and current input conditions were proposed.
Development of Modified Creep-Fatigue Damage Model for High Temperature Life Prediction
Park, Jong-Joo ; Seok, Chang-Sung ; Kim, Young-Jin ;
Transactions of the Korean Society of Mechanical Engineers A, volume 20, issue 11, 1996, Pages 3424~3432
DOI : 10.22634/KSME-A.19126.96.36.19924
For mechanical system operating at high temperature, damage due to the interaction effect of creep and fatigue plays an important role. The objective of this paper is to develop a modified creep-fatigue damage model which separately analyzes the pure creep damage for hold time and the creep-fatigue interaction damage during startup and shutdown period. The creep damage was calculated by the general creep damage equation and the creep-fatigue interaction damage was calculated by the modified equation which is based on the frequency modified strain range method with strain rate term. In order to verify the proposed model, a service of high temperature low cycle fatigue tests were performed. The test specimens were made from inconel-718 superalloy and the test parameters were wave shape and hold time. A good agreement between the predicted lives based on the proposed model and experimentally obtained ones was observed.
A Study on Stress Corrosion Cracking of Fiber Reinforced Composite by Slow Strain Rate Test
Lim, Jae-Gyu ; Choi, Tae-Su ;
Transactions of the Korean Society of Mechanical Engineers A, volume 20, issue 11, 1996, Pages 3433~3440
DOI : 10.22634/KSME-A.19188.8.131.5233
This paper was investigation of the stres corrosion cracking(SCC) mechanism and the properties of corrosion fracture surface of glass fiber reinforced plastics(GFRP) produced by hand lay up(HLU) method in synthetic sea water. Test material is GFRP, that was used vinylester type epoxy acrylate resin and an unsaturated polyester as the matrix and the chopped strand mat(CSM) type E-glss fiber as the reinforcement. The slow strain rate test(SSRT) was performed on dry, wet and saturated wet specimens in sea water. Here the pH concentration of synthetic sea water was 8.2 and the strain rate is 1 x
) and test temperature ranges varied from
. It could be confirmed the fact that wet specimens tested at a particular test temperature ranges were appeared the eviences of SCC such as con-planar, mirror and hackle zone. Moreover, SCC of GFRP in sea water was characterised by falt fracture surfaces with only small amounts of fiber pull-out, in partial.
Elastic Finite Element Analysis for a Flexible Beam Structure.
Jung, Dong-Won ; Lim, Sae-Young ;
Transactions of the Korean Society of Mechanical Engineers A, volume 20, issue 11, 1996, Pages 3441~3453
DOI : 10.22634/KSME-A.19184.108.40.20641
A finite element anlaysis is performed for large deformations of a felxible beam. The total Lagrangian formulation for a general large deformation, which involves finite rotations, is chosen and the exponential map is used to treat finite rotations from the Eulerian point of view. The finite elements results are confirmed for several cases of deformations through comparison to a first order elasticity solution obtained by numerical integration, and the agreement between the two is found to be excellent. For lateral buckling, the point of vanishing determinant of the resulting unsymmetric tangent stiffness is traced to examine its relationship to bifurcation points. It is found that the points of vanishing determinant is not corresponding to bifurcation points for large deformation in general, which suggests that the present unsymmetric tangent stiffness is not an exact first derivative of internal forces with respect to displacement.
An Investigation of Slab-FEM for Rolling Analysis
Song, Jung-Hoon ; Park, Jong-Jin ;
Transactions of the Korean Society of Mechanical Engineers A, volume 20, issue 11, 1996, Pages 3454~3462
DOI : 10.22634/KSME-A.19220.127.116.1154
Compared to a full three dimensional FEM, the Slab-FEM hybrid method reduces the required computation time distinctly and it can be applied to the analysis of a shape rolling process. However, the method is somewhat approximate and predictions by the method contain certain inaccuracies. In the present investigation a parameter called T-factor was introduced to compensate the inaccuracies of the method and proper values of the parameter were estimated for different widths of bars and reduction ratios. Then, the method was applied to analyze cold and hot rollings of rectangular bars and predicted results were compared to those of experiments. Nonuniform distributions of temperature in the bars were predicted by utilizing the temperature equation obtained for a semi-infinite solid under radiation and convection boundary conditions. It was found out that accuracies of spread and roll separating force predictions could be enhanced by using proper values of the T-factor.
Wave Propagation Characteristics along a Simple Catenary with Arbitrary Impedance Condition
Park, Sukyung ; Kim, Seamoon ; Kim, Yang-Hann ;
Transactions of the Korean Society of Mechanical Engineers A, volume 20, issue 11, 1996, Pages 3463~3473
DOI : 10.22634/KSME-A.1918.104.22.16863
The characteristics of wave propagation along a catenary depend on various impedance conditions; i.e., spatial impedance of catenary, impedance of boundaries. In this study, wave propagation along a simple catenary system is studied with arbitrary impedance conditions such as impedance of pantograph, boundary, catenary etc. Seven coupled equations which determine the characteristics of wave propagation along catenary system have been derived and numerically solved. Results demonstrate the role of each impedance condition in the dynamics of catenary system, i.e. the way in which the conditions affect waves on catenary as well as contact force of pantograph. The formulation and suggested solution method can be certainly used for desinging an optimal catenary system for a given pantograph.
Effects of Secondary Forming Process on Mechanical Properties of
/Al Composites Fabricated by Squeeze Casting
Seo, Y.H ; Kang, C.G ;
Transactions of the Korean Society of Mechanical Engineers A, volume 20, issue 11, 1996, Pages 3474~3490
DOI : 10.22634/KSME-A.1922.214.171.12474
A metal matrix composites(MMCs) for A16061 reinforced with silicon carbide particles is fabricated by melt-stirring method. The primary products of MMCs billets are prepared by volume fractions 5 vol% to 20 vol% and particle size
.This paper will be made to examine the microstructure and mechanical properties of fabricated
/Al 6061 composite by melt-stirring and squeeze casting method. The MMC billets is extruded at
under the constant extrusion velocity
=2mm/min using curved shape die. Extrusion force, particle rearrangement, micro structure and mechanical properties of extruded composites will be investigated. The mechanical properties of primary billets manufactured by melt-stirring and squeeze casting method will be compared with extrusion specimen. The effect of volume fraction and size of the reinforcements will be studied. The increase in uniformity of particle dispersion is the major reason for an improvement in reliability due to hot extrusion with optimal shape die. Experimental Young's modulus and 0.2% offset yield strength for the extruded MMCs will be compared with theretical values calculated by the Eshelby method. A method will be proposed for the prediction of Young's modulus and yield strength in
Determination of Mode I Fracture Toughness of Fiber Reinforced Composites by the Elastic Work Factor
Lee, Gyeong-Yeop ; Go, Seung-Gi ;
Transactions of the Korean Society of Mechanical Engineers A, volume 20, issue 11, 1996, Pages 3491~3497
DOI : 10.22634/KSME-A.19126.96.36.19991
The work factor approach was applied to determine
of fiber reinforced composites (AS4/3501) from a single unidirectional (0-deg) DCB specimen. Elastic work factors of DCB specimen for three different symmetrical staking sequences were derived from a simple bending theory and a finite element method. The results showed that elastic work factors calculated from both methods were comparable each other. In particular, the elastic work factor of DCB specimen with symmetrical stacking sequence is independent of stacking sequence. The
determined from the work factor approach was compared with that determined by the compliance method. The results showed that the work factor approach and the compliance method produce comparable results of
can be determined from a single DCB specimen using the work factor approach.
Method to measure
and J-integral for CTS specimen under mixed mode loading
Hong, K.J ; Kang, K.J ;
Transactions of the Korean Society of Mechanical Engineers A, volume 20, issue 11, 1996, Pages 3498~3506
DOI : 10.22634/KSME-A.19188.8.131.5298
A loading device to be used in fracture experiment is presented. It's loading angle can be adjusted from
at intervals of
for a CTS ( compact tension-shear) specimen, so that it is to be useful to measure mixed mode toughness. The equations to give the
and J-integral for the experiment are evluated though finite elemetn analysis in which the loading procedure is simulated and the behaviors of the specimen such as load-displacement curve are estimated. In the course of the evaluation the values
and J-integral calculated through recentrly released numerical methods are employed as the reference ones.
An Analytical Synthesis Method of Dynamic Systems in Terms of Bond Graphs
Park, Jeon-Su ; Kim, Jong-Sik ;
Transactions of the Korean Society of Mechanical Engineers A, volume 20, issue 11, 1996, Pages 3507~3515
DOI : 10.22634/KSME-A.19184.108.40.20607
This paper presents an attempt to find the physical structure of dynamic systems which achieves the behavior of a given system function. The scheme pursued by the paper would be regarded as synthesizing dynamic systems, and a method to synthesize them analytically is proposed by means of bond graph prototypes. The method adopts several conceptsused to synthesize networks in the electrical field, but yet deconstrates its own strengths such as the freedom from assigning causality and determining junction types. Also, itis shown that this method has further advantages in reticulating a given specification into feedforward and feedback components relative to network synthesis and the method is examined though an example to trace the outline of the analytical synthesis of dynamic systems using bond graph prototypes.
Analysis of Material Response Based on Chaboche Unified Viscoplastic Constitutive Equation;
Gwak, Dae-Yeong ; Im, Yong-Taek ; Kim, J.B ; Lee, Hyeong-Yeon ; Yu, Bong ;
Transactions of the Korean Society of Mechanical Engineers A, volume 20, issue 11, 1996, Pages 3516~3524
DOI : 10.22634/KSME-A.19220.127.116.1116
Service conditions for structures at elevated temperatures in nuclear power plant involve transient thermal and mechanical load levels that are severe enough to caeuse inelastic deformations due to creep and plasticity. Therefore, a systematic mehtod of inelastic analysis is needed for the design of structural components in nuclear poser plants subjected to such loading conditions. In the present investigation, the Chabodhe model, one of the unified viscoplastic constitutive equations, was selected for systematic inelastic analysis. The material response was integrated based on GMR ( generallized mid-point rule) time integral scheme and provided to ABAQUS as a material subroutine, UMAT program. By comparing results obtaned from uniaxial analysis using the developed UMAT program with those from Runge-Kutta solutions and experimentaiton, the validity of the adopted Chaboche model and the numerical stability and accuracy of the developed UMAT program were verified. In addition, the developed material subroutine was applied for uniaxial creep and tension analyses for the plate with a hole in the center. The application further demonstrates usefulness of the developed program.
A Computer-Aided Design Program of Man-in-Cab for Heavy Construction Vehicle
Son, Gwon ; Lee, Hui-Tae ;
Transactions of the Korean Society of Mechanical Engineers A, volume 20, issue 11, 1996, Pages 3525~3537
DOI : 10.22634/KSME-A.1918.104.22.16825
This paper presents a CAD program develpoed on a microcomputer in order to support graphic and computational assessment of ergonomic problems associated with the design of a man-in-cab system. The program is coded to help workspace designers with ergonomic evaluations needed in the design stage. This paper proposed a biomechanical -ergonomic evaluations needed using man and workplace models. The human model is developed to have dimensions obtained from the Korean anthropometric data reported in 1992. Its graphical representation is based on a wire-frame model but, whenever necessary, body segments can be represented by a solid model with hidden line/faces removed and shaded. Workplace models are presented for cabs of the excavator, one of the most popular construction vehicles. A workplace model consists of an operator seat, a steering wheel. two control levers, two pedals, and a control panel. The workplace elements can be modified in their sizes, positions, and orientations by changing the reference point and design parameters. An algorithm for the view test is suggested and loaded to provide a visual evaluaiton of the overall layout of a workplace model.
A Study on the Mechanical Properties of EMC and Thermal Stress Anlaysis in Electronic Packagings
Shin, Dong-Kil ; Lee, Jung-Ju ;
Transactions of the Korean Society of Mechanical Engineers A, volume 20, issue 11, 1996, Pages 3538~3548
DOI : 10.22634/KSME-A.1922.214.171.12438
In this study, as a part of basic study for developing the simulation program for the assemssment of reliability of electronic EMC packaging which covers from EMC mixing step to thermal analysis, comparison between a measured and predicted values of material properties of EMC and finitde element analysis of thermal stress are performed. For the experimental testing specimens of fifty, sixty hive and eighty percent filler(
, spherical silica) weight fraction are fabricated using tranfer molding. Coefficient of thermal expansion, elastic modulus and thermla conductivity are measured using these specimens and then these measured values are compared with the predicted values by various equations ( such as dilute suspension method. self consistent method, generalized self consistent method, Hashin-Shtrikman's bounds. Shapery's bounds, Nielsen's method and others). Measured values are distributed within the upper and lower bounds of equations. Measured elastic modulus and coefficient of thermal expansion approaches closely the perdicted values with self consisten mehtod and upper bound of Shaperys equation respectively. However small differences of thermal conductivity between the different filler volume fraction are obserbed. FEM analysis indicates that firstly stress is concentrated at the corner section of EMC and secondly EMC with eighty percent filler weight fraction shows less thermal stress when package is cooling down and relatively high thermal stress when package is heating up.
Robustness of Independent Modal Space Control for Parameter and Modal Filter Errors
Hwang, Jai-Hyuk ; Kim, Joon-Soo ;
Transactions of the Korean Society of Mechanical Engineers A, volume 20, issue 11, 1996, Pages 3549~3559
DOI : 10.22634/KSME-A.19126.96.36.19949
In this study, the effect of parameter and modal filter errors on the vibration control characteristics of flexible structures is analyzed for IMSC ( Independent Modal Space Control). If the control force is designed on the basis of the mathematical model with the parameter and modal filter errors, the closed-loop performance of the vibration control system will be degraded depending on the magnitude of the errors. An asymptotic stability condition of the system with parameter and modal filter errors has more significant effect on the stability condition of the system with parameter and modal filter errors has been drived using Lyapunov approach. It has been found that modal filter error has more significant effect on the stability of closed-loop system than parameter error does. The extent of the response deviation of the closed-loop system is also derived and evaluated using operator thchniques.
Robust Vibration Control of Smart Structures via Discrete-Time Fuzzy-Sliding Modes
Choi, Seung-Bok ; Kim, Myoung-Suk ;
Transactions of the Korean Society of Mechanical Engineers A, volume 20, issue 11, 1996, Pages 3560~3572
DOI : 10.22634/KSME-A.19188.8.131.5260
This paper presents a new discrete-time fuzzy-sliding mode controller for robust vibration control of a smart structure featuring a piezofilm actuator. A governong equation of motion for the smart beam structure is derived and discrete-time codel with mismatched uncertainties such as parameter variations is constructed ina state space. A discrete-time sliding mode control system consisting of an equivalent controller and a discontinuous controller is formulated. In the design of the equivalent part, so called an equivalent controller separation method is adopted to achieve vzster convergence to a sliding surface without extension of a sliding region, in which the system robustness maynot be guaranteed. On the other hand, the discontinuous part is constructed on the basis of both the sliding and the convergence conditions using a time-varying feedback gain. The sliding moide controller is then incorporated with a fuzzy technique to appropriately determine principal control parameters such as a discountinuous feedback gain. Experimental implementation on the forced and random vibraiton controls is undertaken in order to demonstrate superior control performance of the proposed controller.