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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 25, Issue 12 - Dec 2001
Volume 25, Issue 11 - Nov 2001
Volume 25, Issue 10 - Oct 2001
Volume 25, Issue 9 - Sep 2001
Volume 25, Issue 8 - Aug 2001
Volume 25, Issue 7 - Jul 2001
Volume 25, Issue 6 - Jun 2001
Volume 25, Issue 5 - May 2001
Volume 25, Issue 4 - Apr 2001
Volume 25, Issue 3 - Mar 2001
Volume 25, Issue 2 - Feb 2001
Volume 25, Issue 1 - Jan 2001
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Mode I and Mode II Stress Intensity Factors for a Surface Cracked in TiN/Steel Under Hertzian Rolling Contact
Kim, Byeong-Su ; Kim, Wi-Dae ;
Transactions of the Korean Society of Mechanical Engineers A, volume 25, issue 8, 2001, Pages 1163~1172
DOI : 10.22634/KSME-A.2001.25.8.1163
The two dimensional problem of a layered tribological system(TiN/Steel) containing a vertical surface breaking crack and subject to rolling contact is considered in this study. Using finite elements and stress extrapolation method, a series of preliminary models are developed. Preliminary results indicate that the extrapolation technique is valid to determine Modes I and II stress intensity factors for cracks. In the case of TiN/Steel medium, KI and KII were determined for variations in crack length, layer thickness, and load location. The results show that KII reaches maximum values when the contact is adjacent to the crack where Mode I stresses are compressive. KII values decrease with decreased crack length and significantly decrease for reduced layer thickness.
Cutting Force Regulation in Milling Process Using Sliding Mode Control
Lee, Sang-Jo ; Lee, Yong-Seok ; Go, Jeong-Han ;
Transactions of the Korean Society of Mechanical Engineers A, volume 25, issue 8, 2001, Pages 1173~1182
DOI : 10.22634/KSME-A.2001.25.8.1173
Recent noticeable advances of CNC machine tools have considerably improved productivity and precision in manufacturing processes. However, in the respect of productivity some defects still remain because selection of machining conditions entirely depends on the experiences of programmers. Usually, machining conditions such as feed rate and spindle speed have been selected conservatively by considering the worst cases, and it has brought the loss of machining efficiency. Thus, the improvement of cutting force controller has been done to regulate cutting force constantly and to maximize feedrate simultaneously in case that machining conditions change variously. In this study, sliding mode control with boundary layer is applied to milling process for cutting force regulation and in a commercial CNC machining center data transfer between PC and PMC (programmable machine controller) of CNC machine is done using a standard interface method. And in the cutting force measurement, an indirect cutting force measuring system using current signal of AC servo is adopted in order not to use high-priced equipment like tool dynamometer. The purpose of this study is to maximize the productivity in milling process, thus its results can be applied to cases such as rough cutting process.
A Study on the Starved Lubrication for the Piston Ring
Jo, Myeong-Rae ; Han, Dong-Cheol ;
Transactions of the Korean Society of Mechanical Engineers A, volume 25, issue 8, 2001, Pages 1183~1188
DOI : 10.22634/KSME-A.2001.25.8.1183
This paper reports on the starved lubrication for the piston ring. In this analysis, two types of inlet boundary conditions, fully flooded and starved condition, are considered at the leading edge. The inlet position of effective lubrication and squeeze term are obtained by numerically iterative method. The effective lubricated region is reduced due to the starved condition at the inlet. The starved condition at the inlet significantly reduced the minimum oil film thickness(MOFT) at the midstroke of piston, and the friction force is also increased due to the thin oil film thickness. In the starved conditions, the power loss is significantly increased.
Nondestructive Evaluation of Thermal Shock Damage for Alumina Ceramics
Lee, Jun-Hyeon ; Lee, Jin-Gyeong ; Song, Sang-Heon ;
Transactions of the Korean Society of Mechanical Engineers A, volume 25, issue 8, 2001, Pages 1189~1196
DOI : 10.22634/KSME-A.2001.25.8.1189
The objective of this paper is to investigate the applicability of acoustic emission(AE) technique to monitor the progress of the thermal shock damage on alumina ceramic. For this purpose, alumina ceramic specimen was heated in the furnace and then was quenched in the water tank. When the specimen was quenched in the water tank, complex AE signals due to the initiation of micro-cracks and boiling effect were generated by the progress of thermal shock damage. These mixed AE signals have to be classified for monitoring the degree of the thermal shock damage of alumina ceramics. In this paper, the mixed AE signals generated from both the boiling effect and the crack initiation under thermal shock test was analyzed. The characteristics of AE signals were also discussed by considering the variation of bending strength and Yongs modulus of specimens.
Vibration Characteristics of Langevin-Type Piezoelectric Torsional Transducers
Kim, Jin-O ; Gwon, O-Su ;
Transactions of the Korean Society of Mechanical Engineers A, volume 25, issue 8, 2001, Pages 1197~1205
DOI : 10.22634/KSME-A.2001.25.8.1197
The vibrational characteristics of Langevin-type piezoelectric torsional transducers, which consist of a couple of piezoelectric discs and a couple of elastic blocks, have been studied theoretically and experimentally in this paper. The differential equations of piezoelectric torsional motion have been derived in terms of the circumferential displacement and the electric potential. Solutions of the boundary-value problem have yielded the natural frequencies and mode shapes of the transducers. The theoretical solutions have been verified by comparing the numerical results with experimental ones.
A New Kinematic Analysis of 6-3 Stewart Platform Manipulator
Kim, Nak-In ; Lee, Chong-Won ;
Transactions of the Korean Society of Mechanical Engineers A, volume 25, issue 8, 2001, Pages 1206~1212
DOI : 10.22634/KSME-A.2001.25.8.1206
The kinematic analysis of Stewart platform manipulator(SPM) is carried out in order to reduce the calculation time for its forward kinematic solution when the iterative numerical method is employed. The kinematic equations for three substructures of the 6-3 SPM are newly derived by introducing Denavit-Hartenberg link parameters and using kinematic constraints associated with the SPM and substructure kinematics. It is shown that the forward kinematics can be easily solved from three nonlinear equations with three unknown variables only, leading to a great reduction in calculation time.
Study on Scratch Defect of Roll Forming Process
Kim, Nak-Su ; Hong, Seok-Mu ;
Transactions of the Korean Society of Mechanical Engineers A, volume 25, issue 8, 2001, Pages 1213~1219
DOI : 10.22634/KSME-A.2001.25.8.1213
In this paper, modeling of the multi-pass roll forming process with the finite element method and defect prediction in roll forming process are presented. In the roll forming process, there occurs the defect of scratch. It appears on tubes because of the friction between the strip and the roll, the unexpected sliding velocity and the contact pressure when fabricating the tubes. The surface of the product will be not uniform due to the defect. The scratch can be predicted with the simulation modeling of the finite element method, and can be avoided by modifying the design.
Effects of the Pre-strain on Mechanical Properties of the Solid-Phase Formed Thermoplastic Composite
Lee, Jung-Hui ; Jo, Hyeon-Cheol ; Lee, Gyeong-Yeop ;
Transactions of the Korean Society of Mechanical Engineers A, volume 25, issue 8, 2001, Pages 1220~1226
DOI : 10.22634/KSME-A.2001.25.8.1220
This study investigates the effects of the pre-strain level on mechanical properties of the solid-phase formed thermoplastic composite. A uniaxial solid-phase forming was performed at the temperature of 125
and at the constant cross-head speed of 3mm/sec. The composite sheet was formed to various pre-strain levels of 10%, 20%, and 30%. Tension, flexural, and impact tests were carried out to characterize the material properties of a solid-phase formed part. Tensile and flexural strengths decreased with increasing the pre-strain level, while impact strength increased. Various microstructures of the formed part explained the above material behavior.
A Study of Vibration Control of a Slender Structure Using a Multi-Degree-of-Freedom Manipulator
Kim, Nak-In ; Lee, Jong-Won ;
Transactions of the Korean Society of Mechanical Engineers A, volume 25, issue 8, 2001, Pages 1227~1234
DOI : 10.22634/KSME-A.2001.25.8.1227
A multi d.o.f robotic manipulator is considered for multi-axis vibration control of a slender structure, using the concept of the flow source based vibration control. In order not to cause the motion saturation of the manipulator system, a hybrid dynamics associated with the flexible and desired manipulator error dynamics is also modeled as the control object. It is numerically shown that the flexible vibrations and the base motions of a test structure can be effectively controlled with the proposed hybrid dynamics.
New Engineering Approach for Estimating Crack Opening Displacement of Complex Cracked Pipes
Kim, Yeong-Jin ; Heo, Nam-Su ; Kim, Yun-Jae ;
Transactions of the Korean Society of Mechanical Engineers A, volume 25, issue 8, 2001, Pages 1235~1241
DOI : 10.22634/KSME-A.2001.25.8.1235
An engineering estimation equation for the crack opening displacement(COD) is proposed for a complex cracked pipe, based on the reference stress approach. To define the reference stress, a simple plastic limit load analysis for the complex cracked pipe subjected to combined bending and tension is performed considering the crack closure effect in the compressive-stressed region. Comparison with ten published test data and the results from existing method shows that the present method not only reduces non-conservatism associated with the existing method, but also provides consistent and overall satisfactory results.
Fabrication of Micro Lens Array Using Micro-Compression Molding
Gang, Sin-Il ; Mun, Su-Dong ; Lee, Yeong-Ju ; Bu, Jong-Uk ;
Transactions of the Korean Society of Mechanical Engineers A, volume 25, issue 8, 2001, Pages 1242~1245
DOI : 10.22634/KSME-A.2001.25.8.1242
Plastic microlenses play an important role in reducing the size, weight, and the cost of the systems in the fields of optical data storage and optical communication. In the present study, plastic microlens arrays were fabricated using micro-compression molding process. The design and fabrication procedures for mold insert were simplified by using silicon instead of metal. A simple but effective micro compression molding process, which uses polymer powder, were developed for microlens fabrication. The governing process parameters were temperature and pressure histories and the micromolding process was controlled such that the various defects developing during molding process were minimized. The radius and magnification ratio of the fabricated microlens were 125
and over 3.0, respectively.
Point Data Reduction in Reverse Engineering by Delaunay Triangulation
Lee, Seok-Hui ; Heo, Seong-Min ; Kim, Ho-Chan ;
Transactions of the Korean Society of Mechanical Engineers A, volume 25, issue 8, 2001, Pages 1246~1252
DOI : 10.22634/KSME-A.2001.25.8.1246
Reverse engineering has been widely used for the shape reconstruction of an object without CAD data and the measurement of clay or wood models for the development of new products. To generate a surface from measured points by a laser scanner, typical steps include the scanning of a clay or wood model and the generation of manufacturing data like STL file. A laser scanner has a great potential to get geometrical data of a model for its fast measuring speed and higher precision. The data from a laser scanner are composed of many line stripes of points. A new approach to remove point data with Delaunay triangulation is introduced to deal with problems during reverse engineering process. This approach can be used to reduce a number of measuring data from laser scanner within tolerance, thus it can avoid the time for handling point data during modelling process and the time for verifying and slicing STL model during RP process.
Thermal Analysis of Automotive Disc Brake Using FFT-FEM
Lee, In ; Choe, Ji-Hun ; Kim, Do-Hyeong ;
Transactions of the Korean Society of Mechanical Engineers A, volume 25, issue 8, 2001, Pages 1253~1260
DOI : 10.22634/KSME-A.2001.25.8.1253
Transient thermal analysis of a three-dimensional axisymmetric automotive disk brake is presented in this paper. Temperature fields are obtained using a hybrid FFT-FEM scheme that combines Fourier transform techniques and finite element method. The use of a fast Fourier transform algorithm can avoid singularity problems and lead to inexpensive computing time. The transformed problem is solved with finite element scheme for each frequency domain. Inverse transforms are then performed for time domain solution. Numerical examples are presented for validation tests. Comparisons with analytical results show very good agreement. Also, a 3-D simulation, based upon an automotive brake disk model is performed.
Modeling and Application of Active Fiber Composites
Ha, Seong-Gyu ; Lee, Yeong-U ; Kim, Yeong-Ho ;
Transactions of the Korean Society of Mechanical Engineers A, volume 25, issue 8, 2001, Pages 1261~1268
DOI : 10.22634/KSME-A.2001.25.8.1261
Effective material properties of active fiber composites with interdigitated electrodes are derived as a function of the fiber volume fraction. For the purpose of applying the rule of mixture, three unit cell models are introduced; each for the deformation and stress continuities in the out of plane and in-plane directions, and the continuity of the electrical displacement in the longitudinal direction. Derived effective material properties are compared with the results by the finite element method; good agreements are observed between them. As an application, the electromechanical behavior of the angle ply laminates with the active fiber layers bonded on the top and bottom surfaces are investigated; the angle of piezoelectric fiber to maximize the twisting curvature is obtained using the present model.
Study on the Fatigue Crack Initiation Life Under Spherical Contact
Jo, Yong-Ju ; Kim, Tae-Wan ; Lee, Mun-Ju ;
Transactions of the Korean Society of Mechanical Engineers A, volume 25, issue 8, 2001, Pages 1269~1276
DOI : 10.22634/KSME-A.2001.25.8.1269
In case of contact fatigue, the accurate calculation of surface tractions and subsurface stress is essential to the predication of crack initiation life. Surface tractions influencing shear stress amplitude have been obtained by contact analysis based on influence function. Subsurface stress has been obtained by using rectangular patch solutions. In this study, to simulate asperity contact under sliding condition, the tip of asperity was simulated by sphere and to calculate crack initiation life in the substrate, dislocation pileup theory was used.
The Delamination and Fatigue Crack Propagation Behavior in A15052/AFRP Laminates Under Cyclic Bending Moment
Song, Sam-Hong ; Kim, Cheol-Ung ;
Transactions of the Korean Society of Mechanical Engineers A, volume 25, issue 8, 2001, Pages 1277~1286
DOI : 10.22634/KSME-A.2001.25.8.1277
Aluminum 5052/Aramid Fiber Reinforced Plastic(Al5052/AFRP) laminates are applied to the fuselage-wing intersection. The Al5052/AFRP laminates suffer from the cyclic bending moment of variable amplitude during the service. Therefore, the influence of cyclic bending moment on the delamination and the fatigue crack propagation behavior in Al5052/AFRP laminate was investigated in this study. Al5052/AFRP laminate composite consists of three thin sheets of Al5052 and two layers of unidirectional aramid fibers. The cyclic bending moment fatigue tests were performed with five different levels of bending moment. The shape and size of the delamination zone formed along the fatigue crack between Al5052 sheet and aramid fiber-adhesive layer were measured by an ultrasonic C-scan. The relationships between da/dN and ΔK, between the cyclic bending moment and the delamination zone size, and between the fiber bridging mechanism and the delamination zone were studied. Fiber failures were not observed in the delamination zone in this study. It represents that the fiber bridging modification factor should turn out to increase and that the fatigue crack growth rate should decrease. The shape of delamination zone turns out to be semi-elliptic with the contour decreased non-linearly toward the crack tip.
A Study on Material Degradation and Fretting Fatigue Behavior
Gwon, Jae-Do ; Seong, Sang-Seok ; Choe, Seong-Jong ;
Transactions of the Korean Society of Mechanical Engineers A, volume 25, issue 8, 2001, Pages 1287~1293
DOI : 10.22634/KSME-A.2001.25.8.1287
Fretting is a potential degradation mechanism of structural components and equipments exposed to various environments and loading conditions. The fretting degradation, for example, for example, can be observed in equipments of nuclear, fossil as well as petroleum chemical plants exposed to special environments and loading conditions. It is well known that a cast stainless steel(CF8M) used in a primary reactor coolant(RCS) degrades seriously when that material is exposed to temperature range from 290
for long period. This degradation can be resulted into a catastrophical failure of components. In the present paper, the characteristics of the fretting fatigue are investigated using the artificially aged CF8M specimen. The specimen of CF8M are prepared by an artificially accelerated aging technique holding 180hr at 430
respectively. Through the investigations, the simple fatigue endurance limit of the virgin specimen is not altered from that obtained from the fatigue tests imposed the fretting fatigue. The similar tests are performed using the degraded specimen. The results are not changed from those of the virgin specimen. The significant effects of fretting fatigue imposed on both virgin and degraded specimen on the fatigue strength are not found.
Injection Molding Analysis of Map Pocket with a Speaker Grill Using Shell Element
Kim, Hong-Seok ; Jo, Myeong-Sang ; Son, Jung-Sik ; Seo, Tae-Su ; Kim, Tae-Ung ;
Transactions of the Korean Society of Mechanical Engineers A, volume 25, issue 8, 2001, Pages 1294~1301
DOI : 10.22634/KSME-A.2001.25.8.1294
In order to reduce the time and cost for assembly, automobile speaker grills have been injection molded with door trims or map pockets in one piece recently. However, several defects such as short shots or air traps can easily occur due to the decreased fluidity of the melting polymer according to the excessive heat transfer to the mold. Therefore, it is necessary to optimize the resin feed system and predict possible defects by CAE analysis. However it is not possible to obtain exact analysis results for the speaker grill by using general shell elements since the heat transfer in the thickness direction which is the dominant factor of the filling stage can not be considered. Therefore, there have been several efforts to simulate the injection molding nature of the speaker grill by using shell elements with an effective thickness which is smaller than the actual thickness of the part. Two empirical values have been recommended for the effective thickness in real practice. One is 50∼70% of the thickness of the speaker grill and another is the gap distance between the adjacent holes. In this paper, CAE analyses of a map pocket with a speaker grill were conducted using shell elements with both of these recommended effective thicknesses, and the predicted flow fronts were compared with the findings from injection molding experiments. The commercial code MOLDFLOW was used for injection molding analysis and an 850 ton injection molding machine was used for experiments.
An Experimental Study on The Coupling Path and Acoustic Modal Characteristics of a Coupled System of Passenger Compartment and Trunk
Lee, Jin-U ; Kim, Gyu-Beom ; Lee, Jang-Mu ; Kim, Seok-Hyeon ; Park, Dong-Cheol ;
Transactions of the Korean Society of Mechanical Engineers A, volume 25, issue 8, 2001, Pages 1302~1307
DOI : 10.22634/KSME-A.2001.25.8.1302
This study identifies the major coupling path by examining the variation of the coupled acoustic modal frequencies and modes. A 1/2-size acryl compartment model is designed and manufactured for the measurement and analysis of coupled acoustic modes. Due to acoustic coupling, a new acoustic mode appears in a low frequency range. This coupling affects only longitudinal acoustic modes of compartment. Experimental result shows that the package tray holes contribute to the coupling much more than the back seat and hole size is an important design factor to control low frequency acoustic modes in the coupled system.
Development of a Hybrid Haptic Master System Without Using a Force Sensor
Park, Gi-Hwan ; Bae, Byeong-Hun ;
Transactions of the Korean Society of Mechanical Engineers A, volume 25, issue 8, 2001, Pages 1308~1316
DOI : 10.22634/KSME-A.2001.25.8.1308
A hybrid type master system is proposed to take the advantage of the link mechanism and magnetic levitation mechanism without using a force sensor. Two different types of electromagnetic actuators, moving coil type and moving magnet types are used to drive the master system which is capable of 4-DOF actuation. It is designed that the rotation motions about x-y axis are decoupled and the whole system is represented by simple dynamic equations. The force reflection is achieved by using the simple relation between the force and applied current and position. The simulation and experimental results are presented to show its performance.