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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 21, Issue 12 - Dec 1997
Volume 21, Issue 11 - Nov 1997
Volume 21, Issue 10 - Oct 1997
Volume 21, Issue 9 - Sep 1997
Volume 21, Issue 8 - Aug 1997
Volume 21, Issue 7 - Jul 1997
Volume 21, Issue 6 - Jun 1997
Volume 21, Issue 4 - Apr 1997
Volume 21, Issue 5 - Jan 1997
Volume 21, Issue 3 - Jan 1997
Volume 21, Issue 2 - Jan 1997
Volume 21, Issue 1 - Jan 1997
Selecting the target year
Prediction of engineering constants for plain and 8-hardness satin woven composites
Byeon, Jun-Hyeong ;
Transactions of the Korean Society of Mechanical Engineers A, volume 21, issue 11, 1997, Pages 1757~1764
DOI : 10.22634/KSME-A.19220.127.116.117
The geometric and elastic models based on the unit cell have been proposed to predict the geometric characteristics and the engineering constants of plain and satin woven composites. In the geometric model, length and inclined angle of the yarn crimp and the fiber volume fraction of woven composites have been predicted. In the elastic model, the coordinate transformation has been utilized to transform the elastic constants of the yarn crimp to those of woven composites, and the effective elastic constants have been determined from the volume averaging of the constituent materials. Good correlations between the model predictions and the experimental results of carbon/epoxy and glass/epoxy woven composites have been observed. Based on the model, the effect of various geometric parameters and materials on the three-dimensional elastic properties of woven composites can be identified.
Design of optimal fiber angles in the laminated composite fan blades
Jeong, Jae-Yeon ; Jo, Yeong-Su ; Ha, Seong-Gyu ;
Transactions of the Korean Society of Mechanical Engineers A, volume 21, issue 11, 1997, Pages 1765~1772
DOI : 10.22634/KSME-A.1918.104.22.1685
The layered composites have a character to change of structure stiffness with respect to the layup angles. The deformations in the fan-blades to be initially designed by considering efficiency and noise, etc., which arise due to the pressure during the fan operation, can make the fan inefficient. Thus, so as to minimize the deformations of the blades, it is needed to increase the stiffness of the blades. An investigation has been performed to develop the three dimensional layered composite shell element with the drilling degree of freedom and the optimization module for finding optimal layup angles with sensitivity analysis. And then they have been verified. In this study, the analysis model is engine cooling fan of automobile. In order to analyzes the stiffness of the composite fan blades, finite element analysis is performed. In addition, it is linked with optimal design process, and then the optimal angles that can maximize the stiffness of the blades are found. In the optimal design process, the deformations of the blades are considered as multiobjective functions, and this results minimum bending and twisting simultaneously.
Optimum design of injection molding cooling system via boundary element method
Park, Seong-Jin ; Kwon, Tai-Hun ;
Transactions of the Korean Society of Mechanical Engineers A, volume 21, issue 11, 1997, Pages 1773~1785
DOI : 10.22634/KSME-A.1922.214.171.1243
The cooling stage is the very critical and most time consuming stage of the injection molding process, thus it cleary affects both the productivity and the part quality. Even through there are several commercialized package programs available in the injection molding industry to analyze the cooling performance of the injection molding coling stage, optimization of the cooling system has npt yet been accomplished in the literature due to the difficulty in the sensitivity analysis. However, it would be greatly desirable for the mold cooling system designers to have a computer aided design system for the cooling stage. With this in mind, the present study has successfully developed an interated computer aided design system for the injection molding cooling system. The CAD system utilizes the sensitivity analysis via a Boundary Element Method, which we recently developed, and the well-known CONMIN alforuthm as an optimization technique to minimize a weighted combination (objective function) of the temperature non-uniformity over the part surface and the cooling time related to the productivity with side constranits for the design reality. In the proposed objective function , the weighting parameter between the temperature non-uniiformity abd the cooling time can be adjusted according to user's interest. In this cooling system optimization, various design variable are considered as follows : (i) (design variables related to processing conditions) inlet coolant bulk temperature and volumetric flow rate of each cooling channel, and (ii) (design variables related to mold cooling system design) radius and location of each cooling channel. For this optimum design problem, three different radius and location of each cooling channel. For this optimum design problem, three different strategies are suffested based upon the nature of design variables. Three sample problems were successfully solved to demonstrated the efficiency and the usefulness of the CAD system.
Prediction of Fracture Resistance Curves for Nuclear Piping Materials(II)
Chang, Yoon-Suk ; Seok, Chang-Sung ; Kim, Young-Jin ;
Transactions of the Korean Society of Mechanical Engineers A, volume 21, issue 11, 1997, Pages 1786~1795
DOI : 10.22634/KSME-A.19126.96.36.1996
In order to perform leak-before-break design of nuclear piping systems and integrity evaluation of reactor vessels, full stress-strain curves and fracture resistance (J-R) curves are required. However it is time-consuming and expensive to obtain J-R curves experimentally. The objective of this paper is to modify two J-R curve prediction methods previously proposed by the authors and to propose an additional J-R curve prediction method for nuclear piping materials. In the first method which is based on the elastic-plastic finite element analysis, a blunting region handling procedure is added to the existing method. In the second method which is based on the empirical equation, a revised general equation is proposed to apply to both carbon steel and stainless steel. Finally, in the third method, both full stress-strain curve and finite element analysis results are used for J-R curve prediction. A good agreement between the predicted results based on the proposed methods and the experimental ones is obtained.
Prediction of Fracture Resistance Curves for Nuclear Piping Materials(III)
Chang, Yoon-Suk ; Seok, Chang-Sung ; Kim, Young-Jin ;
Transactions of the Korean Society of Mechanical Engineers A, volume 21, issue 11, 1997, Pages 1796~1808
DOI : 10.22634/KSME-A.19188.8.131.526
In order to perform leak-before-break design of nuclear piping systems and integrity evaluation of reactor vessels, full stress-strain curves and fracture resistance(J-R) curves are required. However it is time-consuming and expensive to obtain J-R curves experimentally. To resolve these problems, three different methods for predicting J-R curves from tensile data were proposed by the authors previously. The objective of this paper is to develop a computer program based on those J-R curve prediction methods. The program consists of two major parts ; the main program part for the J-R curve prediction and the database part. Several case studies were performed to verify the program, and it was shown that the predicted results were, in general, in good agreement with the experimental ones.
Control of a 3-DOF vertical articulated robotic system using nonlinear transformation control
Yang, Chang-Il ; Baek, Yun-Su ;
Transactions of the Korean Society of Mechanical Engineers A, volume 21, issue 11, 1997, Pages 1809~1818
DOI : 10.22634/KSME-A.19184.108.40.2069
Mathematical models of industrial robots or manipulators are highly nonlinear equations with nonlinear coupling between the variables of motion. As the working speed has been fast, the effects of nonlinear terms have become serious. So the control algorithm based on approximately linearized equation looses the efficiency. In order to design the control law for the nonlinear models, Hunt-Su's nonlinear transformation method and Marino's feedback equivalence condition are used with linear quadratic regulator(LQR) theory in this study. Nonlinear terms of the system are eliminated and coupled terms are decoupled by this feedback law. This method is applied to a 3-D.O.F. vertical articulated manipulator by both experiments and simulations and compared with PID control which is widely used in the industry.
Force control of the direct-drive robot using learning controller
Hwang, Yeong-Yeun ;
Transactions of the Korean Society of Mechanical Engineers A, volume 21, issue 11, 1997, Pages 1819~1826
DOI : 10.22634/KSME-A.19220.127.116.119
Direct-drive robots are suitable to the position and force control with high accuracy, but it is difficult to design a controller because of the system's nonlinearity and link-interactions. This paper is concerned with the study of the force control of direct-drive robots. The proposed algorithm consists of feedback controllers and a neural network. After the completion of learning, the output of feedback controller is nearly equal to zero, and the neural network controller plays an important role in the control system. Therefore, the optimum retuning of parameters of feedback controllers is unnecessary. In other words, the proposed algorithm does not require any knowledge of the controlled system in advance. The effectiveness of the proposed algorithm is demonstrated by the experiment on the force control of the parallelogram link-type direct-drive robot.
A study on the clamping type forging of helical gear
Choe, Jae-Chan ; Choe, Yeong ; Tak, Seong-Jun ; Jo, Hae-Yong ;
Transactions of the Korean Society of Mechanical Engineers A, volume 21, issue 11, 1997, Pages 1827~1836
DOI : 10.22634/KSME-A.1918.104.22.1687
In this paper, the clamping type forging of helical gears has been investigated. Clamping type forging is an operation in which the product is constrained to extrude sideways through an orifice in the container wall. Punch is cylindrical shaped. The punch compresses a cylindrical bilet placed in a die insetr. As a consequence the material flows in a direction perpendicular to that of punch movement. The forging has been analysed by using the upper-bound method. A kinematically admissible velocity field has been developed, wherein, an involute curve has been introduce to re4present tooth profile of the gear. Numerical calculations have been carried out to investigate the effects of various parameters, such as module, number of teeth, helix angle, friction factor and initial height of billet on the forging of helical gears. Some firgiing experiments were catrried out with aluminium alloy to show the validity of the analysis. Good agreement was found between the predicted values of the forging load and obtained from the experimental results.
Active noise control with the active muffler in automotive exhaust system
Kim, Heung-Seob ; Hong, Jin-Seok ; Oh, Jae-Eung ;
Transactions of the Korean Society of Mechanical Engineers A, volume 21, issue 11, 1997, Pages 1837~1843
DOI : 10.22634/KSME-A.1922.214.171.1247
This study experimentally demonstrates the use of active muffler attached to the automotive exhaust system to reduce exhaust noise. For improving the signal to noise ratio in the process of estimation of secondary path transfer functions, the on-line algorithm that conventional inverse modeling is combined with adaptive line enhancer is used as the control algorithm. Active muffler is designed that the primary noise and the control sound are propagated as a plane wave in the outlet. Therefore, the error microphone could be placed out of the tail pipe center of a high temperature and the radiation noise to the outside could be reduced in the whole area around the outlet. The control experiment for reducing exhaust noise with active muffler is implemented during run-up at no load. From the experimental results presented, compared with the conventional off-line method, the proposed on-line method is capable to acquire a reduction of exhaust noise above 5 dB in overall sound power level.
A study on the improvement method of the stress field analysis in a domain composed of dissimilar materials
Song, Kee-Nam ;
Transactions of the Korean Society of Mechanical Engineers A, volume 21, issue 11, 1997, Pages 1844~1851
DOI : 10.22634/KSME-A.19126.96.36.1994
Displacement fields and interface stresses are obtained by modifying the potential energy functional with a penalty function which enforces the continuity of stresses at the interface of two-materials. Based on the displacement field and the interface stresses, a new methodology to generate a continuous stress field over the entire domain including the interface of the dissimilar materials has been proposed by combining the L
projection method of stress-smoothing and the Loubignac's iterative method of improving the displacement field. Stress analysis was carried out on two examples which are made of highly dissimilar materials. As a result of the analysis, it is found that the proposed method provides improved continuity of the stress field over the entire domain as well as predicting accurate nodal stresses at the interface. In contrast, the conventional displacement-based finite element method provides significant stress discontinuties at the interfaces. In addition, it was found that the total strain energy evaluated from the improved continuous stress field converge to the exact value as increasing the number of iterations in the proposed method.
A study on the development of an efficient subspace iteration method
Lee, Byeong-Chae ;
Transactions of the Korean Society of Mechanical Engineers A, volume 21, issue 11, 1997, Pages 1852~1861
DOI : 10.22634/KSME-A.19188.8.131.522
An enhanced subspace iteration algorithm has been developed to solve eigenvalue problems reliably and efficiently. Basic subspace iteration algorithm has been improved by eliminating recalculation of converged eigenvectors, using Krylov sequence as initial vectors and incorporating with shifting techniques. The number of iterations and computational time have been considerably reduced when compared with the original one, and reliability for catching copies of the multiple roots has been retained successfully. Further research would be required for mathematical justification of the present method.
Noncontact 3-dimensional measurement using He-Ne laser and CCD camera
Kim, Bong-chae ; Jeon, Byung-cheol ; Kim, Jae-do ;
Transactions of the Korean Society of Mechanical Engineers A, volume 21, issue 11, 1997, Pages 1862~1870
DOI : 10.22634/KSME-A.19184.108.40.2062
A fast and precise technique to measure 3-dimensional coordinates of an object is proposed. It is essential to take the 3-dimensional measurements of the object in design and inspection. Using this developed system a surface model of a complex shape can be constructed. 3-dimensional world coordinates are projected onto a camera plane by the perspective transformation, which plays an important role in this measurement system. According to the shape of the object two measuring methods are proposed. One is rotation of an object and the other is translation of measuring unit. Measuring speed depending on image processing time is obtained as 200 points per second. Measurement resolution i sexperimented by two parameters among others; the angle between the laser beam plane and the camera, and the distance between the camera and the object. As a result of these experiments, it was found that measurement resolution ranges from 0.3mm to 1.0mm. This constructed surface model could be used in manufacturing tools such as rapid prototyping machine.
Design of sensing element for 3-component load cell using parallel plate structure
Kim, Gap-Sun ; Kang, Dae-Im ; Jeong, Su-Yeon ; Joo, Jin-Won ;
Transactions of the Korean Society of Mechanical Engineers A, volume 21, issue 11, 1997, Pages 1871~1884
DOI : 10.22634/KSME-A.19220.127.116.111
This paper describes the design process of a 3-component load cell with a multiple parallel plate structure which may be used to measure transverse forces and twisting moment simultaneously. Also we have derived equations to predict the bending strains on the surface of the beams in the multiple parallel plate structure under transverse force or twisting moment. It reveals that the bending strains calculated from the derived equations are in good agreement with the results from finite element analysis and experiment. Also we have evaluated the rated output and interference error of each component, which can be efficiently used to design a 3-component load cell with a multiple parallel plate structure.
suspension dynamics of HDD for high track density
Kim, Chung-Joo ; Chun, Jeong-Il ; Byun, Yong-Kyu ; Ro, Kwang-Choon ; Chung, Chung-Choo ; Jeong, Tae-Gun ;
Transactions of the Korean Society of Mechanical Engineers A, volume 21, issue 11, 1997, Pages 1885~1895
DOI : 10.22634/KSME-A.1918.104.22.1685
As track density needs to increase to the order of 10, 000 tpi, the suspension has become a critical component in hard disk drives. One of the main obstacles to attain high track density is the structural resonances of the suspension in lateral direction. We investigate the suspension dynamics through the experimental modal analysis and the finite element method. An LDV (Laser Doppler Vibrometer) is employed to measure the response of the suspension which is excited by a shaker and an inpulse hammer for the free condition and the loaded condition, respectively. After comparing the experimental and numerical results, we study how the initial geometry of the bend region affects the suspension dynamics. It is found that the natural frequency of the sway mode decreases as the bend ratio and the bend angle increase. The shape of torsional mode changes as the mass of a slider increases, resulting in a local decrease in the natural frequency.
Micromechanical behavior of unidirectional composites under a transverse shear loading
Choi, Heung-Soap ; Achenbach, J.D. ;
Transactions of the Korean Society of Mechanical Engineers A, volume 21, issue 11, 1997, Pages 1896~1911
DOI : 10.22634/KSME-A.1922.214.171.1246
Effects of fiber-matrix interphases on the micro-and macro-mechanical behaviors of unidirectionally fiber-reinforced composites subjected to transverse shear loading at remote distance have been studied. The interphases between fibers and matrix have been modeled by the spring-layer which accounts for continuity of tractions, but allows radial and circumferential displacement jumps across the interphase that are linearly related to the normal and tangential tractions. Numerical calculations for basic cells of the composites have been carried out using the boundary element method. For an undamaged composite the micro-level stresses at the matrix side of the interphase and effective shear stiffness have been computed as functions of fiber volume ratio
and interphase stiffness k. Results are presented for various interphase stiffnesses from the perfect bonding to the case of total debonding. For a square array composite the results show that for a high interphase stiffness k>10, an increase of
increases the effective transverse shear modulus G over bar of the composite. For a relatively low interphase stiffness k<1, it is shwon that an increase of
slightly decreases the effective transverse shear modulus. For the perfect bonding case, G over bar for a hexagonal array composite is slightly larger than that for a square array composite. Also for a damaged composite partially debonded at the interphase, local stress fields and effective shear modulus are calculated and a decrease in G over bar has been observed.
Three-dimensional finite element analysis of hot square die extrusion by using split ALE method
Kang, Yeon-Sick ; Yang, Dong-Yol ;
Transactions of the Korean Society of Mechanical Engineers A, volume 21, issue 11, 1997, Pages 1912~1920
DOI : 10.22634/KSME-A.19126.96.36.1992
In the analysis of metal forming process, ALE(Arbitrary Lagrangian Eulerian) finite element methods have been increasingly used for the capability to control mesh independently from material flow. The methods can be divided into two groups i.e., coupled and split formulations. In the present work, the split ALE formulation is used for computational efficiency. A split ALE finite element method developed for rigid-viscoplastic materials and applied to the analysis of hot square die extrusion. Since thermal state greatly affects the product quality, an ALE scheme for temperature analysis is also presented. As computational examples, profile shapes as square and cross-like sections are chosen.
Design and evaluation of binocular type six-component load cell by using experimental technique
Kang, Dae-Im ; Kim, Gab-Sun ; Jeong, Su-Yeon ; Joo, Jin-Won ;
Transactions of the Korean Society of Mechanical Engineers A, volume 21, issue 11, 1997, Pages 1921~1930
DOI : 10.22634/KSME-A.19188.8.131.521
This paper presents the effective technique to design a six-axis load cell by using experimental design with an orthogonal array. A binocular structure is used as a basic sensing element for a load cell instead of the parallel plate structure. The finite element method is adopted to obtain strain distributions of the sensing element, and by doing the analysis of variances, its results are utilized in determining the factor which is more influential to the output strain. Calibration test results show that the developed six-axis loa cell with the maximum capacities of 196 N in forces and 19.6 N. m in moments is evaluated to be useful with the coupling error less than 2.5%.
Post-buckling analysis using a load-displacement control
Gwon, Yeong-Du ; Im, Beom-Su ; Park, Cheol ; Choe, Jin-Min ;
Transactions of the Korean Society of Mechanical Engineers A, volume 21, issue 11, 1997, Pages 1931~1942
DOI : 10.22634/KSME-A.19184.108.40.2061
A new load/displacement parameter method is developed for the cases that loads are applied to one or more points, and displacements of a structure are controlled at one or more points sinultaneously. The procedure exploits a generalized Riks method, which utilizes load/displacement parameters as scaling factors in order to analyze the post-buckling phenomena including snap-through or snap-back. A convergence characteristic is improved by employing new relaxation factors in incremental displacement parameter, particularly at the region where exhibits severe numerical instability. The improved performance is illustrated by means of numerical example.
The analysis of the shift transient characteristics for the Ravigneaux type automatic transmission
Kim, I.C ; Yi, S.J ;
Transactions of the Korean Society of Mechanical Engineers A, volume 21, issue 11, 1997, Pages 1943~1949
DOI : 10.22634/KSME-A.19220.127.116.113
In this paper, the analysis of the shift transient characteristics for the Ravigneaux type automatic transmission has been carried out using dynamic models of the automatic trnasmission. It is necessary to understand the overall system including multi-plate clutch, band brake, one way clutch, and planetary gears. The equations of motion are derived from the dynamic models of the automatic transmission. The GUI computer simulation program has been developed to analyze the shift transient characteristics of the vehicle equipped with the Ravigneaux type automatic transmission.
Optimum mesh size of the numerical analysis for structural vibration and noise prediction
Kim, Jeung-Tae ; Kang, Jun-Soo ;
Transactions of the Korean Society of Mechanical Engineers A, volume 21, issue 11, 1997, Pages 1950~1956
DOI : 10.22634/KSME-A.1918.104.22.1680
An engineering goal in vibration and noise professionals is to develope quiet machines at the preliminary design stage, and various numerical techniques such as FEM, SEA or BEM are one of the schemes toward the goal. In this paper, the research has been focused on the sensitivity effect of mesh sizes for FEM application so that the optimum size of the mesh that leads to engineering solution within acceptable computing time could be generated. In order to evaluate the mesh size effect, three important parameters have been examined : natural frequencies, number of modes and driving point mobility. First, several lower modes including the fundamental frequency of a 2-D plate structure have been calculated as mesh size changes. Since theoretical values of natural frequencies for a simple structure are known, the deviation between the numerical and theoretical values is obtained as a function of mesh size. The result shows that the error is no longer decreased if the mesh size becomes a quarter wavelength or smaller than that. Second, the mesh size effect is also investigated for the number of modes. For the frequency band up to 1.4 kHz, the structure should have 38 modes in total. As the mesh size reaches to the quarter wavelength, the total count in modes approaches to the same values. Third, a mobility function at the driving point is compared between SEA and FEM result. In SEA application, the mobility function is determined by the modal density and the mass of the structure. It is independent of excitation frequencies. When the mobility function is calculated from a wavelength to one-tenth of it, the mobility becomes constant if the mesh becomes a quarter wavelength or smaller. We can conclude that dynamic parameters, such as eigenvalues, mode count, and mobility function, can be correctly estimated, while saving the computing burden, if a quarter wavelength (.lambda./4) mesh is used. Therefore, (.lambda./4) mesh is recommended in structural vibration analysis.
A study on the characteristics of torsional vibration for 4*4 vehicles drivetrain
Choi, Eun-O ; Kim, Hei-Song ; Hong, Dong-Pyo ;
Transactions of the Korean Society of Mechanical Engineers A, volume 21, issue 11, 1997, Pages 1957~1964
DOI : 10.22634/KSME-A.1922.214.171.1247
Torsional vibration is to vibrate strongly when the ignition pulses of the engine is excited with natural frequency of driveline. Torsional vibration like this can cause various noises as rattle and booming. For this study multi-degree of freedom analysis model of torsional vibration, which is combined with mass moment of inertia and torsional spring, was developed toward two wheel drive, four wheel drive and torsional vibration characteristics were compared and analyzed through the natural frequences, mode shapes and frequency response characteristics which was acquired by the simulation of it. The pertinence of that model was proved by the field test and the outcome of the simulations coincided with feeling test. Therefore, four wheel drive simulation model is considered to be useful thing for reducing torsional vibration of driveline and developing full-time four wheel drive vehicles.
Effects of defence holes on notched strength and fatigue properties in plain woven composite
Kim, Jung-Kyu ; Shim, Dong-Suk ; Han, Min-Gyu ;
Transactions of the Korean Society of Mechanical Engineers A, volume 21, issue 11, 1997, Pages 1965~1971
DOI : 10.22634/KSME-A.19126.96.36.1995
The relaxation of stress concentration in notched members can be very significant in the improvement of notched strength and fatigue life. This paper investigated the relationship of stress concentration factor, and notched strength and fatigue life. The stress concentration factors were analyzed by FEM. Uniaxial tensile and fatigue tests were carried on plain woven composite specimens which have a main hole and two defence holes. From experimental results, the notched strength and the fatigue limit increased up to about 50% and 30% respectively due to the reduction in stress concentration. The fatigue lives predicted by Juvinall's approach were underestimated than test results and this trends were remarkable as nothed strength increased. This is because of the underestimation of a coefficient. A in S-N curve (.sigma.
). Therefore, considering notched strength the coefficient A was modified. The fatigue lives by this process were agreed well with the experimental results.sults.