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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 27, Issue 12 - Dec 2003
Volume 27, Issue 11 - Nov 2003
Volume 27, Issue 10 - Oct 2003
Volume 27, Issue 9 - Sep 2003
Volume 27, Issue 8 - Aug 2003
Volume 27, Issue 7 - Jul 2003
Volume 27, Issue 6 - Jun 2003
Volume 27, Issue 5 - May 2003
Volume 27, Issue 4 - Apr 2003
Volume 27, Issue 3 - Mar 2003
Volume 27, Issue 2 - Feb 2003
Volume 27, Issue 1 - Jan 2003
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3-D Finite Element Mesh Generation of Tires Considering Detailed Tread Pattern
Cho, Jin-Rae ; Kim, Ki-Whan ; Hong, Sang-Il ; Kim, Nam-Jeon ; Kim, Kee-Woon ;
Transactions of the Korean Society of Mechanical Engineers A, volume 27, issue 10, 2003, Pages 1615~1622
DOI : 10.3795/KSME-A.2003.27.10.1615
Being contacted directly with. ground, the tire tread part is in shape of complex patterns of variable ASDs(anti-skid depth) to satisfy various tire performances. However, owing to the painstaking mesh generation job and the extremely long CPU-time, conventional 3-D tire analyses have been performed by either neglecting tread pattern or modeling circumferential grooves only. As a result, such simplified analysis models lead to considerably poor numerical expectations. This paper addresses the development of a 3-D tire mesh generation considering the detailed tread pattern and shows that the contact pressure and frictional energy distribution of tires considering the detailed pattern become better than those by the simplified tire model.
Theoretical Temperature Analysis for 88316 Piping Weld
Kim, Jong-Sung ; Lee, Seung-Gun ; Jin, Tae-Eun ; Kwon, Soon-Man ;
Transactions of the Korean Society of Mechanical Engineers A, volume 27, issue 10, 2003, Pages 1623~1629
DOI : 10.3795/KSME-A.2003.27.10.1623
In this paper, the arc beam is considered as a moving disc heat source with a pseudo-Gaussian distribution of heat intensity. The solution for temperature distribution on welds is derived by using the image heat source method and the superposition method. It is general solution in that it can determine the temperature-rise distribution in and around the arc beam heat source, as well as the width and depth of the melt pool (MP) and the heat-affected zone (HAZ) in welding short lengths, where quasi-stationary conditions may not have been established. As a comparative study, the results of this analytical approach has been compared with that of the finite-element modeling. As a result, The theoretical analysis presented here has shown good consistency and is more time/cost-effective method compared with FEM.
Deformation and Fracture Behavior of Structural Bulk Amorphous Metal under Quasi-Static Compressive Loading
Shin, Hyung-Seop ; Ko, Dong-Kyun ; Oh, Sang-Yeob ;
Transactions of the Korean Society of Mechanical Engineers A, volume 27, issue 10, 2003, Pages 1630~1635
DOI : 10.3795/KSME-A.2003.27.10.1630
The deformation and fracture behaviors of a bulk amorphous metal, Zr-based one (Zr
22.5/: Vitreloy), were investigated over a strain rate range (7x10
-1/). The uniaxial compression test and the indentation test using 3mm-diameter WC balls were carried out under quasi-static loading conditions. As a result, at the uniaxial compressive state, the fracture stress of the material was very high (～1,700MPa) and the elastic strain limit was about 2%. The fracture strength showed a strain rate independent behavior up to 4 s
-1/. Using indentation tests, the plastic deformation behavior of the Zr-based BAM up to a large strain value of 15% could be achieved, even though it was the deformation under locally constrained condition. The Meyer hardness of the Zr-based BAM measured by static indentation tests was about 5 GPa and it revealed negligible strain hardening behavior. At indented sites, the plastic indentation occurred forming a crater and well-developed multiple shear bands were generated around it along the direction of 45 degree when the indentation load exceeded 7kN. With increasing indentation load, shear bands became dense. The fracture surface of the specimen after uniaxial compressive tests showed vein-like pattern, typical morphology of many BAMs.
Estimation of Bolted Joint Strength of Flat Plate of Glass-Mat Reinforced Thermoplastics
Kang, Wan-Seok ; Min, Ji-Hyun ; Lee, Jae-Wook ; Im, Yong-Taek ;
Transactions of the Korean Society of Mechanical Engineers A, volume 27, issue 10, 2003, Pages 1636~1643
DOI : 10.3795/KSME-A.2003.27.10.1636
In this study, bolted joint made of Glass-Mat Reinforced Thermoplastics (GMT) specimen was under tensile loading to investigate the relation between joint strength and glass-fiber weight fraction of the flat plate specimen. The effect of molding conditions such as the initial size of a GMT charge and molding temperatures was investigated under plane strain condition. In consideration of the specimen geometry, minimum end distance and width of the specimen to induce the bearing fracture mode of the bolted joint were determined. And finally, the effect of the outer diameter of washer and clamping pressure on joint strength was also investigated. Since joint strength is dependent on the local glass-fiber weight fraction, experimentally measured strength was modified, considering its irregular values of the specimen molded under various processing conditions in order to obtain a reasonable correlation between the two.
Development of Design System for EPS Cushioning Package of Monitor Using Axiomatic Design
Yi, Jeong-Wook ; Ha, Dae-Yul ; Lee, Sang-Woo ; Lim, Jae-Moon ; Park, Gyung-Jin ;
Transactions of the Korean Society of Mechanical Engineers A, volume 27, issue 10, 2003, Pages 1644~1652
DOI : 10.3795/KSME-A.2003.27.10.1644
The monitor product is packed by cushioning materials because the monitor can be broken during transportation. However, the addition of the cushioning material increased the volume of the product. Therefore, it is required that the usage of cushioning material be minimized. In practice, design engineers have followed the ad hoc design with experiences of predecessors. Automation of the design process is very important for the reduction of engineering cost, and can be achieved by an excellent design process and software development. According to Axiomatic design, a design flow is defined and a software system is developed for automated design. At first, a basic model is defined. A user can modify the model from menus and design is carried out according to the input from the user. Finite element models are automatically generated based on the design. A nonlinear finite element analysis program called LS/DYNA3D is linked for the impact analysis. The process of Design of Experiments using orthogonal array is installed to minimize the maximum acceleration in drop test. Therefore, a new design can be proposed by the system. The program is designed according to the Independence Axiom of Axiomatic design. FRs and DPs of the software system are defined and decomposed by zigzagging process. Independent modules can be generated by analysis of the full design matrix and each module is coded as class in Object Oriented Programming (OOP). Design results are discussed.
Spectral Element Analysis for the Dynamic Characteristics of an Axially Moving Timoshenko Beam
Kim, Joo-Hong ; Oh, Hyung-Mi ; Lee, U-Sik ;
Transactions of the Korean Society of Mechanical Engineers A, volume 27, issue 10, 2003, Pages 1653~1660
DOI : 10.3795/KSME-A.2003.27.10.1653
The use of frequency-dependent spectral element matrix (or exact dynamic stiffness matrix) in structural dynamics is known to provide very accurate solutions, while reducing the number of degrees-of-freedom to resolve the computational and cost problems. Thus, in the present paper, the spectral element model is formulated for the axially moving Timoshenko beam under a uniform axial tension. The high accuracy of the present spectral element is then verified by comparing its solutions with the conventional finite element solutions and exact analytical solutions. The effects of the moving speed and axial tension on the vibration characteristics, the dispersion relation, and the stability of a moving Timoshenko beam are investigated, analytically and numerically.
A Study on Efficient Generation of Beam-Mass Model for Simplification of the Crankshaft in the Large Marine Engine
Suh, Myung-Won ; Shim, Mun-Bo ; Kim, Ki-Hyun ; Kim, Kyu-Hee ;
Transactions of the Korean Society of Mechanical Engineers A, volume 27, issue 10, 2003, Pages 1661~1666
DOI : 10.3795/KSME-A.2003.27.10.1661
The purpose of this study is to develop the simplified model of the crankshaft in the large marine engine for dynamic analysis. Because the actual engine system is under complex dynamic loading condition and it has multi-cylinder, the dynamic analysis is purchased at a high computation cost. In spite of this burden, the dynamic analysis must be perfonned to assure structural integrity of operating marine engine. Therefore, simplification of the analytic model is necessary for dynamic analysis. Beam-mass model, which is generated with the section property method, is the model simplified effectively. Section property method can provide desired section information by optimization technique. By applying beam-mass model to the crankshaft in the large marine engine, the usefulness of the proposed method was proven.
Calculation of Sidewall Lateral Stiffness of a Radial Tire Using Material Properties of Rubber Compounds
Kim, Yong-Woo ; Kim, Jong-Guk ;
Transactions of the Korean Society of Mechanical Engineers A, volume 27, issue 10, 2003, Pages 1667~1675
DOI : 10.3795/KSME-A.2003.27.10.1667
This paper has considered the calculation of lateral stiffness of radial tire's sidewall, which consists of cord stiffness and rubber sheet stiffness, by using the material constants of rubber compounds of tire. We have suggested and illustrated how to calculate the rubber sheet lateral stiffness by considering the following aspects. First, the rubber sheet consists of various kinds of rubber compounds with different thickness along the sidewall in the radial direction. Secondly, equivalent Young's modulus of the rubber sheet can be calculated by using available experimental data of rubber compounds. The present method enables us to divide the calculation domain as many as we want, which can reduce numerical error in the calculation of geometrical and mechanical properties. We have illustrated the calculation by using the data of the radial tire for passenger car of P205/60R15.
The Influence of Temperature on Low Cycle Fatigue Behavior of Prior Cold Worked 316L Stainless Steel (II) - Life Prediction and Failure Mechanism -
Hong, Seong-Gu ; Yoon, Sam-Son ; Lee, Soon-Bok ;
Transactions of the Korean Society of Mechanical Engineers A, volume 27, issue 10, 2003, Pages 1676~1685
DOI : 10.3795/KSME-A.2003.27.10.1676
Tensile and low cycle fatigue tests on prior cold worked 3l6L stainless steel were carried out at various temperatures ftom room temperature to 650
. Fatigue resistance was decreased with increasing temperature and decreasing strain rate. Cyclic plastic deformation, creep, oxidation and interactions with each other are thought to be responsible for the reduction in fatigue resistance. Currently favored life prediction models were examined and it was found that it is important to select a proper life prediction parameter since stress-strain relation strongly depends on temperature. A phenomenological life prediction model was proposed to account for the influence of temperature on fatigue life and assessed by comparing with experimental result. LCF failure mechanism was investigated by observing fracture surfaces of LCF failed specimens with SEM.
Bending Behaviors of Stainless Steel Tube Filled with Al5Si4Cu4Mg Closed Cell Aluminum Alloy Foam
Kim, Am-Kee ; Lee, Hyo-Jin ; Cho, Seong-Seock ;
Transactions of the Korean Society of Mechanical Engineers A, volume 27, issue 10, 2003, Pages 1686~1694
DOI : 10.3795/KSME-A.2003.27.10.1686
The foam-filled tube beams can be used for the front rail and firewall structures to absorb impact energy during frontal or side collision of vehicles. In the case of side collision where bending is involved in the crushing mechanism, the foam filler would be effective in maintaining progressive crushing of the thin-walled structures so that much impact energy could be absorbed. In this study, bending behaviors of the closed-cell-aluminum-alloy-foam-filled stainless steel tube were investigated. The various foam-filled specimens including piecewise fillers were prepared and tested. The aluminum-alloy-foam filling offered the significant increase of bending resistance. Their suppression of the inward fold formation at the compression flange as well as the multiple propagating folds led to the increase of load carrying capacity of specimens. Moreover, the piecewise foams would provide the easier way to fill the thin-walled shell structures without the drawback of strength.
Fatigue Crack Initiation around a Hole under Out-of-phase Biaxial Loading
Huh, Yong-Hak ; Park, Pi-Lip ; Kim, Dong-Jin ;
Transactions of the Korean Society of Mechanical Engineers A, volume 27, issue 10, 2003, Pages 1695~1702
DOI : 10.3795/KSME-A.2003.27.10.1695
Fatigue crack initiation around a hole subjected to biaxial fatigue loads with a phase difference was investigated. Axial and torsional biaxial fatigue loads with different phase differences and biaxiality of 1/√3 were applied to thin-walled tubular specimens. Five phase differences of 0, 45, 90, 145 and 180 degrees were selected. Directions of the fatigue crack initiation around the hole were found to approach to the circumferential direction of the specimen with increment of the phase difference for fatigue tests with phase differences less than 90
. Whereas directions for tests with phase differences greater than 90
got away from the circumferential direction and those were symmetric to the directions for tests with phase difference less than 90. . Furthermore, it was shown that the fatigue initiation life decreased with increment of phase difference for fatigue tests with phase differences less than 90
, but it increased for tests with phase difference greater than 90
. The crack initiation direction can be successfully explained by using the direction of the maximum tangential stress range obtained around the hole and at far-field.
Finite Element Analysis for Fatigue Crack Closure Behavior Using Reversed Plastic Zone Size
Choi, Hyeon-Chang ;
Transactions of the Korean Society of Mechanical Engineers A, volume 27, issue 10, 2003, Pages 1703~1711
DOI : 10.3795/KSME-A.2003.27.10.1703
An elastic-plastic finite element analysis is performed to investigate detailed closure behaviour of fatigue cracks in residual stress fields and the numerical results are compared with experimental results. The finite element analysis performed under plane stress using contact elements can predict fatigue crack closure behaviour. The mesh of constant element size along crack surface can not predict the opening level of fatigue crack. Specially, the mesh of element sizes depending upon the reversed plastic zone size included the effect of crack opening point can precisely predict the opening level. By using the concept of the mesh of element sizes depending upon the reversed plastic zone size included the effect of crack opening point, the opening level of fatigue crack can be determined very well.
Acceleration Feedforward Control in Active Magnetic Bearing System Subject to Base Motion by Filtered-x LMS Algorithm
Kang, Min-Sig ;
Transactions of the Korean Society of Mechanical Engineers A, volume 27, issue 10, 2003, Pages 1712~1719
DOI : 10.3795/KSME-A.2003.27.10.1712
This paper concerns on application of active magnetic bearing(AMB) system to levitate the elevation axis of an electro-optical sight mounted on moving vehicles. In such a system, it is desirable to retain the elevation axis within the predetermined air-gap while the vehicle is moving. An optimal base acceleration feedforward control is proposed to reduce the base motion response. In the consideration of the uncertainty of the system model, a filtered-x least-mean-square(FXLMS) algorithm is used to estimate the frequency response function of the feedforward control which cancels base motions. The frequency response function is fitted to an optimal feedforward control. Experimental results demonstrate that the proposed control reduces the air-gap deviation to 27.7% that by feedback control alone.
Measurement of the Dynamic Transmission Error of Helical Gears by the Accelerometers
Kim, Dae-Sik ; Cho, Do-Hyun ; Park, Chan-Il ; Choi, Deo-Kki ; Park, Chan-Gook ;
Transactions of the Korean Society of Mechanical Engineers A, volume 27, issue 10, 2003, Pages 1720~1727
DOI : 10.3795/KSME-A.2003.27.10.1720
The object of this work is to develop the measurement method of the transmission error of the helical gears. For this purpose, experimental set up is designed by 3D CAD software. It consists of the motor, inverter, powdered brake equipment, torque sensor and helical gearbox. In this study, tangential linear accelerometers were used as the methods for the transmission error measurement. the acceleration signals are transmitted to the signal conditioners through the slip rings and the transmission errors are obtained by a specially designed circuit board. The transmission errors are analyzed in the frequency domain. As a result, The periodicity of the transmission error is confirmed in the mesh frequency and its harmonics. The magnitude of harmonic components is very dependent on the natural frequencies of the gear system. It usually increases with the rotational speed. However, it does not always increase with torque.
Design of a Vertical Lathe for the Improved Stability at High Speed Machining
Ro, Seung-Hoon ; Shon, Jae-Yul ; Ro, Kyung-Ho ; Kim, Sung-Chul ;
Transactions of the Korean Society of Mechanical Engineers A, volume 27, issue 10, 2003, Pages 1728~1737
DOI : 10.3795/KSME-A.2003.27.10.1728
The vertical lathe is a very popular machine tool in modem manufacturing industries because of its small area of installation. The small installation area is highly desirable for the flexibility improvement of the manufacturing systems such as FMS, CIM, and IMS. The vertical lathe, however, has much taller height compared to the traditional horizontal lathe, and consequently more severe vibrations. In this study, the structure of a vertical lathe is analyzed to investigate the dynamic properties and further to establish some ideas of the design alteration for the improved dynamic stability even at the higher operating speed. The simulation model is implemented to apply those design alterations for the optimization. The result of this study is not only prosperous but also ready to be applied to the optimum design of various machine tool structures for the improved stability.
SPH Parameters for Analysis of Penetration Phenomenon at Hypervelocity Impact of Meteorite
Lee, Sung-Soo ; Seo, Song-Won ; Min, Oak-Key ;
Transactions of the Korean Society of Mechanical Engineers A, volume 27, issue 10, 2003, Pages 1738~1747
DOI : 10.3795/KSME-A.2003.27.10.1738
Smoothed Particle Hydrodynamics (SPH), a pure Lagrangian numerical method, is applied to analysis of penetration phenomenon of bumper plate which is installed outside of spacecraft hull to protect the spacecraft against hypervelocity meteorite impact. Effects of SPH parameters, such as artificial viscosities, smoothing lengths, numbers of particles and time increments, are analysed by comparing the SPH simulation results with experimental ones with regard to subsequent formation of debris cloud. An optimum range of parameter values is determined by error analysis and various SPH numerical results are compared with experiments.
A Study on the Forming of Fine Gear Housing using Rapid Prototyping
Lee, Seung-Soo ; Kim, Min-Ju ; Park, Jeung-Bo ; Jeon, Eon-Chan ;
Transactions of the Korean Society of Mechanical Engineers A, volume 27, issue 10, 2003, Pages 1748~1753
DOI : 10.3795/KSME-A.2003.27.10.1748
This paper describes the forming of fine gear housing using RP system. In order to apply 3D model formed through CAD software to RP system, it is necessary of transforming 3D model into STL file format. Besides, when the same shape is formed repetitively, we must solve the program that the shape accuracy of prototype is irregular. Therefore, we will make an experiment on influence of 3D model, file transformation and prototype on facetres, AutoCAD system value. On the basis of experimental result, we will develop an automatic file transformation program for RP. In the final process, we will manufacture on a better prototype according to the experiment result of fine gear housing.
Three Dimensional Molecular Dynamics Simulation of Nano-Lithography Process for Fabrication of Nanocomponents in Micro Electro Mechanical Systems (MEMS) Applications
Kim, Young-Suk ; Lee, Seung-Sub ; Na, Kyoung-Hoan ; Son, Hyun-Sung ; Kim, Jin ;
Transactions of the Korean Society of Mechanical Engineers A, volume 27, issue 10, 2003, Pages 1754~1761
DOI : 10.3795/KSME-A.2003.27.10.1754
The atomic force microscopy (AFM) based lithographic technique has been used directly to machine material surface and fabricate nano components in MEMS (micro electro mechanical system). In this paper, three-dimensional molecular dynamics (MD) simulations have been conducted to evaluate the characteristic of deformation process at atomistic scale for nano-lithography process. Effects of specific combinations of crystal orientations and cutting directions on the nature of atomistic deformation were investigated. The interatomic force between diamond tool and workpiece of copper material was assumed to be derived from the Morse potential function. The variation of tool geometry and cutting depth was also evaluated and the effect on machinability was investigated. The result of the simulation shows that crystal plane and cutting direction significantly influenced the variation of the cutting forces and the nature of deformation ahead of the tool as well as the surface deformation of the machined surface.
Automatic Quadrilateral Mesh Generation Using Updated Paving Technique in Various Two Dimensional Objects
Yang, Hyun-Ik ; Kim, Myung-Han ;
Transactions of the Korean Society of Mechanical Engineers A, volume 27, issue 10, 2003, Pages 1762~1771
DOI : 10.3795/KSME-A.2003.27.10.1762
In part of mechanical design analysis, quadrilateral mesh is usually used because it provides less approximate errors than triangular mesh. Over the decades, Paving method has been considered as the most robust method among existing automatic quadrilateral element mesh generation methods. However, it also has some problems such as unpredictable node projection and relatively large element generation. In this study, the aforementioned problems are corrected by updating the Paving method. In so doing, a part of node projection process is modified by classifying nodes based on the interior angles. The closure check process is also modified by adding more nodes while generating elements. The result shows well shaped element distribution in the final mesh without any aforementioned problems.
Design, Fabrication, and Performance Evaluation of a Sensorized Superelastic Alloy Microrobot Gripper
Kim, Deok-Ho ; Kim, Byung-Kyu ; Kang, Hyun-Jae ; Kim, Sang-Min ;
Transactions of the Korean Society of Mechanical Engineers A, volume 27, issue 10, 2003, Pages 1772~1777
DOI : 10.3795/KSME-A.2003.27.10.1772
This paper presents the design, fabrication, and calibration of a piezoelectric polymer-based sensorized microgripper. Electro discharge machining technology is employed to fabricate super-elastic alloy based micro gripper. It is tested to present improvement of mechanical performance. For integration of force sensor on the micro gripper, the sensor design based on the piezoelectric polymer PVDF film and fabrication process are presented. The calibration and performance test of force sensor integrated micro gripper are experimentally carried out. The force sensor integrated micro gripper is applied to perform fme alignment tasks of micro opto-electrical components. It successfully supplies force feedback to the operator through the haptic device and plays a main role in preventing damage of assembly parts by adjusting the teaching command.
Vibration Control of Plates Using Resonant Shunted Piezoelectric Material
Kim, Young-Ho ; Park, Chul-Hue ; Park, Hyun-Chul ;
Transactions of the Korean Society of Mechanical Engineers A, volume 27, issue 10, 2003, Pages 1778~1784
DOI : 10.3795/KSME-A.2003.27.10.1778
Vibration control of plates with a passive electrical damper is presented in this paper. This electrical absorber, piezoelectric patches connected with a resistor and an inductor in series, is analogous to the damped mechanical vibration absorber. For estimating the effectiveness of piezoelectric absorber, the governing equations of motion are derived using a classical laminate plate theory and Hamilton principle. The developed theoretical analysis is validated experimentally for a simply-supported aluminum plate in order to demonstrate the performance of passive electrical damper. The result shows that the vibration amplitude is reduced about 14dB for the targeted first vibration mode.
A Comparative Study of Methods to Predict Fatigue Crack Growth under Random Loading
Lee, Hak-Joo ; Kang, Jae-Youn ; Choi, Byung-Ik ; Kim, Chung-Youb ;
Transactions of the Korean Society of Mechanical Engineers A, volume 27, issue 10, 2003, Pages 1785~1792
DOI : 10.3795/KSME-A.2003.27.10.1785
Methods to predict fatigue crack growth are compared in a quantitative manner for crack growth test data of 2024- T351 aluninum alloy under narrow and wide band random loading. In order to account for the effect of load ratio, crack closure model, Hater's equation and NASGRO's equation have been employed. Load interaction effect under random loading has been considered by crack closure model, Willenborg's model and Wheeler's model. The prediction method using the measured crack opening results provides the best result among the prediction methods discussed for narrow and wide band random loading data.
Optimal Design of a Multi-Layered Plate Structure Under High-Velocity Impact
Yoon, Deok-Hyun ; Park, Myung-Soo ; Yoo, Jeong-Hoon ; Chung, Dong-Teak ;
Transactions of the Korean Society of Mechanical Engineers A, volume 27, issue 10, 2003, Pages 1793~1799
DOI : 10.3795/KSME-A.2003.27.10.1793
An optimal design of a multi-layered plate structure to endure high-velocity impact has been suggested by using size optimization after numerical simulations. The NET2D, a Lagrangian explicit time-integration finite element code for analyzing high-velocity impact, was used to find the parameters for the optimization. Three different materials such as mild steel, aluminum for a multi-layered plate structure and die steel for the pellet, were assumed. In order to consider the effects of strain rate hardening, strain hardening and thermal softening, Johnson-Cook model and Phenomenological Material Model were used as constitutive models for the simulation. It was carried out with several different gaps and thickness of layers to figure out the trend in terms of those parameters' changes under the constraint, which is against complete penetration. Also, the measuring domain has been shrunk with several elements to reduce the analyzing time. The response surface method based on the design of experiments was used as optimization algorithms. The optimized thickness of each layer in which perforation does not occur has been obtained at a constant velocity and a designated total thickness. The result is quite acceptable satisfying both the minimized deformation energy and the weight criteria. Furthermore, a conceptual idea for topology optimization was suggested for the future work.
Electrical Conductivity of Dielectric on WEDM Characteristics
Kim, Chang-Ho ; Yeo, Hong-Tae ;
Transactions of the Korean Society of Mechanical Engineers A, volume 27, issue 10, 2003, Pages 1800~1808
DOI : 10.3795/KSME-A.2003.27.10.1800
This work deals with the electrical conductivity of dielectric on output parameters such as metal removal rate and surface roughness value of a carbon steel(SM25C) and sintered carbides cut by wire-electrical discharge machining(W-EDM). Dielectric has several functions like insulation, ionization, cooling, the removal of waste metal particles. The presence of minute particles(gap debris) in spark gap contaminates and lowers the breakdown strength of dielectric. And it is considered that too much debris in spark gap is generally believed to be the cause of arcing. Experimental results show that increases of cobalt amount in carbides affects the metal removal rate and worsens the surface quality as a greater quantity of solidified metal deposits on the eroded surface. Lower electrical conductivity of the dielectric results in a lower metal removal rate because the gap between wire electrode and workpiece reduced. Especially, the surface characteristics of rough-cut workpiece and wire electrode were analyzed too. Debris were analyzed also through scanning electron microscopy(SEM) and surface roughness tester. Micro cracks and some of electrode material are found on the workpiece surface by energy dispersive spectrometer(EDS).