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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Transactions of the Korean Society of Mechanical Engineers A
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Journal DOI :
The Korean Society of Mechanical Engineers
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Volume & Issues
Volume 20, Issue 12 - Dec 1996
Volume 20, Issue 11 - Nov 1996
Volume 20, Issue 10 - Oct 1996
Volume 20, Issue 9 - Sep 1996
Volume 20, Issue 8 - Aug 1996
Volume 20, Issue 7 - Jul 1996
Volume 20, Issue 6 - Jun 1996
Volume 20, Issue 5 - May 1996
Volume 20, Issue 4 - Apr 1996
Volume 20, Issue 3 - Mar 1996
Volume 20, Issue 2 - Feb 1996
Volume 20, Issue 1 - Jan 1996
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Adaptive Analysis Methods for the Accuracy Control of Finite Element Solutions
Oh, H.S ; Lee, D.I ; Choi, J.H ; Lim, J.K ;
Transactions of the Korean Society of Mechanical Engineers A, volume 20, issue 7, 1996, Pages 2067~2077
DOI : 10.22634/KSME-A.19126.96.36.1997
In adaptive finite element analysis, r- and h-methods are generally used on the basis of a discretization error estimator. In this paper, an rh-method is proposed as a new adaptive method which can improve the adaptivity performance by using both of them. This suggested rh-method moves nodal coordinates of initially given model to adjust element discretization errors and thereafter performes the h-method tdo obtain the specified accuracy of finite element solutions. Numerical experiments for various plane problems were performed using 4-noded isoparametric quadrilateral elements. As a result, the rh-method has been shown to be an accurate and efficient adaptive analysis method to obtain as improved solution.
Incompatible Three-Dimensional Hexagonal Finite Elements by Multivariable Method
Ju, Sang-Baek ; Sin, Hyo-Chol ;
Transactions of the Korean Society of Mechanical Engineers A, volume 20, issue 7, 1996, Pages 2078~2086
DOI : 10.22634/KSME-A.19188.8.131.528
This paper introduces two three-dimensional eight-node hexagonal elements obtained by using multivariable variational mehtod. Both of them are based on the modified hellinger-reissner principle to employ incompatible displacements and assumed stresses of assumed strains. The internal functions of element are introduced to as element formulation through two different methods : the first one uses the functions determined directly from the element boundary condition of the incompatible displacements ; while the second, being a kind of B-bar mehtod, employs the modification technique of strain-displacement matrix to pass the patch test. The elements are evaluated on the selective problems of bending and material incompressibility with regular and distorted meshes. The results show that the new elements perform with good accuracy in both of deformation and stress calculation and they are insensitive to distorted geometry of element.
Strength Evaluation of Bonded Dissimilar Materials by Using Stress Singularity Factor
Jeong, Nam-Yong ; O, Bong-Taek ;
Transactions of the Korean Society of Mechanical Engineers A, volume 20, issue 7, 1996, Pages 2087~2096
DOI : 10.22634/KSME-A.19184.108.40.2067
Recentrly advantages in composite and light weight material techniques have led to the increased use of bonded dissimilar materials such as ceramics/metal bonded joints, IC package, brazing, coating and soldering in the various industries. It is required to analyze the evaluation method of fracture strength and design methodology of bonded joints in dissimilar materials. Stress singularity according to changes of scarf angles for bonded scarf joints in dissimilar materials was investigated by the boundary element method and static experiments. In this paper, effect of the stress singularity factors at the interface edges of scarf joints on various dissmilar materials combinations were investigated by analysis of its stress and stress singularity index using 2-dimensional elastic program of boundary element method. And the variations of stress singularity index by changes for Young's modulus ratios of materials and scarf angles were investigated. Also, it is found that stress singularities at bonded interface edges are disappeared for certain combination of scarf angle in a pair of bonded dissimilar materials. As the results, it is proposed that the strength evaluation by using stress singularity factors,
, considering stress singularity at the interface edges of bonded dissimilar materials, is very useful.
Analysis of Contact Singular Stresses with Relief Notch by Using Dynamic Photoelasticity(II)
Lee, Eok-Seop ; Hwang, Si-Won ; Nah, Gyeong-Chan ;
Transactions of the Korean Society of Mechanical Engineers A, volume 20, issue 7, 1996, Pages 2097~2107
DOI : 10.22634/KSME-A.19220.127.116.117
The dynamic photoelastic technique had been utilized to investigate the possibillity of relieving the large local singular stresses induced at the corner of a right- angle- indenter. The indenter compressed a semi-infinite body dynamically with an impact load applied on the top of the indenter. The effects of the geometric changes of the indenter in terms of the diameter (d) and the location (1) of the stress relieving notch on the behavior of the dynamic contact stresses were investigated. The influence of stress relieving notches positioned along the edge of the semi-infinite body on the dynamic contact stresses were also studied by changing the diameter (D) and the location (L) of the notch. A multi-speak-high speed camera with twelve sparks were used to take photographs of full field dynamic isochromatic fringe patterns. The contact singular stresses were found to be released significantly by the stress relief notches both along the indenter and the edge of the semi-infinite body. The optimal position and geometry of the stress relieving notches were obtained with the aid of limited experimental results.
Analysis on the Measured Natural Frequencies Due to the Structure-Exciter Interaction
Han, Sang-Bo ;
Transactions of the Korean Society of Mechanical Engineers A, volume 20, issue 7, 1996, Pages 2108~2117
DOI : 10.22634/KSME-A.1918.104.22.1688
The purpose of this paper is to investigate the influence of the exciter attached for the measurement of natural frequencies when extracting the frequency response functions of the test structure in experimental modal analysis. The procedure is first to model the attached exciter as an additional degree of freedom system and next to verify the suggested model by experimentally extracting the natural frequencies of the test structure with various values of exciter mass, stinger stiffness and attachment position of the exciter on the test structure. It is concluded that as additional degree of freedom system which includes the natural frequency of the exciter itself and axial stiffness of stinger should be considered to quantatively define the coupling effects of structure-exciter interaction on the measured natural frequencies. It is not the mass of the exciter itself but the coupling effect of the additional degree of freedom mass-spring system consisting of exciter body and armature coil that characterizes the natural frequency deviation. Therefore, when the natural frequency of this additional mass-spring system is outside of the test frequency range, the coupling effect of structure-exciter interaction can be minimized.
Process Development to Form Net-Shape Nosing Shells by the Backward Tracing Scheme of the Rigid-Plastic FEM and Its Experimental Confirmation
Kim, Sang-Hyeon ; Lee, Jin-Hui ; Im, Hak-Jin ;
Transactions of the Korean Society of Mechanical Engineers A, volume 20, issue 7, 1996, Pages 2118~2133
DOI : 10.22634/KSME-A.1922.214.171.1248
A preform is designed by the backward tracing scheme of the rigid-plastic finite element method(FEM) for net-shape shell nosing components without machining after forming. The current process of the shell nosing requires cost-consuming machining to produce final products. Here, the backward tracing scheme of the rigid-plastic FEM, a novel method for preform design of metal forming processes, derives a sound preform for net-shape shell nosing product. The current process is simulated by the rigid-plastic finite element analysis to check the metal flow involved in the forming with a trial preform and its modified preform. The two preforms are found to be inadequate for net-shape shell nosing product. The first application of the back ward tracing scheme derives a preform producing a not-shape shell nosing product. The first application of the backward tracing scheme derives a preform producing a net-shape product numerically, but it is difficult to be formed economically as a preform. Thus an improved preform is designed by the badkward tracing scheme, which is suitable for net-shape manufacturing of the shell nosing components in view of economy of production and forming characteristics of the product. The preform in the current process and a modified preform are confirmed by a series of experiments and the results give the same deformation with the numerical ones. Finally the newly designed preform by the FEM was experimentally proved to be adequate in obtaining net-shape products.
A Study on Thermal Shock Characteristics of Functionally Gradient Ceramic/Metal Composites
Song, Jun-Hee ; Lim, Jae-Kyoo ;
Transactions of the Korean Society of Mechanical Engineers A, volume 20, issue 7, 1996, Pages 2134~2140
DOI : 10.22634/KSME-A.19126.96.36.1994
This study was carried out to anlayze the heat-resistant characteristics of functionally gradient material(FGM) composed with ceramic and metal. The thermal fracture behavior of plasma-sprayed FGM and conventional coating material(NFGM) was exaimined by acoustic emession technique under heating and cooling. Furnace cooling and rapid cooling tests were used to examine the effect of temperature change under various conditions, respectively. At the high temperature above
, it was shown that FGM gives higher thermal resistance compared to NFGM by AE signal and fracture surface analysis.
Effects of Metallic Parameters for Distribution of Fatigue Crack Growth Rate - Dependence of Grain Size -;
Yoon, Han-Yong ;
Transactions of the Korean Society of Mechanical Engineers A, volume 20, issue 7, 1996, Pages 2141~2147
DOI : 10.22634/KSME-A.19188.8.131.521
The strength of material is scattered owing to the inhomogenity of microstructure, in spite of the same material. Therefore, in order to design the mechanical structure with the reliability engineering, it is important to grasp the statistical nature of material strength. In this paper, effects of grain sezes for the statistical nature of the fatigue crack growth was discussed. And the statistical nature of mechanical properties was compared with the statistical nature of the fatigue crack growth rate.
Thermoviscoelastic Stress Analysis by the Finite Element Method
Sim, Woo-JIn ; Park, In-Kyu ;
Transactions of the Korean Society of Mechanical Engineers A, volume 20, issue 7, 1996, Pages 2148~2158
DOI : 10.22634/KSME-A.19184.108.40.2068
Uncoupled, quasi-static and linear thermoviscoelastic problems are analyzed in time domain by the finite element approximation which is developed using the principle of virtual work and viscoelasticity matrices instead of shear and bulk relaxation functions as in usual formulations. The material is assumed to be isotropic, homegeneous and thermorheologically simple, which means that the temperature-time equivalence postulate is effective. The stress-strain laws are expressed by relaxation-type hereditary integrals. In spatial and time discritizations, isoparametric quadratic quadrilateral finite elements and linear time variations are adopted. For explicit derivations, the viscoelastic material is assumed to behave standard linear solid in shear and elastically in dilatation. Two-dimensional examples are solved under general temperature distributions T = T(x, t), and compared with other opproximate solutions to show the versatility of the presented analysis.
A Stochastic Analysis of Variation in Fatigue Crack Growth of 7075-T6 Al alloy
Kim, Jung-Kyu ; Shim, Dong-Suk ;
Transactions of the Korean Society of Mechanical Engineers A, volume 20, issue 7, 1996, Pages 2159~2166
DOI : 10.22634/KSME-A.19220.127.116.119
The stochastic properties of variation in fatigue crack growth are important in reliability and stability of structures. In this study,the stochastic model for the variation of fatigue crack growth rate was proposed in consideration of nonhomogeneity of materials. For this model, experiments were ocnducted on 7075-T6 aluminum alloy under the constant stress intensity factor range. The variation of fatigue crack growth rate was expressed by random variables Z and r based on the variation of material coefficients C and m in the paris-Erodogan's equation. The distribution of fatigue life with respect to the stress intensity factor range was evaluated by the stochastic Markov chain model based on the Paris-Erdogan's equation. The merit of proposed model is that only a small number of test are required to determine this this function, and fatigue crack growth life is easily predicted at the given stress intensity factor range.
Calculation of Stress Intensity Factors for a Thick Pipe Using Weight Function Method
Lee, Hyeong-Yeon ; Lee, Jae-Han ; Yoo, Bong ;
Transactions of the Korean Society of Mechanical Engineers A, volume 20, issue 7, 1996, Pages 2167~2173
DOI : 10.22634/KSME-A.1918.104.22.1687
An approximate weight function technique using the indirect boundary integral equation has been presented for the analysis of stress intensity foactors(SIFs) of a thick pipe. One-term boundary integral was introduced to represent the crack surface displacement field for the displacement based weight function technique. An explicit closed-form SIF solution applicable to symmetric cracked pipes without any modification of the solution including both circumferential and radial cracks has been derived. The necessary information in the analysis is two or three reference SIFs. In most cases the SIF solution were in good agreement with those available in the literature.
Bending Vibration of a Pretwisted Rotating Cantilever Beam
Park, Jung-Hun ; Yoo, Hong-Hee ;
Transactions of the Korean Society of Mechanical Engineers A, volume 20, issue 7, 1996, Pages 2174~2181
DOI : 10.22634/KSME-A.1922.214.171.1244
Equations of chordwise and flapwise bending motions of pretwisted rotatin cantilever beams are derived. The two motions are coupled to each other due to the pretwist angle of the beam cross section. As the angular speed, hub radius ratio, and pretwist angle vary, the vibration characteristics of the beam change. It is found that engenvalue loci veering phenomena and associated mode shape variations occur between two vibration modes due to the pretwist angle. The effect of the pretwist angle on the critical angular speed is also investigated.
High Temperature Densification Forming Process of Tool Steel Powder Compact
Choi, Hak-Hyeon ; Jeon, Yun-Cheol ; Kim, Gi-Tae ;
Transactions of the Korean Society of Mechanical Engineers A, volume 20, issue 7, 1996, Pages 2182~2195
DOI : 10.22634/KSME-A.19126.96.36.1992
Densification characteristics and behavior of tool steel powder compact during high temperature forming processes were investigated under pressure less sintering, sinter forging and hot isostastic pressing. In pressureless sintering, full density was obtained at a closely controlled temperature near the solidus of the material. Finite element calculations from constitutive model for densification by power law creep and diffusional flow were compared with experimental data. Agreements between theoretical calculations and experimental data were good in hot isostatic pressing but not as good in sinter forging.
An Experimental Study on the Damage Mechanism of Particle Impact in a Scratched Glass
Suh, Chang-Min ; Chung, Seong-Muk ; Lee, Mun-Hwan ;
Transactions of the Korean Society of Mechanical Engineers A, volume 20, issue 7, 1996, Pages 2196~2204
DOI : 10.22634/KSME-A.19188.8.131.526
The damage mechanism by the impact of steel ball on the soda-lime glass having a different surface roughness was investigated. An initiation and a propagation behavior of cracks formed by each impact velocity were quantitatively studied. A 4-point bending test was carried out to evaluate the remaining bending strength of a scratched soda-lime glass which impacted by the steel ball. As the surface roughness was increased, the shape of cracks became more irregular rather than those of the smooth specimens. The phenomenon of turning up in the wing of cone cracks occurred even at the lower velocity than the critical velocity caused the crushing. The threshold velocity of cracks initiation generally became lower than those of smooth specimen. An initiation and a propagation behavior of radial cracks had no relation with the direction of scratch on the surface. The remaning benidng strength of the scratched specimen according to impact velocity had no big difference compared with those of the smooth specimen.
Analysis on the Walking Volumes of a Hexapod System with General 3R Link Legs
Han, Gyu-Beom ; Yang, Chang-Il ; Baek, Yun-Su ;
Transactions of the Korean Society of Mechanical Engineers A, volume 20, issue 7, 1996, Pages 2205~2212
DOI : 10.22634/KSME-A.19184.108.40.2065
In order to move the body of a walking robot translationally, and step over the obstacles, the walking robot must have at least 3 degrees of freedom for each leg. Therefore each leg of the general walking robots can be composed of 3-link system with 3 revolute joints. In this paper, the colsed form of inverse kinimatic solutions is shown for this general 3R linkage. Moreover, in order to have efficient walking volume in rough terrain, the workspace of each log is obtained considering the twist angles and the offsets in D-H parameters. When we design a walking robot, the information of the walking volume is needed for planning desired trajectories of the feet effectively. Appropriate knowledge of the walking volume can also be used to maximize linear or angular velocity of minimize power of stress. However, since it is impossible to obrain the information of walking volume in 3-D space directly from the kinematic equations, the walking volume can be searched through the edge detection algorithm using the triangle tracer with closed from inverse kinematic solutions. In this study, we present the closed form inverse kinematic solutions for 3R linkage model, and the walking volume of 6 legged walking robot which is modeled after the darking bettle, Eleodes obscura sulcipennis, through the method of edge detection for an arbitrary 2 dimensional shape using triangle tracer.
Two-Axis Force Rransducer for Measuring Flange Reaction Forces in the Tape Transport of VCR
Joo, Jin-Won ; Kim, Seung-Hwan ; Kim, Gap-Soon ; Lee, Kyeong-Won ;
Transactions of the Korean Society of Mechanical Engineers A, volume 20, issue 7, 1996, Pages 2213~2222
DOI : 10.22634/KSME-A.19220.127.116.113
This paper presents the design process and evaluaation results of a two-axis force transducer for measuring flange reaction forces. A double-cantilever beam structure is used as a sensing element, and its optimal configuration is determined based on the derived strain equations to maximize the sensitivity and minimize the regid body displacements. To reduce the coupling errors between two-axis forces, strain distributions by finite elemetns analysis are utilized and the Wheaststone bridge cricuits composed of strain gages are built such that the output voltage should be zero, although strains of four strain gages are not zero. Calibration test shows that the two-azxis force transducer developed in this paper is useful in measuring flange reaction forces within the coupling error of 5.53%.
Free Vibration of the Composite Laminated Cylindrical Shells Stiffened with the Axial Stiffeners
Lee, Young-Shin ; Kim, Young-Wann ;
Transactions of the Korean Society of Mechanical Engineers A, volume 20, issue 7, 1996, Pages 2223~2233
DOI : 10.22634/KSME-A.1918.104.22.1683
The analytical solutions for the free vibration of cross-ply laminated composite cyllindrical shell with axial stiffeners(stringers) are presented usint the energy method. The stiffeners are taken to be smeared over the surface of shell with the smeared stffener theory. The effect of the parameters such as the stacking sequences, the shell thichness, the shell radius-to stringer depth ratio, the stringer depth-to width ratio, the shell length-to radius ratio are studied. By comparison with the previously published experimental results and the analytical results for the stiffened isotropic cylindrical shell and the unstiffened orthotropic composite laminated cylindrical shell, it is shown that natural frequencies can be determined with adequate accuracy.
A Study on Fatigue Behavior Considering Effects of Redistributing Tensile Residual Stress and Crack Closure in SS330 Weldment
Lee, Yong-Bok ; Jeong, Jin-Seong ; Jo, Nam-Ik ;
Transactions of the Korean Society of Mechanical Engineers A, volume 20, issue 7, 1996, Pages 2234~2245
DOI : 10.22634/KSME-A.1922.214.171.1244
In this study residual stress in weldment was considered about the effect on the fatigue propagation and about the effect of redistribution of residual stress. Then, fatigue tests were conducted by the center notched specimens machined with welded plate. The residual stress and its redistribution after the crack growth were measured by the magnetizing stress indicator and hole-drilling method. Fatigue crack propagation was estimated by the specimens having residual stress redistributed after the cracks growth and having the effects of crack closure. Crack growth rates were predicted and compared with experimental results. It had been found that the predicted crack propagation rates have a good agreement with experimental results when the redistribution of residual stress was considerd.
Sensitivity Analysis of Material and Process Variables Affecting on the Stamping Formability
Kim, Youngsuk ; Park, KeeChul ;
Transactions of the Korean Society of Mechanical Engineers A, volume 20, issue 7, 1996, Pages 2246~2256
DOI : 10.22634/KSME-A.19126.96.36.1996
To investigate the effect of material and precess variables on stamping formability of sheet materials, simulations for the cup drawing and the Yoshida buckling test were carried out using ABAQUS, commercial nonlinear finite element analysis code. The various factor effects on stamping formability of sheet materials were analyzed by the designed process according to Taguch's orthogonal array experiment. Cup drawing simulation showed that local neckling was very sensitive to plastic anisotropy parameter of sheet material and friction coefficient between sheet and tool interface. Simulations for the Yoshida buckling test have clarified that buckling behaviour of sheet material was mostly susceptible to yield stress and sheet thickness mostly. However, plastic anisotropy parameter and strain hardening coefficient affect moderately buckling behaviour of steel sheets after the buckling initiation.
A Study on the Improvement of Prediction Accuracy for Rolling Force in Continuous Cold Rolling Mill
Song, Gil-Ho ; Park, Hae-Doo ; Kim, Shin-Il ;
Transactions of the Korean Society of Mechanical Engineers A, volume 20, issue 7, 1996, Pages 2257~2265
DOI : 10.22634/KSME-A.19188.8.131.527
In the cold rolling mill, it is very important that a constrained static flow stress of rolled strip and rolling force calculation model be exactly considered to improve an prediction accuracy for rolling forces. Therefore, in this study, the values of the constrained static flow stress are used by deriving the regression equation which is a function of rolling conditions(FDT, CT) and chemical compositions(C, Si, Mn), previously applied by making the tables of yield strength for hot coils with size. And with the consideration that an elastic deformation part of an rolled strip appears at the entry and delivery side of the contacting area between the work roll and rolled strip is calculated. By applying these methods, the more accurate prediction for rolling force is obtained. As a results, the deviation of thickness is significantly reduced in the rolling direction.