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蔡泳晳,金東燮 嶺南大學校 工業技術硏究所 1983 연구보고 Vol.11 No.1
The behavior of thin flat plates under transverse loading such that the non-linear geometric relationships must be included in the analysis gives rise to the large deformation theory of the plate. In present study, nonlinear analysis of a thin plate has been carried out by the finite element method based on the load incremental approach. Employing the method, it is shown that the small deformation theory is applicable to the plate if w/h≤0.3, and above this range large deformation theory is adequate. For the case of the clamped rectaugular plate with a circular hole, it is found that the stress concentration factor around the hole is about 1.6∼1.65.
유한 요소법과 광탄성 실험법에 의한 외부 굴절 균열의 응력 확대 계수 해석
채영석 嶺南大學校 工業技術硏究所 1982 연구보고 Vol.10 No.1
The stress field in the vicinity of the crack-tip is mainly affected by the stress intensity factor which is functions of the shape of crack, the crack length and the state of load applied on the body. In the analysis of stress intensity factor, there are many theoretical, numerical and experimental methods that have been proposed by many analysts. In this study, a numerical method is described in terms of the enriched element formulation in singular effect using finite element method. And a newly exploited teflon molding method is attempted for the completion of teflon-epoxy experimental method. Comparing above mentioned results, the stress intensity factor for external deflected crack is evaluated.
유한 요소법에 의한 균열선단 개구형 변위와 J적분과의 관계에 관한 연구
蔡泳晳 嶺南大學校 工業硏究技術所 1983 연구보고 Vol.11 No.1
The purpose of analysis in elastic-plastic fracture mechanics is to determine the value of a characterizing parameter. In present study, a numerical method is described for the incremental elastic-plastic analysis by finite element method. Employing the method, we obtain the stress-strain distributions of material and plastic zone size. Special attention is given to the singular environment at a crack tip, characterized by Rice's J-integral, and its relationship with the crack-tip opening displacement.
황평,채영석,이택순,황재석,김동섭 영남대학교 공업기술연구소 1984 연구보고 Vol.12 No.1
The nonlinear analysis must be carried out when the deflection is large enough to cause non-linear behavior of the plate and the results of stress distributions are significantly different from those of ordinary small deflection theory. In present study, the nonlinear analysis of stiffened plate has been done based on von Karman's non-linear plate equations for isotropic plate using Lagrangian description finite element method. In this method, it is shown that the small deflection theory to the plate is applicable when the deflection of the plate is less than about a half of the plate thickness and above this range, large deformation theory is adequate. For the case of perforated rectangular plate with clamped boundary condition, it is found that the stress intensity of the edge reduces but that of the hole tip increases. In that case, doubler decreases the stress intensity at the tip, while stiffener decreases stress intensity at the tip and edge. It is also found that the maxinmum load carrying capacity of perforated stiffened plate increases 5 times as much as in the perforated plate. This method would be applied and extended to solve both geometrical nonlinearity and material nonlinearity problems and be useful to save computation time in engineering sense.
전원기,채영석 嶺南大學校 工業技術硏究所 1991 연구보고 Vol.19 No.1
A combined experimental and numerical approach was used for viscoelastic analysis of polymeric materials. Relaxation tests were conducted at two different temperatures to determine a master curve of the tensile relaxation modulus of epoxy. By assuming the constant Poisson's ratio, Prony series representation of the tensile relaxation modulus was obtained and was used for viscoelastic finite element program. The specimen geometry selected for simulation was an edge-cracked bimaterial strip. Three different rates of bond-normal and bond-tangential displacements were chosen for the loading condition. Near-tip fracture parameters and the reactions along the edges were computed. The results showed very little differences in stress intensity factors and crack opening displacements in comparison with elastic solutions. The reactions, however, changed with time, Which was different from the elasticity.
원공 주위에 생긴 두 비대칭 crack의 응력확대계수에 관한 연구
權在度,蔡泳晳 嶺南大學校府設 基礎科學硏究所 1983 基礎科學硏究 Vol.3 No.-
The stress field in the vicinity of the crack-tip is mainly affected by the stress intensity factor. In the analysis of stress intensity factor, there are many theoretical, numerical and experimental methods that have been proposed by many analysts. In this study, a numerical method using finite element method and photoelastic experimental method are described. Using above mentioned methods, the stress intensity factor for two unsymmetric cracks around a circular hole is evaluated. The results show that New-man's solution for the symmetric cracks using boundary collocation method is applicable to the longer crack for an unsymmetric case.
다꾸찌방법을 사용한 여러변수들이 패키지균열에 미치는 신뢰도 평가
권용수,박상선,박재완,채영석,최성렬,Kwon, Yong-Su,Park, Sang-Sun,Park, Jae-Wan,Chai, Young-Suck,Choi, Sung-Ryul 대한기계학회 1997 大韓機械學會論文集A Vol.21 No.6
Package crack caused by the soldering process in the surface mounting plastic package is evaluated by applying the maximum energy release rate criterion. It could be shown that the crack propagation from the lower edge of the ie pad is easily occurred at the maximum temperature during the soldering process, where the pressure acting on the crack surface is assumed by the saturated vapor pressure at maximum temperature. The package crack formation depends on various parameters such as chip size, relative thickness, material properties, the moisture content and soldering temperature etc. The quantitative measure of the effects of the parameters could be easily obtained by using the taguchi's method which requires only a few kinds of combinations with such parameters. From the results, it could be obtained that the more significant parameters to effect the package reliability are the orders of Young's modulus, die pad size, down set, chip thickness and maximum soldering temperature.
Analysis of Mixed-mode Crack Propagation by the Movable Cellular Automata Method
Chai, Young-Suck,Lee, Choon-Yeol,Pak, Mikhail Korean Society for Precision Engineering 2008 International Journal of Precision Engineering and Vol.9 No.4
The propagation of a mixed-mode crack in soda-lime silica glass is modeled by movable cellular automata (MCA). In this model, a special fracture criterion is used to describe the process of crack initiation and propagation. The results obtained using the MCA criterion are compared to those obtained from other crack initiation criteria, The crack resistance curves and bifurcation angles are determined for various loading angles. The MCA results are in close agreement with results obtained using the maximum circumferential tensile stress criterion.