• Transactions of the Korean Society of Mechanical Engineers
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• v.4 no.3
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• pp.113-118
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• 1980

Stresses were calculated for finite-width orthotropic laminates with a circular hole and remote uniaxial loading using a two-dimensional finite-element analysis with both uniform stress and uniform displacement boundary conditions. Five different laminates were analyzed: quasi-isotropic [0.deg./.+-.45.deg./90.deg.].$\_$s/, 0.deg., 90.deg., [0.deg./90.deg.]$\_$s/, and [.+-.45.deg.]$\_$s/, Computed results are presented for selected combinations of hole diameter-sheet-width ratio d/w and length-to width ratio L/w. For small L/w values, the stress-concentration factors K$\_$tn/ were significantly different for the uniform stress and uniform displacement boundary conditions. Typically, for the uniform stress conditions, the K$\_$tn/ values were much larger than for the infinite-strip reference conditions; however, for the uniform displacement conditon, they were only slighty smaller than for this reference. The results for long strips are also presented as width-correction factor. For d/w.leg.33, these width-correction factors are nearly equal for all five laminates.

• The Journal of Engineering Geology
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• v.1 no.1
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• pp.68-84
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• 1991

A numerical analysis using Universal Distinct Element Code program for the nuclear waste disposal cavern has been performed for a typical Korean crystalline rock condition with same geometry of Swedish low and intermediate nuclear waste disposal repository(S.F.R). The stress concentration, displacement and safety factor for the typical single cross section of cavern, 5 caverns and a silo are analyzed.

• Structural Engineering and Mechanics
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• v.36 no.6
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• pp.669-678
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• 2010

In general means, the stress concentration problem of elastic plate with a rectangular hole can be investigated by numerical methods, and only approximative results are derived. This paper deduces an analytical study of the stress concentration due to a rectangular hole in an elastic plate under bending loads. Base on classical elasticity theory and FEM applying the U-transformation technique, the uncoupled governing equations with 3-DOF are established, and the analytical displacement solutions of the finite element equations are derived in series form or double integral form. Therefore, the stress concentration factor can then be discussed easily and conveniently. For the plate subjected to unidirectional bending loads, the non-conforming plate bending element with four nodes and 12-DOF is taken as examples to demonstrate the application of the proposed method. The inner force distribution is obtained. The solutions are adequate for the condition when the hole is far away from the edges and the thin plate subjected to any transverse loadings.

• Restorative Dentistry and Endodontics
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• v.18 no.2
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• pp.395-411
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• 1993

The purpose of this study was to examine the clear concept of the designs for cavity preparations. Among the several parameters in cavity designs, profound understanding of isthmus width factor would facilitate selection of the appropriate cavity preparation for a specific clinical situation. In this study, the cavities were prepared on maxillary first premolar and filled with gold inaly. A two - dimensional model was composed of 1037 - node triangle elements. In this model, isthmus was varied in width at 1/4, 1/3 and 1/2 of intercuspal width and material properties were given for four element groups, i.e., enamel, dentin, pulp and gold. The 500N occlusal load varied in direction and it was examined using three types of load : concentrated load, divided load and distributed load. The models were also examined with empty cavities using the devided load and distributed load. These models were analyzed the displacement and strees distribution by the two - dimensional Finite Element Method. The results were as follows : 1. All experimental models which filled with gold inlay after cavity preparation were similar direction of displacement with control model under same load type. But in the models with empty cavities, as isthmus width was wider, the degree of displacement was increased at same load type. 2. Among the experimental models which were filled with gold inaly after cavity preparation, the model II showed the least stress concentration under concentrated load and divided load. But in the models with empty cavities, the model III showed the largest stress concentration and tooth fracture is expected regardless isthmus width. 3. All experimental models showed similar displacement pattern beneath restorative material under a concentrated load. In the models with empty cavities, a divided load resulted in a lingual displacement of the lingual cusp, but a distributed load resulted in a buccal displacement of the lingual cusp. In regard to the above results, the restored models were stronger than empty models in respect to the bending moment and tensile stress. The empty models are expected to fracture regardless isthmus width. The safest isthmus width was 1/3 of intercuspal distance, which showed the least stress concentration in respect to the effect of stress distribution.

• Geotechnical Engineering
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• v.14 no.1
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• pp.93-108
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• 1998

In this study, the analytic solutions and numerical methods were used to estimate the shape and size effects on the stability of underground openings. The stability of underground openings was evaluated by scrutinizing the effects of the rock mass quality, the state of in-situ stresses and the lateral earth pressure coefficient on the displacement, the stress concentration and the plastic region developed in the vicinity of the openings. The analytic solutions have shown that the stress concentration factor is inversely proportional to the radius of curvature of openings. Through parametric study on the various shapes and sizes of underground openings the characteristics of the controlling factors concerned with the stability were analyzed. Then, the study was extended to the horseshoe-shaped openings commonly used for under ground storage. Through the extended study the effects of the stress ratio and the height-towidth ratio of openings on the maximum displacement and plastic region developed around the openings were estimated. The results have shorn that the height-to-width ratio of domestic storage caverns can be increased economically without stability problem, as far as the lateral earth pressure coefficient is appropriate.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.21 no.1
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• pp.93-103
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• 1997

Charpy V-notch impact tests were performed on the full-, half-and third-size specimens from two ferritic SA 508 Cl. 3 steels for nuclear pressure vessel. New normalization factors were proposed to predict the upper shelf energy(USE) and the ductile-brittle transition temperature(DBTT) of full-size specimens from the measured data on sub-size specimens. The factors for the USE and the DBTT are $(Bb^2/Kt); and; (Bb/R)^1/2/, $ respectively, where B the width, b the ligament size, $K_{t}$ the elastic stress concentration factor, and R the notch root radius. These correlations successfully estimated the USE and DBTT of the full-size specimens based on sub-size specimen data. In addition, the size effects were studied to develop the correlations among absorbed energy, lateral expansion(LE) and displacement. It was also found that the LE was able to be estimated from the displacement obtained by the instrumented impact test, and that the displacement would be used as a criterion for the toughness of the steels corresponding to change in their yield strength.h.

• Smart Structures and Systems
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• v.19 no.2
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• pp.203-211
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• 2017

This paper provides a numerical solution for multiple confocal elliptic dissimilar cylinders. In the problem, the inner elliptic notch is under the traction free condition. The medium is composed of many confocal elliptic dissimilar cylinders. The transfer matrix method is used to study the continuity condition for the stress and displacement along the interfaces. Two cases, or the infinite matrix case and the finite matrix case, are studied in this paper. In the former case, the remote tension is applied in y- direction. In the latter case, the normal loading is applied along the exterior elliptic contour. For two cases, several numerical results are provided.

• Structural Engineering and Mechanics
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• v.22 no.5
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• pp.613-629
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• 2006

In this paper a recently developed scaled boundary finite element method (SBFEM) is applied to simulate stress concentration for two-dimensional structures. In addition, a simple and independent formulation for evaluating the coefficients, not only of the singular term but also higher order non-singular terms, of the stress fields near crack-tip is presented. The formulation is formed by comparing the displacement along the radial points ahead of the crack-tip with that of standard Williams' eigenfunction solution for the crack-tip. The validity of the formulation is examined by numerical examples with different geometries for a range of crack sizes. The results show good agreement with available solutions in literatures. Based on the results of the study, it is conformed that the proposed numerical method can be applied to simulate stress concentrations in both cracked and uncracked structure components more easily with relatively coarse and simple model than other computational methods.

• Restorative Dentistry and Endodontics
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• v.19 no.2
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• pp.384-408
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• 1994

The purpose of this study was to evaluate the fracture resistance of tooth restored with gold inlay. A profound understanding of the isthmus width factor, which is one of the several parameters of cavity designs, would facilitate the appropriate cavity preparation in a specific clinical situation. In this study, the cavities for gold inlay were prepared in maxillary left first premolar. A three-dimensional model was designed using I-DEAS program. The model was composed of 2515- nodes and 2172 isoparametric brick elements. In the model isthmus width was varied into 1/4, 1/3 and 1/2 of intercuspal width respectively, and numeric values of the material properties of enamel, dentin and gold was set. Three types of load : concentrated load, divided load and distributed load was 500N. The empty cavities in the model were also examined using divided load and distributed load. The three - dimensional Finite Element Method was used to analysis the displacement and stress distribution. The results were as follows : 1. All of the experimental models which were filled with gold inlay revealed similar direction of displacement to that of the natural tooth model under the same load type. But in the models with empty cavities, as the isthmus width increased, the degree of displacement increased in the case of divided load type. 2. All experimental models which were filled with gold inlay showed stress concentration at load points, but in the models with empty cavities at divided load type, as isthmus width increased, stress was concentrated at the comer of the pulpal floor. 3. In the models with empty cavities at divided load type, tooth fracture was expected regardless of isthmus width, but all experimental models which were filled with gold inlay after cavity preparation were not susceptible to fracture. 4. In all experimental models which were filled with gold inlay after cavity preparation, displacement patterns were similar under both concentrated and divided load types. In the models with empty cavities, a divided load resulted in a bucco-lingual cuspal displacemenat in both sides, but a distributed load resulted in a lingual displacement of the tooth.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.6 no.3
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• pp.58-64
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• 1997

A micromechanics model to describe the elastic behavior of fiber or whisker reinforced metal matrix composites was developed and the stress concentrations between reinforcements were investigated using the modified shear lag model with the comparison of finite element analysis (FEA). The rationale is based on the replacement of the matrix between fiber ends with the fictitious fiber to maintain the compatibility of displacement and traction. It was found that the new model gives a good agreement with FEA results in the small fiber aspect ratio regime as well as that in the large fiber aspect ratio regime. By the calculation of the present model, stress concentration factor in the matrix and the composite elastic modulus were predicted accurately. Some important factors affecting stress concentrations, such as fiber volume fraction, fiber aspect ratio, end gap size, and modulus ratio, were also discussed.