• Proceeding of EDISON Challenge
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• 2015.03a
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• pp.234-238
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• 2015

When we use a Finite Elements Method (FEM) to solve a linear static analysis problem, number of elements need to be sufficiently small for convergence of the solution. If we analysis a part, whose curvature is varying heavily, we face to determine how small the elements size is, because the calculated stress is increased as the elements are smaller. In this case, we need to analysis with mesh insensitive method, stress linearization. We can get a solution that is not varying with the elements size if the size is smaller than a certain level. In this paper, we evaluate a pressure vessel having geometrical discontinuities using stress linearization. First, we analysis the vessel with global model, including all part of the vessel, using large shell elements. Second, we analysis the local part of the vessel, which is the small part occurring maximum stress, using small continuum elements. Last, we evaluate the safety of the pressure vessel according to the ASME Sec. VIII Div 2.

• Journal of the Society of Naval Architects of Korea
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• v.40 no.6
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• pp.49-57
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• 2003

This method surely needs a hole that causes local strength and stiffness deterioration of the structure because of stress intensity. In this work, three dimensional stress analysis of pin-loaded joint for quasi-isotropic composite laminates was performed using commercial finite element software. Stress distribution was calculated near the edge of the pin-leaded hole and effects of the stacking sequence on the delamination were investigated. Also, the delamination strength of the composite laminates was predicted using the Ye-delamination failure criterion and compared with the experimental results. finally, newly modified failure criterion has been suggested owing to the consideration of effects of interlaminar normal stress on the delamination strength.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 1995.10a
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• pp.43-49
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• 1995

Sasol Advanced Synthol Reactor was divided into two chambers by grid plate perforated with diffuser holes. The reactor has high stress level beacuse of membrane stress due to internal pressure, thermal stress due to temperature difference and local stress due to structural discontinuity at the juncture of grid plate and shell. Moreover, geometric nonlinear behaviors may appear in the grid plate because of pressure difference between two chambers. In order to survey the stress level and geometric nonlinear behaviors around grid plate, heat transfer analysis, linear static analysis and geometric nonlinear analysis were performed using NISA II developed by EMRC. This paper demonstrates the result of accessment for linear static and geometric nonlinear analysis under various load combinations.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 1999.10a
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• pp.87-94
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• 1999

The structural behavior of welded steel box columns subjected to axial compression and combined load of axial and horizontal load is described. The nonlinear stress-strain relation of the material and residual stress resulted from welds were included in the analysis. Inelastic buckling analysis of hollow rectangular sections of various width-thickness and slenderness ratios was carried out using the semi-analytical and spline finite strip method to investigate the local and global bucking stress and mode interaction. The buckling stress was compared with test results and design curves. Post-buckling behavior was traced by the finite element program(ADINA) and compared with experimental results. The comparison showed that the ultimate stress can be used for the design purpose.

• Structural Engineering and Mechanics
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• v.39 no.5
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• pp.643-659
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• 2011

The design of box girders requires the determinations the buckling stress of the flange and the webs. Existing design equations available in codes of practice ignore the interactions between the box girder components. The paper illustrates the influence of the geometric interaction on the buckling stress of box girders. Generalized equations are first derived in terms of the web the flange geometric properties. Industrial examples are then presented showing the variation of the flange buckling stress for various stiffening configurations. The influence of the flange/web proportions on the buckling stress of box girder components is also highlighted. It is shown that buckling strength of the flange is largely affected by the restraints imposed by the webs or attached diaphragms. Graphs are presented showing various limiting states of box girders. These graphs are useful to use in practice in order to achieve economical and efficient design of box girders and rationally predict local buckling stress.

• Structural Engineering and Mechanics
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• v.20 no.1
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• pp.123-141
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• 2005

Design details pertaining to the connection between some recently developed fiber reinforced polymer (FRP) composite deck systems and the supporting girders require openings through cells of the deck. This significantly changes the stress distribution in these components. As a result, the conventional assumptions that deck designs are controlled by their stiffness, and not strength, needs a closer examination. This paper proposes an analytical method to investigate the stress states and failure mechanisms using a type of "global-local" modeling perspective, incorporating classical lamination theory and first ply failure criterion with use of appropriate stress concentration factors around the cutouts. The use of a "smeared-stress" approach is presented as a potential means of simplifying certain FRP specific complexities, while still enabling prediction of overall failure.

• Steel and Composite Structures
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• v.31 no.1
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• pp.43-51
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• 2019

This paper is concerned with the numerical calculation of mixed-mode stress intensity factors (SIFs) of 2-D isotropic functionally graded materials (FGMs) by the natural element method (more exactly, Petrov-Galerkin NEM). The spatial variation of elastic modulus in non-homogeneous FGMs is reflected into the modified interaction integral ${\tilde{M}}^{(1,2)}$. The local NEM grid near the crack tip is refined, and the directly approximated strain and stress fields by PG-NEM are enhanced and smoothened by the patch recovery technique. Two numerical examples with the exponentially varying elastic modulus are taken to illustrate the proposed method. The mixed-mode SIFs are parametrically computed with respect to the exponent index in the elastic modulus and external loading and the crack angle and compared with the other reported results. It has been justified from the numerical results that the present method successfully and accurately calculates the mixed-mode stress intensity factors of 2-D non-homogeneous functionally graded materials.

• International Journal of Advanced Culture Technology
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• v.12 no.2
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• pp.258-269
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• 2024

This study aims to examine the effects of child care teachers' job stress and personality on child abuse protective behaviors, which consist of perception and reporting intention of child abuse, and to verify the moderating effect of past child abuse experience. A survey was conducted on 246 child care teachers nationwide, and the collected data were analyzed through regression analysis and t-test. The results showed that job stress had a negative effect and personality had a positive effect on child abuse protective behaviors. In addition, there was a significant difference in the influence of job stress and personality on protective behaviors according to the presence or absence of past child abuse experience. Based on these results, practical implications for preventing child abuse by child care teachers were discussed.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.28 no.7
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• pp.977-985
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• 2004

An evaluation of fatigue life of welded components is complicated due to various geometrically complex welding details and stress raisers in vicinity of weld beads, ego under cuts, overlaps and blow holes. These factors have a considerable influence on the fatigue strength of welded joints, as well as the welding residual stress which is relaxed depending on the distribution of local stress at the front of the stress raisers. To reasonably evaluate fatigue life, the effect of geometries and welding residual stress should be taken into account. The several methods based on the notch strain approach have been proposed in order to accomplish this. These methods, however, result in differences between analytical and experimental results due to discrepancies in estimated amount of relaxed welding residual stress present. In this paper, an approach that involves the use of a modified notch strain approach considering geometrical effects and a residual stress relaxation model based on experimental results was proposed. The fatigue life for five types of representative welding details, ego cruciform, cover plate, longitudinal stiffener, gusset and side attachment joint, are evaluated using this method.

• Journal of the korean academy of Pediatric Dentistry
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• v.42 no.2
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• pp.119-125
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• 2015

Dental stress is suggested as a main reason for behavioral problems in dentistry, especially in children. Heart rate is a useful measure of dental stress. The purpose of the present study is to examine the effect of dental stress on children receiving restorative treatment under local anesthesia by using recently introduced a wrist-watch type heart rate monitoring device. Eighteen children with no previous dental experience, who needed dental treatment involving local anesthesia, were included in this study. In each session, heart rate was recorded. The largest increase was observed during local anesthesia and the highest values were recorded during preparation. However, no significant relationship was found between the measurements(p > 0.05). Regarding the number of visits, heart rate on the second session is significantly higher than the first session and the third session(p < 0.05). There was no significant different correlation between the first session and third session(p > 0.05). Based on the present study, children who have no previous dental treatment appeared to be more stressed at the second session and need at least 3 sessions to feel less stressed during dental treatment including dental injection.