• Journal of the Computational Structural Engineering Institute of Korea
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• v.18 no.4 s.70
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• pp.453-458
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• 2005

This study deals with elasto-plasticity of granular micro-structures which recovers continuum elasto-plasticity in its counterpart. The theory is based on doublet mechanics that assumes particles of finite size and connecting linear springs, and it makes extensions to plasticity. The result shows that the micro model has one to one relationship with the continuum model in the simplest case. Micro-strain and micro-stress of two dimensional plane stress problem were calculated, which shows the behavior of the specimen and verifies the effectiveness of this model.

• Journal of Welding and Joining
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• v.23 no.6
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• pp.18-28
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• 2005

본 일반 지침은 용접 이음부나 구조물의 피로강도 평가에 사용되는 기준응력 계산에 관한 내용으로 핫스팟 응력(Hot Spot Stress, 이하 HSS)이라고 칭하는 응력 평가용 해석 기술 및 관련 내용을 다룬다. 국제용접협회 (IIW: International Institute of Welding)발간 지침서의 주요내용에 대한 간략한 소개와 함께 대한용접학회 용접강도연구위원회의 Round-Robin 시험결과를 바탕으로 유한요소 응력해석 기반 용접 이음부의 HSS 평가 방법에 관한 내용을 정리하였다.

• Journal of the Korean Society for Nondestructive Testing
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• v.34 no.1
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• pp.53-59
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• 2014

Because a molten steel carrier is used in high-temperature and corrosive environments, erosion and corrosion decrease the thickness of the structure and expand the vent hole for emitting gas generated from refractory bricks. This increases the stress throughout the structure and introduces a significant stress concentration around the vent hole. In addition, the high-temperature environment degrades mechanical properties such as the yield and tensile strengths. These problems seriously affect the safety of the structure. In this study, the safety of a 10-year-old structure was evaluated by analyzing the stress distribution and measuring the mechanical properties of the structure. The mechanical properties were directly measured on the structure surface using the instrument indentation technique.

• Korean Journal of Food Science and Technology
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• v.32 no.4
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• pp.974-978
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• 2000

The vane method was used to measure yield stresses of five commercial kochujang samples under a controlled shear-rate operating condition. Magnitudes of vane yield stress were higher than those of yield stress using Casson model with a concentric cylinder viscometer. Magnitudes of vane yield stresses showed great differences between the static $({\sigma}_s)$ and dynamic yield stresses $({\sigma}_d)$ of kochujang samples with undisturbed structure (UDS) and with broken down structure (BDS). A dimensionless yield number $(N{\sigma}_o)$ was determined from the ratio of ${\sigma}s$ to ${\sigma}d$ in order to describe the existence of temporary structure of kochujang.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.28 no.1A
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• pp.1-13
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• 2008

The web of a horizontally curved plate girder bridge is, in general, subject to not only longitudinal flexural in-plane stress but also out-of-plane bending stress. Therefore, the induced stresses in the fillet welded joints at the intersection of the web and flange plates in the curved plate girder bridge can be considerably high, and the welded joints of gusset plates connecting the main girder to the floor beams or sway bracings can be subject to much more severe situation than those in the ordinary straight plate girder bridge. In order to investigate the cause of fatigue crack occurred in a curved girder bridge that has been served in about 23 years, in this study, field load tests have been performed to obtain the stress characteristics at the welded joint under the real traffic flow. Using the test results, we have investigated the causes of the occurrence of various fatigue cracks and have estimated the fatigue lives for the cracks. In addition, the characteristics of structural behavior at welded joint of the curved girder bridge have been examined by comparing the FE analysis and the field test result.

• Journal of the Korean Society of Hazard Mitigation
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• v.9 no.1
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• pp.41-47
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• 2009

Transverse rib web of orthotropic steel decks is highly susceptible to stress concentration due to out-of-plane and oil canning deformation caused by longitudinal rib distortion. In particular, stress concentrations are observed in the crossing point of longitudinal rib-transverse rib-deck plate, and cutout parts of transverse rib. The main objective of this study is to improve structure performance and to reduce the stress concentration of aforementioned susceptible parts. It is known that the installation of diaphragm alleviates stress concentrations between crossing point ant cutout. The influence of transverse rib placement and cutout width on stress concentrations was thoroughly investigated through numerical analyses. The numerical result showed that diaphragms produce the structural details for improved structure performance, when the transverse rib was placed in the same location with diaphragms. In any case, it is certain that the installation of diaphragms has more advantageous than the case without diaphragms in terms of structure performance of orthotropic steel decks. In this study, the distance ratio($y_i/y_{total}$) is defined as the ratio of the distance($y_{total}$) between the deck plate and longitudinal rib bottom to the distance($y_i$) between the deck plate and crossing point of longitudinal rib-transverse rib in cutout part. It has been found that the optimal distance ratio was 0.85 from the numerical simulation.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.39 no.1
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• pp.1-8
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• 2011

A coupled thermal/structural analysis of mechanical ablation is performed based on domain/boundary decomposition and finite element method. The ablative material non-linearity and boundary non-linearity can be easily localized within a few subdomains and/or on the boundary interfaces. An enthalpy method is applied to simplify the effect of heat of pyrolysis in the ablative subdomains. In addition, maximum in-plane shear stress is considered as a surface recession criterion for the mechanical ablation simulation. The basic characteristics of the proposed method are examined carefully through numerical experiments.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2011.11a
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• pp.933-937
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• 2011

In order to determine optimal design length of adhesive joint of a composite pressure vessel with separated dome, stress analysis of joint part according to changes of adhesive length was done. Adhesive length has a range of 50mm to 300mm as design variables. The ratio of adhesive length with any stress gradient to initial non-stressed adhesive length was called "stress gradient length ratio" and selected as objective function. The stress gradient length ratio of joint part with adhesive length of more than 200mm was increased very slowly with increase of adhesive length. It means that adhesive length of about 200mm could be the optimal value to ensure the structural safety of joint part against internal pressure of 2,500 psi.

• Computational Structural Engineering
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• v.10 no.3
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• pp.185-193
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• 1997

The order of the stress singularity that occurs at the termination of an interface between materials exhibiting bilinear stress-strain response under plane strain conditions has been calculated, The governing equation of elasticity together with traction-free boundary condition and interface continuity condition defines a two-point boundary value problem. The stress components near the free edge are assumed to be proportional to r/sup s-1/, with solutions existing only for certain values of s. Finding these values entails the solution of an eigenvalue problem. Because it has been impossible to integrate the differential equations analytically, the integration has been performed numerically with a shooting method coupled with a Newton improvement scheme.

• Computational Structural Engineering
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• v.6 no.1
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• pp.91-98
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• 1993

Minimum weight design of the boom of an excavator with stress and displacement constraints was performed. The procedure of analysis consists of the following steps. The finite element model of the boom was built up by using 227 triangular plate elements each of which has three nodes. And then the finite element program was implemented and its accuracy was verified by comparing its results with those of the commercial structural analysis package-ANSYS 4.4A. For the constraints of stresses and displacements, the design sensitivities of those were computed using direct differentiation method. To verify the reliability of them the results were compared with those of the finite difference method. The optimum design value was obtained by using PLBA(Pshenichny-Lim-Belegundu-Arora)non-linear optimization program which adopts the active set strategy. Using the above results, minimum weight design of an excavator boom showed an effect of 27% reduction in weight.