• 대한조선학회논문집
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• 제57권4호
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• pp.198-206
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• 2020

In this study, the dynamic structural behavior of pressure vessels due to pressure pulse initiated by implosion of neighbouring airbacked equipments including Unmanned Underwater Vehicles (UUV), sensor system, and so on were dealt with for the structural design and safety assessment of pressure hulls of submarine. The dynamic buckling and collapse responses of pressure vessel in deep sea were investigated considering the effects of initial hydrostatic pressure and fluid-structure interactions. The governing equations for circular cylindrical shells were formulated theoretically assuming a relatively simple displacement fields and the derived nonlinear simultaneous ordinary differential equations were analysed by developed numerical solution algorithm. Finally, the introduced safety assessment procedures for the dynamic buckling behaviors of pressure hulls due to implosion pressure pulse were validated by comparing the theoretical analysis results with those of experiments for examples of simple cylinders.

• 한국압력기기공학회 논문집
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• 제12권1호
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• pp.11-16
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• 2016

Fuel assembly's mechanical characterization test facility (FAMeCT) in KAERI was constructed with upgraded functional features such as increased loading capacity, underwater vibration testing and severe earthquake simulation for extended fuel design guideline. This facility is designed and developed to provide out-pile fuel data for accident analysis model and fuel licensing. Functional tests of FAMeCT were performed to confirm functionality, structural integrity, and validity of newly-built fuel assembly mechanical test facility. Test program includes signal check of data acquisition system, load delivering capacity using real-sized fuel assemblies and a standard loading cylindrical rigid specimen. Fuel assembly's lateral bending test was carried out up to 30 mm of pull-out displacement. Limit case axial compression loading test up to 33 kN was performed to check structural integrity of UCPS (Upper Core Plate Simulator) support frame. Test results show that all test equipment and measurement system have acceptable range of alignment, signal to noise ratio, load carrying capacity limit without loss of integrity. This paper introduces newly constructed fuel assembly's mechanical test facility and summarizes results of functional test for the mechanical test equipment and data acquisition system.

• 한국CDE학회논문집
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• 제19권1호
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• pp.19-28
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• 2014

The filament winding method is widely used to manufacture products of fiber reinforced plastics (FRP), such as high pressure vessels, launch tubes and pipes. For reducing winding time, the method of winding by filament band which consists of several filament fibers is used. NC winding machine is used for precise winding and NC path is needed. Before filament winding, users should verify that winding path which presented by a line is appropriate by filament winding simulation. Also, the used length of each filament is different. So, if the peak filament exhausted, it causes to stop manufacturing. In this research, we developed software which visualizes 3D graphic of filament band winding path and simulates winding process on real time. And we proposed algorithm about calculation of each filament usage. We use geodesic equation for generating filament band surface and calculating the usage length of each filament.

• 한국압력기기공학회 논문집
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• 제17권1호
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• pp.1-7
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• 2021

This paper presents sensitivity analysis results of strain on notches under cycling loading to 2-D finite element density considering plasticity. Cylindrical notched specimens having some stress concentrations were modeled with 2-D axisymmetrical finite element having various finite element densities. Elasto-plastic finite element analysis was performed for the various finite element models subjected to cycling loading considering plasticity. The finite element analysis results were compared to investigate sensitivity of the finite element analysis variables such as von-Mises effective stress, accumulated equivalent plastic strain, and equivalent plastic strain to 2-D finite element density. As a result of the comparison, it was found that the accumulated equivalent plastic strain is more sensitive than the others whereas the von-Mises effective stress is much less sensitive.

• 한국해양공학회지
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• 제26권2호
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• pp.79-84
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• 2012

This study aimed to analyze the nonlinear buckling of ring-stiffened circular cylinders under uniform external pressure, e.g. hydrostatic pressure, considering material nonlinearity and initial imperfection. In the present study, we analyzed the collapse pressure of pressure vessels using ANSYS Workbench, which is a framework of finite element methods. First, linear buckling analysis is performed to find collapse modes of the model. Second, scaling the first mode shape with small factor, geometric model is pre-deformed. And then, by analyzing the nonlinear buckling of the pre-deformed shape, the collapse pressure is estimated. To verify the validity of the analyses, we compared the results with Ross' experimental results. Finally, we applied it to ring-stiffened circular cylindrical shell of the pressure hull of a small submarine.

• 한국가시화정보학회지
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• 제21권2호
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• pp.14-23
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• 2023

The pressure difference across stenotic blood vessels is a commonly used clinical metric for diagnosing many cardiovascular diseases. At present, most clinical pressure measurements rely solely on invasive catheterization. In this study, we propose a novel method for non-invasive pressure estimation using the incompressible Navier-Stokes equations and a 3D multi-path integration approach. We verify spatio-temporal convergence on an in-silico dataset of a cylindrical straight pipe phantom with steady and pulsatile flow fields. We then evaluate the proposed method on an in vitro dataset of reconstructed control, pre-operative, and post-operative carotid artery cases acquired from 4D flow MRI. The performance of our method is compared to existing approaches based on the pressure Poisson equation and work-energy relative pressure. The results demonstrate the proposed method's high accuracy, robustness to spatio-temporal subsampling, and reduced sensitivity to noise, highlighting its great potential for non-invasive pressure estimation.

• 한국안전학회지
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• 제21권3호
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• pp.38-44
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• 2006

The majority of both small and large-scale experiments on gas explosion have been carried out in the explosion instruments with cylindrical tubes of a high length/diameter ratio and vessels of a high height/length ratio, focusing on investigating the interaction between propagating flame and obstacles inside the tubes or vessels. The results revealed that there is a strong interaction between the propagating flame and turbulence formed after the flame passes the obstacle. However this paper focuses on analyzing the pressure impact or profile outside the vent in vented gas explosion in a partially confined chamber by performing gas explosion experiments in a reduced-scale experimental assembly properly constructed. This study has considered eight different cases in gas explosion based on variation of three kinds of parameters such as height of vessel, shape of the vent and vent size, and reveals that the large vessel with big size circle vent is more danger to the target than others because the overpressure is spread out faraway horizontally and vertically.

• Journal of Welding and Joining
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• 제16권2호
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• pp.111-121
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• 1998

It is well recognized that a excessive temperature gradient from the junction of head to skirt in axial direction in a hot pressure vessel can cause unpredicted high thermal stress at the junction and/or in axial direction of a skirt. this thermal stress resulting from axial thermal gradient may be a major cause of unsoundness of structural integrity. In case of cyclic operation of hot pressure vessels, the thermal stress becomes one of the primary design consideration because of the possibility of fracture as a result of cyclic thermal fatigue and progressively incremental plastic deformation. To perform thermal stress analysis of the junction and cylindrical skirt of a vessel, or, at least, to inspect quantitatively the magnitude and effect of thermal stress, the temperature profile of the vessel and skirt must be known. This paper demonstrated the temperature distribution and thermal stress analysis for the junction of skirt to head using F.E. analysis. Effect of air pocket in crotch space was quantitatively investigated to minimize the temperature gradient causing the thermal stress in axial direction. Effect of the skirt height on thermal stresses was also studied. Analysis results were compared with theoretical formulas to verify th applicability to the strength calculation in design field.

• 예술인문사회 융합 멀티미디어 논문지
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• 제7권2호
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• pp.427-435
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• 2017

환경문제로 국내 시내버스의 대부분은 압축천연가스(CNG)를 연료로 사용하며, 연료 저장용기는 내압을 받는 압력용기를 사용하고 있다. 내압을 받는 압력용기는 여러 가지의 형태와 목적을 지니고 있다. 연료가 가연성이고 고압으로 인한 폭발성을 지니고 있으므로 압력용기의 파손사고는 많은 재산피해와 인명피해를 일으킨다. 이에 대한 안전한 설계가 반드시 필요하므로 유한요소해석을 이용하여 많은 연구들이 진행되고 있다. 본 연구에서 유한요소 해석 소프트웨어인 ANSYS를 이용한 응력해석을 탄성이론의 구형 돔 형상 응력이론식과 실린더 형상 응력이론식을 비교하여 해석의 타당성을 입증 하기위해 돔의 형상이 완전 구형인 모델을 설계하여 관찰하였고 실제 사용중인 ASME 규격이론을 바탕으로 압축천연가스(CNG)로 설계된 모델에 대해서도 응력분포를 분석하였다. 유한요소 해석 소프트 웨어를 사용하여 돔 형상이 완전이 구형인 모델을 해석 하였을 때 이론과 잘 일치 하였고 ASME 규격이론을 바탕으로 설계한 모델에서는 너클부분에 응력집중 현상이 발생하였다.

• 한국재료학회지
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• 제8권4호
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• pp.283-287
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• 1998

구미와 일본에서는 균열이 실린더벽을 과통하므로서 발생되는 일부누설로 인하여 실린더가 불안전 파괴가 이루어진 후 급속파단으로 전개되는 판당전 누설(Leak Before Break, LBB)를 전제로 한 구조건전성의 확인 시험연구가 널리 수행되고 있다. 본고에서는 Gs-C25 실린더의 구조건전성을 LBB개념의 도입과 파괴역할을 이용하여 평가하였다. 내부압력 80bar일때의 실린더에서 응력확대계수 계산은 구조물의응력확대계수가 극단적으로 큰 디멘젼을 지닌 측균열인 경우에서만 재료의 인성계수 $K_{lc}$ /와 $K_{eff}$ 에 도달된다는 것을 나타내었으며, 반면에 원주균열은 파괴 인성치 $K_{lc-}$ 와 $K_{eff-}$ 값까지는 어떠한 경우에도 도달되지 않았다. 구조물의 국부적인 취성파괴는 균열을 함유한 누설로 유도되는 범위에서, "$K_{1}$ 구조물$\geq$$K_{lc}$ 및 $K_{eff}$ "의 조건을 만족시에만 발생되며, 이는 축균열이 원주균열보다 훨씬 더 위험하다는 것을 증명한다.는 것을 증명한다.