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곽시영,홍준호 (사)한국CDE학회 2016 한국 CAD/CAM 학회 학술발표회 논문집 Vol.2016 No.동계
In order to carry out VIV/Structural coupled analysis, we designed 3D modeling of manifold frames and pipes that work properly in deep-sea than 3000m and extracted natural frequency of frames and major items by carrying out modal analysis. Using the frequency, we calculated changes of pressure field by time and the results were used in initial values to carried out structural analysis on frames and main pipes. In addition, we examined stability of whole pipe used in manifold with stress analysis of them.
CT를 활용한 A 356 주조시편의 내부결함에 따른 충격 및 피로 특성
곽시영,남정호 (사)한국CDE학회 2014 한국 CAD/CAM 학회 학술발표회 논문집 Vol.2014 No.2
Despite an advantage of making complicated components in geometry, the casting process has a risk like weak mechanical characteristic due to existence of porosity like shrinkage. This porosity will become the cause of water leak and fracture under working load. But, the quantification of the influence of the porosity is too difficult in the actual situations. Therefore, most analysis is conducted by defect test about failure surface after accidents. In this study, inner defect geometry data of casting aluminum specimens was extracted using CT(Computed Tomography). Fatigue and impact tests for each specimen were conducted. And then, the impact value and fatigue life are compared and estimated about the influences of the geometry conditions like the defect size, location etc.
A356 합금 시편의 수축공 결함형상에 대한 피로해석용 형상 모델링 방법
곽시영,조인성 한국주조공학회 2019 한국주조공학회지 Vol.39 No.1
During the casting process, it is possible to minimize shrinkage and blowholes by modifying the casting design. However, it is impossible to eliminate these factors completely. Therefore, mechanical design engineers apply a sufficient safety factor owing to the possibility of insufficient performances of the cast products. In this paper, prediction method of the fatigue life of cast products containing shrinkage is conducted by using CT (computed tomography) and the SSM (shape simplification method), and additional fatigue analyses are carried out. The analysis results are then compared to results from actual experiments on samples with shrinkage defects. It is found to be that the considering actual shrinkage in cast products by means of stress and fatigue analyses is more accurate and effective. It is also considered that the proposed hot spot method provides us a good tool to predict the fatigue lifes of cast product.
ESPI 장비를 활용한 사형 주조품의 잔류응력 측정 및 주조 열응력 해석
곽시영,남정호 한국주조공학회 2020 한국주조공학회지 Vol.40 No.1
Many studies involving a thermal stress analysis using computational methods have been conducted, though there have been relatively few experimental attempts to investigate thermal stress phenomena. Casting products undergo thermal stress variations during the casting process as the temperature drops from the melting temperature to room temperature, with gradient cooling also occurring from the surface to the core. It is difficult to examine thermal stress states continuously during the casting process. Therefore, only the final states of thermal stress and deformations can be detemined. In this study, specimens sensitive to thermal stress, were made by a casting process. After which the residual stress levels in the specimens were measured by a hole drilling method with Electron Speckle-Interferometry technique. Subsequently, we examined the thermal stresses in terms of deformation during the casting process by means of a numerical analysis. Finally, we compared the experimental and numerical analysis results. It was found that the numerical thermal stress analysis is an effective means of understanding the stress generation mechanism in casting products during the casting process.
곽시영,유승목,김용현 (사)한국CDE학회 2013 한국 CAD/CAM 학회 학술발표회 논문집 Vol.2013 No.1
선진국에서는 변전시설에 사용되는 내수성 및 고압기밀성이 요구되는 고압차단기용 절연 탱크류 제품인 GIS tank 및 CB tank 등을 경량화, 원가절감, 제작용이성, 고내식성, 품질지속성 등의 사유로 알루미늄 주조품으로 사용하고 있다. 국내에서 제작되고 있는 고압차단기용 절연 탱크류의 제품들은 소형의 경우에는 알루미늄 주조품이 개발되어 사용되고 있으나, 대형제품의 경우 관련 기술 개발이 저조하여 국산화 되지 못하고 여전히 스틸 판재를 제관, 용접 및 가공하여 제품을 제작하고 있는 실정이다. 스틸 판재를 이용하여 CB tank를 제작할 경우 방식처리에도 불구하고 설치 후 1-2년 사이에 부식현상이 심각하게 진행되어서 알루미늄 재질의 제품을 적용하는 해외 설비와 비교할 때 외관 유지 보수에 많은 비용과 시간이 소요되어서 알루미늄 주조품의 개발이 시급한 상황이다. 본 연구에서는 기존에 강판 가공 및 용접에 의하여 제작되고 있는 CB tank를 알루미늄 재질의 제품으로 대체하기 위해 구조해석을 이용하고 주조제품 고유의 보강방안을 마련하여 경량화 및 안정성 있는 제품을 개발하였다.