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다중 블록 격자를 이용한 원뿔 직관 모양의 벌류트 유동의 수치해석
배황(H. Bae),강현구(H.G. Kang),윤주식(J.S. Yoon),박기철(K.C. Park),장근식(K.S. Chang) 한국전산유체공학회 2006 한국전산유체공학회지 Vol.11 No.1
Numerical investigation of a centrifugal compressor volute having a modified straight conical duct has been made. Three-dimensional Reynolds-Averaged Navier-Stokes equations with k-ε turbulence equation are solved To avoid coordinate singularity at the central axis of the duct, multi-block H-type grid is generated on the circular cross-sections of the volute and stretched toward the solid wall boundary. We obtained numerical results with three different mass flow rates at the volute inlet, namely, with the inlet conditions that give small, medium and large mass flow rates at the outlet of the conical duct. Agreement with the experimental results is observed.
액압 벌지 시험으로 구한 대변형 응력-변형률 선도에 미치는 판재 굽힘 영향 해석
박기철(K. C. Park),배기현(K. H. Bae),남재복(J. B. Nam) 한국소성가공학회 2012 한국소성가공학회 학술대회 논문집 Vol.2012 No.10
In order to investigate the effect of thickness and bending deformation on the flow curve from bulge test, forming simulations of bulge tests for two different tool dimensions are done. One is 106㎜ diameter and the other case is 206㎜ diameter tool. In the case of 106㎜ diameter tool, difference between input flow curve and measured stress according to bulge test procedure is 3.3% and it is 3times larger than 206㎜ diameter case. Therefore, thickness effect correction is essential for bulge with 106㎜ diameter tool. By considering the deformation of thickness center of specimen, thickness averaged stress, and dimension of surface subjected to pressure, the bending effect could be eliminated and the measured stress error is within 0.5%. The thickness effects elimination are done by two methods. One is utilizing some FEM results and the other is simple analytical considerations. Both methods showed good results.
레벨링 공정 해석에 의한 교정 조건이 열연 고강도 강판의 잔류응력에 미치는 영향 연구
박기철(K. C. Park) 한국소성가공학회 2009 한국소성가공학회 학술대회 논문집 Vol.2009 No.5
In order to analyze the effect of leveling conditions on residual stress evolution of hot rolled high strength steels, a numerical algorithm was developed. It was able to implement the effect of plastic fraction (intermesh) in leveling, line tension, work roll bending, and initial residual stress and curl distribution. The effect of work roll bending on residual stress and curl were studied by using the developed program. The validity of simulated results was verified from comparison with the experimentally measured residual stress and curl in a sheet.