코너부 구조거동을 고려한 선박용 파이프 루프 설계식 개발

박치모(Chi-Mo Park) 대한조선학회 2012 대한조선학회 학술대회자료집 Vol.2012 No.5

Many longitudinally-arranged pipes in ships are equipped with loops as a measure to reduce stresses caused by displacement loads conveyed from the hull girder bending and/or thermal loads of carried fluid of non-ambient temperature. But as the loops have some negative effects such as causing extra manufacturing cost and occupying extra space, the number and the dimensions of the loops need to be minimized. In the meanwhile, a design formula for pipe loops has been developed by modeling them as a spring element of which stresses and axial stiffness are calculated based on the beam theory. But as the beam theory turns out to be inappropriate to deal with the complex structural behavior in the curved corner portion of the loop, this paper aims at improving the previously developed design formula by adopting correction factors which can allow for the gap between the results of beam theory and a more accurate analysis. This paper chose a finite element analysis with two-dimensional shell elements with some validation work for it. The paper ends with a sample application of the proposed formulas showing their accuracy and efficiency.

곡선부의 구조 특성을 고려한 선박용 파이프 루프 설계식 개발

박치모(Chi-Mo Park),배병일(Byoung-Il Bae) 한국해양공학회 2012 韓國海洋工學會誌 Vol.26 No.5

Many longitudinally-arranged pipes in ships are equipped with loops as a measure to reduce stresses caused by displacement loads conveyed from the hull girder bending and/or thermal loads of carried fluid of non-ambient temperature. But as the loops have some negative effects such as causing extra manufacturing cost and occupying extra space, the number and dimensions of the loops need to be minimized. In the meanwhile, a design formula for pipe loops has been developed by modeling them as a spring element of which stresses and axial stiffness are calculated based on the beam theory. But as the beam theory turns out to be inappropriate to deal with the complex structural behavior in the curved corner potions of the loop, this paper aims at improving the previously developed design formula by adopting correction factors which can allow for the gap between the results of beam theory and a more accurate analysis. This paper adopts a finite element analysis with two-dimensional shell elements with some validation work for it. The paper ends with a sample application of the proposed formulas showing their accuracy and efficiency.

코너부 구조거동을 고려한 선박용 파이프 루프 설계식 개발

박치모(Chi-Mo Park) 한국해양환경·에너지학회 2012 한국해양환경·에너지학회 학술대회논문집 Vol.2012 No.5

Many longitudinally-arranged pipes in ships are equipped with loops as a measure to reduce stresses caused by displacement loads conveyed from the hull girder bending and/or thermal loads of carried fluid of non-ambient temperature. But as the loops have some negative effects such as causing extra manufacturing cost and occupying extra space, the number and the dimensions of the loops need to be minimized. In the meanwhile, a design formula for pipe loops has been developed by modeling them as a spring element of which stresses and axial stiffness are calculated based on the beam theory. But as the beam theory turns out to be inappropriate to deal with the complex structural behavior in the curved comer portion of the loop, this paper aims at improving the previously developed design formula by adopting correction factors which can allow for the gap between the results of beam theory md a more accurate analysis. This paper chose a finite element analysis with two-dimensional shell elements with some validation work for it The paper ends with a sample application of the proposed formulas showing their accuracy and efficiency.

상용소프트웨어를 이용한 원환보강 원통의 최종강도 해석(Ⅱ)

박치모(CHI-MO PARK),이승훈(SEUNG-HOON LEE) 한국해양공학회 2002 韓國海洋工學會誌 Vol.16 No.1

Despite the frequent use of ring-stiffened cylinders as a submarine pressure hull or members of various types of offshore structures, their ultimate strength analysis methods have not been well established because of their complex structural characteristics. This paper has established the method how to use commercial softwares based on the finite element method to implement the ultimate strength analysis of ring-stiffened cylinders covering both types of initial imperfection, i.e. initial deformation and initial stress by combining two separately offered functions of common commercial finite element softwares, linear elastic buckling analysis and nonlinear stress analysis. Developed method was applied to one of the world-widely used commercial softwares, ABAQUS for the analysis of ring-stiffened cylinders. This paper ends with some useful information about the imperfection sensitivity of ultimate strength ring stiffened cylinders.

CAESAR-II를 이용한 파이프 루프의 구조 거동 특성 연구

박치모(Chi-Mo Park),윤성룡(Seong-Ryong Yoon) 한국해양공학회 2013 韓國海洋工學會誌 Vol.27 No.2

Most ships and offshore structures are equipped with a variety of pipes, which inevitably contain curved portions. The structural design of these pipes mostly relies on the commercial code, CAESAR?Ⅱ, which was especially developed for the structural analysis of pipes. This study conducted stress analyses of the same pipe unit, including loops, using both CAESAR?Ⅱ and MSC/NASTRAN, and compared the results to investigate the characteristics of CAESAR?Ⅱ. A parametric study was then conducted of the various design variables of pipe loops using CAESAR?Ⅱ to draw some useful information about the structural characteristics of the loops.

선박 해양구조물 파이프 루프 곡선부의 응력 해석

박치모(Chi-Mo Park),배병일(Byoung-Il Bae) 한국해양공학회 2011 韓國海洋工學會誌 Vol.25 No.5

Most ships and offshore structures are equipped with a variety of pipes, which inevitably contain curved portions. While it has been a usual practice to conduct bending stress analyses of these curved pipes using the straight-beam theory, this paper adopts two different types of finite elements, straight-beam elements and two-dimensional shell elements, for finite element analyses of a variety of curved pipes. It then compares the analysis results for two different types of elements to determine correction factors, which can be used to transform the bending displacements and bending stresses obtained by straight-beam elements to those obtainable by two-dimensional shell elements. The paper ends with a practical suggestion on how to efficiently use these correction factors to estimate the combined axial and normal stresses in a curved portion of a pipe.

선박용 파이프 루프 곡선부의 구조해석에 관한 연구

박치모(Chi-Mo Park),배병일(Byoung-Il Bae) 한국해양공학회 2010 韓國海洋工學會誌 Vol.24 No.5

Many pipes that are arranged longitudinally in ships have loops at intervals to prevent the failure of the pipes as they absorb large portions of the axial load caused by the bending if the hull girder and/or thermal loads when the pipes are carrying very hot fluids. Since the loops are curved at corners, an efficient method for conducting the structural analyses of these curved portions is required. In this paper, a pipe loop was analyzed by an analytical method and by the finite-element method in four different ways, i.e., based on straight-beam elements, curved-beam elements, 2-D shell elements, and 3-D solid elements. The results if the five analyses were compared to check the validity of the current curved-beam theory. The paper includes some suggestions on how to analyze the pipe loops efficiently.

코너부 곡률을 고려한 선박용 파이프 루프 설계식 개발

박치모(Chi-Mo Park),양박달치(Park-Dal-Chi Yang) 한국해양공학회 2009 韓國海洋工學會誌 Vol.23 No.4

Many longitudinally arranged pipes in ships are subject to considerable displacement loads caused by the hull girder bending of ships and/or thermal loads in some special pipes through which fluids with highly abnormal temperatures are conveyed. As these loads may cause failure in the pipes or their supporting structures, loops have been widely adopted as a measure to prevent such failure, with the idea that they can lower the stress level in a pipe by absorbing some portion of these loads. But since such loops have some negative effects, such as causing extra manufacturing cost and occupying extra space, the number and dimensions of the loops need to be minimized. This research developed design formulas for pipe loops, modeling them as a spring element, for which the axial stiffness is calculated based on the beam theory, incorporating the effects of the curvature of loop corners and the flexibility of the straight portion of the pipe. The accuracy of the proposed design formulas was verified by comparing two results respectively obtained by the proposed formulas and MSC/NASTRAN. The paper ends with a sample application of the proposed formulas showing their efficiency.

대형 선박의 파이프 루프 설계식 개발(Ⅱ)

박치모(Chi-Mo Park),양박달치(Park-Dal-Chi Yang),이종훈(Jong-Hoon Lee) 한국해양공학회 2009 韓國海洋工學會誌 Vol.23 No.1

Many logitudinal pipes in ships are subject to considerable loads, caused by hull girder bending in the ships and/or thermal loads in some special pipes through which fluids with highly abnormal temperatures are conveyed. As these loads may cause failure in the pipes or their supporting structures, loops have been waidely adopted to prevent such failure, based on the idea that they can lower the stress level in a pipe by absorbing some portion of these loads. But as the loops also have some negative effects, such as causing extra manufacturing cost, deteriorating the function of the pipe, and occupying extra space, the number and dimensions of these loops need to be minimized. This research developed design formulas for pipe loops, modeling them as a spring element, for which the axial stiffness is calculated based on the beam theory, incorporating the flexibility effect of the straight portion of the pipe. The accuracy of the proposed design formulas was verified by comparing two results obtained from the proposed formulas and MSC/NASTRAN. This paper concludes with a sample application of the proposed formulas, shoing their efficiency.

상용소프트웨어를 이용한 원환보강 원통의 최종강도 해석(Ⅰ)

박치모(CHI-MO PARK),이승훈(SEUNG-HOON LEE) 한국해양공학회 2001 韓國海洋工學會誌 Vol.15 No.2

Despite the increasing necessity of accurate estimation of ring-stiffened cylinders' ultimate strength, the complex structural behavior of cylinders has made their design mainly depend on empirical formulas mostly based on limited test data rather than theoretical background. This paper has developed the imperfection method which enables the ultimate strength analysis of buckling-sensitive structures by combining two separate functions covered by common commercial finite element softwares, which are linear elastic buckling analysis and nonlinear stress analysis. Developed method was applied to two of the world most renowned softwares, MSC/NASTRAN and ABAQUS, for the analysis of ring-stiffened cylinders and unexpectedly big difference in their analysis results was found. This tells that many widely used commercial softwares have their different strong points and weak points and the choice of commercial software should be cautiously made after thorough inspection. This paper ends with some useful information about which of the two aforementioned softwares is more appropriate respectively for the linear elastic buckling analysis and the ultimate strength analysis of ring-stiffened cylinders.