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Study on Section Properties of Asymmetric-Sectioned Vessels

선박의 비대칭 단면 특성에 대한 연구

  • Choung, Joon-Mo (Dep't of Naval Architecture and Ocean Engineering, Inha University) ;
  • Kim, Young-Hun (Dep't. of Naval Architecture, Ocean & IT Engineering, Kyungnam University)
  • 정준모 (인하대학교 조선해양공학과) ;
  • 김영훈 (경남대학교 조선해양IT공학과)
  • Received : 2010.09.29
  • Accepted : 2010.11.16
  • Published : 2010.12.20

Abstract

This paper presents definition of symmetry of a ship section where three symmetries are proposed: material, geometric, and load symmetries. Precise terminologies of centroid, moment plane, and neutral axis plane are also defined. It is suggested that force vector equilibrium as well as force equilibrium are necessary condition to determine new position of neutral axis due to translational and rotational mobility. It is also stated that new reference datum of ENMP(elastic neutral moment plane), PNMP(fully plastic moment plane), ENAP(elastic neutral axis plane), and INAP(inelastic neutral moment plane) are required to define asymmetric section properties such as second moment of area, elastic section modulus, yield moment, fully plastic moment, and ultimate moment. Since collision-induced damage and flooding-induced biaxial bending moment produce typical asymmetry of section, the section properties are calculated for a typical VLCC. Geometry asymmetry is determined from ABS and DNV rules and two moment planes of 0/30 degs are assumed for load asymmetry. It is proved that the property reduction ratios directly calculated from second moment of area are usually larger than area reduction ratio. Reduction ratio of ultimate moment capacity shows almost linearly proportional to area reduction ratio. Mobility of elastic and inelastic neutral axis planes is visually provided.

Acknowledgement

Supported by : 인하대학교

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Cited by

  1. Residual Longitudinal Strength of a VLCC Considering Probabilistic Damage Extents vol.49, pp.2, 2012, https://doi.org/10.3744/SNAK.2012.49.2.124