Now showing 1 - 3 of 3
  • Placeholder Image
    Publication
    Roll dynamics of a Ro-Ro ship
    (01-12-2002) ;
    Venkata Ramana Reddy, J.
    The prediction of ship stability during the early stages of design is very important from the point of safety. Ships experience six modes of rigid body motions in a seaway, which can be split into two groups as translatory and oscillatory motions. Out of the six motions of a ship, the critical motion leading to capsize of a vessel is the rolling. In the present study, particular attention is paid to the performance of a ship in beam sea. The rolling motion of a ship has been described by a nonlinear differential equation taking into account the nonlinearities in both the restoring moment and the damping moment. Solution of differential equation of roll motion is sought using MATLAB. The effect of different representation of restoring moment on roll motion is investigated. It is seen that, the effect of different representation of restoring moment on roll motion depends on the characteristics of the GZ curve. A parametric investigation is undertaken to identify the effect of different parameters viz., wave steepness, encountering frequency etc., on the capsizing conditions of a ship. The rolling response of ship is determined in the frequency domain. The analysis has been carried out by varying both the wave steepness and the wave frequency. The approach has been demonstrated considering a Ro-Ro ship as test vessel.
  • Placeholder Image
    Publication
    Numerical simulation of ship stability for dynamic environment
    (01-01-2003) ;
    Venkata Ramana Reddy, J.
    The prediction of ship stability during the early stages of design is very important from the point of vessel's safety. Out of the six motions of a ship, the critical motion leading to capsize of a vessel is the rolling motion. In the present study, particular attention is paid to the performance of a ship in beam sea. The linear ship response in waves is evaluated using strip theory. Critical condition in the rolling motion of a ship is when it is subjected to synchronous beam waves. In this paper, a nonlinear approach has been tried to predict the roll response of a vessel. Various representations of damping and restoring terms found in the literature are investigated. A parametric investigation is undertaken to identify the effect of a number of key parameters like wave amplitude, wave frequency, metacentric height, etc. © 2002 Elsevier Science Ltd. All rights reserved.
  • Placeholder Image
    Publication
    Non-linear roll dynamics of a Ro-Ro ship in waves
    (01-10-2005) ;
    Lee, S. K.
    ;
    Reddy, J. Venkata Ramana
    ;
    Lee, Gyoungwoo
    This paper is a continuation of a technical note published in Ocean Engineering in Vol. 30 (2003). Stability of Ro-Ro ships was subjected to rigorous investigation by many researchers recent past. Stability of a ship is to be ensured during design stage for various loading conditions. Two typical conditions of departure and arrival are usually chosen by naval architects. Out of all types of motions of a ship, the critical motion leading to capsize is the roll. Ship roll motions are very complicated and difficult to analyze, as there are various parameters involved in the motion. Large angle roll motions are nonlinear in many aspects. For larger angles of roll many nonlinearties become significant. Various representations of damping and restoring terms found in the literature are investigated and their solutions are analyzed. Data of a Ro-Ro vessel is used to demonstrate the applicability of the proposed procedure. In the present study, the problem of ship safety has been considered with regard to the rolling motion of a ship in beam waves. A parametric investigation is undertaken to identify and quantify the effect of a number of key parameters viz., wave slope, wave frequency etc. on the capsizing conditions of a ship. Nonlinear response of ship is determined in the frequency domain. © 2005 Elsevier Ltd. All rights reserved.