International Shipbuilding Progress - Volume 33, issue 388

Authors: Senjanović, I. | Ljubetić, M. | Vukman, Š.

Article Type: Research Article

Abstract: An universal way for launching of ships and offshore structures by means of turning pads is described, that makes building structures on a horizontal berth possible and, making use of this advantage, leads shipbuilding to the high automatic industrial production. The launching system is now under construction after the extensive and complex theoretical and experimental investigations are terminated. The investigations were undertaken in order to verify the launching procedure and to define optimal values of basic parameters of the launching system for given conditions. Description of the launching system, investigation procedures and resulting analyses, will be published in several papers. …In this first paper a review of the performed investigations and some basic results are presented. Show more

DOI: 10.3233/ISP-1986-3338801

Citation: International Shipbuilding Progress, vol. 33, no. 388, pp. 218-230, 1986

Authors: Datta, T.K. | Jain, A.K. | Ramdasi, S.

Article Type: Research Article

Abstract: A parametric study is conducted to investigate the influence of some of the nonlinear effects produced by the variable submergence and the methods used for calculating hydro-dynamic forces, on the dynamic response of Tension Leg Platforms. The nonlinear effects included in the study are the variable added mass and the tension fluctuation in the tethers produced due to the variable buoyancy and the vertical wave forces. In addition, the nonlinearity due to relative-velocity squared drag force is considered. Hydrodynamic forces on the large diameter members of the super structure are obtained by means of modified Morison’s equation using (i) average …water particle kinematics across the diameter of the members, (ii) water particle kinematics calculated at the centre of the cross-section, and (iii) water particle kinematics same as (ii) above, but the inertia coefficient is modified to take into account any diffraction effect. The effect of variable submergence on the water particle kinematics is included by both Chakrabarti’s [1] and Hogben’s [2] approaches. The nonlinear equation of motion is solved in time domain by using iterative step by step integration procedure. Two integration algorithms namely. Newmark’s – beta-method and Argyris 3rd order integration scheme have been used. Relative efficiencies of the two integration schemes have been examined in relation to obtaining the steady-state surge response of the T.L.P. Show more

DOI: 10.3233/ISP-1986-3338802

Citation: International Shipbuilding Progress, vol. 33, no. 388, pp. 231-236, 1986