As environmental regulations have become more onerous, the demand for LNG and LNG carriers has increased. The LNG cargo containment system (LNG CCS) is one of the most important facilities in LNG carriers, and many membrane types of LNG CCS have been developed so far. Traditionally, sloshing model tests are performed and a series of statistical approaches are used to obtain design sloshing pressures. Then, these design loads are utilized to analyze the structural safety of LNG CCS. In the sloshing model test, the flat and almost rigid plate is used as the LNG CCS instead of a real model, and thus, the hydroelasticity effect cannot be considered. In the present research, the effect of hydroelasticity on sloshing pressure was investigated in a fluid-structure interaction simulation. A wet drop simulation was conducted, and its results subsequently were compared with wet drop experimental test results to ensure their validity. Then, two types of structure model, namely a flat-rigid plate model and a flat-flexible CCS model, were generated to investigate the effect of hydroelasticity. Also, a fluid hitting analysis model was devised to realize the sloshing phenomenon, and the two generated structure models were applied as the structure domain in the analysis. In the fluid hitting simulations, it was found that the hydroelasticity effect on sloshing pressure is significant. Thus, correction factors, which are quantitative values of the effect of hydroelasticity, were derived (and are proposed herein). Finally, a structural safety assessment procedure for consideration of the hydroelasticity effect was derived (and is suggested herein). 相似文献
An overview of the many water-impact (slamming) problems in ship and ocean engineering is given. Theoretical and experimental
drop tests of horizontal and nearly horizontal elastic plates are reviewed. It is shown that maximum pressure cannot be used
to estimate maximum slamming-induced stresses when maximum pressure is large, because dynamic hydroelastic effects then become
important. Further, the significance of hydroelasticity increases with decreasing dead-rise angle, increasing impact velocity,
and increasing the value of the highest local natural period of the structure. It is emphasized that the slamming problem
must be hydrodynamically studied from a structural point of view. Comparisons between theory and full-scale measurements of
slamming-induced local strains in the wet-deck of a catamaran are presented. The importance of the rigid body vertical accelerations
and the influence of the side-hulls on the impact velocity are pointed out.
Received: October 4, 2000 相似文献
The relatively high rates of bulk carrier casualties in recent years, as well as structural features such as large deck openings, make this vessel type a suitable example for investigating the influence of hydroelastic modelling on predicting wave-induced loads and responses. Two- and three-dimensional fluid–flexible structure interaction models, due to their different degree of complexity and associated data requirements, can be used at different stages of the design process when estimating wave-induced loads, namely preliminary and detailed design stages, respectively.
In this paper, therefore, two- and three-dimensional hydroelasticity theories are applied to predict and compare the dynamic behaviour of a bulk carrier hull, based on OBO MV Derbyshire, in waves. Both symmetric and antisymmetric motions and distortions are incorporated in these investigations. The three-dimensional structural model consists entirely of shell finite elements, representing all major external and internal structural components, whilst the two-dimensional model is generated using Timoshenko beam finite element and finite difference discretisations. Issues relevant to the structural modelling stage, for both idealisations, are discussed. The in vacuo dynamic characteristics are compared for all models, with particular emphasis on the influence of hatch openings, shear centre and warping on the antisymmetric dynamics of the structure. For the wet analysis the fluid–flexible structure interaction is carried out using two-dimensional (Timoshenko beam and strip theory) and three-dimensional (beam and shell finite element idealisations combined with potential flow analysis based on pulsating source distribution over the mean wetted surface) analyses. Comparisons are made between steady-state responses predicted by two- and three-dimensional models in bow quartering regular waves.
It is shown that whereas the predicted symmetric dynamic responses obtained from two- and three-dimensional models are in good agreement, differences are observed for the antisymmetric dynamic characteristics. It is thought that this may be due to inadequacies in the beam models employed when simulating the global dynamic behaviour of this highly non-prismatic hull girder whilst allowing for the effects of warping. 相似文献
The theory and procedure established by Wu and Moan in 1996 and 2005 and Wu and Hermundstad in 2002 were applied to a high-speed
transatlantic pentamaran containership. Nonlinear time-domain simulations of ship motions and load effects were carried out
in different sea states. The simulated responses were validated against model tests with satisfactory results. The short-term
probabilities of exceedance were estimated by using different stochastic analysis procedures. The long-term probabilities
of exceedance were obtained based on the short-term results. These served as information about loading in a reliability-based
design approach. The load effects in a semiprobabilistic design were also calculated at an appropriate probability of exceedance
level. 相似文献