Prediction Of Non-upright Damaged Ship’s Motion And Wave Loads

For vessels are often facing the danger of compartments flooding caused by damagedstructure in some cases, aimed at improving the safety of vessels and giving more accurate loadsinformation to residual strength assessment, researches on prediction of damaged ships’ motionand wave loads were carried out.Firstly, damaged hulls with heeling angles were selected as the focus, and damaged vessels’floating conditions were calculated based on the weight of flooding water and the position ofdamaged compartments.Based on the interpolation method with B-spline curve, the programmodeling and meshing hulls’3D wet surface was developed to provide mesh information for thefollowing hydrodynamic calculation.Secondly, calculation method of damaged ship’s motion and wave load in frequency domainwas studied based on3D linear potential theory. As Green function’s numerical calculationmethod is the key for potential theory, numerical calculation method and property of finite andinfinite water-depth Green function were studied, and the finite water-depth Green functioncalculation program was developed. The effect of vessels’ speed was taken into consideration bythe method of assuming high encounter frequency and low forward speed. Non-upright vessel’smass matrix and hydrostatic restoring matrix were derived to calculate the damaged ship’sresponse in wave, including the ship’s motion and wave excitation load. Wigley III hull’shydrodynamic coefficients、wave-induced loads and motion were calculated and numericalresults were compared with tests’ and Wadam program’s results.The self-developed program wasfitted well.Thirdly, intact and damaged vessel models’ tests were carried out in basin. The models’motion and wave-induce loads in regular wave were measured. Numerical predictions match theresults of model tests well. Further more, the influence of damage and heeling angle to thevessel’s responses in waves was analysed by comparing the intact vessel’s responses with thedamaged one’s.Finally, the responses of a205,000t bulk carrier in intact and damaged condition werecalculated by the self-developed program.The results in intact condition were compared with testand Sesam program. The influence of damage and heeling angle to the bulk carrier’s motion andwave-induced loads was analysed. The damaged bulk carrier’s wave-induced loads werecalculated by rules’ formulas、short term prediction and long term prediction,and the differences were studied. Moreover, the motion and wave loads of a damaged bulkship were studied in finitewater-depth and the effect of finite water-depth was analysed.