An experimental study of hull girder loads on an intact and damaged naval ship

Abstract

The study reported in this paper is focused on experimental investigation of the hull girder loads on an intact\ud and damaged naval ship DTMB 5415 at zero speed. The experimental campaign was carried out in head and\ud beam regular waves at the University of Strathclyde. The effect of the use of moorings in the model experimental\ud setup was investigated in the context of loads assessment, and the moorings are shown to influence the\ud measured hull girder loads at some wave frequencies compared to the free drift case. Therefore the tests in beam\ud seas are performed with free drifting model while the moored model setup was adopted for head seas. The\ud results for ship motions are compared with those from a previous campaign giving an insight into repeatability\ud and uncertainty of measurements. The roll decay of the ship in both intact and damaged conditions is analysed\ud and the linear and quadratic extinction coefficients for the model and the ship scale are reported and detailed\ud discussion on intact-versus-damaged ship roll damping behaviour is given. The results for the hull girder loads\ud are presented for intact and damaged ship. An investigation of the nonlinear effects due to wave height variation\ud in the range wave height to wave length from 1/50 to 1/22 on the shear force and bending moment values was\ud carried out for a range of wave lengths to ship length ratios from 0.8 to 1.4. The results of the extensive\ud campaign are compared against similar experimental studies forming a benchmark data for validation of\ud numerical methods

Experimental Investigation of the Mooring System of a Wave Energy Converter in Operating and Extreme Wave Conditions

“…The objective is the calculation of the damped natural frequency and the identification of linear and quadratic damping of the model, via logarithmic decrease analysis. The methodology used in [40,41] has been chosen as the most effective in this study. Pitch free decay tests were carried out on the free model applying manually an inclination angle with respect to the transverse or longitudinal axis of the hull.…”

Excessive Acceleration Criterion: Application to Naval Ships

“…Alternatively, an estimation of roll damping could be performed, referring to experimental results or numerical simulations. In the first case, a roll decay test should be performed, and an estimation of linear, quadratic, and roll damping coefficients could be made from the time history of decay [29]. If a numerical simulation is performed, great attention should be dedicated to degrees of freedom, grid refinement, and dimensions of the domain, which represent the main sources of uncertainty, because is still limited the experience of simulations of this phenomenon.…”

Verification and validation of numerical modelling of DTMB 5415 roll decay

“…Roll decays have been performed for the well-known benchmark naval hull form DTMB 5415, used in experimental campaign in Begovic et al (2013bBegovic et al ( , 2015Begovic et al ( , 2017. The main particulars of the fibreglass model (1/51 scale) are given in Table 1.…”