The forecasting for ship motion and load is always an important issue for the design of hull structure. It had a direct impact on the security capability of ship in the actual navigation. Therefore, based on the potential flow theory and hydroelasticity method, a comprehensive research on time domain prediction of ship motion and load is studied in detail. According to typical wave spectrum, the calculation of short-crested waves is established. And the interaction between hull and wave in complex ocean environment is simulated using nonlinear hydroelasticity method. Finally, the characteristics of ship motion and load in different wave cases are analyzed. And some advices are given to guide the ship design and navigation.
With the development of ship scale, hull hydroelasticity effect in waves is becoming more and more evident. And the dynamic phenomenon of springing and whipping in hull structure during the ship navigation often happens. Therefore, the reliability of hull structure strength under hydroelasticity vibration has gradually become an important index in the field of ship design.
In order to effectively simulate the structural response of ship in waves, the potential flow theory was developed. And the numerical simulation of ship motion and wave load was studied using ideal inviscid fluid. The general hydroelasticity prediction in the shipbuilding industry is divided into two main methods, which are frequency-domain potential flow method and time-domain potential flow method. For the frequency-domain potential flow method, the relatively simple frequency-domain Green function is often applied to obtain ship motion and low-frequency wave load quickly and effectively in the numerical simulation of interaction between ship and wave. Although the traditional frequency domain method is relatively highly efficient, there are still some shortcomings in the numerical simulation of nonlinear loads, especially towards the high frequency wave-induced vibration. But for time-domain potential flow method, due to the consideration of time variation in the numerical simulation, its advantages appear obviously in instantaneous wave force. Therefore, in order to further consider the impact of high-frequency load like slamming, a series of research for motion and load simulation were taken using the time-domain hydroelasticity forecasting method. Combining the theories of hydrodynamics and hull elastic deformation, Heller and Abramson (1959) firstly proposed linear hydroelasticity method for ship navigation in waves. Then, Kaplan (1972) simplified ship as an elastic Timoshenko beam and calculated hull motion and load. In his research, the wave slamming was also simulated as a kind of nonlinear excitation in time domain. The hull bending moment in irregular wave is synthesized further using wave-induced bending moment and slamming bending moment in Dai (1980) research. And, according to the cubic spline function and momentum slamming theory, Li (2009) developed a kind of time-domain hydroelasticity forecasting method to consider the nonlinear characteristics of slamming and wetted surface caused by large-scale hull motion. Yu (2018) also applied this time-domain method to simulate the hydroelasticity vibration responses of a large ship sailing in regular and irregular waves. The numerical results are proved to be effective by comparing with the experimental results in the segmented model test.
