Simulation System for Dynamic Analysis of the Ship Structures

A vibration and fatigue simulation system^[1]–[3] based on the dynamic analysis in time domain of the ship structures when subjected to a certain sea state is presented. The development of the system is based on VC++ and OpenGL. The system covers the simulation of 3D waves, ship hull, free vibration and forced vibration of the ship, as well as the fatigue damage prediction of the ship structures. Irregular waves are simulated by linear superposition of a series of regular cosine waves for a certain sea state. On the basis of this expression of the irregular waves, the wave loads can also be obtained in a similar way. The stress history of the ship structures may be acquired by a dynamic response analysis. The free vibration of the ship hull can give the natural frequencies and the relevant vibration modes. The forced vibration can show the time variant displacement, velocity and acceleration caused by the exciting force of the propeller, main engine and wave slamming. The fatigue prediction is performed by means of rain flow counting and Miner rule^[16]. The numerical example shows the system is applicable in the vibration response and fatigue perdition of the ship structures and the visual interface is user-friendly.