Hydrodynamic elastic response analysis of ship hulls considering slamming impact loads due to the voyage in large amplitude regular and irregular waves is conducted. Ship hull structures are modeled as elastic body on the base of Timoshenko's beam theory. The momentum slamming theory is used to derive nonlinear hydrodynamic forces considering the intersection between wave particles and ship section. The hydrodynamic coefficients are derived in time domain considering the memory effect, which numeric approach was proposed by Xia(1998). The irregular waves are represented in time domain using single summation method and ISSC wave spectrum. From the developed program, we can obtain the various design information such as time histories of relative displacement, velocity, acceleration, vertical shear force, and vertical bending moment of all sections of ship involving the effects of slamming.
When a ship navigates in rough seas it frequently experiences various types of impacts from the waves including slamming impact. If the slamming has produced sufficient momentum, the ship hull may vibrate vertically, horizontally, longitudinally, torsionally, or in any combination of these, depending on what portion of the ship has been affected. Generally this hull vibration is referred to as whipping. Associated with this whipping phenomenon, the ship can take appreciable hull stress.
Jasper and Church (1963) developed a theoretical analysis of hull whipping induced by bow-flare type of slamming for head sea condition considering the relative velocity of the hull section to water surface. Chuang (1981, 1982) expanded the previous theory in the field of horizontal and torsional mode of the hull. On the other hand, Bishop etc. (1978, 1979) used a non-uniform Timoshenko's beam model and calculated slamming forces using a semi-empirical approach, where impact pressures were based upon the method of Stavovy and Chuang (1976) with momentum theory proposed by Leibowitz(1961, 1963).