Features ensure structural safety ships under the action of loads from shock waves

The modern shipping market is characterized by an increase in the specialization fleet with the simultaneous increase in the ships size, in order to save costs on the scale effect. Nevertheless, the vessel of considerable dimensions, even being in full load, on the counter wave are extreme loads from the shock waves in the bottom and collapse of the sides. Taking into account the straightness of the contours of most merchant ships, the extreme forces at the extremities are mainly due to the action of slamming, whipping and flooding (from the rolling of waves). Additional loads when submerging the tip and leaving the water, when the hull is exposed, are characterized by high dynamic coefficients, which leads to a sudden increase in the stress level in the plates and the longitudinal set, which can significantly exceed the calculated and permissible parameters. In order to reduce the dynamism of shock loads, the vessels are forced to reduce the speed, which is limited mainly by the phenomenon of broaching when the vessel is suddenly lagged to the wave. At low speeds, the shock loads are linearized to a certain extent and do not depend on the shape of the hull contours to the extent that for high-speed vessels. The statistics of accident rate of sea vessels testifies that at an adverse combination extreme loadings from action of waves emergence of dangerous cracks and fractures of vessels in sections of extremities where the calculated bending moments have the minimum values is possible. Such accidents with the exhaustion of the level of structural safety occur with enviable regularity, both on new ships and on ships with significant service life. Accidents are usually explained by an increase in the level of effective stress concentration associated with an increase in the number of intermittent connections while optimizing the weight of the hull a modern marine vessel. The analysis of full-scale experiments and residual damages hulls of the vessels carried out by the authors allowed to reveal a number of essential features in work of designs at action of shock loadings which earlier dropped out of the field of view branch science. The authors, in the work, these features are considered on adequate mathematical models.