Dynamic problems of propulsion system of naval vessels

Ship propulsion systems are subjected to specific sea loads due to waving and dynamical impacts associated with mission of a given ship. Sea waving can be sufficiently exactly modelled by means of statistical methods. Knowledge of a character of impulse loading which affects ship shaft line can makes possible identifying potential failures by means of on-line vibration measuring systems. The modelling of impulse impact form and next its identification makes possible identification of explosion power, distance from explosion epicentre, a kind of explosion, elastic or plastic deformation of shaft line. The presented results related to the performed experimental test do not make possible assigning unambiguously the modelled signal features to those of the recorded ones during the real test. Analysis of forces acting on shaft-line bearings, problems of underwater explosion, and models of excitation due to underwater explosion has been described in the paper. In particularly simulated static bending stresses in propeller shaft due to weight of propeller, a simplified shaft-line model for critical speed calculation, run of changes of shock wave pressure and ship hull acceleration measured on hull surface during underwater explosion, schematic diagram of the performed experimental test, run of the assumed vibration acceleration model, spectrum of the assumed vibration acceleration model are represented.