Fatigue Strength Assessment Of Wave Penetrating Catamaran(WPC)

Fatigue damage is a latent failure mode and one of the main collapse modes for naval architectures and ocean structures. Fatigue of ship structure is paid more attention by structure researchers and organizations in the world. At present, the main classification societies in the world have issued their own fatigue assessment rules of ship structures as the guidance notes. But the subject of fatigue strength evaluation in the many classification society rules is mainly focus on large vessel. Hot spots, loads and other issues of fatigue strength evaluation are not applicable for high speed craft, such as small water-plane area twin hull craft (SWATH), wave penetrating catamaran(WPC) and foil assisted hull. Fatigue evaluation method for high speed crafts is discussed in this paper, according to DNV Fatigue Assessment of Ship Structures and DNV Rules for Classification of High Speed, Light Craft and Naval Surface Craft. A fast WPC is studied in this paper. The main contents are as follows:(1) Introduce the basic principle points of DNV fatigue assessment methods and simplified method in DNV Fatigue Assessment of Ship Structures. The results of simplified FEM are analyzed.(2) The whole ship finite element model is built feasibly referring to ship structural drawing.(3) Introduce the loads calculation parts of DNV Rules for Classification of High Speed, Light Craft and Naval Surface Craft. The fatigue loads of WPC are calculated. The finite element model is analyzed under the loads.(4) The fine mesh size is defined in local part of the whole ship model. Very fine mesh zones incorporated into WPC model is analyzed. The hot spot stress is obtained by FEM. Evaluation of hot spot stress for fatigue analysis is accomplished.