Research On Wave Load And Fatigue Strength Of Aluminum Alloy High Speed Ship

In recent years, the failure of ship structural component which caused by fatigue problems have been more and more prominently. For aluminum alloy vessels, which mostly are high-speed vessels, the resistance to fatigue is weaker than steel vessels. Structure of high-speed vessels often bears alternating stress that waves slam. Because of the slamming flutter stress, the fatigue damage is greater than low-frequency waves stress caused. Therefore, for the accurate prediction of the life of aluminum alloy vessels and limit state, the research of structure fatigue strength is meaningful.The work of this article is to assess the structural fatigue strength of a 60m aluminum alloy high-speed vessel by using fatigue simplified algorithm and direct calculation of the spectral analysis. The main contents are as follows:1. Introduce the basic principles of fatigue assessment methods, including the S-N curve and the Miner linear fatigue cumulative damage theory based on the function of continuous load spectrum and continuous piece wise load spectrum.2. According to "The hull structure fatigue strength of guide 2007" and "Rules for construction and classification of Sea-going high-speed craft" by CCS, the simplified algorithm of fatigue load, the stress range calculation and the degree of fatigue damage accumulation are discussed in detail. And the fatigue life of eight longitudinal beams at the junction of board and the bulkhead is also calculated.3. Describe the basic principles of the spectral analysis methods of fatigue strength assessment, including the transfer function of fatigue stress response, structural stress response spectrum, short-term and long-term distribution of stress range and the cumulative fatigue damage calculation.4.Use Hydrostar to calculate the movement response in regular waves and wave loads and get the hydrodynamic pressure of hull surface, Research on wave loads of aluminum alloy high speed ship.5. By using MSC.PATRAN to build a 60m ship model of finite element and refinement hot spot stress zone. Through self-programming automatically extract the finite element analysis results. then calculate fatigue life and the degree of fatigue damage accumulation at the hot spot, and analyze the fatigue assessment results of aluminum alloy high-speed vessel.