The Application Of Structural Fatigue Strength Assessment Rules Of Civilian Ship In Military Vessel Design

With the increasing development of Chinese Navy,fatigue problems of military vessels have been paid more attention to.In recent years,civilian rules have developed at a stunning rate,but the development of naval rules is not as fast as that of civilian ones.Therefore,combined its own characteristics of naval ships with advanced fatigue assessment method referred,systematic research on fatigue assessment for naval hulls can be carried out to provide technical support.The possibility of applying fatigue assessment for civil ships to naval ones is emphasized in this thesis,and the main study includes the following aspects:1)Four simplified fatigue calculations are studied systematically by analyzing the specification for commercial ship rules and warship rules.The comparison of civil fatigue rules gives references and application of civilian rules in military vessel design.2)According to the principle of spectral fatigue analysis,specific research is conducted to apply spectral fatigue analysis to fatigue assessment of military vessels.Also detailed instructions are proposed to key issues.3)Wave slamming loads are calculated based on 3D-hydroelastic nonlinear time domain theory,and the influence of slamming on the fatigue load is taken into consideration.Combined with equivalent damage principle,new methods are proposed to solve fatigue strength assessment with slamming effects considered.The advantages and disadvantages as well as limitations are listed by comparing these methods.4)According to various simplified calculation method,direct spectral fatigue analysis and calculation methods considering slamming effects,a naval vessel is assessed in terms of fatigue strength as an example.