Research On Fatigue Strength Assessment Method Of Container Ships

Container ship is one of the main type of transport ship in the world,it is popular due to its high transport efficiency and low costs.However,the fatigue strength problem of large container ships become more serious because of its large opening structural characteristic and the development of large-scale container ship.At Present,the researches in this field are not comprehensive and extensive.In the dissertation,the research on the suitable fatigue strength assessment method of the typical structure for large container ship was achieved combined with the fullscale calculation.The main contents are as follows:1)The fatigue strength assessment simplified method for the longitudinal structure was studied based on BV rules and CCS rules which are representative among all classification society rules,and the process of fatigue strength assessment was provided.The differences between two simplified methods presented by two rules were analyzed,and comaparetive analysis was carried out base on the fullscale assessment results.2)The conventional design wave approach and BV rule design wave approach of fatigue strength assessment for the hatch corner structure were respectively studied,and then the process and principle were provided.The introduction of hatch corner structure forms and characteristics were made.The comaparetive analysis was carried out base on the fullscale assessment results of two design wave approaches.3)The spectral fatigue analysis approach was studied as a more accurate method for the hatch corner structure which are on complex loading state,and then the process and principle were provided.The analysis was carried out base on the fullscale assessment results,and also the comaparetive analysis with design wave approach assessment results was carried out.4)For large container ship it's easy to induce bow slamming due to the large bow flare structure form,and the slamming will lead to sudden vibration which is referred to whipping,and whipping will cause serious fatigue damage.To solve this problem,a fatigue strength assessment method suitbale for enrineering application of large container ship was proposed based on three dimension nonlinear time domain simulation hydroelasticity analysis method.Then the analysis was carried out base on the fullscale assessment results,and also the comaparetive analysis with the assessment results under the effect of linear load was carried out.