Buckling Strength And Fatigue Strength Research Based On Common Structural Rules For Double Hull Oil Tankers

Since the last decade of the twentieth century, due to the increasing focus on the global marine environment, the governments of many countries and the international societies of ship industry have paid more and more attention to the security problem of Oil Tankers. In order to meet the need of designing, building and testing of the modern ships, it is necessary to develop a system of easily applicable and apprehensible rules based on the basic mechanical principles. Under the background mentioned above, IACS (International Association of Classification Societies) organized the major Classification Societies all over the world to the compile Common Structural Rules for Double Hull Oil Tankers and Common Structural Rules for Bulk Carriers, which have come into effect since the 1st April,2006.So as to better understand CSR, the theories and approaches applied need profound analysis and interpretation. The purpose of this thesis is to probe the theory and method of the evaluation of buckling strength and fatigue stress in CSR. Buckling strength is an essential and complicated subject in ship construction. Fatigue problem is a very important cause to marine accidents, for which the problem of cumulative damage in fatigue, esp. the check research on fatigue strength in some key areas is quite necessary. Besides that, to solve the fatigue problem needs a large amount of verification tests and rich long-time earned practical experience to reach reliable approach and result. This thesis deals with the problem of buckling strength and fatigue strength through the following aspects:(1) Though the discussion about buckling of steel boards and buckling theory, this thesis deepens the understanding of the testing method in Common Structural Rules for Double Hull Oil Tankers.(2)The profound analysis of the relative requirements about "advanced buckling Analyses" in CSR builds the foundation for specific engineering calculation.(3) This thesis evaluates the buckling strength of a 27000DWT oil tanker carrying chemicals, gains a reasonable calculation result and offers suggestions for the improvement of the virtual structure of the ship. (4) The study on theory of cumulative damage in fatigue deepens the understanding of fatigue testing theory in CSR.(5) This thesis studies the evaluation method of ship structural fatigue, elaborates the method of identification and calculation of a ship's fatigue load and emphasizes the introduction of S-N curve and the theory and application of cumulative damage in fatigue.(6) Applied with the fatigue strength evaluation method based on the hot-spot stress of FEA, the lower bending angle of the hopper tank in 27000DWT oil tanker gets the fatigue strength testing, which turns out be to a satisfactory result and proves the effectiveness of the fatigue strength evaluation method in CSR.(7) In the end of the thesis is a concise conclusion and the prospect of the study also gets out laid.