Study On The Monitoring Method Of Ice Load Exerted On Hull Structure

As people's demand for energy continues to expand,the exploitation and transportation of oil and gas resources in the polar regions are increasing.The polar regions are rich in natural resources and have huge potential for resources.In addition to renewable resources such as fisheries,hydropower,wind power,and forests,there are also non-renewable oil and natural gas.The abundant natural resources in the polar regions have promoted the development of the shipping industry in the ice region.At the same time,its harsh natural environment and complex ice conditions have also caused certain threats to ships sailing in the ice region.Therefore,it is particularly important to analyze the ice load acquisition during the navigation of the ice area.The method for determining the ice load mainly includes numerical analysis method,model test method and hull monitoring method.The hull monitoring is divided into overall monitoring and partial monitoring.Based on the indirect monitoring method of local ice load on the hull,this paper focuses on the two major problems including ill-posedness of the mathematical model and unit size determination in the implementation process.The main work contents are as follows:A brief review of the application examples of the hull ice load determination method and the mathematical model of the local ice load indirect monitoring method,points out the ill-posedness of the mathematical model and studies the solution to the problem.The advantages and disadvantages of the regularization method and the new mathematical model based on new theory or hypothesis are discussed respectively.Finally,the ill-posedness of the mathematical model is eliminated from the root by optimizing the position of the measuring point.The finite element model of the icebreaker is established.Based on the finite element model of the whole ship and the local finite element model of the monitored area,the structure response of all candidate points is extracted to form the total transfer matrix.By comparing the differences of the transfer matrices obtained by the two methods,a more efficient and convenient total transfer matrix construction method is summarized.The specific application of D-optimal design and sequential exchange algorithm in measuring point optimization is studied.The hull three-dimensional curved frame structure and flat panel frame are used as examples to illustrate that the combined application of D-optimal design and sequential switching algorithm can completely eliminate the ill-posedness of the mathematical model.The indirect monitoring study of the local ice load of the icebreaker is based on the assumption that the ice load in each load cell is evenly distributed.However,this assumption depends on the size of the unit,and there is no basis for judging whether the unit is suitable.By dividing multiple load cell schemes on a flat panel and applying different functional loads,the rule of judging whether the unit division scheme can meet the precision requirement during the indirect monitoring process of load is summarized.Based on the above research conclusions,the method of optimizing the position of the measuring point,selection criteria for the number of measurement points,the selection of the load identification algorithm for solving the non-pathological problem,and the law of judging whether the size of the carrying unit is appropriate from the calculation result are verified and analyzed in the real ship.