Research On Ship Structure Monitoring And Assessment System For The Polar Ship

In recent years,global warming has accelerated the melting of Arctic ice and snow.In the context of economic globalization and the deepening of regional integration,the value of the Arctic in terms of strategy,economy,scientific research,environmental protection,shipping channels and resources has been continuously raised.China should seize the opportunity to ensure that its interests in these regions are not infringed.Compared with Finland and Russia and other near polar countries,there is less data on polar environment information in our country at present,and the design and construction experience of polar vessels is alsorelatively insufficient.However,the structural design based on the rules and the finite element simulation can hardly comprehensively and accurately assess the risk of the polar ship hull structure in the real polar environment.Therefore,it is necessary to monitor and evaluate the shipstatus in service through intelligent equipment to assist the crew in making decisions.Based on the sensing technology and LAN technology,the state monitoring and evaluation system for polar ships can not only evaluate the strength of the hull structure in real time,but also store the evaluation results for a long time.This will not only allow researchers and shipping personnel to grasp the state of the polar vessel structure in real time,but also provide researchers with valuable reference data for future design and research.Therefore,in the moment when the requirements of ship intelligence are gradually increasing,Ship Structure Monitoring and Assessment System will become an essential choice for polar ships.The main contents of this paper include the followings:1.According to the characteristics of the polar ship and the purpose of the different monitoring points in the stress monitoring system,the methods of selecting points are given separately.There are two characteristics of the polar region,i.e.the ice load and the low temperature.They are fully considered in this paper.And the candidate measuring points can be optimized through the method of comparing the stress response between the intact ship and ship which candidate element is damaged.At the same time,the solution of correcting drift of sensor caused by low temperature is given.2.The load inversion method that can be used in polar ships is proposed,which are respectively the shear stress distribution method and the influence coefficient matrix method,and the theoretical models and examples are both given.For the influence coefficient matrix method,the stress response of the model under impact load is calculated by finite element method.The calculation of load inversion has also been designed.At the same time,the effect of measuring point on the inversion results is also analyzed so that a reasonable arrangement of measuring points for inversion of load can be given.3.After the location of the monitoring points has been determined,methods of strength assessment based on real-time stress data are also given to evaluate the yield strength and fatigue strength.On the basis of the traditional assessment methods,the influence of low temperature and dynamic effect on the structural strength is also considered for polar ships.Finally,two methods of damage identification are proposed to identify the deformation and the change of natural frequencyof the structure respectively.