Optimal AE Sensor Locations Research Based On Non-destructive Testing Of Offshore Platforms

As the large basic facilities of offshore oil resource development, offshoreplatform is the base of activities and production on the sea, whose place of theenvironment is very bad, it’s so easy to cause the structure damage, leading to theentire structure failure. The structure destruction of offshore platform willdirectly endanger the life safety of personnel on the platform, and cause greateconomic losses and serious Marine pollution of the environment. Detection ofoffshore platform State is the important link of the safety and protection on offshoreplatform. Acoustic emission signal is from the defects of material itself,whenmonitoring offshore platform by acoustic emission technology, the defect of acousticemission signal of the defect can be receiving by sensors,which make the changeof the defects be mastered in time by staff,so as to avoid the happening of the majoraccident, and to improve the safety of the offshore platform.There are so much structure node on Offshore platform, and unit price of sensoris expensive. From the economic into consideration, we hope that the sensor are aslittle as possible to obtain the comprehensive information and the precise positioning,therefore, the optimal number of sensor selection and spotting optimization is verynecessary. This is a limited point problem.This paper are in research the problems of the AE sensor optimization placementon offshore platform in study, whose purpose is to ensure the best possible solutionefficiency and benefit, to achieve the purpose of structural health monitoring underthe premise of getting enough in structural health status information, guaranteeing theaccuracy of the nondestructive testing results and positioning precision.Firstly, we take a service of jacket platform in the Bohai Bay for thestudy,ANSYS software is used to make the three-dimensional diagram.We use graphtheory to numerical modeling of offshore platforms, the model is abstracted as a graphtheory problem: Each node is instead of a vertex, Connection node of each jacket steel pipe connected to one side of the corresponding two vertices instead, so we get agraph. Graph always expressed by matrix methods.Finally, We draw the graph to aweighted matrix representation.Secondly, On investigating the introduction of Acoustic emission mechanism ofcrack formation and extension、AE wave propagation and attenuation，Underlaboratory conditions，We do off lead analog AE experiments on an steel pipe who is6m long, getting different signal amplitude the AE sensor received when sensorare in the different Off lead position from off lead position.From the experiment wederive detection range of acoustic emission sensors on Offshore platforms, whichprovide the basis for the sensor arrangement.Finally, On the combination of graph theory,We use the greedy algorithm tooptimize the sensor arrangement,give the implementation of system programs tooptimize the arrangement of emission sensors.According to project needs anddifferent location methods, two optimization programs are put forward and throughverification.The results show that this method is effective in practical applications,and the number of sensors needed is very little, therefore, The program has features ofpractical application of engineering-oriented、 low economic cost、easy to operate.