Research On Acoustic Emission Monitoring Technology Of Offshore Platform Structure

Due to the severe sea conditions,large-scale offshore engineering equipment such as ultradeepwater drilling platforms undergo large changes in external loads and internal stresses during service,and the structure is prone to fatigue cracks,which reduces load-bearing capacity.Therefore,R&D can be used to monitor the safety of offshore platform structures in real time.The acoustic emission testing technology is necessary to realize the safety monitoring and damage warning of the structure.This paper aims at the safety monitoring of large-scale ocean engineering structures such as ultra-deepwater drilling platforms.Based on the characteristics of large-scale oceanographic structure acoustic emission detection,an acoustic emission monitoring hybrid positioning method suitable for large ocean engineering structures is proposed for the first time;The large-scale strut model is the research object,and the study of the acoustic emission attenuation characteristics of the strut structure and the acoustic emission characteristics of the strut structure under combined load and bending load and bending and shear loads are studied.The main work of the paper includes:(1)The acoustic velocity sound velocity measurement method and attenuation characteristic measurement method are described in detail.The sound velocity of the super-large floating body strut is measured by using the material acoustic matrix automatic test method.The acoustic emission attenuation characteristic of the strut is studied by the Hsu-Nielsen method.The acoustic attenuation characteristics of the strut bar,the circumferential direction and the 45° direction were analyzed.The influence factors of the attenuation characteristics of the strut acoustic emission signal were analyzed and discussed.(2)Aiming at the problem of acoustic emission monitoring and positioning of offshore platforms,For the first time,an acoustic emission monitoring hybrid positioning method was proposed by using finite element stress field analysis for regional hazard classification,combining acoustic emission time-of-flight positioning method and regional positioning method.A logic flow chart of acoustic emission monitoring hybrid positioning method is given.(3)The ultimate strength analysis of the strut structure under combined load and bending loads and combined bending and shearing loads was carried out,and the ultimate load,failure mode and stress distribution of the struts under these two typical conditions were obtained.According to the stress analysis results,the division of key measurement areas and key areas of interest in the acoustic emission monitoring hybrid positioning method was performed.(4)Acoustic emission real-time monitoring of the strut model under combined load and bending and shear loads was carried out,and the acoustic emission signal characteristics of the strut structure during loading were obtained.Comparing and analyzing the correspondence between acoustic emission signals and structural deformations,and the rationality and effectiveness of the acoustic emission monitoring hybrid positioning method are verified.