MFC-based Stress Intensity Factor Montoring And Fatigue Life Assessment Of Damaged Structure

The fracture of the engineering structure due to fatigue can cause unpredictable hazards.The structural health monitoring of marine structures is one of the effective approaches to avoid structural failure caused by cyclic loading and structural deterioration.With the development of marine resources,offshore platforms and deep submersibles are developing rapidly.Traditional structural monitoring methods are difficult to meet the requirements of complex marine environments for the health monitoring of marine structures.Therefore,there is an urgent need for a structural health monitoring system that can be applied to the marine environmentThis paper aims at the problems of high noise and low sensitivity of traditional structural health monitoring system in complex marine environment,and carries out a marine structural health monitoring research based on stress intensity factor.A set of structural health monitoring programs was designed based on using macro fiber composite sensors to obtain real-time stress intensity factors during fatigue crack growth of marine structures.And fatigue crack growth Lifetime research was conducted combined with linear elastic fracture mechanics.The main research contents and research resuits of this article are as follows:(1)Design the health monitoring system program,build a test platform,and explore the MFC sensor acquisition method of stress intensity factor.(2)Simulate the stress intensity factor of the cracked structure using the extended finite element method,and the simulation data of the structure under various working conditions is analyzed and fitted to obtain the SIF extended formula,so as to replace the empirical formula in complex structures and boundary conditions.Expert system to evaluate the security of the system.(3)Write SHM system combined with Paris fatigue crack growth formula using Qt.The collected basic data is converted into an assessment of the structural fracture rate and remaining life,and a complete set of structural health monitoring system is obtained.Finally,the safety assessment and remaining life prediction of the structural health monitoring system for the structure are verified through experiments,and the feasibility of the structural health monitoring system in this paper is verified.The comparison of experimental solutions,numerical solutions and empirical formulas verifies the accuracy of the SIF expansion formula obtained by numerical simulation and the feasibility of structural health monitoring systems including MFC sensors in fatigue crack monitoring.The results show that the structural health monitoring scheme in this paper is reasonable and feasible,and has practical significance for practical application in marine structures.