Research On Defect Location Of Steel Bar Based On D-S Data Fusion And Multiple Damage Indicators

As the basic component unit of large structures,steel bars is widely used in the fields of machinery,architecture,transportation and other fields.Due to the influence of the environment and the force condition,it is easy to produce cracks,corrosion pits and other defects.If it is not checked in time,the damage will be expanded,which will cause damage of the whole structure and is very easy to cause a major accident.Therefore,it is necessary to detect and study the damage of the steel bar in advance.In this paper,the damage of the steel bar is identified by using the theory of modal analysis and experimental modal analysis.And D-S evidence theory is used to fuse the data obtained by different damage identification methods.The main work is as follows:1.The research status of structural damage identification based on modal analysis is summarized,and the research status of structural damage identification based on modal testing at home and abroad is introduced,and the basic theories of various modal analysis methods are introduced.2.The Ansys finite element software is used to analyze the theoretical mode of the steel bar with cracks and corrosion pits.Simulation of cracks with rectangular notch and simulation of corrosion pits with elliptical pits are carried out.Through the modal analysis,the natural frequencies,the modal shape and other modal parameters of the damage bar are obtained.3.Methods of the modal curvature,modal curvature change rate,and modal strain energy change rate are used to deal with the theoretical mode shapes with different defects,and the corresponding damage location indicators are obtained respectively.Compare the advantages and disadvantages of these three kinds of damage index and select the optimal index synthetically.4.Modal test bench is set up,and the modal experiment is carried out on the steel bar with defects(cracks and corrosion pits),the modal analysis software of "DHDAS" is used to analyze and collect data.According to the method of modal curvature,modal curvature change rate,and element modal strain energy change rate,the experimental data are processed,which can obtain the corresponding damage location index.Finally,D-S evidence theory data fusion rules are used to determine the final damage location.In this paper,the location identification of the steel bar with defects is carried out from the view of theory and experiment,which provides reference for the nondestructive identification of dynamic and complex structures.