Dynamic Characteristic Calculation And Crack Damage Diagnosis Method Of I-section Crack Beam Structure

I-section and multiple I-section beam structures have been more and more commonly used in the field of aerospace,mechanical,civil engineering,and so on.Crack is one of the common diseases of the bridge structure.The structural dynamic characteristics such as natural frequencies and mode shapes will change because of the presence of cracks,which means that the dynamic characteristics have great potential for diagnosis of cracks.Thus,how to accurately obtain the dynamic characteristics of cracked bridge structures is a new research hotspot in the field of bridge engineering.Due to the existence of cracks,the local stiffness of bridge structure may reduce,and its service life will be affected.If cracks can be detected in time and certain measures are taken,further damage can be avoided.So it is imperative to study for research on dynamic characteristic calculation and crack damage diagnosis method of cracked I-section beam structure.The main research in this paper has been carried out as follow:1.Local flexibility of cracks of cracked multiple I-section beam is obtained.Mode shape functions of multiple I-section beam are obtained based on the recursive formula.Dynamic characteristic equation of multiple I-section cracked beam under arbitrary boundary conditions are obtained by solving boundary conditions.The natural frequencies and vibration shapes of cracked multiple I-section beam are calculated.Then the influences of crack depth,cracks location and number of cracks on the natural frequency are discussed.2.Dynamic characteristic calculation of multiple I-section beam under spring-mass system is established based on finite element simulation method and the dynamic characteristic.Numerical simulation of multiple I-section cracked beams carrying a springmass system are carried out.3.Two kinds of crack damage identification methods of cracked beams are formed.On the basis of the research results of determining the vibration mode function of multiple Isection cracked beams by recursive formula,a damage identification method based on low-order mode shape is obtained.Based on the finite element simulation method,the accurate calculation method of dynamic characteristics of multiple I-section cracked beams under the action of spring mass system is established.The crack damage identification method of multiple I-section beam under the action of spring mass system based on hybrid artificial neural network is formed,and the accurate identification of crack depth and position is realized.