Study On Crack Parameter Identification Of Beam Structure

Beam structure,as an important bearing and component unit,has been widely used in aerospace equipment,mechanical equipment,highway bridge structure and other industries.To develop crack parameter identification technology of beam structure is an important guarantee to avoid or reduce accidents or disasters,and realize the safe operation of the structure.This paper studied the crack parameter identification of beam structure based on the curve of frequency influence and the static deformation,and derived local flexibility equations with the crack arbitrary crack direction of beam structure.It provides a reference for the dynamic analysis of the beam structure with crack and crack detection.Based on the study of the relationship between the crack parameters and the natural frequencies of the beam structure,a method of the crack parameters identification is established by using dynamic modeling and vibration testing.In this method,the local flexibility and position of the crack can be determined by testing the whole structure or local structure.Furthermore,the crack depth can be further identified on the basis of the relationship between the local flexibility and the crack depth.The method is simple and suitable for parameter identification of different types and shapes of cracks.Based on the principle of strain energy,a method for measuring the crack equivalent stiffness of beam structure based on the principle of static deformation is proposed by studied on the relationship between the crack equivalent stiffness and the deflection of the beam structure.The method can accurately measure the equivalent stiffness of the crack,only needs to determine the deflection of the cracked beam structure and the crack location.It can be used to measure the equivalent stiffness of the different type and shape cracks in the beam structure.Based on the theory of fracture mechanics and the principle of strain energy,the crack local flexibility equation with arbitrary crack direction of beam structure underbending is derived.The varied rule of crack local flexibility with the crack direction angle and depth is studied.Furthermore,the identification of crack parameters considering the crack orientation angle is discussed.At the same time considering the beam crack local flexibility under different working conditions under the direction of crack angle was calculated by finite element method,which are compared with the results calculated by the equation.The results verify the validity of the equations derived.