| Stringer is the main bearing component of the aircraft structure.Axial loads,stress and fatigue load caused by low temperature are the main loads of the stringers.Thus,the structure condition monitoring method is an important measure to ensure the integrity of the aircraft structure.Ultrasonic guided wave testing technology has many advantages,such as long distance testing,high efficiency and low cost.It has been widely used in nondestructive testing of pipes,plates and rails.However,the challenge of the guided wave propagation characteristics in the aircraft stringer is that it has complex section.The solution of this problem is a great significance for the realization of aircraft stringer structure state monitoring.For the study of ultrasonic guided wave propagation characteristics in the aircraft stringers,this paper completed the following work:(1)Introducing the fundamental of guided wave propagation and the application in SHM.(2)A semi-analytical finite element method(SAFE)is developed using mathematical software MATLAB,and the ultrasonic guided wave propagation dispersion curves and vibration mode of each modal.The dispersion curves of four typical aircraft stringer are acquired by SAFE.(3)Mesh size can affect the dispersion curves by using SAFE.Geometric and physical parameters can also affect the dispersion curves,and the influence on different modes is different.(4)According dispersion curves and vibration characteristics of each mode to choose the better frequency and vibration mode.The finite element simulation results and experimental results verify the correctness of ultrasonic guided wave propagation theory in aircraft stringer.This paper studies the propagation characteristics of guided waves in aircraft stringer by the theory,simulation and experiment,which laid a theoretical foundation for the application of ultrasonic guided wave detection in aircraft stringer. |
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