基于波传播和阻抗特性的裂纹梁损伤识别

ased on wave propagation theory, the wave solution of a simple supported beam with a crack is investigated. To characterize the local discontinuity due to cracks, a rotational spring model is proposed to model the crack, on the basis, a method for crack identification is proposed in this paper, which makes use of the driving-point mechanical impedance characters of the cracked beam stimulated by harmonic force. Subsequently, the proposed method is verified by a numerical example of a simply supported beam, and some graphs depicting the driving point impedance characters of the simple supported cracked beam are drawn, It is shown that the first resonant frequency and the first anti-resonant frequency decrease synchronously due to the presence of crack, and the decreases of the frequencies increase with the increase of size of the crack. Combined with the graph correlating the first resonance frequency with driving point location, the proposed method can identify the presence of the cra