Vibrodiagnostics of the Edge Crack-Type Surface Damage in a Cantilever Composite Beam at Main, Super-, and Subharmonic Resonances

The paper presents analytical and numerical methods based on finite element modeling for determining vibrodiagnostic indicators of the presence of a transverse edge crack closing in a cantilever composite beam made of orthotropic material. The results of studies of the effect of its presence on the change in the main vibration frequency and on the ratio of the amplitudes of the dominant harmonics at the main, superharmonic order 1/2, and subharmonic order 2 resonances are presented. It has been shown that for a composite beam reinforced in the bending plane with unidirectional fibers with their laying angles relative to the axis of 0...40°, it is advisable to use the change in the natural vibration frequency as a vibration diagnostic indicator, and for larger angles, the ratio of the amplitudes of the dominant harmonics at super- and subharmonic resonances may be of practical importance.