Analysis of efficiency of the method for spectral vibrodiagnostics of fatigue damage to structural elements. Report 4. analysis of distortion of Harmonicity of a cycle of rod element vibration in the presence of closing cross cracks

摘要

Based on the asymptotic method of nonlinear fracture mechanics and the statements of the linear elastic fracture mechanics, analytical relationships have been obtained, which relate a constant component and the amplitudes of even harmonics, the ratios between maximum deviations of different signs and half-periods of prismatic rod displacements to the length of a closing transverse crack. The analytical solution is compared with the data of the experimental determination of the above parameters in bending vibrations of a cantilever rod of a rectangular cross section with an edge transverse crack. Analysis of the results of analytical and experimental investigations has shown that harmonic analysis of the strain waveform for rod elements at resonant vibrations can be used as an efficient diagnostic method for detecting fatigue damages such as closing cracks.