VIBRATION OF A BEAM WITH A BREATHING CRACK

A continuous cracked beam vibration theory is used for the prediction of changes in transverse vibration of a simply supported beam with a breathing crack. The equation of motion and the boundary conditions of the cracked beam considered as a one-dimensional continuum were used. The eigenfrequency changes due to a breathing edge-crack are shown to depend on the bi-linear character of the system. The associated linear problems are solved over their respective domains of definition and the solutions are matched through the initial conditions. The changes in vibration frequencies for a fatigue-breathing crack are smaller than the ones caused by open cracks. The method has been tested for the evaluation of the lowest natural frequency of lateral vibration for beams with a single-edge breathing crack. Experimental results from aluminium beams with fatigue cracks are used for comparison with the analytical results.