Structural testing of fatigued structures

摘要

The structural responses of beams and tubes is investigated in theory and experiment in order to locate and assess damage in the form of fatigue cracks. Crack length measurements are performed in transversely vibrating beams by determining the resonant frequency, which is stabilized through a phase locked loop. Cracks are initiated and propagate from the notch of the structure which is vibrating at resonance. The frequency in relation to the crack length is modeled including the nonlinearity effect due to closing of the crack. Fatigue tests were also carried out with piezoelectrically excited microstructures.