The use of antiresonances for crack detection in beams

This paper deals with the identification of a single open crack in a vibrating beam, either under axial or bending vibration, based on measurements of damage-induced shifts in natural frequencies and antiresonant frequencies. It is found that an appropriate use of frequencies and antiresonances may avoid the non-uniqueness of the damage location problem, which occurs in symmetrical beams when only frequency data are employed. The theoretical results are confirmed by a comparison with dynamic measurements on cracked steel beams under free-free boundary conditions.