CRACK IDENTIFICATION IN THE BEAM-TYPE STRUCTURES

Based on the theory of Bernoulli-Euler beam vibration, a simple function between parameters of crack and fractional change of the natural frequency was obtained for beam-type structures. Effect of the geometry and crack parameters on the natural frequency was discussed. Due to the fact that the relations between the natural frequencies and the parameters of the crack, namely, the location and the depth of the crack are very complex, a feasible crack identification method was proposed. It is tested that the location and the depth of the crack can be worked out when at least three orders of the fractional changes of the natural frequency are known. The experimental results showed that in the case of the lesser frequency error, the approach presented here is suitable for damage detection on practical engineering.