Experimental study on cracks detection for cantilever beam-type structures

An experimental investigation on the identification of crack location and size is presented. The cracked specimens were made through the wire-cut machine, the cantilever beams were excited next to the free end by means of an impulse force hammer, and the signal is obtained with the PXI system. In order to obtain the more accurate natural frequencies of systems, the method of zoom FFT is adopted to improve frequency resolution of the transient signal measured. Based on the method of crack detection with wavelet finite elements, by providing the first three natural frequencies through vibration measurements, curves of crack equivalent stiffness versus crack location are plotted, and the intersection of the three curves predicts the crack location and size. The effectiveness and the practicality of crack identification through vibration measurements are verified through experimental study.