frequency measurement of aluminium beam with multiple cracks

Abstract

It has been observed that the dynamic behaviour of a structure changes due to the presence of a crack. Analysis of such phenomena is useful for fault diagnosis and the detection of cracks in structures. An experimental setup is designed in which an aluminium cantilever beam with two cracks is excited by a hammer and accelerometer attached to the beam provides the response. The cracks are assumed to be open to avoid non-linearity. The effects of crack ratios and positions on the fundamental frequencies of slender cantilever beams with two edge cracks are investigated experimentally and compared with numerical results obtained using a finite element code. The experiments are conducted using specimens having edge cracks of different depths at different positions to validate the numerical results obtained. Fourteen numbers of beams having crack depth 2mm, 4mm with the variation in location of 2nd crack are taken to perform the experiment. The experimental results of frequencies can be obtained from Fast Fourier Transform (FFT) analyzer. The numerical results are shown to be in good agreement with the experimental results for the considered crack ratios.