抄録
Flaw detection technology by tapping sound has been established as a powerful method to diagnose structures such as bridges, buildings, tunnels, towers etc. If those structures have defects, the stiffness of the structure decreases, the natural frequencies are also changed and the influence by those changes should appear in tapping sound. Using these features, the purpose of this study is to investigate the possibility of defect diagnosis and estimation of defect position using a cantilever system as the simplest structure. First, the FEM model is made by Salome-Meca. Second, the natural frequencies and the natural vibration modes for the cantilevers without and with defects which are located at every 20 mm, are calculated. And then changes on the natural frequencies and the mode shapes are investigated and examined in order to estimate the defect position. The results show that it is possible to estimate the defect position for the defect positions 250 mm and 405 mm of the cantilever even though the estimated values have some errors of a few percent. It has become clear that the estimation of defect position by analysis of tapping sound obtained from the experimental results can be sufficiently available in this study, if several problems are complemented.
