Crack detection in plates by sensitivity analysis

A non destructive method to assure integrity of plates is presented. This method is based on evaluation of Local Modal Crack Sensitivity (LMCS) of the plate, to be used with the quantitative eigenfrequency shift, to localize the damage itself. The method was applied to two types of rectangular plates with uniform thickness, that is simply supported along all edges (SSSS) and completely free (FFFF). Free flexural vibrations were first studied and analytical expressions of eigenmodes were found. Measurement of the natural frequencies of the uniform and cracked steel plates was then simulated by using Finite Element Method (FEM). The results obtained show the robustness of the method and a good agreement between the actual and detected positions of the crack.