Identification of a crack in a beam by the boundary element method

A method to detect a crack in a beam is presented. The crack is not modeled as a massless rotational spring, and the forward problem is solved for the natural frequencies using the boundary element method. The inverse problem is solved iteratively for the crack location and the crack size by the Newton-Raphson method. The present crack identification procedure is applied to the simulation cases which use the experimentally measured natural frequencies as inputs, and the detected crack parameters are in good agreements with the actual ones. The present method enables one to detect a crack in a beam without the help of the massless rotational spring model.