Identification of multiple cracks in a beam using natural frequencies

A simple method to identify multiple cracks in a beam is presented. The cracks are modeled as rotational springs and the forward problem is solved using the finite element method. The inverse problem is solved iteratively for the locations and sizes of the cracks using the Newton-Raphson method. Numerical examples are provided for the identification of triple cracks in a cantilever beam as well as double cracks. The detected crack locations and sizes are in excellent agreement with the actual ones.