Damage identification in beams using inverse methods

Beams, made of brittle materials like concrete or cement, show increasing crack development during their service life due to mechanical and environmental loadings. This local damage can be translated into a reduction of the local bending stiffness. Stiffness modifications, while assuming constant mass distribution, can be observed by monitoring the vibrational behavior of the beam. In this paper the modal parameters of an undamaged beam are monitored and compared with the vibration behavior of the beam subjected to controlled damaging. Selected stiffness parameters in the finite element model are adjusted in such a way that the computed modal quantities match the measured quantities. FEMtools has been used to establish a damage distribution in beams associated with increasing stress patterns. State of the art scanning laser modal equipment has been used for this purpose. It has been found that modal updating is indeed a possible tool to reconstruct the damage patterns.