Sensitivity to progressive damage of modal parameters of an elastic beam: Experimental and numerical simulation

The aim of this article is twofold: (1) to provide more insight into the patternof changes in modal parameters, including natural frequencies and mode shapes, of beamsand girders resulting from the increasing of damage level, and (2) verication of numericalmodelling of the problem using data from experiments on an aluminum box beam. tothis end, rst an impact hammer test has been conducted on the 2.6 meter long singlespan aluminum beam while a progressive damage has been applied at several stages. themodal parameters of the undamaged and damaged beam at dierent intensities have beenextracted, and the trend of their changes with respect to the increase in damage levelhas been studied. then this process has been simulated numerically by dynamic finiteelements method (dfem) and the modal parameters have been extracted from numericalsimulation. finally the similarity between the experimental and numerical results hasbeen investigated. the results show that at low levels of damage, the modal parameterschange very slightly, especially when just a part of the ange has been damaged, but whenthe damage has been extended to penetrate the beam web, the modal parameters haveshown considerable sensitivity to the damage. also the sensitivity of the dierent modesto damage has not been the same, though relatively good agreement has been observedbetween the trend of changes in the modal parameters obtained from experimental andnumerical studies, except for a number of modal parameters at very extensive damagelevel.