Damage Evaluation in Cracked Vibrating Beams Using Experimental Frequencies and Finite Element Models

Abstract

The paper focuses on the problem of locating and quantifying damage in vibrating beams due to cracks. The problem is shown to have certain peculiarities that, to some extent, make it easier to solve than classical situations of structural identification. The solution of the problem is based on the minimization of the objective function that compares analytical and experimental data. A fairly general automated procedure is developed using a finite element code as a routine to evaluate modal quantities. The data necessary to locate and quantify damage correctly are discussed. General considerations lead to the conclusion that at least one measurement more than the expected number of cracked sections is necessary to obtain a unique solution. The procedures developed are applied to the study cases: a supported beam and a clamped beam with one or two cracks, using both simulated and experimental data. Satisfactory results are obtained. Although only beams were considered, the methodology developed can be extended to any kind of framed structure.

Detection of Damage in Beams Subjected to Diffused Cracking

“…In previous papers [16,17], starting from the classical problem of damage identi"cation in a vibrating beam due to single cracks, it was pointed out that very few data are required for the evaluation of damage quantities. The same consideration holds good even when a discretized model is used [16], although this has not been taken into account. The peculiarity of damage detection is precisely the circumstance that only a few parameters need to be determined, since the damaged sections are very few, albeit unknown.…”

A State of the Art Review of Modal-Based Damage Detection in Bridges: Development, Challenges, and Solutions

“…Generally, an assumption of linear-stationary structural response is made to allow the use of a Fourier-type transform to obtain the frequency content of measured vibration data, prior to employing peak-peaking to discern modal frequencies. The global nature of modal frequencies may not always lend itself well to damage localisation in complex structures [34][35][36], although they can be utilised to do so for more regular geometries when given the undamaged and damaged states, in addition to a sufficient number of frequencies depending on geometry complexity, for instance; two for a beam and three for an arch [37,38].…”

Identification of breathing cracks in a beam structure with entropy

“…In open crack models, the crack is considered remain open during the vibration and it is the most widely used [33,34] modeling technique to avoid the complexity resulting from bi-linearity of the breathing crack models. These models are less sensitive to smaller crack depths [35][36][37][38] and lead to lesser crack severity predictions than what they really are [4]. Therefore, recent studies are more in the favor of breathing models, which mitigates those problems by mimicking the real open-close phenomenon of breathing cracks [1,39,40].…”