Detection and localization of multiple small damages in beam

Abstract

Localizing small damages often requires sensors be mounted in the proximity of damage to obtain high Signal-to-Noise Ratio in system frequency response to input excitation. The proximity requirement limits the applicability of existing schemes for low-severity damage detection as an estimate of damage location may not be known a priori. In this work it is shown that spatial locality is not a fundamental impediment; multiple small damages can still be detected with high accuracy provided that the frequency range beyond the first five natural frequencies is utilized in the Frequency response functions (FRF) curvature method. The proposed method presented in this paper applies sensitivity analysis to systematically unearth frequency ranges capable of elevating damage index peak at correct damage locations. It is a baseline-free method that employs a smoothing polynomial to emulate reference curvatures for the undamaged structure. Numerical simulation of steel-beam shows that small multiple damages of severity as low as 5% can be reliably detected by including frequency range covering 5–10th natural frequencies. The efficacy of the scheme is also experimentally validated for the same beam. It is also found that a simple noise filtration scheme such as a Gaussian moving average filter can adequately remove false peaks from the damage index profile.

Damage detection based on output-only measurements using cepstrum analysis and a baseline-free frequency response function curvature method

“…It should be noted that the range fWR incorporates only the first four natural frequencies and there is no need to acquire the data of higher natural frequencies for accurate detection. 6…”

“…It implies that when the cepstrum technique is employed along with the baseline-free FRF curvature method, it enhances the effectiveness of the method against noise. The range of fWR: It has been established that for detection and localization of less severe single/multiple damages by using the baseline-free FRF curvature method, the range fWR must include higher frequencies. 6 By investigation, it was found that the results were significantly improved by readjusting the range of fWR from fifth to tenth natural frequencies. However, it is a challenging task to obtain accurate data at higher natural frequencies in an actual experimental setup.…”

“…5,6 Accurate damage detection for miscellaneous damage locations and severity levels requires high fidelity recovery of structure's frequency exhibiting adequate PSD in higher natural frequencies. 6,7 In this study, the frequency response function (FRF) recovery toolthe cepstrum techniquecustomized for the FRF curvature method is reported. Figure 1 indicates a comparison between the original FRF obtained directly from the response signal and the regenerated FRFs by applying cepstrum pre-processing.…”

On the use of finite differences for vibration-based damage localization in laminated composite plates

“…The first damage scenario, denoted by DS1, corresponds to a single damaged area of 40 mm × 40 mm at the center of the plate, whereas the second, designated DS2, has two damaged areas of 40 mm × 40 mm each: one at the center an another at the upper right corner. The multiple damage scenario DS2 is considered here, since it is still a challenge to localize multiple damage, in particular if it is small, because in such a case the noise influence is most important and may lead to false positives (Nayyar et al. , 2021).…”

Analysis of Timoshenko beam with Koch snowflake cross-section and variable properties in different boundary conditions using finite element method

“…Some other important results in the field can be found in the literature. [25][26][27][28][29][30][31] Many investigations have been done in the term of Timoshenko beam with different cross-sections and boundary conditions; nevertheless, none considered the shapes of Koch snowflake iterations as the beam's cross-section. We, for the first time, in an original and novel study, analyzed the Timoshenko beam with the first, second, and third iteration of the Koch snowflake cross-section, which are unique structures.…”