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This paper deals with methods of interpreting the results of vibration measurement to identify structural changes in beam-like structures. We briefly presented an own developed damage assess method, that consider a large number of frequencies for the weak-axis banding vibration modes; it allows first a precise localization and afterwards evaluation of the damages. For the first step, recognition of the damage position, we introduce an algorithm implemented in C++ with the interface done using EXCEL features, indicating by one number the damage probable position, based on the Minkowski metrics. To avoid uncertainties, a graphic representation of all results is also presented. The method is tested for values determined by calculus for a randomly selected location, with and without measurement results debased by noise, proving its reliability.

Accurate frequency evaluation is very important in the damage detection processes because the dynamic response is less sensitive to damage. Therefore, to be able to detect transverse cracks in early stage, it is necessary to read precisely the frequencies. In the literature are presented several methods, more or less complex and resource consuming, destined to improve the frequencies readability. In practical applications simple and fast methods for frequency evaluation are requested; the process should be adequate to be automated. The paper presents an original method for identifying the correct frequency of generated or acquired signals. The method is based on the analysis of the original signal cropped by rectangular windows in order to rearrange successively the spectral lines aiming to find the highest peak achieved in a region of interest for the frequency-amplitude pairs.

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