DISCRETE WAVELET BASED DAMAGE LOCALIZATION ON BEAM-LIKE STRUCTURES
Damage Localization, Damage Quantification, Structural Health Monitoring, Wavelet Transform.
This research investigates damage detection using Discrete Wavelet Transform (DWT) as method of analysis. In addition, the influence of boundary conditions, such as the Wavelet mother type and decomposition level, and many others, were also investigated regarding the efficacy of the method. Static and dynamic regimes were considered. The objective is to define, through the wavelet coefficients, a method able to detect, localize and quantify damage. For Static analysis, Discrete Wavelet Transform (DWT) data treatment is made onto displacement data obtained in beams submitted to transverse static loads applied at selected points over its length. Modal analysis is performed onto the first five levels of vibration modes of the structures. Three beam supports are investigated: simply supported, cantilever, and double-clamped. For each one, diverse parameters of influence were analyzed. As the localization of probable region of the damage and the quantification of this damage are the main goal, understanding how damage localization is impacted by the boundary conditions of each case is crucial to ensure the reliability of the method. Additionally, the influence of a baseline function for comparison, decomposition level, wavelet mother type, damage severity and the polynomial order were also studied. Damage was simulated through a local reduction of the elasticity module of one or more elements. The method then treats the displacement or modal data and reveals the probable region with damage with good precision. Two statistical damage indicators were developed: d1 - index for damage localization; d2 -index for damage quantification. Results show good potential for the proposed DWT-based for both damage localization and quantification indexes. The approach has shown great concordance between many indexes of damage localization, but at the same time a limitation of the method for damage near the edges of a beam. Also, for damage quantification, must be noticed that the damage severity prediction curves were found to be very similar, regardless the type of its supports.