Damping is one of the most sensitive properties of materials and structures, in macro and microscopic scale, which makes it particularly sensitive to the presence of cracks and micro-cracks and a good parameter to the characterization of structural damages. The aim of this work was to develop an algorithm to allow the incorporation of the damping characterization to the natural frequencies of vibration technique (by impulse excitation), already well established for the non-destructive determination of elastic moduli by ASTM E1876 and correlated standards for ceramic materials. It was developed an algorithm for determining the damping based on the time-frequency domain signal analysis, logarithmic decrement method and on the equivalent viscoelastic model. The algorithm was validated using an arbitrary wave form signal generator and applied to characterize two materials, a high alumina refractory castable with and without thermal shock damage, and a SAE-1020 steel. The algorithm was effective to recovery the frequencies and respective damping of the arbitrary simulated signals and to characterize the specimens, limiting the analysis to the vibration mode of interest, thereby minimizing the modes interference. This algorithm allowed the successful integration of the damping characterization to the impulse excitation technique.
algorithm; damping; ceramic materials; natural frequencies; ASTM E1876
