Acoustic emission (AE) is one of structural health monitoring techniques providing meaningful information about damages within the materials. To classify crack types in AE analysis, an optimal transition line between shear and tensile cracks has been still demanding. There exist numerous studies investigating this subject in the literature. The researchers have adopted the ratio of RA value and average frequency parameters of the signals for classification; however, it is concluded that the transition line is mostly based on the empirical conditions.
In this study, parameter- and signal- based AE analyses were combined for crack classification of damage activities of concrete under flexure. After monitoring damage processes of the concrete simultaneously by AE, spectrum analysis was conducted on the AE signals and their weighted peak frequencies were obtained. By evaluating dominant frequency characteristics of the signals, they were classified as tensile or shear crack and the classification was verified by parameter-based analysis. Afterwards, AE signals were labelled using crack types obtained from signal-based analysis, RA and average frequency parameters were distributed and the optimal transition line was determined.

acoustic emission; concrete; crack type; RA value; frequency