DISTRIBUTION CHARACTERISTICS OF AE AMPLITUDE DATA IN THE FREQUENCY DOMAIN UNDER UNIAXIAL COMPRESSION FOR POLYMER CEMENT MORTARS WITH ADDED ADMIXTURE

Abstract

 The distribution characteristics of amplitude data in the frequency domain of voltage waveforms obtained from AE sensors were investigated during uniaxial compression loading of polymer cement mortar with added admixture materials. First, the amplitude spectrum was calculated from the AE sensor waveform data using the Short-Time Fourier Transform (STFT). Next, from the amplitude data in the frequency domain at each time step, a histogram and four statistical measures (mean amplitude, standard deviation, skewness, and kurtosis) were calculated. The results showed that, during fracture, where axial stress decreased rapidly, the peak frequency of the histogram decreased, and the slope on the higher amplitude side of the peak became more gradual. Additionally, during the loading stage from maximum volumetric strain to maximum stress, it was inferred that void breakage and crack propagation increased, resulting in a gradual increase in mean amplitude. This caused the amplitude data distribution to change, with both standard deviation and skewness increasing due to the generation of AE signals of various magnitudes.