Abstract: On the basis of modal acoustic emission and narrow-band signal theory, the mathematical expression of multi-modal AE signal is given. A mixed parameter composed of logarithm cepstral coefficients and fractal dimension is presented as the characteristic coefficients of rub-impact AE signal, and the AE recognition system based on Gaussian mixture model is also established. Because the eigenvector of each modal wave in rub-impact AE signal is different, so a model of probability density function of eigenvector is built and it is regarded as a clustering. Training model is established with mean, covariance matrix and probability of each clustering. Sum likelihood probability weighted by maximal ratio combining to likelihood probability of Gaussian model will be obtained when the tested signal is recognized, if the probability is larger than a set threshold, it can be confirmed that rub-impact AE is available. Rub impact AE signals are sampled from rotor test stand, the types of input model of Gaussian are sorted by AE wavrform shapes and its fractal dimensions, then white noise and non-stationary noise are added to simulate the real AE signal. In the end, this Gaussian mixture model is used for AE recognition. The results indicate that the model has high recognition rate and good anti-noise ability.

Key words: Acoustic emission recognition, Cepstral coefficients, Fractal dimension, Gaussian mixture model