Characteristic Analysis and Experimental Verification of Acoustic Emission Source of Titanium Alloy Crack

In order to meet the needs of in-service monitoring of titanium alloy damage, an acoustic emission real-time dynamic monitoring technology was proposed. For analyzing the characteristics of crack acoustic emission sources in titanium alloy, a two-dimensional model of titanium alloy was established with finite element analysis method. Three kinds of force source functions were used to study the crack acoustic emission sources with different types, different center frequencies and different conduction distances in the material. And the characteristic frequencies and modes of the acoustic emission sources were analyzed through wavelet method by combining dispersion curves. It is found that the bipolar source produces clear results in the direction parallel to the X-axis source, which are consistent with S0 mode in the middle and low frequency range. However, in the Z-axis source direction, the characteristic frequency is always within 0~200 kHz, which fails to clearly demonstrate the waveform mode generated by Lamb wave. The monopole source 1 parallel to the X-axis source direction produces the clearest results in the middle high frequency and high amplitude region, but it is difficult to identify the mode at the low frequency due to the aliasing. In the Z-axis source direction, A0 mode identification is the clearest. The result of monopole source 2 parallel to the X-axis source direction is the most accurate to reflect the center frequency, but the clarity of S0 mode identification is weaker than those of the other two sources. The Z-axis source direction also reflects the weak definition. Finally, the simulation results are consistent with the verification conclusion employing the lead-breaking experiment, validating its reliability.