44 Acoustic Emission Characteristics of Defects …
513
Fig. 44.11 Waveform and spectrum of crack propagation AE signal (VS 900-M)
Fig. 44.12 Waveform and spectrum of plastic deformation AE signal (VS 900-M)
44.4.3 Frequency Spectrum Feature of AE Signals
In order to obtain the acoustic emission signals of crack cracking and plastic deformation accurately, the VS900-M sensors were arranged near the crack and plastic deformation regions in the loading test. Figures 44.11 and 44.12 are typical waveforms
and spectrum of crack propagation AE signals and plastic deformation AE signals
during the test, which are obtained by wide band sensor VS900-M. Figure 44.11
shows that the crack propagation AE signals waveform is a typical burst signal, its
frequency is mainly distributed in the range of 100–350 kHz, and the peak frequency
is rich near 170 and 350 kHz. However, the plastic deformation AE signals waveform
is a mixture of continuous and burst signals. Its frequency range is mainly less than
150 kHz, and its peak frequency is rich near 70 kHz.
44.5 Conclusions
Through the research of this study, the defect location method and the acoustic
emission characteristics of truss structure in AE test are obtained. It lays a foundation
for field AE test and provides a possibility for defect evaluation.
1. The AE attenuation in steel tube is not too large. The average amplitude is greater
than 65 dB at 8 m away from the sensor.
513
Fig. 44.11 Waveform and spectrum of crack propagation AE signal (VS 900-M)
Fig. 44.12 Waveform and spectrum of plastic deformation AE signal (VS 900-M)
44.4.3 Frequency Spectrum Feature of AE Signals
In order to obtain the acoustic emission signals of crack cracking and plastic deformation accurately, the VS900-M sensors were arranged near the crack and plastic deformation regions in the loading test. Figures 44.11 and 44.12 are typical waveforms
and spectrum of crack propagation AE signals and plastic deformation AE signals
during the test, which are obtained by wide band sensor VS900-M. Figure 44.11
shows that the crack propagation AE signals waveform is a typical burst signal, its
frequency is mainly distributed in the range of 100–350 kHz, and the peak frequency
is rich near 170 and 350 kHz. However, the plastic deformation AE signals waveform
is a mixture of continuous and burst signals. Its frequency range is mainly less than
150 kHz, and its peak frequency is rich near 70 kHz.
44.5 Conclusions
Through the research of this study, the defect location method and the acoustic
emission characteristics of truss structure in AE test are obtained. It lays a foundation
for field AE test and provides a possibility for defect evaluation.
1. The AE attenuation in steel tube is not too large. The average amplitude is greater
than 65 dB at 8 m away from the sensor.