#Product Trends
Aigtek power amplifier ultrasonic nondestructive testing applications
Acquisition of Lamb wave signal in homogeneous aluminum plate
Experimental name:
Acquisition of Lamb wave signal in homogeneous aluminum plate
Research direction: Nondestructive testing and damage monitoring of structures based on ultrasonic guided wave
Experimental content:
PZT (piezoelectric sensor) was used as the excitation sensor and receiving sensor to test Lamb wave signals in homogeneous aluminum plate (2024).
Test objective:
To collect signals of two modes, symmetric (S0) and antisymmetric (A0), which exist simultaneously in the fundamental frequency of Lamb wave, and distinguish the two modes by extracting parameters of the time-domain signal.
The experimental significance of the amplifier:
In this paper, by considering the dispersion characteristics of the two fundamental frequency modes of Lamb waves, the Lamb wave time-domain model is strictly derived, and a coupling term that does not change with the propagation time is obtained. This term can be used for modal distinction. The conclusion solves the multi-mode problem based on guided wave nondestructive testing technology. In the verification test, the excitation waveform must be strictly controlled, and a power amplifier that performs well under high frequency/bandwidth conditions is required. The ATA-2022H power amplifier provided by Xi'an Antai Electronics Company fully meets the experimental requirements.
Test equipment: ATA-2022H (power amplifier), PCI-1714 (data acquisition card), PCI-1721 (data output card).
Amplifier model: ATA-2022H
Experimental process (1):
The high-frequency modulation waveform is generated by self-editing LABVIEW program, amplified by the data output card through the power amplifier to drive the force sensor, and then the waveform signal is received by the data acquisition card. The tested structure is shown in Figure 1.a, and the experimental device is shown in Figure 1.b:
Figure 1, (a) the structure under test, (b) the experimental device.
Test result (1)：This result is used to analyze the accuracy of parameter extraction under different
excitation bandwidths. The test results and fitting results are as follows:
FIG. 2.
(a) Fourier transform results corresponding to different excitation waveform
(b) controlled by bandwidth factor.
(c) The sampling results (OS) and the summation Results (RS)
(d) Correlation analysis between fitting results and sampling results.
Note:
The results are completely consistent with the theoretical results, reflecting from the side that the performance of the amplifier under different bandwidths fully meets the ideal assumption.
Experimental process (2):
By testing a plate-like structure with a larger area, the schematic diagram of the tested structure is as follows:
FIG. 4 measurement signal (blue line) and excitation signal (red line), excitation P-P voltage: 36V
Description:
The measured signal verifies the correctness of the theoretical derivation, and it can be seen from the signal that the electromagnetic noise of the whole signal is very small, which is related to the stability of the amplifier.
The performance of the amplifier in this experiment:
Provide a stable power amplification signal to excite the PZT sensor to excite an almost ideal excitation waveform. In the experiment, the capacitance of PZT is 3.42nF.
Reasons for choosing this amplifier:
Excellent performance in bandwidth, frequency and power, meeting the experimental requirements, the parameters of the power amplifier: voltage 200Vpp, current 500mA, power 50W, frequency DC-1MHz.
