Application Cases

Experiment Name: Construction of a Pressure-Resistant Structure Damage Identification System

Research Direction: The structural damage identification system based on Lamb waves is divided into three main parts: Lamb wave excitation, signal acquisition, and signal post-processing. First, the modulated Lamb wave is input from a computer into an arbitrary function generator. Then, the voltage is increased to a certain value through a power amplifier. A piezoelectric sensor network is used to achieve Lamb wave excitation and reception. The piezoelectric actuator converts the voltage signal into a vibration signal, causing the tested structure to vibrate. The receiver then converts the received structural vibration response signal back into a voltage signal, and data analysis and processing are performed through the data acquisition section.

Test Equipment: ATA-2022B High-Voltage Amplifier, Arbitrary Function Generator, Oscilloscope, Data Acquisition Card, etc.

Experimental Process:

Figure 1: Schematic diagram of the test procedure

The test procedure is shown in Figure 1. The excitation signal selected is a five-cycle sine wave modulated by a Hanning window. Since the arbitrary function generator cannot directly input this specific waveform, we chose to create the Lamb wave waveform using software and import it into the arbitrary function generator after format conversion, using this as the excitation signal. To ensure the output result exceeds the oscilloscope's minimum range and avoid the signal being undisplayable, the signal is amplified by a power amplifier before output. A program written in LabVIEW is used for data acquisition and signal processing. The experimental platform built according to the flowchart is shown in Figure 2.

Figure 2: Experimental platform

An experimental platform was constructed. This experiment used an arbitrary function generator to obtain the required Lamb waves and a high-voltage amplifier to amplify the voltage signal. The equipment used for signal acquisition was a data acquisition card, the sensors used were piezoelectric ceramic patches, and the test structure was a 6061 aluminum alloy plate measuring 600 × 600 × 2 mm.

First, a five-cycle Lamb wave with a center frequency of 200 kHz was edited using software and imported into the arbitrary waveform generator for dual-channel output. The maximum output voltage of the arbitrary function generator is 10 V. Channel 1 was connected to an oscilloscope for comparing and positioning the received waveform. Channel 2 was amplified 10 times by the high-voltage amplifier and then connected to the excitation piezoelectric ceramic patch. The piezoelectric ceramic patch was attached to the polished aluminum alloy plate using quick-drying adhesive, and the positive and negative electrodes were connected via soldered wires. When attaching the piezoelectric ceramic patch, care was taken to apply the adhesive evenly and press for 30 seconds, waiting several hours for optimal bonding effect. The piezoelectric ceramic patch has a diameter of 10 mm, a thickness of 1 mm, and a maximum driving voltage of 200 V/mm. The oscilloscope used Channel 1 to display the excitation signal generated by the arbitrary function generator, while Channels 2, 3, and 4 were connected to the receiving sensors on the structure under test, serving as reception signals.

Experimental Results:

The damage localization method based on the elliptical trajectory method was verified. The echo signal was acquired, and the arrival time of the echo peak caused by the damage was read to locate the damage position. Meanwhile, damage imaging was achieved based on a probability-based damage imaging algorithm, and the effectiveness of the finite element results and the algorithm was verified through experiments. The results show good damage imaging performance, with an overlap rate between the actual damage and the imaging results reaching 81.3%. This provides a reference for the engineering application of structural damage identification technology.

Power Amplifier Recommendation: ATA-2022B

Figure: ATA-2022B High-Voltage Amplifier Specifications

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