Application Cases

【Overview】
In this study, the Aigtek ATA-3040C power amplifier was used to build an experimental system for steel plate defect detection, providing theoretical and experimental foundations for the engineering application of air-coupled ultrasonic technology in defect detection of steel pipelines.

Experiment Name: Steel Plate Defect Detection Experiment Based on Air-Coupled Ultrasonic Oblique Incidence

Research Direction: Application of Air-Coupled Ultrasonic Technology in Nondestructive Testing of Metal Components

Experiment Objective:
To address the challenges of severe energy attenuation and high detection difficulty in ultrasonic testing of steel pipelines caused by the acoustic impedance mismatch between air and metal. The optimal detection angle for air-coupled ultrasonic oblique incidence was derived and verified to improve detection signal energy and accuracy. The influence of steel plate defect dimensions (depth, width) on the detection signal was analyzed to achieve qualitative defect assessment based on signal characteristics. This study provides theoretical and experimental foundations for the engineering application of air-coupled ultrasonic technology in defect detection of steel pipelines.

Testing Equipment:
Hardware: Function generator, arbitrary waveform high-voltage amplifier, power amplifier, air-coupled transmitting/receiving probes (diameter 28 mm, center frequency 200 kHz), Q235 steel plate specimen (200 mm × 400 mm), preamplifier, oscilloscope.

Figure 1: Schematic Diagram of the Experimental Platform

Experimental Procedure:
The probe lift-off distance was 30 mm, with a spacing of 160 mm. The excitation signal was a 5-cycle sine wave at 200 kHz, with a frequency-thickness product of 1.6 MHz·mm.
Steps: The function generator produced a burst of five excitation pulses, which were amplified by the high-voltage amplifier to drive the transmitting probe to generate ultrasonic waves. After propagating through the steel plate and undergoing mode conversion, the waves were received by the receiving probe. The signal was amplified by the preamplifier and finally acquired and displayed by the oscilloscope.

Experimental Results:
Based on the relationship between the transmission coefficient and the incident angle of ultrasonic waves propagating through air and the steel plate, the optimal incidence angle was theoretically derived to be 2.4° for a frequency-thickness product of 1.6 MHz·mm. At this angle, the ultrasonic wave transmission energy and signal amplitude were maximized, as verified by finite element simulation and experiments.
The air-coupled ultrasonic oblique incidence method effectively detects defects in steel plates. Both simulations and experiments showed that the received signal amplitude was highest without defects and decreased with increasing defect depth. This method offers high detection sensitivity and accuracy. However, it is currently only applicable to steel plates with a thickness ≤10 mm. Future work will extend its application to steel plates thicker than 10 mm and gas pipelines to further improve detection accuracy.

Advantages of Aigtek Amplifiers in This Application:

1. Wide bandwidth and high-frequency response – Precisely covers the 200 kHz operating frequency, ensuring完整 (完整,完整) reproduction of the 5-cycle pulse signal.

2. High voltage and high power output (100 Vp-p/500 Wp) – Overcomes the strong acoustic impedance mismatch between air and metal, ensuring high signal-to-noise ratio penetration signals.

3. High output stability and low distortion – Ensures data consistency in full-band frequency sweep tests and multiple repeated experiments.

Recommended Product: ATA-3040C Power Amplifier

Figure: ATA-3040C Power Amplifier Specifications and Parameters

The experimental materials in this article are compiled and released by Xi'an Aigtek Electronics. Aigtek has become a large-scale instrument and equipment supplier with a wide range of products in the industry. Demo units are available for free trial. Xi'an Aigtek Electronics is a high-tech enterprise specializing in the research, development, production, and sales of electronic testing instruments such as power amplifiers, high-voltage amplifiers, power signal sources, preamplifiers for weak signals, high-precision voltage sources, and high-precision current sources.