Application Cases

Experiment Name: Application of Voltage Amplifier in Research on Defect Detection of Farmland Irrigation Pipelines

Research Direction: Pipeline Inspection, Ultrasonic Testing

Figure: Schematic Diagram of the Pipeline

Test Objective:
When using ultrasonic guided waves for structural inspection, the guided wave is first excited to propagate within the structure. When the guided wave encounters discontinuities or defects within the structure, reflections occur. By capturing and analyzing the reflected signals, the possibility of defects in the structure can be assessed. The frequency of ultrasonic guided waves is lower than that of conventional ultrasonic flaw detection, typically not exceeding 500 kHz. Consequently, they experience less attenuation during propagation within the structure, making them suitable for rapid, large-scale, long-distance inspections with high detection efficiency.

This study investigates the localization of pipeline defects using ultrasonic guided wave testing technology. The L(0,1) mode of ultrasonic guided waves was selected to detect pipeline defects. The propagation characteristics of the L(0,1) mode were observed in liquid-filled versus empty pipes, intact versus defective pipes, and straight versus bent pipes. The propagation characteristics in straight and bent pipes were compared, and the influence of defects on propagation characteristics and energy distribution was analyzed. The study found that when the L(0,1) mode propagates in a liquid-filled pipe, a significant portion of its energy is dissipated in the liquid. The wave propagation speed in an intact pipe is greater than in a defective pipe. Energy loss during propagation in bent pipes is generally higher than in straight pipes. Based on these characteristics, real-time pipeline monitoring can be achieved to prevent resource waste caused by pipeline leakage.

Testing Equipment: ATA-2042 High-Voltage Amplifier, Straight and Bent Steel Pipes, Function Generator, Digital Oscilloscope, Computer, Switch, Piezoelectric Sensors

Figure: Schematic Diagram of the Experimental System for Defect Detection in Farmland Irrigation Pipelines

Experimental Procedure:
The piezoelectric sensors used were longitudinally extensional piezoelectric ceramic wafers, with their length direction oriented parallel to the pipeline axis. A total of eight piezoelectric ceramic wafers were arranged at one end of the pipeline. Four of these wafers were used to excite the signal, which consisted of a 10-cycle sinusoidal signal modulated by a Hanning window. After amplification by the amplifier, the signal generated longitudinal modes within the pipeline. The remaining four piezoelectric ceramic wafers were used to receive the signals.

Experimental Results:

1. In liquid-filled versus empty pipes, when the L(0,1) mode propagates in a liquid, a portion of  its energy is dissipated in the liquid. However, overall, this does not have a significant impact; the wave can still propagate in the liquid-filled pipe and is not affected by the liquid medium.

2. In intact versus defective pipes, the guided wave propagation speed in an intact pipe is greater than in a defective pipe. This allows for effective detection of defects and cracks in the pipeline. Furthermore, the size of the defect influences the defect echo signal of the guided wave; the larger the defect, the greater the amplitude of the end-face echo.

3. In straight versus bent pipes, the energy loss during wave propagation in bent pipes is generally higher than in straight pipes. Regardless of the changes in the guided wave propagation path, defect localization can still be achieved.

   
   

Figure: ATA-2042 High-Voltage Amplifier Specifications and Parameters