Application Cases

Experiment Name: Study on the Application of Power Amplifiers in Ultrasonic Guided Wave Attenuation Characteristics of Rails

Research Direction: Ultrasonic Testing

Experimental Content:
Rails serve as solid media for sound propagation with excellent acoustic waveguide properties, making them suitable for detecting internal rail damage using ultrasonic signals. Mechanical waves are employed as detection signals, rendering the method largely unaffected by rail electrical parameters or traction return currents. The equipment is characterized by simple principles, safety, reliability, ease of installation and maintenance, and lower power consumption compared to other detection technologies. This approach is particularly suitable for real-time rail condition monitoring in sections with slab tracks, tunnels, poor primary rail parameters, or severe waterlogging on-site. Additionally, it is effective for detecting rail breaks in long-distance continuously welded rails.

Testing Equipment:
ATA-4012 high-voltage power amplifier, signal source, oscilloscope, etc.

Experimental Procedure:
The detection system typically consists of piezoelectric transducers and signal transmission/reception modules. The signal transmission module applies high-voltage pulse excitation signals to guided wave transducers mounted on the rail. The piezoelectric transducers generate ultrasonic guided waves via the inverse piezoelectric effect. These waves propagate through the rail and are received by ultrasonic guided wave transducers at the receiving end. The collected signals are analyzed for specific features, or the presence of corresponding ultrasonic guided wave signals within a given time frame is detected to assess rail integrity within the monitored section.

Experimental Results:
Common types of high-speed rail damage include corrugation, surface contact fatigue cracks, internal cracks, and internal weld defects. The ultrasonic guided wave rail break monitoring system primarily targets internal rail cracks, internal weld defects, and rail fractures. Ultrasonic guided wave receiving nodes are installed ahead of weld joints in continuously welded rails. When internal defects occur in the weld, the receiving nodes detect reflected waves from the defect. In the event of a rail fracture within the monitored section, the receiving nodes fail to detect ultrasonic guided wave signals from the transmitter. If internal cracks develop in the rail, the ultrasonic guided wave signals at the receiving nodes exhibit significant attenuation.

Additionally, numerous rail holes on-site can cause attenuation of ultrasonic guided waves. The field installation of the ultrasonic guided wave rail break monitoring system must account for the impact of rail holes on wave attenuation. This experiment provides theoretical guidance for the setup and installation of rail break monitoring systems in continuously welded rails, reducing the false alarm rate of existing systems.

Role of the Power Amplifier in This Experiment:
In this study, the ATA-4000 series high-voltage power amplifier produced by Aigtek was used to amplify signals generated by an arbitrary function generator, thereby exciting vibrations in the ultrasonic guided wave transducers. The high-voltage power amplifier features the following characteristics: high speed and wide bandwidth, high output voltage slew rate enabling faithful amplification of high-speed pulse signals with steep edges or complex waveforms; suitability for driving piezoelectric elements such as piezoelectric transducers and actuators; excellent step response, accurately reproducing signals even during rapid repetitions or high-speed transitions; and low output impedance, ensuring reliable performance even with capacitive or inductive loads.

Figure: Specifications of the ATA-4000 Series High-Voltage Power Amplifier