Application Cases

Experiment Name: Analysis of Excitation Methods for Bending Modal Guided Waves in Tubes Under Helical Loading

Experiment Content:

This paper first theoretically analyzes the excitation response of a pipe under helical tangential loading based on the modal expansion method. It derives the formula for the excitation amplitude of bending modes under helical loading. Furthermore, it investigates the effects of target mode, helical angle, loading method, and excitation frequency on the purity of the target mode. The paper summarizes the excitation methods for pure bending modes in tubes under helical loading and provides case studies. Based on the magnetostrictive effect, an experiment for the excitation of bending modes using a helical configuration was designed. The experimental results are in good agreement with the finite element numerical simulations and theoretical derivations, further validating the correctness and feasibility of the theoretical analysis presented in this paper.

Research Direction: Non-Destructive Testing

Testing Equipment:

• Arbitrary waveform signal generator

• ATA-3080 power amplifier

• Magnetostrictive guided wave sensor

• Signal conditioning module

• Signal acquisition device

Experimental Process:

Figure: Experimental Setup

The experimental setup includes an arbitrary waveform signal generator, an ATA-3080 power amplifier, a magnetostrictive guided wave sensor, a signal conditioning module, and a signal acquisition device. The experimental process is as follows:

First, the arbitrary waveform signal generator (Rigol DG1022) produces the excitation signal. The signal is then amplified by the power amplifier (Aigtek ATA-3080) and flows through the excitation coil of the magnetostrictive guided wave sensor. Due to the magnetostrictive effect, the sensor exerts a force on the pipe, exciting ultrasonic guided waves. At one end of the pipe, a strip of iron-cobalt alloy is helically bonded with epoxy resin adhesive, with a helical angle of 12.8°, a strip width of 20 mm, and a thickness of 0.15 mm. Enamel wire (diameter 0.8 mm) is wound around it for 30 turns, and permanent magnets are evenly placed along the helical direction. This configuration generates an alternating magnetic field perpendicular to the axis of the strip, exciting shear waves in the pipe. The echo signals are received by the magnetostrictive guided wave sensor. The signals are then processed by a weak signal conditioning module (including preamplification and filtering) and transmitted to the signal acquisition device (NI PXIe-1082). The signal acquisition device is used for display and post-processing. The signal receiving device uses an iron-cobalt alloy strip covering one-quarter of the circumference of the pipe, reducing interference from axisymmetric modes. The receiving transducer is also wound with 30 turns of enamel wire for shear strain sensing. Through these steps, the experiment can effectively excite and detect ultrasonic guided waves in the pipe, analyzing the characteristics of bending modal guided waves.

Experimental Results:

Figure: Experimental Results

The experimental results are in good agreement with the analytical calculations and simulation results, validating the accuracy of the finite element simulations. They also further confirm the correctness of the theoretical analysis and the feasibility of the excitation method for pure bending modes in tubes under helical loading.

Power Amplifier Recommendation: ATA-3080C

Figure: Performance Parameters of the ATA-3080C Power Amplifier

This material is compiled and released by Aigtek. For more case studies and product details, please continue to follow us. Aigtek, based in Xi’an, has become a widely recognized supplier of instruments and equipment with a broad product line and considerable scale. We offer free trials of demo units. For more information on power amplifiers and other products, please visit our official website at www.aigtek.cn or call 029-88865020.