Application Cases

Experiment Name: In-Situ Air-Coupled Ultrasonic Measurement of Delamination Defects in CFRP Plates

Experiment Content:
Air-coupled ultrasonic technology can detect defects in in-service CFRP plates to ensure their operational safety. Traditional air-coupled ultrasonic methods typically rely on linear defect indices, which are ineffective for characterizing small-sized defects. Moreover, the scanning step size entirely limits their imaging spatial resolution, leading to a trade-off between imaging spatial resolution and detection efficiency. To address these issues, a nonlinear defect index and an adaptive weighted imaging algorithm are proposed. The nonlinear defect index utilizes the relative nonlinear coefficient of Lamb waves to enhance the detection capability for small-sized defects. Considering the beam width, the adaptive weighted imaging algorithm establishes the relationship between any imaging point and all scanning paths. In this approach, the imaging spatial resolution can be arbitrarily set, eliminating the dependency on the scanning step size.

Research Direction: Non-Destructive Testing of Composite Materials

Testing Equipment: ATA-2041 high-voltage amplifier, signal generator, power amplifier, two-dimensional motion platform, preamplifier, high-speed data acquisition card, etc.

Figure 1: Schematic Diagram of the Experimental Setup

Experimental Procedure:
An arbitrary signal function generator produces a sinusoidal pulse signal modulated with a Hanning window and a center frequency of 200 kHz. The excitation signal voltage is then increased to 400 Vpp using a voltage power amplifier to ensure that the air-coupled ultrasonic transducer generates sufficient acoustic energy. An XZ adjustment platform controls the horizontal distance between the two air-coupled ultrasonic transducers and the vertical distance between the air-coupled ultrasonic sensor and the CFRP plate. An angle adjuster regulates the incidence and reception angles θ of the air-coupled ultrasonic transducer to ensure the generation of Lamb waves in the CFRP plate and eliminate interference from direct waves. An XY motion platform performs step-by-step scanning along the 0° and 90° fiber directions. Due to significant signal attenuation in air, a preamplifier amplifies the received signals from the air-coupled ultrasonic transducer. A high-speed data acquisition card captures the echo signals and uploads them to a host computer for processing and imaging.

Experimental Results:

Figure 2: Experimental Results

The experimental results demonstrate that the proposed nonlinear defect index can characterize small-sized defects more accurately than the linear defect index. When increasing the scanning step size to improve detection efficiency, the adaptive weighted imaging algorithm achieves better imaging spatial resolution compared to the traditional defect probability imaging algorithm. For a small defect with a diameter of 10 mm, the area detection error of the proposed method is only 7.8%, whereas the error of the traditional method is 22.4%.

Power Amplifier Recommendation: ATA-2041 High-Voltage Amplifier

Figure: ATA-2041 High-Voltage Amplifier Specifications

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