Application Cases

Experiment Name: Damage Detection of Aircraft Composite Stiffened Panels Using Wave Packet Separation DAS Localization Method

Research Direction: Nondestructive Testing

Test Objective:
The DAS localization algorithm overlays an infinite number of circles with different amplitudes obtained from time-domain projection, ultimately determining the damage location based on the highest amplitude value.

Testing Equipment: Host Computer, ATA-4315 High-Voltage Power Amplifier, Aircraft Panel, PZT Sensors

Figure: Experimental System

Experimental Procedure:
The experimental monitoring object for corrosion damage localization was an actual aircraft panel. The acid corrosion experiment was conducted on a real aircraft panel as shown in Figures 5.2(a) and 5.2(b). In Figure 5.2(a), the panel material is aviation aluminum alloy with an anti-corrosion coating on the surface. The panel dimensions are 650 mm × 800 mm. The panel is composed of double-layer plates with thicknesses of 2.5 mm and 3 mm, joined by riveting. Three U-shaped beams and two I-shaped beams are fixed onto the panel, also connected by riveting. Sixteen PZT sensors are arranged on the inner surface of the aircraft panel, forming a 4×4 square array.

Experimental Results:
As an elastic wave, Lamb waves generate reflections when encountering discontinuous media during propagation, and similarly produce scattering signals when encountering damage. Given the propagation velocity of Lamb waves, the propagation distance can be inferred from the signal propagation time. As shown in Figure 5.3, from the piezoelectric actuator to the damage and then to the piezoelectric sensor, since the propagation distance is fixed and the positions of piezoelectric actuator k and the piezoelectric sensor are known, the potential damage location lies on a circle with actuator k and the sensor as foci. Each pair of actuator-sensor scattering signals defines an ellipse. If multiple actuator-sensor signal paths exist within the array, the intersection points of multiple ellipses can be used to deduce the damage location. As illustrated in Figure 5.3, the circle corresponding to actuator-sensor pair k and the ellipse corresponding to another actuator-sensor pair intersect, yielding the final damage location.

Figure: ATA-4315 High-Voltage Power Amplifier Specifications and Parameters