Published on 01-Nov-2023

Air-coupled ultrasonic testing with SONOAIR® R&D

Air-coupled ultrasonic testing with SONOAIR® R&D

SONOAIR® R&D features a free configuration of the sender characteristics with a pulser voltage of up to 800 V. Through a combination of a pre-amplifier on the receiver (probe integrated or external) and a post-amplifier inside the electronics the system generates an ultra-low noise level of less than 1nV/√Hz. 

The receiver dynamic of 120 dB provides an industry leading signal to noise ratio (SNR) even with highly attenuating materials and leads to clear and reproduceable measurements results.

Measurement Method: Transmission

Air-coupled ultrasonic testing in through-transmission is the ideal measurement method to detect common defects in modern multilayer composite structures including delaminations, air inclusions, kissing bonds, and impact damages. 

By using air as the couplant even very small defects can be located. With a wavelength in air of only 0.85 mm discontinuities from approximately 1 mm size can be detected. 

In addition, the SONOAIR technology can be used to inspect highly attenuating materials which are impossible or difficult to test with liquid coupled ultrasonic inspection systems. This applies particularly to foams, multi-layer honeycombs, plastics, ceramics, wood and concrete. Modern fiber-composite structures such as CFRP or GFRP can be inspected without any compromises with respect to minimum defect sizes compared to immersion or squirter ultrasonic testing systems.

Application examples

SONAOIR R&D provides the flexibility to display measurement results via A-, C- or D-scans. In addition, the raw data is available for post-processing. The below C-scans represent a combined color-coded image consisting of the maximum amplitudes of each individual measurement point (A-scans). The smallest detectable defect size and the level of ultrasound conductivity highly depend on the material characteristics, the expected defect type, the test frequency, the measurement resolution and the scanning speed. The sample scans have been recorded with a resolution of 1 x 1 mm and a scan speed of 100 mm/s.

C-Scan of bonded plastic plates

Test method: Transmission
Type of defect: Air inclusions and incomplete adhesive adhesion
Probe: CF400
Defect size: min. Ø 2mm

Software - SONOWARE Basic / Advanced

The SONOWARE inspection software for air-coupled ultrasonic testing was designed especially for the use in laboratories and offline production environments. SONOWARE Basic is ideal for the fast inspection of test samples. The intuitive user interface enables the user to quickly parametrize the SONOAIR hardware, perform the measurement and evaluate the results. 

SONOAIR Advanced is the perfect software to develop new test and evaluation methods. The complete raw data is available in a binary format. In addition, an extensive tool box of filters and post-processing capabilities is provided to optimize the measurement results.


Maximum resolution and high sensitivity - Piezocomposite Technology made in Germany

Due to the strong damping properties of air, low frequencies in the kHz range are used in air-coupled ultrasonic testing. It is therefore all the more important that the ultrasonic transducers have a particularly high sensitivity in order to ensure high penetration and improved resolution. We achieve this, among other things, by installing preamplifiers in the receiver search unit as well as by using the SONOTEC piezo composite technology, which enables a flexible use of the matching materials in our CFC and CF probes.

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