Standards Development

Scope

This document is intended for mechanized array ultrasonic testing techniques (A-UT) using the total focusing method (TFM) data processing and for air-coupled ultrasonic testing technique (AC-UT) applied to non-destructive testing of carbon fibre-reinforced plastic (CFRP) and glass fibre-reinforced plastic (GFRP) composites.

The techniques contained within this document are intended to be used on flat, plane test objects where the material thickness differs by less than 20 %.

This document addresses ultrasonic testing via contact or immersion techniques using ultrasonic array probes as well as testing in pitch-catch or through-transmission technique using single element air-coupled ultrasonic probes.

Advanced mechanized ultrasonic testing using array probes and signal processing or air- coupled probes enables the detection, sizing, and characterization of a wide range of manufacturing and in-service imperfections in fibre-reinforced plastic (FRP) composites by image evaluation.

By scanning the test object under test using linear or matrix array ultrasonic probes or air-coupled ultrasonic probes, inhomogeneities and discontinuities can be detected and be characterized by the evaluation of C-scan and B-scan images generated by the space-resolved and processed acoustical response from the test object.

The objectives of testing with array probes are:

— Detection of imperfections, inclusions and inhomogeneities;

— Determination of material thickness;

— Determination of sound velocities;

— Determination of position and size of imperfections;

— Determination of depth position of imperfections (coverage);

The objectives of testing with air-coupled probes are:

— Detection of imperfections, inclusions and inhomogeneities;

— Determination of lateral position and size of imperfections.

Usually, ultrasonic array tests are performed from one side of the test object. If access to both sides of the test object is possible, additional testing from the opposite side of the test object can be performed to enhance the outcome of the tests.

Testing with air-coupled ultrasonic probes is usually performed in transmission, meaning that the test object is positioned between the transmitting and receiving probes. Air-coupled testing is performed using air as the couplant.

Ultrasonic array testing can be performed in contact with the test object using a suitable couplant or in an immersion tank using a defined water-path between the probes and the test object.