Principle and Application of WPS-02 with PA Wheel Probe

SIUI NDT

1. Overview

The PA wheel probe can be configured with PA ultrasonic instrument, and the interconnection of ultrasonic transmitting and receiving signals and probe real-time position signals is achieved through the cable, which establishes a set of small PA ultrasonic testing equipment equivalent to immersion method that can realize high-quality PA ultrasonic testing similar to immersion method for various testing objects such as lamination of composite materials, corrosion of inner wall of pipes and relatively smooth surface. See Fig. 1 for the appearance of the probe.

2. Composition and principle of WPS-02 with PA wheel probe

2.1 Composition

2.2 Main technical specifications

Main technical specifications are shown in Table 1.

2.3 Principle and features

The acoustic wheel of the PA wheel probe is made of rubber with good sound transmission performance. It is an elastic arc-shaped capsule with convex surface. The core is equipped with a special PA ultrasonic probe. Its emission surface can be adjusted within a certain angle to facilitate the adjustment of the sound beam perpendicular to the tested material. The capsule from the probe emission surface to the acoustic wheel surface is filled with water as couplant, thus forming a testing system similar to immersion method. The surface of the capsule is in direct contact with the tested material. The elasticity of the rubber and the convex arc structure of the capsule ensure close contact with the surface of the tested material under various conditions. When performing wheel scan, only a little couplant is applied on the surface of the workpiece, so that ultrasound is transmitted and received smoothly with good penetration, and high quality ultrasonic testing signals are obtained. The signals together with the real-time position signals output by the PA wheel probe, are interconnected with the instrument through cables, and the instrument synthesizes and processes the signals to obtain the testing map. High quality ultrasound testing similar to water immersion is performed. Features are as follows:

• The contact surface with the tested specimen is a soft convex rubber wheel. When rolling scan, only a small amount of couplant is needed to obtain high quality coupling effect;
• 25 mm water thickness, can adapt to the thickness of up to 50 mm composite material testing;
• 51.2 mm wide beam coverage, a wide coverage of scan with high testing efficiency;
• Transparent capsule, low sound attenuation, strong penetration;
• Laser guided device to guide the scan track;
• PA ultrasonic probe can be selected or customized according to the testing process, supporting a variety of tested objects;
• High-precision waterproof encoder, real-time position signals;
• Simple adjustment and operation to obtain high-quality C-scan testing spectrum, convenient and fast.

3.? Operating precautions

3.1 Plastic wheels on both sides of the acoustic wheel remain close to the surface of the specimen

The key to ensure stable coupling during WPS-02 testing is to keep the black plastic wheels on both sides of the acoustic wheel close to the surface of the tested specimen, see Fig. 3. Under this condition, the distance between the probe and the surface of the tested specimen is fixed, the sound path and incident angle are unchanged, and the amplitude is stable. Please pay attention to the description above when using.

While ensuring that the acoustic wheel does not deform, it is also found that there is a blind area for edge testing due to the obstruction of plastic wheels on both sides of the acoustic wheel, which is a disadvantage of PA wheel probes.

3.2 Adjustment of the middle wheel

The middle wheel of WPS-02 is only used for longitudinal testing of curved workpieces and testing of workpieces with width less than 85mm (i.e., widths less than plastic wheels on both sides of the acoustic wheel). Under these two testing conditions, plastic wheels on both sides of the acoustic wheel do not touch the workpiece, and the acoustic wheel capsule will be severely deformed, see Fig. 4. It floats up and down when rolling, resulting in constant changes in the distance and incidence angle between the probe and the workpiece surface that requires additional support. At this time, carefully adjust the middle wheel according to the actual situation of the tested specimen, so that the deformation of the acoustic wheel can be reduced as much as possible when rolling.

3.3 Use of magnetic stand

The WPS-02 magnetic stand can provide 0~ 12kg adsorption force (wheel probe weight 1.5kg incl. water couplant), but it needs to ensure a certain distance from the workpiece surface (≥ 1mm). When the magnet directly contacts the workpiece, adsorption force and friction force are very large, resulting in the wheel probe difficult to move forward. ?

The technique to remove the wheel probe from the workpiece is to force it apart in the width direction of the wheel probe. See Fig. 5.

4. Test results

4.1 Carbon fiber composite plate lamination test (thickness 5mm)

See Fig. 6~8 for the testing equipment, the specimen and test results of carbon fiber composite plate lamination.

4.2?Honeycomb composite plate testing (thickness 12mm)

See Fig. 9 for testing equipment and testing results of a honeycomb composite plate.