Rapid inspection of composite and additive manufactured components using advanced ultrasonic techniques

To build lighter, more fuel efficient aircraft, industry has rapidly adopted new technologies. Lighter, stronger, corrosion resistant structures are possible using advanced composite materials, while the shortage of metals such as titanium drives the development of additive manufacturing methods. These technologies enable the manufacture of intricate shapes and variation of material properties throughout the part to meet local loading conditions. This presents challenges for Non-Destructive Testing. Intricate geometries can require time consuming manual inspection. Varying properties invariably mean that components are highly anisotropic making ultrasonic testing difficult due to changing acoustic velocities and high levels of structural noise. Combined with the need to inspect every part the process can become a bottleneck to production throughput. This paper describes the development of a robotic inspection system aimed at reducing the time to inspect components with complex geometry. The heart of the system comprises two 6-axis robotic arms capable of working independently and cooperatively. By reading in CAD data the system is able to manipulate transducers around highly complex shapes accurately at high speed. Phased array ultrasonic testing or full matrix capture (FMC) algorithms have been developed that allow wide swathes of data to be acquired in a single pass, while simultaneously coping with surface curvature and features such as radii. Custom software allows the inspection of parts with highly variant thickness by referencing each A-scan to the CAD data where front and rear interfaces cannot be reliably detected. An algorithm combining aspects of FMC and the synthetic aperture focusing technique reduces the effects of coherent noise and acoustic velocities that vary with angle. Analysis and sentencing is made easier by displaying 3D data wrapped around a CAD image. In addition to A and B-scans, a rotatable and zoomable image shows features mapped in 3D and displayed within the part