Browsing by Author "Foster, Euan"

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    Development of a phased array ultrasound roller probe for inspection of wire + arc additive manufactured components
    (Elsevier, 2022-06-25) Vithanage, Randika K. W.; Mohseni, Ehsan; Lines, David; Loukas, Charalampos; Foster, Euan; MacLeod, Charles N.; Pierce, S. Gareth; Gachagan, Anthony; Ding, Jialuo; Williams, Stewart
    The wire + arc additive manufacturing (WAAM) process, which combines an electric arc as a heat source and metal wire as feedstock is proving to be very effective when producing medium to large scale metal components. The non-destructive testing (NDT) of WAAM parts, while they are being produced, provides early intervention opportunities to rectify manufacturing nonconformities and to perform in-process quality assurance of the parts. This attracts a significant amount of material, time and cost savings. Therefore, this paper presents the research, development and validation of a high temperature phased array ultrasound testing (PAUT) roller probe to perform robotically delivered in-process NDT of WAAM components. The experimental results confirm that the PAUT roller probe can endure surface temperatures up to 350 °C, can be autonomously deployed via a robotic arm and can detect 1 mm diameter flat-bottom holes located 6 mm, 9 mm and 12 mm deep under the unmachined surface of a Ti-6Al-4V WAAM calibration block.
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    Increasing the speed of automated ultrasonic inspection of as-built additive manufacturing components by the adoption of virtual source aperture
    (Elsevier, 2022-06-15) Zimermann, Rastislav; Mohseni, Ehsan; Vithanage, Randika K. W.; Lines, David; Foster, Euan; MacLeod, Charles N.; Pierce, Stephen Gareth; Marinelli, Gianrocco; Williams, Stewart; Ding, Jialuo
    Wire + Arc Additive Manufacture (WAAM) is an economical manufacturing technique to build components. To maintain the commercial and technical benefits, inspection is desired at each layer of the build. New conformable phased array roller-probes offer the potential to inspect the as-built sample in-process or on completion. A challenge with such inspections is the refraction of the ultrasonic waves at multiple interfaces. The Synthetic Aperture Focusing Technique (SAFT) and Total Focusing Method (TFM), combined with Full Matrix Capture (FMC) acquisition enabled imaging through the as-built WAAM surface. However, single-element firings, associated with FMC are a limiting factor due to the lower energy at transmission, while the high number of firings and subsequent larger data size negatively affect inspection speed. This work introduces the concept of Virtual Source Aperture (VSA) for ultrasonic roller-probe inspection, through modelling of VSA on custom-designed calibration WAAM block. The concept is then demonstrated on a mock as-built WAAM sample inspection with reference defects. The results demonstrate that a markedly lower number of transmissions are required to match the performance of the FMC counterpart while increasing the energy levels. Moreover, an almost 50% reduction in the data size enabled a doubling of the inspection speed.