Browsing by Author "Gachagan, Anthony"

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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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    Multi-layer ultrasonic imaging of as-built wire + arc additive manufactured components
    (Elsevier, 2021-10-13) Zimermann, Rastislav; Mohseni, Ehsan; Lines, David; Vithanage, Randika K. W.; MacLeod, Charles N.; Pierce, Stephen G.; Gachagan, Anthony; Javadi, Yashar; Williams, Stewart; Ding, Jialuo
    Non-Destructive Evaluation (NDE) of metal Additively Manufactured (AM) components is crucial for the identification of any potential defects. Ultrasonic testing is recognised for its volumetric imaging capability in metallic components and high defect sensitivity. However, conventional ultrasonic techniques suffer from challenges when deployed on components with curved and non-planar geometries, such as those often encountered in AM builds. The body of work introduces the concept of inspection of Wire+Arc Additive Manufacture (WAAM) components from their non-planar as-built surface, eliminating the requirement for post-manufacturing machining. In-situ or post-manufacturing inspection is enabled via an autonomously deployed conformable phased array roller-probe deploying Synthetic Aperture Focusing Technique (SAFT)-surface finding and multi-layer adaptive Total Focusing Method (TFM) algorithms, for fully focussed imaging of the as-built WAAM component. The concept of the imaging approach is demonstrated by inspection, through the as-built surface, of two titanium WAAM components, one containing reference bottom-drilled holes, and the other with intentionally introduced Lack of Fusion (LoF) defects. The TFM images of the WAAM components feature sufficient Signal-to-Noise Ratio to enable defect detection along with strong agreement against reference X-Ray CT data, confirming the competency of the approach for volumetric or layer-specific inspection of as-built WAAM components.
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    Remote ultrasonic imaging of a wire arc additive manufactured Ti-6AI-4V component using laser induced phased array
    (IEEE, 2021-06-28) Lukacs, Peter; Davis, Geo; Stratoudaki, Theodosia; Williams, Stewart; MacLeod, Charles N.; Gachagan, Anthony
    Additive manufacturing (AM) has been revolutionizing the manufacturing industry due to its ability to significantly reduce waste and produce components with intricate shapes. Laser Ultrasonics (LU) is a non-contact and couplant free method to generate and detect ultrasound. LU can accommodate complex component shapes; thus, it has the potential to provide a reliable in-process inspection method for AM components. In recent years the development of Laser Induced Phased Arrays (LIPAs) helped overcome the inherently low signal amplitudes of LU at the non-destructive, thermoelastic regime. In this paper, the Full Matrix Capture data acquisition method is used and a LIPA of 68 elements is synthesized in post processing. The Total Focusing Method imaging algorithm is applied for ultrasonic imaging. The technique is demonstrated on a highly scattering titanium alloy Wire Arc Additive Manufactured (WAAM) component producing high quality ultrasonic images, accurately imaging defects at depths up to 10mm below the inspection surface
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    Remote Ultrasonic Imaging of a Wire Arc Additive Manufactured Ti-6Al-4V Component using Laser Induced Phased Array
    (Cranfield University, 2021-08-18 14:42) Lukacs, Peter; Williams, Stewart; Davis, Geo; MacLeod, Charles; Stratoudaki, Theodosia; Gachagan, Anthony
    Supporting dataset for the publication: "Remote Ultrasonic Imaging of a Wire Arc Additive Manufactured Ti-6Al-4V Component using Laser Induced Phased Array".The file contains all the signals used to produce the images in the paper, using information mentioned in the paper, e.g. pitch and filter centre frequency.
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    Ultrasonic phased array inspection of wire plus arc additive manufacture samples using conventional and total focusing method imaging approaches
    (British Institute of Non-destructive Testing, 2019-03-01) Javadi, Yashar; MacLeod, Charles N.; Pierce, Stephen G.; Gachagan, Anthony; Lines, David; Mineo, Carmelo; Ding, Jialuo; Williams, Stewart W.; Vasilev, Momchil; Mohseni, Ehsan; Su, Riliang
    In this study, three aluminium samples produced by wire + arc additive manufacture (WAAM) are inspected using ultrasonic phased array technology. Artificial defects are machined using a centre drill, ø 3 mm, and electrical discharge machining (EDM), ø 0.5-1 mm, in a cylindrical through-hole topology. The samples are first inspected using a singleelement wheel probe mounted on a KUKA robot in order to investigate the feasibility of using a conventional ultrasonic transducer approach. Unfortunately, the wheel probe is found to be unsuitable for scanning the WAAM specimens and ultrasonic phased arrays are employed next. The set-up includes 5 MHz and 10 MHz arrays (128 elements) in direct contact with the sample surface using both the conventional and total focusing method (TFM) imaging techniques. Using an FIToolbox (Diagnostic Sonar, UK) as the controller, a phased array aperture of 32 elements is used to perform a focused B-scan with a range of settings for the transmit focal depth. All of the reflectors (including those located near the WAAM top surface) are successfully detected with a combination of conventional phased array and TFM, using a range of settings and set-ups, including bottom surface inspection, application through a plexiglass wedge and variation of the scanning frequency.