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Contemporary 2D Ultrasonic arrays suffer from low SNR and limited steering capabilities. Yet, there is a great desire in the industry to increase the operational frequency, in order to enhance their volumetric imaging resolution. State-of-the art arrays use an orthogonal matrix of rectangular elements as this is a natural step forward from the conventional 1D array structure. The objective of this work is to evaluate properties of triangular, rather than rectangular ceramic pillars in a 1-3 connectivity piezoelectric composite for application in a hexagonal-element 2D array. A 3MHz prototype device exploiting new hexagonal substructure have been manufactured. Measured mechanical cross-coupling level is -21.9dB between neighbouring hexagonal elements, providing validation of simulation result. Corroboration between measured and FE modelled device behaviour is demonstrated.

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 single-element 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.

Specimens with intentionally embedded weld defects or flaws can be employed for training, ‎development and research into ‎procedures for mechanical property evaluation and ‎structural integrity assessment. It is critical that the artificial defects are ‎a realistic ‎representation of the flaws produced by welding. Cylindrical holes, which are usually ‎machined after welding, ‎are not realistic enough for our purposes as it is known that they ‎are easier to detect than the naturally occurring ‎imperfections and cracks. Furthermore, it is ‎usually impractical to machine a defect in a location similar to where the real ‎weld defects ‎are found. For example, electro-discharge machining can produce a through hole ‎‎(cylindrical reflector) which ‎neither represents the weld porosity (spherical voids) nor the ‎weld crack (planar thin voids).‎‏ ‏In this study, the aim is to ‎embed reflectors inside the weld intentionally, and then locate ‎them using ultrasonic phased array imaging. The specimen is ‎an 8 mm thick 080A15 ‎Bright Drawn Steel plate of length 300 mm. Tungsten rods (ø2.4-3.2 mm & length 20-25 ‎mm) and ‎tungsten carbide balls (ø4 mm) will be used to serve as reflectors simulating ‎defects within the weld itself. This study is ‎aligned to a larger research project investigating ‎multi-layer metal NDE found in many multi-pass welding and wire arc ‎additive ‎manufacturing (WAAM) applications and as such, there is no joint preparation as the first ‎layer is deposited over ‎the plate surface directly and subsequent layers contribute to the ‎specimen build profile, similar to the WAAM samples. A ‎tungsten inert gas welding torch ‎mounted on a KUKA robot is used to deposit four layers for each weld, with our process ‎‎using nine passes for the first layer, down to six passes for the last layer. During this procedure, ‎the tungsten artificial ‎reflectors are embedded in the weld, between the existing layers. The ‎sample is then inspected by a 10 MHz ultrasonic ‎phased array in direct contact with the ‎sample surface using both conventional and total focusing method (TFM) imaging ‎‎techniques. A phased array aperture of 32 elements has been used. The phased array ‎controller is FIToolbox (Diagnostic ‎Sonar, UK). Firstly, a focused B-scan has been ‎performed with a range of settings for the transmit focal depth. Secondly, a ‎full-aperture ‎TFM method has been processed. All the reflectors of interest were detected successfully ‎using this ‎combination of B-scan and TFM imaging approaches.‎

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, ø3 mm, and electro-discharge machining (EDM), ø0.5-1 mm, in a cylindrical through hole topology. The sample was first inspected by a single element wheel probe mounted on a KUKA robot in order to investigate the feasibility of using a conventional ultrasonic transducer approach. Unfortunately, the wheel probe was found to be unsuitable for scanning of the WAAM specimens and ultrasonic phased arrays were employed next. The setup included 5 MHz and 10 MHz arrays (128 elements) in direct contact with the sample surface using both conventional and total focusing method (TFM) imaging techniques. Using FIToolbox (Diagnostic Sonar, UK) as the controller, a phased array aperture of 32 elements was used to perform a focussed B-scan with a range of settings for the transmit focal depth. All the reflectors (including those located near the WAAM top surface) were successfully detected by a combination of conventional phased array and TFM, using a range of settings and setups including bottom surface inspection, application through a Plexiglas wedge and variation of the scanning frequency.