[1A5] Towards guided wave inspection of concrete using magnetostrictive patch transducers
Z West¹, S Khan¹, L Marston², R Young³, M Mulheron⁴ and O Trushkevych¹
¹University of Warwick, UK
²Fibre Technology Ltd, UK
³Lateral Logic Ltd, UK
⁴University of Surrey, UK
Infrastructure is ageing, and non-destructive inspection methods and condition monitoring are preferable for all structures including concrete. Ultrasonic testing is widely used as a non-destructive inspection method. Ultrasonic inspection of concrete structures uses compression (longitudinal) ultrasonic or P-waves (for example Pundit system). Bulk shear waves and medical ultrasound-style phased array data acquisition have also been used (for example MIRA system). To operate the systems, an operator input is required, with issues of access often a problem, also point-by-point scanning is often used. Guided ultrasonic waves can propagate long distances and can solve challenges of accessibility, reduce inspection times and lower the associated costs. Guided waves use the structure (plate, pipe) as a waveguide and can propagate long distances and inspect large areas from a single access point. Previously, tendons and rebar were inspected with longitudinal guided waves to detect and characterise debonding by monitoring guided wave leakage. Here, we explore the use of surface and guided shear horizontal waves (SH)1 for inspection of concrete plates and prisms, using magnetostrictive patch transducers. These transducers are highly effective at generating shear waves and can be applied to samples using pressure (no liquid couplant is required). They are lightweight and potentially low cost and can be left in situ if necessary. Based on the motion of the patch, we explore wave modes generated and achieve SH0 and SH1 mode generation in 30 mm-thick concrete plate using a 30 mm wavelength transducer; we explore the propagation of surface waves in the presence of defects such as flat-bottomed holes. We also test randomly oriented needle-like patches and report ultrasound generation directly in steel fibre-reinforced concrete using magnetostriction.
