[7A4] Modelling and simulation of ultrasonic arrays for sizing non-sharp defects
Shivaprasad Shridhara Bhat, Jie Zhang and Nicolas Larrosa
Department of Mechanical Engineering, University of Bristol, Bristol BS8 1TR, United Kingdom
Structural components exposed to harsh operating environments initiates several damage mechanisms, introducing microscale defects, that, if allowed to grow beyond a critical size, results in catastrophic failure of the component. The ultrasonic array-based non-destructive evaluation has grown rapidly over the last few decades for detection and characterization of a range of defects in structural components. Most of the existing structural integrity assessments assume defects to be sharp cracks, and often this assumption is over-conservative, leading to a pessimistic assessment of structural components and a severe underestimation of their safety margin against fracture. The present work addresses the problem of modelling non-sharp defects for simulating ultrasonic waves using a two-dimensional finite-difference-time-domain scheme in an isotropic, homogenous medium. The study further examines the optimal gridding requirement for modelling array transducers and circular scatterers. The numerical models are validated against ultrasonic experiments performed on an aluminium specimen having side-drilled holes. The numerical models are further extended to investigate the ultrasonic responses from notch with varying tip radii.
