Two-dimensional (2D) ultrasonic arrays for non-destructive evaluation enable the detection and characterisation of sub-surface defects in three-dimensions (3D). An important industrial application for this technology is the in-situ inspection of jet-engine turbine blades for root cracking. However modern jet-engine turbine blades are cast from single crystals of nickel-based superalloys because of their excellent mechanical properties at high temperature. Single-crystal materials are elastically anisotropic, which causes ultrasonic waves to propagate with different velocities depending on the direction of the wave and which significantly reduces the quality of the inspection.

Rolls-Royce and Bristol University collaborated through an EngD programme to build on RCNDE research and use wave propagation modelling to correct ultrasonic imaging algorithms, thereby enabling the reliable volumetric inspection of single-crystal aerospace components. The programme also found ways to overcome physical access constraints for in situ inspection and evaluated defect detection sensitivity and sizing capability.