A mathematical model based approach for sizing cracks in stainless steel welds

摘要

Ultrasonic arrays are developing into a viable tool for use within industry for the non-destructive testing of safety critical components. Steel welds are notoriously difficult to inspect due to the highly scattering nature of the material microstructure and ultrasound arrays have demonstrated tremendous potential in realising a step change in our ability to tackle this problem. However, to exploit the full potential of this technology it is necessary to develop sophisticated algorithms underpinned and shaped by a sound mathematical understanding of the underlying wave processes. In this paper a physical model based approach is developed for the sizing of zero volume (lack of fusion) cracks in steel welds. The interaction of the ultrasound waves with the flaw is contained in the full matrix capture data recorded by the array and transformed into the frequency domain in the form of scattering matrices. These scattering matrices are used in conjunction with an analytical approximation (based on the Kirchhoff model) to objectively determine the size of the crack.