Guided wave tomography using recursive wavefield extrapolation operators

volker, arno; TNO; Netherlands

Volker, A.; TNO; Netherlands

ID: ECNDT-0169-2018
Session: Guided Waves Techniques 1
Room: G3
Date: 2018-06-14
Time: 14:10 - 14:30

Guided wave tomography is an advanced technology for quantitative wall thickness mapping at physically inaccessible locations like pipe supports. The wall thickness imaging algorithm uses the measured phase (time) at a specific frequency. The accuracy of the model greatly affects the sizing accuracy and detection threshold. Particularly for seam welded pipes there is a measurable amount of anisotropy. Moreover for small defects advanced forward modelling approaches are required to accurately model the defect interaction. This is achieved by using recursive wavefield propagation operators that include anisotropy. The inversion scheme is not only estimating the wall loss profile but also the anisotropy, local material changes and transducer ring alignment errors. This makes the approach more robust. The approach will be demonstrated on different defect sizes and a comparison will be made between different tomographic reconstruction schemes.