INSPECTION PROCEDURE ASSESSMENT USING MODELING CAPABILITIES

Before carrying out inspections on technical components, criteria have to be met to qualify the inspection procedure. The inspection qualifi cation can be performed by technical justification or performance demo nstration. The qualification of non-destructive testing methods can be checked on full scale mock-ups where real or realistic defects are im plemented. To minimize costs it will become mandatory to model the ins pection procedure. In the case of ultrasonic testing, the modelling in cludes the ultrasonic probe, the pulse-defect interaction and the prob e geometry. The applied modelling code is the elastodynamic finite int egration technique (EFIT) which includes mode conversion effects. The results of the code are either wave fields, A-scans at different probe positions or complete r.f. data fields. Examples demonstrate the effi ciency in modelling angle beam probes which transmit both pressure, sh ear and subsurface longitudinal waves. These waves are scattered by ho rizontal or surface breaking cracks. The modelled r.f. data fields are used within the synthetic aperture focusing approach to predict the u ltrasonic image which would be obtained in performing the experiment. In addition it will be shown that the EFIT wave fronts for anisotropic homogeneous media are explicitly related to the group velocity in the se media.