Inspection procedure assessment using modelling capabilities

Before carrying out inspections at technical components, criteria have to be met to qualify the inspection procedure. The inspection qualification can be performed by technical justification or performance demonstration. The qualification of non-destructive testing methods can be checked on full scale mock-ups where real or realistic defects are implemented. To minimize caosts it will become mandatory to model the inspection procedure. In the case of ultrasonic testing, the modelling encounters the ultrasonic probe, the pulse/defect interaction and the probe geometry. The applied modelling code is the Elastodynamic Finite Integration Technique (EFIT) which allows to include mode conversion effects. The results of the code are either wave fields, A-scan at different prob epositions or complete rf-data fields. Examples demonstrate the efficiency in modelling angle beam probes which transmit both pressure-, shear- and subsurface longitudinal waves. These waves are scattered by horizontal or surface breaking cracks. The modelled rf-data fields are used within SAFT to predict the ultrasonic 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 these media.