Quantitative Modellierung von Ultraschallprüfsituationen - Vergleich von Theorie und Experiment

A system model is presented to calculate the electrical voltage at the terminal of the receiver as it is produced by the scattered field of a flaw in an ultrasonic scattering experiment. In this model, the diffraction field of the transmitter is given by the solution of the boundary value problem of a surface traction of finite extension on the surface of the elastic half space. The resulting displacement vector is given as an elastic plane wave decomposition. Performing the same spectral decomposition for the diffraction field of the receiver, the application of a reciprocity identity allows the calculation of the electrical voltage at the receiver. The modeled wave fronts (A-Scans) and amplitude dynamic curves are compared with experiment for tandem- and LLT-inspection situations. The absolute amount of the maxima of the theoretical and experimental amplitude dynamic curves agree within 1-2 dB; this is within measurement precision. The shape of the modeled wave fronts are in good ag reement with experiment. The results are compared with those given by a model where the diffraction field of the transducers are calculated by a beam model.