ABSTRACT
For better evaluation of infrared measurements in non-destructive testing, especially for objects with complex geometry or small dimensions, it is beneficial to combine with the same viewing angle an image of a camera in the visible range with the image of an infrared camera. In the hybrid camera developed by us, a beam splitter is used which combines the visible and the infrared wavelength regions under the same viewing angle to form a hybrid image. The applications of this new technique range from the localization and the verification of false indications in non-destructive testing applications to the retrieval of 3D surface information with a hybrid picture as texture with defect indications and the filtering of laser markings displayed in the IR image to area and process monitoring.
ABSTRACT
Nondestructive testing of adhesive joints is of great interest. The method of second harmonic generation promises to give early information about failure of adhesive layers. In the case of resonance the amplitude of strain in a soft interface layer is strongly increased and, therefore, the layer considerably contributes to A2, the amplitude of the second harmonic. The nonlinear behavior of such a layer and its influence on A2 was studied by means of the finite element method. In the experimental situation all materials along the sound path contribute to A2. The dependence of the calculated and measured effects on the layer thickness, the velocity of sound, and the nonlinearity coefficient beta are reported.
