Ultraschallpruefvorrichtung zum Untersuchen des nichtlinearen Verhaltens von Grenzflaechenbereichen
Using an ultrasonic testing device for investigating the non-linear response of boundary layers (10), the frequency components of a pulsed transmit signal transmitted by a transmitter (1, 3, 6) and sent to a transmit head (9), said signal having a basic frequency which can be received via a broadband receiving head (16) can be separated in a frequency analyzer (18). The amplitudes of the frequency components linked harmonically with the transmit frequency and the dc voltage component can be aggregated in a summer (26) with alternating positive and negative signs after passing through correspondingly tuned filters (20, 21, 22). The final signal thus formed and presented to output (27) of the summer (26) can be compared by means of a comparator circuit (30) and a threshold value circuit (42) with calibrated measurements stored in memory devices (31, 32, 33, 34). In a modified form of the version example, the binding force in the boundary layer (10) to be investigated can be determined fr om the end signals presented to the output (27) of the summer (26) by means of an end signal converter, whereby the amplitude of the dc voltage component is separated via a dc voltage filter and is routed to the summer which aggregates the amplitude of the dc voltage component with negative sign.
DE 1993-4324143 A: 19930719