The paper presents new NDT method of conducting solids. Tested sample is excited by harmonic electrical and ultrasonic signals with different frequencies. On the defect caused non linearity new harmonic signal is created with frequency given by subtraction of exciting frequencies fE and fU. It was found that the amplitude of the intermodulation component Ui is linear function of electrical excitation and quadratic function of ultrasonic excitation. High sensitivity of this method follows from the fact that the signal giving information on tested sample quality has frequency different from exciting signals. The signal to noise ratio and high sensitivity for NDT analyses is based on the application of special electrical filters. Experimental verification of this method was performed on the samples of aluminum and dural plates and on the thick conducting films, both without and with cracks prepared artificially.
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