ИСТИНА

The paper presents the results of experimental investigations of nonlinear elastic properties of boundary between two flat rough surfaces of solids. The plates made of aluminum and steel were used as the samples. The study of the elastic properties of the boundaries was carried out using surface acoustic waves (SAW). SAW at the interface of solids were excited and taken by wedge transducers at frequencies of 1.25 MHz and 2.5 MHz. Experimental studies were performed on automated ultrasonic complex RITEC RPR-5000. We investigated the effect of the static pressure applied to the boundary of two solids and the amplitude of the probing SAW of 1.25 MHz on efficiency of SAW second harmonic generation on the frequency 2.5 MHz at the border of rough surfaces. According to the results of experimental measurements of the amplitudes of first and second harmonics of the SAW on the rough edge of solids nonlinear acoustic parameter of the second order depending on the external pressure applied to the interface for fixed values of the amplitude of the probe wave was calculated. The features of calculated nonlinear parameter were caused by changes in the contact acoustic nonlinearity with increasing external pressure applied to the border. The experimental results were analyzed on the basis of the theory of contact acoustic nonlinearity.