THEORETICAL AND EXPERIMENTAL-STUDY OF EXCESS NOISE IN ELASTIC SOLIDS

Experimental results of excessive mechanical noise detection for sampl es under small loads within the linear range of the dependence between the deformations and the mechanical strains are reported. Typical val ues of sample strains were similar to(2-5)x10(7) N/m(2). The mechanica l noise investigation consisted in measuring the radial (''barrel-shap ed'') oscillations of a cylinder compressed by screw press. Small disp lacement capacitive sensors with a resolution similar to 10(-11) cm (0 .001 Angstrom) in the frequency range 0.2-20 kHz were used. It has bee n found experimentally that for the sample made from an inhomogeneous material (limestone with marble impregnations) under loads that are fa r from being destructive (in the Hook's law region) the relationship b etween the mechanical noise power in the low-frequency region 5-12 kHz and mechanical strain is nonlinear, namely, quadratic, which is the f irst experimental confirmation of the existence of excessive mechanica l noises in mechanical systems.