THE LIMITING VALUE OF THE PARAMETER OF ELASTIC NONLINEARITY IN STRUCTURALLY INHOMOGENEOUS-MEDIA

The limiting possibilities for the increase in the nonlinear parameter s of microinhomogeneous media are analyzed on the basis of the hypothe sis assigning the nonlinear properties of microinhomogeneous media (su ch as bubbleous liquids, porous, granular, and cracked media) to a sin gle structural mechanism. It is established that the limit to the incr ease of nonlinear parameters is determined by the ratio between the li near elastic moduli of the host material and the ''soft'' inclusions ( defects) rather than by the nonlinear properties of the inclusions. Th e estimated Limiting value of the nonlinear parameter is practically i ndependent additional factors (the resonance properties and spatial or ientation of soft defects and the multilevel internal structure of the medium). The physical limit to the elastic nonlinearity of any microi nhomogeneous medium is caused by the limitation imposed on the values of the ratio between the elastic moduli of the host material and the s oft inclusions by the atomic structure of elastic bodies. Since the ra tio of the elastic moduli can vary within four to five orders of magni tude, the maximal possible value, for example, of the quadratic parame ter of nonlinearity is 10(4)-10(5), which agrees well with the experim ental data.