NONLINEAR ELASTIC-CONSTANTS OF SOLIDS WITH CRACKS

Experimental data on a cracked medium exhibiting high acoustic nonline arity is a commonly observed phenomenon. Here a physical model of a me dium with cracks is suggested to explain the observed phenomena. The m odel is based on the assumption of uniform stress that is valid for a low concentration of cracks. The crack behavior is described using the model in which a crack is represented as an elastic contact of two ro ugh surfaces, pressed one to the other under the action of internal st resses in the surrounding solid. Linear and nonlinear acoustic constan ts of the fractured medium are calculated. It is shown that, in this m edium, negative values of the Poisson's ratio and anomalously high val ues of the nonlinear constants are possible. (C) 1997 Acoustical Socie ty of America. [S0001-4966(97)05910-9].