ASA 130th Meeting - St. Louis, MO - 1995 Nov 27 .. Dec 01

2pPA8. The model describing the higher-order elastic constants of solids with cracks.

Alexander M. Sutin

Veniamin E. Nazarov

Inst. of Appl. Phys., Russian Acad. Sci., 46 Ulyanov str., Nizhny Novgorod 603600, Russia

There are many experimental data showing that third-order elastic constants of solids with cracks can be anomalously high and can exceed these parameters for homogeneous solids more than a thousand times. Here a physical model of a medium with cracks is suggested to explain such high nonlinearity. The model is based on the assumption that the stress applied to a single crack is the same as that applied to the whole body, that is valid for a low concentration of cracks. The crack behavior was described using the model in which a crack can be presented as an elastic contact of two rough surfaces, pressed one to another under the action of internal stresses in the surrounding solid. The nonlinear behavior of a crack is due to the contact area changing when the crack is undergoing stress or extension. Linear and nonlinear elastic constants of the medium with cracks are calculated; it is shown that in this medium negative values of Poisson's ratio and anomalously high values of the third-order constants are possible.