Crack Growth Based on Energy Balance

Abstract

When a solid is fractured new surfaces are created in the medium in a thermodynamically irreversible manner. Material separation is caused by the rupture of atomic bonds due to high local stresses. The phenomenon of fracture may be approached from different points of view, depending on the scale of observation. At one extreme is the atomic approach where the phenomena of interest take place in the material within distances of the order of 10⁻⁷ cm. At the other extreme is the continuum approach, which considers material behavior at distances greater than 10⁻² cm. In the atomic approach, the problem is studied using the concepts of quantum mechanics; the continuum approach uses the theories of continuum mechanics and classical thermodynamics. The complex nature of fracture prohibits a unified treatment of the problem, and the existing theories deal with the subject either from the microscopic or from the macroscopic point of view. A major objective of fracture mechanics is to bridge the gap between these two approaches.