Chapter 13 - Theoretical aspects

Abstract

This chapter discusses the working of theory of critical distances (TCD), its theoretical basis, and its comparison with other theories of fracture. The TCD model closely resembles the continuum mechanics end of the spectrum. There has been very little work done for placing the TCD on a firm theoretical foundation within continuum mechanics. The TCD is a modification of linear elastic fracture mechanics (LEFM) in which the existence of mechanisms at the microstructural level is represented by the introduction of a single length scale parameter, L. Alike LEFM, TCD also has the advantage of continuum mechanics theories that it is not confined to one particular mechanism of failure. LEFM can predict failure (within certain limitations) if the failure occurs by crack propagation, irrespective of the mechanism of crack propagation involved. TCD can be understood by Finite Fracture Mechanics (FFM). The importance of FFM is that while being completely valid from the point of view of continuum mechanics, it also represents an important feature of the physical mechanism of cracking processes. The chapter also examines the relationship between the TCD and other methods for predicting fracture.