scope:

A general overview of the subject of elastic-plastic fracture is presented. The discussion is carried out with the aid of a simple expression which permits the factors important to fracture control to be treated systematically. Such treatment allows the reader to see how factors such as material strength, material toughness, service conditions, crack size, inspection levels, etc. are related to one another. At various points in the discussion it is apparent that more work is needed to clarify certain issues relevant to fracture control. The issues to be clarified seem to group themselves into the following four categories.

(1) Concerns related to how one applies fracture mechanics models to real structures;

(2) Questions about measurement of toughness in the laboratory;

(3) Questions involving the relationship between the effects of real imperfections on fracture behavior and the manner in which those imperfections are treated for fracture control calculations;

(4) Concerns about the current practice of extending the results of linear elastic analyses beyond the range of "small scale yielding." Thus, in addition to discussing current fracture control strategies, this discussion attempts to outline the kind of research needed to help develop more effective elastic-plastic fracture control practices.