scope:

Requirements for new directions in fracture research emerge from considerations of the basic lack of applicability of K parameters for definition of the fracture extension resistance of nonfrangible metals. New research is required into fact,ors relating to the increase in plastic work energy resistance defined by R curves. The urgency of such studies evolves from the increasing use of metals of low-intensity plane stress (low-shelf low-tearing-energy) characteristics in structures of high-compliance features. A case is presenkd for the mutual consideration of metaltype structure-type relationships in fracture-safe design. Present fracture-safe design practices do not include a rational approach to this question. The report provides an introduction to these considerations in terms of extension of fracture mechanics concepts, as well as metallurgical factors and engineering practices. The importance for understanding the interact,ion of these factors cannot be overstated, and considerable emphasis is placed on introductory aspects. Data presentation of 11 curve research is limted to illustrative examples, which document the reality of fracture extension processes in determining conditions for structure failure. The report is intended as a precursor to topical reports on the subject.