Abstract

Calibration functions for two-dimensional fracture test specimens, representing the relation between load, plastic displacement and uncracked ligament length, have been recently developed through the use of the Common Format Equation (CFE) proposed by Donoso and Landes. In the CFE, the behavior of the fracture test specimen is expressed as the product of three terms: a constraint factor, ?*; a geometry and ligament size-dependent function, G, and a hardening function H. One of the main assumptions of the CFE approach is that, for any given two-dimensional fracture test specimen geometry, the behavior may be predicted from the material stress-strain behavior, by using the appropriate G function. In other words, the material tensile properties, normally obtained with smooth cylindrical specimens, are transferred to the notched two-dimensional fracture specimens by means of the hardening function H. In another work by Donoso and Landes it has been further shown that calibration curves for planar, two-dimensional fracture specimens, may also be obtained directly from cylindrical specimen tensile data, using a model based on the CFE. In this model, the normalized load is directly related to true stress, and the normalized displacement to true strain, as obtained from a conventional tensile test performed with cylindrical specimens. In this context, one can expect that the same approach may be applied to the transfer of material properties from smooth cylindrical specimens to notched cylindrical specimens. The latter is a type of geometry that is deserving a lot of attention presently, because of some advantages when compared to planar specimens. In this work, both numerical and experimental data for a ferritic steel and a weld metal, are obtained and analysed in order to develop the calibration function for notched cylindrical specimens under tension load, based on the CFE approach. It is shown that the geometry function obtained, which depends on the ratio of the diameter d of the notched sector (the ligament of the specimen), to the diameter D of the cylindrical portion of the specimen, normalizes the load-plastic displacement data to a common format that depends solely on the material properties. Copyright © 1996 Elsevier Science Ltd.