The Engineering Flaw Assessment Method, EFAM, is presently being developed at GKSS. It consists of several individual documents for determining material properties and the crack driving force. The present paper briefly describes the document EFAM ETM 97 which provides guidance for estimating the crack tip opening displacement (CTOD) and the J‐integral as driving force parameters for homogeneous structures. The CTOD and J can be expressed as functions of applied force or applied strain.

A simulation of 3D crack extension using a cohesive zone model (CZM) has been carried out for a side‐grooved compact tension specimen and a surface‐crack tension specimen of aluminium 2024FC. Detailed finite element calculations were conducted by assuming crack extension only along the crack plane (mode I). For comparison, a 2D plane strain simulation is also presented. Load, displacement and crack extension histories are predicted and compared with the experiment. It is shown that the 2D approximation appears to agree reasonably well with experimental results, and that the 3D calculation gives very good agreement with test data. The determination of the CZM parameters is also discussed. Numerical results show that the CZM is a workable computational model which involves only a few microstructurally motivated phenomenological parameters for crack extension simulation.

Crack growth resistance can be substantially affected by the constraint conditions of a structural member which in turn are mainly a function of geometrical variables and the degree of plasticity. Standardized test methods are restricted to high constraint conditions as represented by deeply cracked bend‐type specimens and may hence lead to conservative structural assessments. It is demonstrated that adjusted testing can be used to reduce the degree of conservatism. Due to rapidly increasing computer capabilities, a combination of conventional R‐curve testing with micromechanical models emerges as an accurate tool which may permit routine evaluations of practical situations in the near future.

A simple engineering method for estimating a lower bound fracture toughness in the ductile‐to‐brittle transition region is presented. It is based on empirical evidence that the lower tail of the failure probability versus fracture toughness curve tends to be a straight line rather than a Weibull curve. Fitting the lower tail by a straight line, however, gives an engineering lower bound at a theoretical failure probability of zero. The method enables one to obtain lower bounds using small data sets of three or four specimens.

This communication gives an introduction to the Engineering Flaw Assessment Method (EFAM) presently being developed at GKSS. The EFAM consists of various documents describing experimental procedures for determining fracture properties under various conditions, as well as analytical procedures for estimating the crack tip opening displacement in terms of δ5 , the rate of δ5 , (dδ5 /dt), and the J‐integral as driving force parameters.