TY - JOUR
AB - Fatigue crack propagation is by far the most important failure mechanism. Often cracks under lowcycle fatigue conditions and, especially, short fatigue cracks cannot be treated with the conventional stress intensity range ΔK-concept, since linear elastic fracture mechanics is not valid. For such cases, Dowling and Begley (ASTM STP 590:82–103, 1976) proposed to use the experimental cyclic J -integral ΔJ^{exp} for the assessment of the fatigue crack growth rate. However, severe doubts exist concerning the application of ΔJ^{exp}. The reason is that, like the conventional J -integral, ΔJ^{exp} presumes deformation theory of plasticity and, therefore, problems appear due to the strongly non-proportional loading conditions
during cyclic loading. The theory of configurational forces enables the derivation of the J -integral independent of the constitutive relations of the material. The
J -integral for incremental theory of plasticity, J^{ep}, has the physical meaning of a true driving force term and is potentially applicable for the description of cyclically loaded cracks, however, it is path dependent. The current paper aims to investigate the application of J^{ep} for the assessment of the crack driving force in cyclically loaded elastic–plastic materials. The properties of J^{ep} are worked out for a stationary crack in a compact tension specimen under cyclic Mode I loading and large-scale yielding conditions. Different load ratios, between pure tension- and tension–compression loading, are considered. The results provide a new basis for the application of the J -integral concept for cyclic loading conditions in cases where linear elastic fracture mechanics is not applicable. It is shown that the application of the experimental cyclic J -integral ΔJ^{exp} is physically appropriate, if certain conditions are observed.
AU - W. Ochensberger
AU - O. Kolednik
DA - 2014/08/15/
DO - 10.1007/s10704-014-9963-3
IS - 189
JF - International Journal of Fracture
PY - 2014
SE - 2014/07/29/
SP - 77-101
TI - A new basis for the application of the J -integral for cyclically loaded cracks in elastic–plastic materials
ER -