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Two-parameter FCG driving force: successive blocking of the monotonic and cyclic plastic zones at microstructural barriers
Last modified: 2011-02-25
Abstract
A micromechanical description of small fatigue crack growth based on the successive blocking of
the monotonic plastic zone (MPZ) and cyclic plastic zone (CPZ) of a crack at microstructural barriers such as
grain boundaries and phase limits is presented. The model allows two different fatigue crack growth thresholds
to be established, one of which, the maximum-controlled fatigue threshold, is dependent on the capability of MPZ to
overcome successive material barriers and the other, the range-controlled fatigue threshold, is associated with the
capability of CPZ to overcome such barriers as well. The implications of this micromechanical model and its
applicability depending on the loading conditions are discussed, linking and supporting in a natural manner with
use of two-parameter crack driving force ( K Kmax ) to characterize the fatigue crack growth in the long crack
regime.
the monotonic plastic zone (MPZ) and cyclic plastic zone (CPZ) of a crack at microstructural barriers such as
grain boundaries and phase limits is presented. The model allows two different fatigue crack growth thresholds
to be established, one of which, the maximum-controlled fatigue threshold, is dependent on the capability of MPZ to
overcome successive material barriers and the other, the range-controlled fatigue threshold, is associated with the
capability of CPZ to overcome such barriers as well. The implications of this micromechanical model and its
applicability depending on the loading conditions are discussed, linking and supporting in a natural manner with
use of two-parameter crack driving force ( K Kmax ) to characterize the fatigue crack growth in the long crack
regime.
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