Digital Repository, ICF12, Ottawa 2009

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Cohesive fracture modelling of overload e®ects in fatigue
V. R. Krishnan, K. D. Papoulia

Last modified: 2013-05-03


A cohesive fracture model is used to capture the e®ect of a single peak overload in a ductile
316L steel alloy under plane stress conditions, viz. crack retardation. Previously, the model
was used to capture the fatigue life at di®erent loading ratios. The model follows a bi-linear
traction-displacement relationship coupled with a nonlinear damage evolution equation. The
rate of damage evolution is characterized by three material parameters corresponding to damage
accumulation, crack closure and stress threshold. The results indicate that a higher peak load
results in higher fatigue crack retardation. The results also agree with experiments that suggest
that strain hardening, not crack closure, is the leading mechanism for the overload e®ect.

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