Modeling the Interactions Between Multiple Crack Closure Mechanisms at Threshold

摘要: Abstract A fatigue crack closure model is developed that includes interactions between the three mechanisms most likely to occur at threshold; plasticity, roughness, and oxide. This model, herein referred as CROP (for Closure, Roughness, Oxide, Plasticity), also efsects of out-of plane cracking multi-axial loading. These features make uniquely suited for, but not limited to, threshold applications. Rough cracks are idealized here two-dimensional sawtooths, whose geometry induces mixed-mode crack- tip stresses. Continuum mechanics crack-tip dislocation concepts combined relate face displacements loads. Geometric criteria used determine loads from crack-face displacements. Finite element results, verify predictions, provide critical information about locations where occurs. Introduction Fatigue occurs when faces contact during cyclic It widely assumed closed shielded no damage while in (ref. 1). Further, normally