Modeling of Crack Closure due to Plasticity and Sliding in Slanted Fatigue Cracks
Sandeep Kibey, Prof. Huseyin Sehitoglu
Crack closure has now been accepted as a crucial retardation mechanism in fatigue crack growth. Researchers in the past have focused on modeling and understanding a variety of closure mechanisms like plasticity induced crack closure, roughness induced crack closure, oxide induced crack closure etc. The bulk of this research, however, has been limited to straight cracks. In components under service, fatigue cracks deviate from their path as they propagate and behavior of such cracks is significantly different from straight cracks. Consequently, it is essential to investigate the effect of crack closure on growth rates of slanted and deflected fatigue cracks.
In this research, fatigue crack closure in slanted and deflected cracks is simulated by developing a finite element model using the commercially available software ABAQUS. This FE model facilitates better insight into the effect of non-planar crack geometry on premature crack face contact and its consequences on crack growth rates. Slanted and deflected cracks are allowed to propagate under local mixed mode conditions when subjected to remote mode I cyclic loading. The resulting closure is due to a combination of plasticity induced crack closure and sliding occurring due to the relative tangential displacements between crack faces as the crack propagates. The effects of crack geometry, friction and contact interaction between crack faces, stress level, and R ratio on crack opening levels are investigated. The present study aims to develop a finite element crack closure model which accounts for the effects of crack deflection, crack orientation, friction and contact interaction between crack surfaces on crack growth rates.
- Andrews, S. and H. Sehitoglu, “A Computer Model for Fatigue Crack Growth from Rough Surfaces,” International Journal of Fatigue, 22:7, 619-630, 2000.
- Kibey, S., H. Sehitoglu, and D. Pecknold, “Modeling of Fatigue Crack Closure in Inclined and Deflected Cracks,” Int. J. Fracture, 129:3, 279-308, 2004. (pdf)