An approach to estimate the crack length with vanishing influence from the microstructure is proposed. A model with a large number of randomly sized, shaped and oriented grains is employed. A series of cracks of lengths from about 1 to 7 grains is inserted in the model. The crack tip opening displacements are then computed. Standard deviation of the crack tip opening displacement decreases from about 20% for a short crack to about 7 % for a crack through 7 grains. From the engineering point of view, a crack shorter than 10 grains sizes is therefore dependent on the microstructural features.
COBISS.SI-ID: 22559015
Microstructurally short cracks with lengths up to about ten grains are known to be strongly influenced by the microstructural features in the neighborhood of the crack tip. These include randomly shaped and oriented crystal grains and strongly orientation dependent deformation behavior of the grains. This new book proposes computational models aiming to quantify the effects of random grain orientations on the variability of crack tip opening and sliding displacements (CTOD, CTSD).
We present a study on the influence of crystallographic orientations of grains on a short crack, which changes its direction due to crossing of a grain boundary. The study shows that the crystallographic orientations significantly affect the crack tip opening displacements. The crack tip opening displacements can be changed by a factor of 7.7 by the crystallographic orientation of the neighboring grains. The study also showed that more distant grains also have a non-negligible influence which can change the crack tip opening displacements by a factor of 3.3.
COBISS.SI-ID: 20743207
In this paper we present a study on the influence of crystallographic orientations of grains on a short advancing crack. The study is based on a finite element model that accounts for 212 grains of random size and crystallographic orientation. A crack is inserted in a given surface grain. Configurations where the crack reaches the first grain boundary have been analyzed. The study showed that a significant crack tip sliding displacement component exists, suggesting that a crack is under a mixed model loading.
COBISS.SI-ID: 20960807
An analysis of the effect of the grain orientations on a short Stage I surface crack is presented. In the single crystal case the crack tip displacements may differ by more than one order of magnitude. Near the crack tip slip is activated on all the slip planes whereby only two are active in the rest of the model. In the polycrystal cases it is shown that pattern of soft and hard grains significantly affects the crack tip displacements. This effect can have a greater impact on the crack tip displacements than the local grain orientation.
COBISS.SI-ID: 20767783