Page 301 - Handbook of Materials Failure Analysis
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6 Results and Discussion 297
70,000
60,000
50,000
Load (N) 40,000 Experiment
30,000
Full model, elastic plastic
Half model (nonlocal)
20,000 Half model (local)
Full model (nonlocal)
Full model (local)
10,000
0
0 1 2 3 4 5 6
COD (mm)
FIGURE 12.10
Effect of symmetric boundary conditions on load-deformation behavior of a 1T CT specimen
(half vs. full model used in local and nonlocal FE analysis).
Symmetry plane
Local model Nonlocal model
FIGURE 12.11
Crack growth path for a full 1T CT specimen (without symmetric boundary conditions, local
vs. nonlocal model).
symmetry are met. Hence, the results of the nonlocal model are more realistic when
compared to those of local model. Due to the above observation, one must be careful
about the use of local damage models for prediction of crack path when the geom-
etry, initial crack configurations, and loading conditions are complex.
6.5 EFFECT OF CRACK DEPTH ON THE PROBABILITY
OF CLEAVAGE FRACTURE IN THE DBTT REGIME
In the DBTT regime, the crack-tip experiences a large stress gradient and hence, the duc-
tilecrackgrowth(oftheorderoffewmicrons)beforeunstablecleavagefracturecannotbe
predicted by the local damage models. This is because of the mesh-dependent nature of
