Crack Tip Controls
Within the options to specify the crack front the user has control over several aspects of the generated mesh. For example:
- The radial midside nodes in the crack front elements may be specified at the quarter-point position or the midside position (or anywhere in between).
- The crack front nodal positions may contain a single node or multiple nodes that can open up to simulate blunting.
- The element rings around the crack front may be biased towards the crack front or evenly spaced.
- The outer size of the element rings around the crack front can be controlled.
These options are easy to specify in the input file. For example, the combination of quarter-point nodes and a single node for each crack front nodal location, which is suitable for the r-0.5 LEFM singularity, is the default option on the *TIP MODEL keyword:
*TIP MODEL, LEFM
The combination of midside nodes and multiple nodes at crack front nodal locations gives an r-1 singularity and is more suited to EPFM. This is requested using:
*TIP MODEL, EPFM
Tip model for LEFM - Quarter point radial nodes and a single node at each crack front position
Tip model for EPFM - Midside radial nodes and multiple nodes at each crack front position
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