A Pre-Meshed Crack is based on a previously generated mesh and uses a node-based named selection to analyze crack fronts. In addition to cracks modeled in CAD and meshed manually in the Mechanical Application, this feature is also useful when you have a pre-existing mesh generated from an external source and imported to the existing database. The referenced named selection must contain references only to nodes.
Selecting the named selection is done through the Details view of the Pre-Meshed Crack object by selecting from the list of valid named selections in the Crack Front (Named Selection) property. Named selections that contain only nodes are offered as choices.
Important: To properly define a Pre-Meshed Crack object, you need to create the necessary node-based Named Selections and generate all crack meshes in advance. For more information on named selections, see Named Selections. As an alternative, a geometric based named selection can be converted into a node-based based named selection using the Worksheet. For more information, see Specifying Named Selections using Worksheet Criteria.
To define a pre-meshed crack:
Select the Model object in the Tree Outline.
Insert a Fracture object into the Tree by right-clicking the Model object and selecting Insert > Fracture.
Note: Only one Fracture object is valid per Model.
Insert a Pre-Meshed Crack object into the Tree by right-clicking the Fracture object and selecting Insert > Pre-Meshed Crack. You can also select the Pre-Meshed Crack option from the Crack group of the Fracture Context Tab.
In the Details View:
- For 2D Analysis
Specify the node-based named selection for the Crack Tip (Named Selection) property. This property defines the nodes to which the crack definition will be scoped.
- For 3D Analysis
Specify the node-based named selection for the Crack Front (Named Selection) property. This property defines the nodes to which the crack definition will be scoped.
Set the Crack Faces Nodes property to (default). This property enables you to specify a crack top face and bottom face using node-based Named Selections. When set to , the following additional properties display:
Top Face Nodes: Specify the top face (nodes) of the crack by selecting a valid node-based named selection from the drop-down list.
Bottom Face Nodes: Specify the bottom face (nodes) of the crack by selecting a valid node-based named selection from the drop-down list.
To further define the crack, use the following controls in the Details View.
Crack ID: A read-only property that displays a unique system generated identification number ID for the crack object. The application uses this identifier when creating solution identifiers for fracture parameters.
Coordinate System: Specifies the coordinate system that defines the position and orientation of the crack. The Y axis of the specified coordinate system defines the crack surface normal. The origin of the coordinate system represents the open side of the crack. You can select the default coordinate system or a local coordinate system that you have defined. The default is the Global Coordinate System. The valid coordinate system must be of type Cartesian.
Solution Contours: Specifies the number of contours for which you want to compute the fracture result parameters.
Symmetry: Specifies the crack symmetry about a line (in 2D analysis) or about a plane (in 3D analysis). The default is .
Suppressed: Toggles suppression of the Pre-Meshed Crack object. The default is No.
Note: The Pre-Meshed Crack object is suppressed automatically if the scoped body is suppressed.