You use the SMART Crack Growth object to simulate fatigue or static crack growth in engineering structures. SMART is a remeshing-based method for crack growth simulation. SMART stands for Separating, Morphing, Adaptive, and Remeshing Technology. SMART automatically uses a combination of morphing, adaptive, and remeshing methods to update mesh changes to simulate static or fatigue crack growth during the solution process. The mesh changes occur around the crack-front region only, leading to a computationally efficient solution of the crack-growth problem.
Points to Remember for Restarting an Analysis
SMART Crack Growth supports restarting the analysis from any intermediate load step. It is important to note the following when restarting an analysis that involves SMART Crack Growth:
To retain the restart points after any load modifications or load step deactivation, it is necessary to scope such loads to node-based or element based Named Selections with the Preserve During Solve property set to . Otherwise, the Restart Type property setting Program Controlled is automatically reset to . That is, point for any load modifications or load step deactivation.
During the solution process, if the total number of substeps, combined from all of the load steps, exceeds 99, the application automatically begins to overwrite the oldest remeshing database files (.rdnn), starting with the first file. However, the application does not update the restart (.rnnn) files with the same number, which could lead to errors. You can use the beta property, Maximum Total Files to Save (Analysis Settings > Restart Controls), to specify a value less than 100, to avoid this issue.
It is not necessary to scope loads to a node-based or element-based Named Selections with Preserve During Solve property set to , if the initially applied load is not modified during subsequent load steps.
Any modifications to pressure scoped to a face and applied directly, will delete all the restart points.
The node-based Named Selection with Preserve During Solve set to , can have nodes from multiple exterior faces of the solid, and these faces need not be in same plane. But they cannot contain internal body nodes - they must be surface nodes.
If you have multiple Named Selections, with the Preserved During Solve property is set to , and these Named Selections include common/overlapped nodes or elements, this could lead to re-meshing failures.
If you interrupt a solution that contains loads which are not scoped to node- or elemental-based Named Selections and the Preserve During Solve property set to Yes, the Restart Type property setting is automatically reset to . You can avoid this automatic change by applying the load using a node-based or elemental- based Named Selection with the Preserve During Solve property set to . This applies the load to the updated nodal or elemental component.
When the Generate Restart Points property is set to , entries in the Equally Spaced Points property are ignored for the remeshing database (.rdnn) files that are created during SMART Crack Growth remeshing.
If the SMART Crack Growth solution is stopped when a specified Stop Criterion is met, the restart point will be available. If you attempt to restart from this point, note that the solver attempts to solve and checks the stop criterion at the end of this load step and stops as the criterion is already met.
If you scope a Thermal Condition load to either bodies or elements, the application updates the element component it creates internally by default. If you scope the load using an element-based Named Selection, you need to set the Preserve During Solve property to .
Recommendation: When you define SMART Crack Growth, the application stores fracture results for time points based on the setting of the Analysis Settings > Output Controls property Store Results At.
Important: If the Store Results At property is not set to the option, the Crack Extension and Total Number of Cycles probe results will not be accurate. This is because these values are derived from the summation of results stored in the results file instead of the summation of results over all solved sub-steps. Therefore, Ansys recommends that you set the Store Results At property to for accurate Crack Extension and Total Number of Cycles probe results. Furthermore, Ansys recommends that you use this property to specify time points, even if you issue additional OUTRES commands through the Commands (APDL) object.
Note:
For additional technical information on this feature, refer to the SMART Method for Crack-Growth Simulation section in the Mechanical APDL Fracture Analysis Guide.
For specific information about the properties of the object, see the SMART Crack Growth object reference page.
For a video example of the feature, see the Fatigue Crack Growth Analysis using SMART Crack Growth Tutorial.