Creating Submodel Boundary Conditions

Submodel boundary conditions drive the boundaries of the submodel with time-dependent variables that were saved during the analysis of the global model. The variables can include displacement or temperature, and Abaqus for CATIA V5 assumes that all degrees of freedom are driven by the global model. See Using Submodeling for an overview of submodeling with Abaqus for CATIA V5. Submodeling is described in detail in About submodeling in the Abaqus Analysis Guide.

Submodel boundary conditions can be applied to point/vertex, curve/edge, or surface/face supports or to a point, line, or surface group. In most cases you apply the boundary condition to the edges and faces that were created when you cut away regions from the global model. You can apply submodel boundary conditions in both mechanical and thermal steps. You can also apply knowledgeware techniques to control the value of a submodel boundary condition (for more information, see Applying Knowledgeware).

This task shows you how to create a submodel boundary condition on geometry.

  1. Click the Submodel Boundary Condition icon .

    The Submodel BC dialog box appears, and a Submodel object appears in the specification tree under the Boundary Conditions objects set for the current step.

  2. You can change the identifier of the boundary condition by editing the Name field.

  3. Select the geometry support (a point, an edge, or a surface). Any selectable geometry is highlighted when you pass the cursor over it. You can select several supports to apply the boundary condition to all supports simultaneously. You can also select an appropriate group.

    The Supports field is updated to reflect your selection.

  4. In the Exterior Tolerance field, do the following:

    • Enter the Absolute exterior tolerance. This is the absolute value by which a driven node of the submodel may lie outside the elements of the global model. The default value is the relative exterior tolerance.

    • Enter the Relative exterior tolerance. This is the fraction of the average element size in the global model by which a driven node of the submodel may lie outside the elements of the global model. The default value is 0.05.

  5. Right-click on the text field for the absolute or relative exterior tolerance to add knowledgeware controls (for more information, see Applying Knowledgeware).

  6. When you create a submodel boundary condition, you must specify the step of the global model from which the data to drive the boundaries of the submodel are extracted. However, in subsequent steps that are propagated from the step in which you created the submodel boundary condition, you can do either of the following:

    • Choose Use results from global model and continue to specify the step in the global model from which the data to drive the submodel will be extracted. In most cases, you will choose this option because it allows you to synchronize the steps in the submodel analysis with the steps that are driving the submodel in the global model.

    • Choose Fixed at current position to freeze the magnitude of the data that will drive the submodel at their final value from the previous step.

  7. If you choose Use results from global model, do the following:

    1. In the Global step number field, enter the step number in the global analysis from which the values of the driven variables will be read. (The first step is step number 1.)

    2. If the time period of the submodel analysis is different from the time period of the global analysis, you can choose to scale the time period of the global step to match the time period of the submodel step. For example, Abaqus determines the displacements of the global model at a time 20% into the global step and applies those displacements at a time 20% into the submodel step.

      If you do not choose to scale the time period of the global step to match the time period of the submodel step, Abaqus applies the displacements of the global model at the same time during the submodel step. For example, Abaqus determines the displacements of the global model one second into the global step and applies those displacements one second into the submodel step. This behavior is probably not desired if the two time periods are different. You choose to scale the time period by toggling on Scale time period of global step to time period of submodel step.

  8. Click More to view the propagation status of the boundary condition. The propagation status shows the following:

    • Whether the boundary condition was Created in this step or Propagated into this step.

    • Whether the boundary condition is Active or Inactive.

  9. Click OK in the Submodel BC dialog box.

    Symbols representing the degrees of freedom driven by the submodel boundary condition are displayed on the geometry.