The QUICK SETUP/SPRINGBACK PROCEDURE

The following is the procedure for setting up a springback analysis using QS/Springback:

Read in the blank results

The blank results are obtained from a draw simulation. They are output as DYNAIN file after each draw simulation. The user can read in the DYNAIN file by selecting BLANK from the QS/Springback tool GUI and then selecting IMPORT MESH from the DEFINE BLANK dialog window.

Trim the blank

If no trim operation is involved, the user can skip this step and continue to Step 3. Refer to Section 9.7.5 for information about trimming blank.

Define blank parameters

The user needs to define the initial blank material and thickness. The blank parameters are needed for the solver to perform initialization prior to springback analysis. These blank parameters should be similar to the blank parameters used in draw simulation.. After the initialization, the thickness, stress and strain recorded in DYNAIN file will override the initial blank parameters.

Select implicit method and coarsen options.

Define Implicit parameters

There are no appropriate default implicit parameters which are good for all springback applictions. The user needs to adjust implicit parameters accordingly. Refer to the LS-DYNA User's Manual for a detailed explanation of all the implicit parameters following the listed cards. Note: control cards list different solver versions.

Control rigid body motion

The user needs to define appropriate constraints on the blank to eliminate the six rigid body motions. This is done by using the SPRINGBACK CONSTRAINT option in the IMPLICIT PARAMETER dialog window (Figure 8.3.2). eta/DYNAFORM will prompt the user to select the contrained nodes.

For most applications, it is recommended to select 3 constraint nodes for springback analysis. The chosen 3 constraint nodes should be well separated from each other and away from the edges and flexible areas in the part. The first constraint node will lock the three translation degrees of freedom and define the reference point in the springback model. The springback displacement is zero at this constraint node. The second constraint node will lock the Y- and Z- translation, while the third constraint node eliminates the translation in Z-direction. For detailed information about springback analysis, contact eta/DYNAFORM's Technical Support at support@eta.com.