The user can select options in this field to create drawbead property, set size of drawbead box, lock drawbead to a specified part and assign drawbead parameters. The Drawbead Parameters field is illustrated in Figure 10.4.4.
Figure 10.4.4 Drawbead Parameter field
In LS-DYNA, each drawbead carries its own property. Prior to creating the drawbead, the user must define the property accordingly. In the create property field, NEW, EDIT, DELETE functions enable the user to create, modify or delete the property, respectively.
l NEW PROPERTY
Click on NEW button to display the DRAWBEAD PROPERTY dialog box illustrated in Figure 10.4.5.
Figure 10.4.5 Drawbead properties dialog box
SECTION TITLE
Allow the user to name title of property, the default title is bead1, bead2 and so on.
STATIC FRICTION COEF.
Allow the user to set the static coefficient of friction between the blank and drawbead. The default static coefficient of friction is 0.1.
DYNAMIC FRICTION COEF.
Allow the user to set the dynamic coefficient of friction between the blank and drawbead. The default dynamic coefficient of friction is 0. It means the dynamic friction between the blank and drawbead is ignored.
BENDING LOAD CURVE ID
Allow the user to define the Fbending component of the drawbead restraining force. The Fbending component is referred as force per unit drawbead length as a function of displacement as illustrated in Figure 10.4.6.
NOTE: The NORMAL FORCE of drawbeads is automatically set to 1.0e-6 by eta/DYNAFORM. Hence, only the BENDING FORCE needs to be defined by the user.
Figure 10.4.6 Drawbead resisting force as a function of the drawbead displacement
The user can click on the button to define the bending curve
of drawbead property using the DRAWBEAD LOAD CURVE dialog box illustrated in
Figure 10.4.7. The user can select one of the curves in the list or select the NEW LOAD CURVE functions to generate drawbead force curve using one of
the following two methods:
AUTO –This function enables the user to create bending curve according to the drawbead section figure and the material of the blank as illustrated in Figure 10.4.8. The user can input all the parameters in the DRAWBEAD FORCE PREDICTION dialog box, following by clicking on the OK button to exit the dialog box. The defined curve ID is specified as the BENDING curve ID for the property.
MANUAL –This function enables the user to manually create a bending curve for the property using the function in the dialog box as illustrated in Figure 10.4.9. Please refer Section 12.13.1 for detailed information about load curve definition.
Figure 10.4.7 Drawbead Load Curve dialog box
Figure 10.4.8 Drawbead Force Prediction dialog box
Figure 10.4.9 Define the Bending curve
FULL LOCK FORCE
This is an optional method to define the BENDING FORCE for the drawbead. If the checkbox is toggled on, the user can manually key in the FULL LOCK FORCE value in the input data field or click on the DEFAULT button to calculate the default full lock force. Then, the BENDING FORCE will calculate automatically according to the FULL LOCK FORCE.
NOTE: The default FULL LOCK FORCE is calculated by the material ultimate tensile strength and the thickness of the blank. The user has to define the blank material and properties prior to obtaining the default FULL LOCK FORCE.
DRAWBEAD DEPTH
Allow the user to define depth of the drawbead. The default depth of drawbead is set as 1.0 (mm).
BENDING CURVE SCALE
Allow the user to set scale factor for the BENDING CURVE. The default scale factor is set as 1.0 (or 100%).
After each new property is created, it is added to the property list and set as the current property.
l MODIFY PROPERTY
Modify current property.
l DELETE PROPERTY
Remove current property.
Note: The current property can be deleted only if no drawbead is assigned. Otherwise, the program prompts:
The property assigned to drawbead. Cannot be deleted.
This function enables the use to change the scale factor of bending curve of a selected drawbead. Prior to changing the percentage value, the user must select one or multiple drawbead. After modification, the user can press the key Enter or remove the focus to update the data.
The DEFINE BOX function is used to define a specific box-shaped volume around the drawbead. The box contains the drawbead nodes and elements between bead and outer edge of the blank. It is implemented to limit the size of the master surface for the drawbead contact. The BOX SIZE is the linear distance between the drawbead line and the surfaces of box. The default size of the drawbead box is 200. The user can key in the size of the box following by pressing the key Enter or removing the focus to update the data.
NOTE: It is highly recommended to define a box around the drawbead to limit the size of the master surface (Blank) considered for the drawbead. It will substantially reduce cost and memory requirements for stamping simulation.
The function enables the user to
project the selected drawbead(s) on a part along the stamping direction or the
working direction of the part. Prior to implementing the function, the user
should pre-select the drawbead(s). Then, click on the button to display the SELECT
PART dialog box illustrated in Figure 10.4.10. The user selects a target part to lock the drawbead(s). Normally, DIE or BINDER is selected as target part.
Figure 10.4.10 Select Part dialog box
After target part is selected, a eta/DYNAFORM QUESTION dialog box illustrated in Figure 10.4.11 is displayed. The user can select YES to project the drawbead(s) on the target part. Else, the user can select NO to cancel the operation.
Figure 10.4.11 eta/DYNAFORM Question dialog box
Figure 10.4.12 Before locking drawbeads on BINDER
Figure 10.4.13 After locking drawbeads on BINDER
After drawbead is locked on a target part, the name of target part is displayed in the LOCK ON box (as illustrated in Figure 10.4.14) whenever a drawbead is selected from the Drawbead list.
Figure 10.4.14 Lock on Part
NOTE: If drawbeads are generated via the menu Setup/AutoSetup/Tools/Drawbeads, it is projected onto the target part along its WORKING DIRECTION.
After all the parameters are defined, the user can click on the OK button to exit the DRAWBEAD dialog box. If remaining drawbeads are not locked on rigid part, a dialog box as illustrated in Figure 10.4.15 is displayed.
Figure 10.4.15 eta/DYNAFORM Question dialog box
The user can select YES to project the drawbead(s) on the target part. Else, select NO to exit the DRAWBEAD dialog box without locking these drawbead(s) on the target part.
This function allows the user to assign parameters to a selected drawbead. First, the user can select one or multiple drawbead from the drawbead list. Then, select a property from the property list and assign full lock force, drawbead box size and lock on drawbead to the specified parts. Finally, click on ASSIGN PARAMETERS button to assign the specified parameters to the selected drawbead.