In the Blank page, the user can define Part, Material, Thickness and Property of blank. Furthermore, the user may define weld line for tailor-welded blank application, contact interface for laminated sheets, blank symmetry constraints and single point constraints, etc. The interface of the Blank page is illustrated in Figure 8.3.16.

Figure 8.3.16  Interface of Blank definition

GEOMETRY

PARTS

As shown in Figure 8.3.17, the Part field allows the user to assign a part as blank for stamping simulation. After clicking the Define geometry… button, the Blank Generator dialog box illustrated in Figure 8.3.18 is displayed. Refer to Section 7.2 for detailed description about defining blank.

Figure 8.3.17  Geometry field

Figure 8.3.18  Blank generator dialog box

After blank parts are defined, the names of each part are displayed in the Part field. The default material, thickness and property are assigned for the part. The user may reassign material, thickness and property for each part.

MATERIAL

The program defines a default type 36 material for blank part, as illustrated in Figure 8.3.19.

Figure 8.3.19  Define material

NoteIf no material is assigned to the Part, the BLANKMAT is listed in material button. After defining the material, the material name is displayed on the button.

The user may click  button to enter the Material interface illustrated in Figure 8.3.20 to modify or create a material.

Figure 8.3.20  Material definition dialog box

In the Material interface, the user may create, edit, import and output a material, or select a material from the material library.

TYPE: Display the defined material type. eta/DYNAFORM currently supports the following material types: 1, 4, 12, 18, 24, 36, 37, 39, 64, 103, 106, 113, 122, 123, 125 and 133.

NAME: Display the defined material name.

NEW: Allow the user to create new blank material. After clicking this button, the list of material types illustrated in Figure 8.3.21 is displayed. The user may select one of the material types from the list. Once a material type is chosen, the Material dialog box illustrated in Figure 8.3.22 is displayed.

Figure 8.3.21  Select material type

Figure 8.3.22  Material dialog box

Forming Limit Curve (FLC): This parameter should be defined if material type 39 is chosen. If no FLC curve is defined, <NONE> is displayed at the FLC input field. To define FLC curve, click  button to display the FLC curve edit dialog box illustrated in Figure 8.3.23.

Note: The FLC curve defined in Sheet Forming is represented in engineering strain.

In the FLC curve edit dialog box, the user may enter the FLC data points directly in the INPUT page. Alternatively, the user may define FLC curve using Keeler’S FLC empirical equation provided in the Formula page. After entering the n and t values, click the Apply button to generate the FLC. The FLC curve is displayed in the show curve interface illustrated in Figure 8.3.23. A detailed description of the curve edit operation is provided in Section 8.3.4.4.

Note: The user may set strain type in the Operation page. The strain type of the exported FLC curve is the same with the selected strain type. The strain type of the imported FLC curve is determined by the strain type label in file.

Figure 8.3.23  FLC Curve

EDIT: Allows the user to edit the material parameters listed in the Material dialog box illustrated in Figure 8.3.24.

Figure 8.3.24  Material Edit dialog box

Note: Edit Material and Define Material dialog boxes are basically identical. The user may modify any parameter in the dialog box, except the material type. To change the material type, the user must create a new set of material properties.

IMPORT: Allows the user to import a material file. The suffix of the file name is “.mat” or other suffix. By default, Import Material window illustrated in Figure 8.3.25 is displayed when the button is hit.

Note: For PC users, the extension of material file may be associated with Microsoft Office Access. The “.mat” extension will not be displayed, but the extension of material files may be viewed from the console model. To display the “.mat” extension, the user must delete the association between the “.mat” extension and Microsoft Office Access.

Figure 8.3.25  Import Material window

After selecting a file, the user may click the Import button to import the selected material and assign it to the selected blank part.

EXPORT: Allows the user to export and write the current material into a file. The file is saved with an extension “.mat”. The Export Material window is illustrated in Figure 8.3.26.

Figure 8.3.26  Export Material window

MATERIAL LIBRARY: This function enables the user to select the type of generic material library in eta/DYNAFORM. There are four types of generic material library supported by eta/DYNAFORM. They are United States, Europe, China, and Japan. The User Defined material library option is provided to enable users to build their own material library.

Figure 8.3.27  Material Library Standard

After selecting a regional material library, the material library GUI illustrated in Figure 8.3.28 is displayed. The user proceeds by selecting a type of material from the library to be assigned as the blank material.

The Material Library interface allows the user to conveniently select a type of material. The right key menu enables the user to expand each node of tree structure. The number listed in the parentheses next to each material indicates the material type. The previously selected material type number will be displayed in the parentheses.

Note: The materials in the material library are only for reference. The user can obtain the detailed material parameters from the material suppliers. Engineering Technology Associates, Inc. assumes no liability or responsibility to any person or company for direct or indirect damages resulting from the use of any information contained in the material library.
The user-defined material is saved in the user-defined directory. The user can set the default path of material library from the Option/Material Library menu.

Figure 8.3.28  GUI of Material Library

·           User Defined

This function allows the user to add, delete, and rename the user-defined material library. The added material library will be shown in the list of material library. The User Defined Standard dialog box is illustrated in Figure 8.3.29.

ADD: Add and define the name of the user-defined material library.

RENAME: Edit the name of the user-defined material library.

DELETE: Remove the user-defined material library.

Figure 8.3.29  User Defined Standard dialog box

·          

This function allows the user to reorder the material models within the material strength level.  Select a material or group of materials and use these buttons to move them up or down in the list.

·           Category

Click the right mouse button at the root node of tree structure to create a new material category, strength level and type of material. Default material categories are Steel and Aluminum. The user can assign a name to the new material category, and rename or delete the material category. As illustrated in Figure 8.3.30, the list of each node is displayed if the right mouse button is hit.

Figure 8.3.30  The corresponding list of each node

·           Strength Level

The material library allows the user to classify the following steel grades: Low, Medium, High, Advanced High, Hot Roll and Cold Roll. Users can easily manage their own material library.

·           Material Name

The user can click the right mouse button of Strength Level to define a new material. The Create Material dialog box illustrated in Figure 8.3.31 is displayed. The user can select material type and edit material parameters in this dialog box. The default material name is similar to its title. The user must specify the path of the new material prior to saving it.

Figure 8.3.31  Create Material dialog box

·           Material Type

The user can click the right mouse button of Material Name to define or import the new material type. The user can also click the right mouse button of Material Type to edit or delete material type. The Create Material Type dialog box is illustrated in Figure 8.3.31, the Import Material dialog box is illustrated in Figure 8.3.32. After the material is imported, the type of material number is automatically assigned.

Figure 8.3.32  Import Material dialog box

THICKNESS

By default, the thickness value for blank is defined in the New Sheet Forming dialog box. The user can edit thickness of blank in the Thickness field.

PROPERTY

By default, the properties of blank are set as illustrated in Figure 8.3.33. These blank properties are good for most stamping simulation.

Figure 8.3.33  Define Blank Properties

ELEMENT FORMULATION: This option allows the user to choose type of element formulation. Currently, 16 shell element formulations are supported in eta/DYNAFORM. In addition, thick shell and solid element formulation are available. The default element formulation is No. 2 BELYSTSCHKO-TSAY shell element formulation. This element formulation is the most popular and economical one for sheet metal forming simulation. For springback analysis, it is recommended to select No. 16 Full Integration element formulation in both draw simulation and springback analysis.

NUMBER OF INTEGRATION POINTS: The default number of integration points is 5. Increasing the number of integration points through the material thickness may improve the precision of simulation results. On the other hand, the simulation time will drastically increase. For draw simulation without considering springback, the default number of integration points through the material thickness is recommended. For a draw forming simulation with subsequent springback analysis, use of 7 or more integration points through the thickness of the material is suggested.

OK: Save the current setting and exit the property definition dialog box.

DEFAULT: Use the default value.

CANCEL: Exit the dialog box without saving the modification of the current setting.

POSITION

This function allows the user to move the position of blank along U, V and W direction illustrated in Figure 8.3.34. After auto positioning, the movement along W direction is listed in the Position field.

Figure 8.3.34  Position field

TRANSFORMATION

In multistage forming setup, the user is allowed to translate/rotate the blank or change the coordinates of blank in the next stage, as illustrated in Figure 8.3.35. The sequence of translation and rotation is very important. Usually, it is suggested to carry out rotation operation first and then translation.

Figure 8.3.35  Transformation

The user may click the Define button in the Blank setup page to enter the Transformation dialog box, as illustrated in Figure 8.3.36. The added transformation operations will be displayed in the list. The user can click the arrows to adjust the sequence of transformation operations, or click the Delete button to delete the defined transformation operation.

Figure 8.3.36  Transformation dialog box

ADD: add translation, rotation or LCS2LCS operation.

EDIT: edit the defined translation, rotation or LCS2LCS operation.

APPLY: add the defined translation, rotation or LCS2LCS operation to the list.

TRANSLATION: define the direction and distance of translation. There are three methods to define translation:

1. Enter the distance along U, V and W directions. The direction of translation and distance is automatically calculated according to the input. If the Direction button is selected, the direction of translation is displayed in the dialog box and marked with an arrow in the display screen. The distance is displayed in the Distance field.

2. Click on the Direction button to define direction of translation. Then, exit the Direction dialog box and key in the desired distance in the data input field of Distance. The direction of translation and distance is automatically calculated according to the input.

3. Click on the 2 Points/Nodes button, followed by selecting two points/nodes from the display screen. The direction of translation and distance is automatically calculated according to the input.

ROTATION: Define rotation axis and angle. Rotate the model about any axis of the current coordinate system with any input angle.

LCS2LCS: Conversion of local coordinate system. The user is allowed to convert the model from one coordinate system to another. The translation and rotation information is automatically output.

SYMMETRY

This function allows the user to create a symmetry condition for the blank to reduce simulation time. The user may define either ½ or ¼ symmetrical condition along the line of symmetry of the blank. ½ and ¼ blank mesh is required for applying ½ and ¼ symmetrical conditions, respectively. By default, <None> is displayed in the field of Symmetry type illustrated in Figure 8.3.37, indicating no symmetry condition is applied to blank. The user may click  button to display the Symmetry Plane dialog box illustrated in Figure 8.3.37.

Figure 8.3.37  Symmetry field

1/2 SYMMETRY

This function allows the user to define ½ symmetrical blank. The interface is illustrated in Figure 8.3.38.

Figure 8.3.38  Define Symmetry Plane

SYMMETRY AXIS: The current user defined symmetry plane information is displayed in this field. The symmetry plane is specified by a point, a vector and WCS direction.

O(0,0): Indicates the coordinate of starting point of the vector defining symmetry plane.

X(1,0): Indicates either UW- or VW-plane chosen as symmetry plane.

UW-PLANE: A plane parallel to LCS’s UW-Plane is chosen as the symmetry plane. The user specifies the location of the plane by using the Select Points function illustrated in Figure 8.3.38. The position of the symmetry plane is displayed in O (0, 0), while the direction of symmetry is displayed in X (1, 0). A vector is displayed in LCS’s UW-Plane on the screen to show the symmetry plane. See Figure 8.3.39 for more details.

VW-PLANE: A plane parallel to LCS’s VW-Plane is chosen as the symmetry plane. The user specifies the location of the plane by using the Select Points function illustrated in Figure 8.3.38. The position of the symmetry plane is displayed in O (0, 0), while the direction of symmetry is displayed in X (0, 1).

2 POINTS ON UV-PLANE: Enables the user to define the vector of the symmetry plane by selecting two points. The symmetry plane is parallel to W axis. The first point of the vector specifies the position of the symmetry plane.

SELECT POINT(S): Allows the user to select one or two points to specify symmetry plane. If the user selects UW-Plane or VW-Plane option, only one point is required to specify the location of symmetry plane. If the user selects the 2 Points on UV-Plane option, then two points are required to define symmetry plane.

TOLERANCE: Default tolerance is 0.01. Nodes falling inside the tolerance are assigned the symmetry boundary condition. The user may increase the tolerance to extend the search range for nodes near the symmetry plane.

Figure 8.3.39  Define Symmetry

1/4 SYMMETRY

This function allows the user to apply a symmetry boundary condition on a ¼ symmetry blank. After defining a vector, another vector normal to the defined vector is automatically created to specify the other symmetry plane. Figure 8.3.40 illustrates a typical definition of ¼ symmetry planes.

Figure 8.3.40  Define 1/4 Symmetry

WELDS

In Sheet Forming, the user can conveniently set up the forming simulation of tailor-welded and composite blanks. After multiple blank parts are defined, the Welds option is activated on the Blank page illustrated in Figure 8.3.41.

Figure 8.3.41  Define Tailor-welded Blank

After the weld lines are defined, the information of weld lines is displayed in Welds list.

ADD WELD

This function allows the user to select adjacent nodes to define weld element. After clicking the Add button, the Blank Weld dialog box illustrated in Figure 8.3.42 is displayed.

Note: The node pair of a weld must consist of two separate nodes with different positions. Different nodes with the same position or identical nodes with the same position are not allowed.

Figure 8.3.42  Define Weld dialog box

NODAL PAIRS: Display number of nodal pairs. After the user selects nodal pairs, the number is displayed in the data box.

OVERLAP BLANK: The user needs to select this option for overlap blank. After selecting this option, the line connecting the nodal pair is normal to its connecting element.

WELD WIDTH: Specify the width of weld. Default width is 1.0 (mm). If the distance between the selected node pair is smaller than the default value, weld is defined for the selected node pair. The user may adjust the width to include the node pairs with a larger gap.

WELD: The user may click this button to select node pair. From the displayed Select Node dialog box, select two rows of nodes required for definition of weld node. After selecting the nodes, weld as illustrated in Figure 8.3.43 is defined between nodal pairs.

Figure 8.3.43  Define Weld

Note: If the nodes are offset manually before defining the weld, the user only needs to select the offset two rows of nodes when defining. If the nodes are not offset before defining the weld, the program will automatically offset the selected nodes 0.05 towards their element directions after the user selects the common nodes for two parts and define the offset nodes as weld. This process is automatically completed by the program. The user only needs to select the common nodes for two parts with different materials or thickness, as illustrated in Figure 8.3.44.

(a)  Before                                       (b)  After

Figure 8.3.44  Offset Node

CLEAR: This button allows the user to remove the current defined welds and combine the node pairs of welds to one node.

FAILURE: The user may define failure criteria for the weld.

NEVER FAILURE: By default, the Never Failure option is chosen to ensure weld does not fail during the stamping simulation.

CONDITIONAL FAILURE: Allows the user to define conditional failure criteria and its relevant parameters. A detailed description is available in the LS-DYNA Keyword User’s Manual.

EDIT

This function allows the user to edit the defined weld. The user may delete the selected nodal pair, add a new nodal pair, modify weld failure criteria, etc.

CLEAR

After a weld line is defined, weld information such as number of nodal pairs, failure criteria of weld is displayed in the weld list illustrated in Figure 8.3.45.

Figure 8.3.45  Welds List

The user may delete a weld by clicking appropriate button listing the correct number of spot welds on the line, followed by clicking the Clear button to remove the current weld definition.

CONTACT

This function allows the user to define the contact types and contact parameters of single surface, and between blank parts.

Figure 8.3.46  Define Contact Between Blanks

SINGLE SURFACE

This option allows the user to define the contact of blank itself and the surface contact of blank with other parts. The program will automatically decide the contact place for the model surface.

BETWEEN PARTS

If the defined blanks are overlapped, Between parts option must be toggled on, otherwise, the calculation will be wrong. At the same time, the user can modify contact parameters such as friction coefficient, contact type, etc. As shown in Figure 8.3.46, if it is not overlap blank simulation, this option does not need to be toggled on by default.

ADVANCED

The user may modify some contact parameters between blanks through advanced options illustrated in Figure 8.3.47.

Figure 8.3.47  Define Advanced Contact Parameters

CONTACT TYPE: This function allows the user to select type of contact algorithm illustrated in Figure 8.3.48.

Figure 8.3.48  Define type of contact algorithm

STATIC FRICTION COEF.

Allows the user to define static coefficient of friction. Default value is 0.125.

VISCOUS FRICTION COEF.

Allows the user to define viscous coefficient of friction. Default value is 0.

VISCOUS DAMPING COEF.

Allows the user to define viscous coefficient of damping. Default value is 20.0.

DYNAMIC FRICTION COEF.

Allows the user to define dynamic coefficient of friction. Default value is 0.

DECAY COEF.

Allows the user to define coefficient of decay. Default value is 0.