PROCESS

The PROCESS definition page includes the basic setup of process parameters. It includes stamping speed, closing force, forming time, etc. The user may change process parameters according to the actual condition. Moreover, the user may add and delete any process. The basic process setup interface is shown in Figure 8.2.60.

 

Figure 8.2.60 Process definition page

PROCESS LIST

On the left of process definition page, all defined process names are listed in the window of Stages. The current process name is highlighted in the list. The user may click another process from to list to switch the current process. The program specifies default process according to the user selected process type at the beginning of the new setup. For example, if the user selects SINGLE ACTION, the program will create closing and drawing as default process. There are also default settings for the basic parameters, including stamping speed, closing power and stage calculation time, etc. The user only needs to change a few parameters as necessary for the analysis.

 

 

8.2.6.1 NEW STAGE

This function allows the user to add a new process in current setup. The user may click NEW STAGE button to switch to a new stage interface, as shown in Figure 8.2.61.

 

Figure 8.2.61 New Stage

 

STAGE NAME

Allow the user to define a name for the current stage. Default stage name are forming1, forming2, forming3, etc.. The user may define a meaningful name for current stage, to make it more convenient to understand, setup and check faults.

 

TYPE OF STAGE

Allow the user to specify a type for current stage. The user may select from the pulling down list. Stage types include normal forming and springback.

 

DEFAULT SETTING

Allow the user to select default setting for the new stage. In default setting, the user may select the program default parameters for the new stage. Otherwise, the user may select to use the parameters from a defined stage for the new stage.

 

USER SETTING OF STAGE: Use an existing stage’s parameters for the new stage. The user may select an existing stage from pulling down list. The new stage will have the same parameters as the selected stage. The user only needs to make few changes as necessary for the new stage.

 

USER DEFAULT SETTING: Use system default parameters to define a new stage.

 

 

INSERT POSITION

Allow the user to specify the insert position of the new stage. Since the stages have to follow the order in actual forming process, the user needs to specify stages’ position accordingly.

 

INSERT BEFORE: Insert current new stage before a specified stage from the pulling down list.

 

INSERT AFTER: Insert current new stage after a specified stage from the pulling down list.

 

 

8.2.6.2 DELETE STAGE

 

This function allows the user to delete the current stage. The user may select a stage from the stage list as current stage, and click DELET STAGE button. The program will pop up a confirmation dialog box as shown in Figure 8.2.62.

Figure 8.2.62 Delete Stage dialog box

 

Click on OK button to delete the current stage or Cancel button to cancel the delete operation.

 

 

8.2.6.3 STAGE NAME & TYPE

 

NAME

Display the current stage name. The user may type in a new name in the name window.

 

 

TYPE

Allow the user to select the current stage type: Drawing or Hydroforming.

 

8.2.6.4 TOOL CONTROL

This function is used to control tools’ action in the current stage. It includes define travel speed, closing force and travel curve, etc. of the tools. See Figure 8.2.56 for a sample tool control.

Figure 8.2.63 Tool Control Option

 

TOOLS

List all defined tools in current stage. Under default condition, the non-active tools in the current stage are not listed. The user may select SHOW ALL option to show all defined tools and activate the tools accordingly.

 

SHOW ALL

List all defined tools in tool list. This option is not selected under default condition.

 

ACTION & VALUE

This group lists all tool control options. There are five control methods of each tool: NON-ACTIVE, STATIONARY, VELOCITY, DISPLACEMENT and FORCE.

 

NON-ACTIVE

Indicate this tool is not used in this stage. Under default condition, not-active tools are not displayed in the tool list. The user may select SHOW ALL option to display all tools.

 

STATIONARY

Indicate this tool is stationary in this stage.

 

VELOCITY

Indicate the tool is controlled by velocity curve in this stage. The user may select one of the standard types provided in eta/DYNAFORM to define velocity curve: TRAPEZOIDAL, SINUSOIDAL, SIN.W-H, TRIANGULAR and VARIABLE. Figure 8.2.64 shows the standard curves. The user may enter the maximum velocity value in velocity input box. Default velocity for drawing process is set as 5000mm/s. For closing process, default velocity is set as 2000mm/s.

 

a)   TRAPEZOIDAL                             b) SINUSOIDAL

 

c)  SIN.W-H                            d) TRIANGULAR

Figure 8.2.64 Different Types of Curves

If the user selects user-define curve,  button is activated to enable the user to define the curve in the define curve dialog box.

 

DISPLACEMENT

Use displacement-time curve to control the tool travel in this stage. The user may click DEFINE button to define displacement-time curve.   The procedure is similar to those described in the velocity curve.

FORCE

Use force to control the tool operation in current stage. Force is usually used for ring closure. There are two types of forces: CONSTANT and VARIABLE. If the user selects constant force, a constant force value is required. For variable force, the user needs to click DEFINE to define force- time curve in the define curve interface.

 

 This button is activated when the user selects force control. The user may use this button to define RIGID BODY STOPPER. Rigid body stopper is mainly used when using force to control the binder ring to prevent lack of closing force that causes binder ring pop away or excessive closing force that restricts the metal flow. The user may specify the parameters for rigid stopper as shown in Figure 8.2.65.

Figure 8.2.65 Rigid body stoppers dialog box

 

UPPER DISP.: The limit of upper maximum displacement of the tool from its initial position.

 

LOWER DISP.: The limit of lower maximum displacement of the tool from its initial position.

 

MAX. VELOCITY: The maximum velocity as function of time that is allowed for the tool with rigid body stopper control during the process.

 

BEGIN TIME: RIGID STOPPER starts to work.

 

END TIME: RIGID STOPPER termination time.

 

DURATION: RIGID STOPPER duration time.

 

After completing RIGID STOPPER defintion, the button’s color becomes blue. Detailed description of RIGID STOPPER is available in LS-DYNA User’s Manual.

 

8.2.6.5 USER DEFINE CURVE

 

In the new setup, all the defined curves are managed by the curve manager. The user may create, import, modify existing curve by the curve manager. Curve manager’s main interface is shown in Figure 8.2.66.

Figure 8.2.66 Curve Manager

IMPORT CURVE

Allow the user to import a curve from a file. The extension of curve files is “.cur”. The curve file is defined according to the standard LS-DYNA keyword format. A typical “.cur” curve format is shown below. After clicking this button, the user needs to select a “.cur” file from the dialog box.

EXPORT CURVE

Allow the user to export current curve to a “.cur” file. The user needs to specify a file name after clicking this button. The program automatically saves the current curve under this name and directory.

INPUT

This page displays coordinates of the points on the current curve. If there is no existing curve, user may create a new curve by entering point coordinates. The user may modify existing curve coordinate in this page, including functions of add, delete, insert and clear of all data points.

 

ADD: Allow the user to add a data point at the end of curve. The program adds two empty input boxes at the end of point list, and automatically specifies the data point as the current point. The point is highlighted in yellow color. The user may enter X and Y coordinates in the input boxes.

INSERT: Allow the user to insert a data point after the current data point. Before clicking this button, the user needs to define the position of the current data point. Click the data point where the new data is inserted below.  The program will highlight the selected data point. After clicking the INSERT button, the program automatically inserts two empty input boxes below the highlighted data point. Enter the X and Y coordinates in the input boxes for the new data point.

DELETE: Allow the user to remove the current data point.

CLEAR ALL: Allow the user to clear all data points in the current curve.

APPLY: The user may click APPLY after add, insert or delete point operation. The program automatically displays the entire curve in the curve display window after the modification.

FORMULA

This page allows the user to use some common mathematic formula, such as linearity, quadratic, cubic, sin (cos) to create a curve. When defining FLC curve of material, the user may create a curve according to the traditional Keeler’s empirical formula.

Figure 8.2.67 Formula Page

 

TYPE: Allow the user to select a math formula type to create a curve. Type of formula includes SIMPLE, QUADRATIC, CUBIC, SIN and COS.

INTERVAL: Allow the user to specify interval of selecting X coordinate points during curve creation. The smaller the value is, the more data points will be required to define the curve. Default interval is 0.1.

ABSCI-START: Allow the user to specify ABSCI- START during curve creation. Default ABSCI-START is 0.

ABSCI-END: Allow the user to specify ABSCI-END during curve creation. Default ABSCI-END is 20.

PARAMETER: Allow the user to input required formula parameter during curve creation. After the user selected one formula type, the expression of the formula is displayed below the interface. For example, formula of QUADRATIC is: . To create curve, the user needs to specify quadratic curve required four parameters A, B, C and D for the point. Under default condition, each formula parameter is set to 1.

APPLY: After defining formula parameters, the user may click APPLY button to create the curve. The created curves are displayed in show curve window. At the same time, coordinates of the data points on the curve are displayed in the INPUT page.

OPERATION

This page allows the user to operate on the entire curve, such as SCALE, TRANSLATE, etc.

 

Figure 8.2.68 Curve Operation

MODE: Define the curve operation mode. Including SCALE and TRANSLATE.

PARAMETER: The user may input curve operation parameters in the input boxes. For example, during curve scale, the user needs to individually enter the scale factors for X-axis and Y-axis. During curve translation, the user needs to enter translate value for X-axis and Y-axis.

APPLY: After specifying operation parameters, the user may click APPLY to operate. After operation, the resulting curve is displayed automatically in the curve display window.

 

CLIPBOARD

This function allows the user to temporarily save the current curve to the clipboard of Auto Setup. The user may load the curve saved in the clipboard into the current curve interface. At the same time, comparison between the curve in clipboard and the current curve is also available. Figure 8.2.69 illustrates the clipboard interface.

Figure 8.2.69 Clipboard Interface

DELETE: The user may select and delete curves from curve clipboard.

CLEAR All: The user can clear all data stored in clipboard.

RESTORE: Allow the user to select curves from the clipboard and restore as the current curve. If the user has already defined current curve, the program will prompt the user to use the curve in clipboard to overwrite the current curve. The program displays a dialog box, as shown in Figure 8.5.70 to prompt the user for confirmation.

 

Figure 8.5.70 User Prompt dialog box

BACK UP: Copy the current curve to the curve clipboard. The program automatically adds a copied curve in the clipboard. All curve information in the clipboard is displayed.

NO.: Number of curves in clipboard.

TYPE: Curve type. Common curve type is time curve.

PNTS: Number of points on the curve.

STATUS: The user may control whether the curve in clipboard is displayed in show curve window. If the option is selected, the curve is displayed in gray color in the show curve window (current curve in blue color).

Note: The curve data on clipboard is not saved in database file. After the user closed eta/DYNAFORM, all the curves in clipboard are removed.

TOOL BAR IN SHOW CURVE INTERFACE

The tool bar is at the top part of show curve interface. The user may operate the curves by using the functions provided in the tool bar. Tool bar interface is shown in Figure 8.5.71.

 

Figure 8.2.71 Curve Tool Bar

MOVE POINT  This function allows the user to move a point on the curve. After clicking this button, the user may move the mouse in show curve window. The program labels the point that is the closest to the cursor with a small circle. The user clicks the left mouse button to select the point. The circle turns red. The user may click and drag the mouse to move the point to a desired location. Release the left mouse button to keep the point at the new location. See figure 8.2.72 for a typical move point operation.

Figure 8.2.72 Move Points on the Curve

INSERT POINT  This function allows the user to insert a point on the curve. After clicking this button, the user may move cursor to the desired location of the curve in show curve window and click the left mouse button to insert a point.

DELETE POINT  This function allows the user to delete points on a curve. After clicking this button, the user may move the cursor to a point on the curve and click the left mouse button to delete the point from the curve.

UNDO  Allow the user to undo the previous operation.

SHOW ALL POINTS  This function displays a small circle on each point on the curve.

SHOW CURSOR LINE  This function allows the user to show cursor line.

PAN  This option allows user to pan the curve in the show curve window.

ZOOM BY WINDOW  This function allows the user to zoom in the curve by window. After clicking this function, the user needs to click and drag the left mouse button to define a rectangle region in the show curve window. Release the mouse button to zoomed in the curve.

ZOOM BY DRAG  This function allows the user to zoom the curve view by dragging the mouse. The user clicks left mouse button of in the show curve window. Holds the mouse button and moves the mouse downward to zoomed out. Move the mouse upward to zoom in the curve.

FIT VIEW  This function allows the user to fill the entire curve in the show curve window.

 

 

8.2.6.6 DURATION

 

This function is used to control the duration of the current stage. Its interface is shown in Figure 8.2.73. The user may select four methods to define current stage’s duration: direct time control, displacement control, to closure control and until home. Each of these four methods has its own advantages for different forming stage and different requirement. The user may select the appropriate control method according to the requirement of the current setup.

Figure 8.2.73 Stage Duration Time Define

DURATION TYPE

The user may select a control type from the TYPE pulling-down menu.

TIME: Allow the user to define a time to control the current stage calculation time. This method is usually used in hydroforming simulation. The user may enter a time value in the input box.

 

TRAVEL Allow the user to specify  the current stage’s calculation time by specifying the travel distance along the working direction of the tool. The user needs to select a reference tool from tool list as shown in Figure 8.2.74. Then, define the displacement value of the tool along its working direction.

Figure 8.2.74 Displacement Control Stage Time

NOTE: As the working direction can be negative or positive, it is possible to set a negative value to indicate the stage time is controlled by the tool travel distance along the opposite direction of its working direction. In Auto Setup, many functions require assigned working direction. Therefore, the working direction definition is very important.

 

CLOSURE Allow the user to use the closure time of two tools as the duration time. The user needs to select two reference tools from tool list as shown in Figure 8.2.68.

 

Figure 8.2.75 Displacement Control Stage Time

 

FULLY MATCH: This option should be selected when the mesh of two selected tools don’t have physical offset. It is not required for the tools with physical offset.

 

GAP: Allow the user to specify the distance from complete closure of the two selected tools to stop the stage calculation. As the calculation time is based on the mesh of the two tools, the thickness of blank has to be taken into account.  If the user selects physical offset meshes to calculate the closure time it is required to define the blank thickness as the gap.

 

NOTE: When using two tools’ closure option, one of the tools has to be stationary, while the other must be controlled by velocity/displacement.

UNTIL HOME Facilitate the movement of selected tool to home position. The user needs to select a moving tool from the tool list as shown in Figure 8.2.76.

 

Figure 8.2.76 Until home

 

 

8.2.6.7 OUTPUT D3PLOT FILE CONTROL

 

This function allows the user to define the number of output steps in D3PLOT files. Under default condition, D3PLOT files are output in equal time interval. In advanced parameters, the user may enter additional time points or specify tool travel distance to insert the required frames at the specific time.

 

FRAMES

Define number of D3PLOT result files for the current stage calculation. The user may change this value in the input box. If specific output time is not defined, D3PLOT files will be generated with equal time interval.

 

ADVANCED

The user may insert some specified frames in advanced options. The program displays a define D3PLOT curve dialog box as shown in Figure 8.2.77.

 

Figure 8.2.77 Add Special Output Frame

TOTAL FRAMES Display the total number of output frames in the D3PLOT files for the current stage.

 

ADD… The user may click this button to add special output frames. The program displays the specified frame dialog box as shown in Figure 8.2.78.

 

Figure 8.2.78 Specified Frame Define

SPECIFIED TIME: Add an output frame by specified time. See Figure 8.2.79 for the interface of this option. The user may enter specified time value in the TIME input box at the lower part of the dialog box. Note: Specified time 0 is the stages starting point. The user may add more time points to control D3PLOT file output at the specified time. If the user enters longer time than current stage calculation time, the program will ignore the invalid input value. Click OK button to complete the operation.

 

Figure 8.2.79 Input Specified Frame for Specified Time

TRAVEL DISTANCE: Add an output frame by specifying travel distance of the tool. See Figure 8.2.80 for the interface of this option. The user may specify a reference tool in tool pulling-down list, then enter a distance value in the DISTANCE input box. This distance value is the distance of the tool travel from the beginning of current stage.

 

NOTE: The selected reference tool must be controlled by velocity in the current stage. Otherwise, the specified distance is meaningless.

 

Figure 8.2.80 Define Output Frame by Tool Travel Distance

DISTANCE TO TERMINATION: Add an output frame by defining the distance to the stage termination. See Figure 8.2.81 for the interface of this option. The user may select a reference tool in TOOL pulling-down list, and then enter a distance value in the DISTANCE input box. This distance value is the distance of the tool from calculation termination.

 

Note: The selected reference tool must be controlled by VELOCITY.  Otherwise, the specified distance is meaningless.

 

Figure 8.2.81 Define Specified Frame by Distance to Termination

After clicking OK, the added specified frame is listed in specified frame list as shown in Figure 8.2.82. Each item in the list shows the control type of the frame, tool name and it’s travel distance as appropriate.

 

Figure 8.2.82 Specified Frame List

EDIT…: The user may select a specified frame from the specified frame list to edit.

 

DELETE: The user may delete a specified frame from the specified frame list.

 

OK: Save current setup result and exit the specified frame setup dialog box.

 

CANCEL: Exit setup dialog box without saving current setup.

 

After the user added specified frames, the program shows the number of specified frames in the current stage. An example is illustrated in Figure 8.2.83.

 

Figure 8.2.83 D3PLOT File of Special Output Time Point

 

8.2.6.8 HYDRO MECHANICAL

 

This function allows the user to set parameters for hydro mechanical forming . The user may select Hydro mech. Option as shown in Figure 8.2.84. The user may select the direction of applied fluid pressure on blank.

 

Figure 8.2.84 Hydro Forming

ABOVE: In press coordinate system, fluid pressure is applied on the top face of blank as shown in Figure 8.2.85.

Figure 8.2.85 Fluid Pressure Applied on  Top Face of Blank

BELOW: In press coordinate system, fluid pressure is applied on the bottom face of blank as shown in Figure 8.2.86.

 

Figure 8.2.86 Fluid Pressure Applied on bottom face of blank

BY NORMAL: Direction of fluid pressure is defined according to blank element normal. The user needs to check the blank element normal carefully, and make sure the element normal are consistent. Otherwise, the analysis will not be correct.

 

 

HYDRO MECH. PARAMETERS

In hydro mech. Parameter setup, the user may specify hydro pressure-time curve and the scope of the pressure. The interface is shown in Figure 8.2.87

 

Figure 8.2.87 Hydro Mech. Parameters Setup

PRESSURE: Set up hydro pressure-time curve. This parameter is essential in sheet hydro forming. The user may click  button to enter hydro pressure- time curve in the define dialog box as shown in Figure 8.2.88.

Figure 8.2.88 Hydro Pressure-Time Curve Defines

CONSTANT: Define hydraulic pressure that does not change with time. The user may enter a constant fluid pressure in Pressure input data field.

 

CYCLE: Define analysis cycle time of fluid pressure application. Default is to renew for every 200 calculation cycles.

 

TIME VARIABLE: Define variable hydraulic pressure curve with time. The user may click EDIT button to enter curve define interface. For detailed description of curve definition, refer to Chapter 12.

 

MASK: Assign mask of applied fluid pressure using closed loop cutting line. Applied fluid pressure can be either inside of the mask, or outside. It is not necessary to define this parameter. The program by default applies fluid pressure on all blank elements. Click the Entire button to display the MASK dialog box as shown in Figure 8.2.89.

Figure 8.2.89 Define Fluid Pressure Apply Cutting line

INSIDE The user may define fluid pressure inside the defined cutting line.

 

OUTSIDE The user may define fluid pressure outside the defined cutting line.

 

PROJECT DIRECTION…: Allow the user to select curve project direction. eta/DYNAFORM adopts one closed loop curve for the definition of fluid pressure mask, hence it is not necessary for the curve to be positioned on top of blank. Only the assigned curve is needed for projection onto the blank. Therefore, the project direction for closed curve is required. After the user click this button, the direction define dialog box is displayed. Detailed description of this function is provided in Section 8.2.3.2. The default project direction is Z-axis of the working coordinate system.

 

DX DY DZ: Display the coordinates of the end point of project direction vector. Default vector starting point is the origin of WCS.

 

POINTS: Display the number of points on curve.

 

INPUT LNS…: The user may define region subjected to applied fluid pressure by defining a closed loop curve as cutting line. After clicking this button, the SELECT CURVE dialog box is displayed.

 

INPUT PTS…: If no curve is provided in the database, the user may define a closed loop curve by clicking this button to create the cutting line using points.

 

Notice: When defining mask to applied fluid pressure, it is better to select the closed loop curve or a closed end point. If the curve/point is not closed, the program automatically closes curve and point.

 

DELETE: The user may delete current defined cutting line. The program displays a confirmation dialog box as shown in Figure 8.2.90.

Figure 8.2.90 Confirmation dialog box

UTILITIES…: The user may click this button to view curve functions.  The user may create the cutting line in curve define dialog box.

 

OK: Accept the current setup and exits the dialog box.

 

CANCEL: Discard the current setup and exits the dialog box.

 

If the user has already defined the region subjected to applied fluid pressure, the PARTIAL is displayed on the button next to MASK. This indicates only part of elements on the blank is subjected to applied fluid pressure.

 

 

8.2.6.9 GRAVITY

 

GRAVITY stage is used to simulate the deformation of blank under gravity load. The settings are similar to normal sheet forming process simulation. It includes basic parameters, blank define, tool define, etc. The interface of GRAVITY stage is shown in Figure 8.2.91.

 

NOTE: Gravity analysis cannot exist in the same setup with other type of analysis.

Figure 8.2.91 Gravity Analysis Process Parameters

 

INITIAL VELOCITY: Allow the user to specify initial velocity of the blank.

 

METHOD: Allow the user to select gravity analysis method: explicit (dynamic relaxation) or implicit. The difference between the characteristics of these two methods is described in LS-DYNA User’s Manual.

 

8.2.6.10 SPRINGBACK

 

The SPRINGBACK under process template is used to simulate the springback of the blank after draw simulation. See Figure 8.2.92.

 

Figure 8.2.92 Springback Analysis

NOTE: Springback analysis cannot exist in the same setup with other type of analysis.

Springback analysis process parameters setup is shown in Figure 8.2.93.

Figure 8.2.93 Springback Analysis Process Parameters

 

CONSTRAINT NODES

Allow the user to select three nodes to constrain the rigid displacement of the blank. The user is prompted to select nodes in NUMBER OF NODES dialog box. The user may click the EDIT button to select three nodes. The program displays the select node dialog box as shown in Figure 8.2.94. The user may select three constraint nodes on the screen. The constrained degree of freedom of the selected constraint nodes is displayed on the screen.

Figure 8.2.94 Constraint Node Define

NOTE: The first selected node is constrained in X, Y, Z direction. The second selected node is constrained in Y, Z direction. The third selected node is constrained in Z direction.

 

CLEAR: Clear all defined constraint nodes. The user may re-define the constraint nodes.

 

OK: Save current setup and exits the dialog box.

 

CANCEL: Exit the dialog box without saving current change.

 

COARSENING MESH

Allow the user to use coarsening mesh technique during springback calculation. During drawing calculation, adaptive mesh technique is adopted to refine the blank mesh. It results in a large number of elements for springback calculation, which brings great challenge to the convergence in implicit solution. This option will merge the adapted mesh in the flat areas prior to springback calculation. It will reduce convergence problem and shorten the computing time.

 

ANGLE: Set the angle criteria for merge neighboring elements. When the element normal angle difference between adjacent elements is less than the given criteria, the program merges these elements. Default angle is 8 degrees.

 

 

ANALYSIS

Allow to user to select springback analysis calculation method: single action springback and multiple actions springback calculation. Single action springback is the default option. Single action springback calculation usually leads to good result. For relatively soft materials, convergent result may not be obtained in single action calculation. The user may consider to use multiple actions springback calculation. Detailed descriptions for these calculation options can be found in LS-DYNA User’s Manual.