(DEFINE_) CURVE/TABLE: Defining Load Curves

All functions have their standard meanings as given in Standard Keyword Top Level Menu Options. The COMPARE option is specific to curves, and is described below.

The table and curve main menu panels are similar.

There are six main areas in the panel, each area grouping together buttons of similar function.

1. Create/abort loadcurve
2. Loadcurve display buttons
3. *DEFINE_CURVE options
4. Loadcurve plot
5. Loadcurve points
6. Loadcurve modification

(1) Create/abort loadcurve

This will exit the current loadcurve creation, saving the curve in the database. This button will be inactive (greyed out) until a label ( LCID ) is given for the loadcurve and there are at least two points in the curve.

CANCEL

Aborts from the current loadcurve creation without saving any of the modifications.

If the loadcurve has any cross references in the database they are displayed in a dialogue window. If there are no cross references to this curve [ no cross references found ] will be displayed.

Resets the curve back to its initial state. Any points which have been added or modified are lost.

Copies the data from an existing loadcurve into the loadcurve currently being created. Any points which have been added since starting the create will be lost.

Checks the loadcurve currently being created for any errors.

Sketch is currently inoperative.

These buttons toggle whether the grid, the curve line and the curve symbols are drawn on the plot.

Resets the scaling on the loadcurve plot so the curve just fits the screen and replots the loadcurve.

Two points are selected using the left mouse button. Xmin, Xmax, Ymin and Ymax are updated and the curve is replotted

The curve is replotted as the scale currently selected by Xmin, Xmax, Ymin and Ymax .

Typing in a value changes the limits for plotting the curve.

By default when creating a curve Xmin and Ymin are -1. Xmax and Ymax are 1. When modifying an existing curve they are set so the curve just fits on the screen (equivalent to AUTOSCALE )

The two log buttons can be used to set the graph x and/or y axis to a logarithmic scale. When a log button is selected, the axis min gets set to the closest power of 10 less than the positive minimum value and the max is set to the closest power of 10 greater than the positive maximum value. The same applies when the ‘Autoscale’ button is pressed when in log mode. The axis min/max can be changed to any value in the corresponding textboxes.

Will display the curve points discretized according to Ansys LS-DYNA rules.

Toggle between white and black background

When toggled on, this button can be used to drag, insert or delete points from the displayed curve(s). Right click on the button to change the option. In drag mode, left mouse click and hold on a point on the curve, then drag. In insert mode, left mouse click at a point on the curve where you wish to add a point. In delete mode, either left mouse click on a point on the curve to delete it, or left mouse click hold to drag a box around a number of points to delete them.

By default when a curve is plotted on the screen the offsets ( SFA, SFO ) and scale factors ( OFFA, OFFO ) are not included. If this button is pressed then they are included in the plot. To ensure that the user is aware of this the SFA, SFO, OFFA and OFFO text boxes turn green (by default they are blue) and the curve line and symbols are plotted in green. Pressing the button again toggles the inclusion off.

Loadcurve values are scaled after the offsets are applied.

Abcissa value = SFA x (Defined value + OFFA)

Ordinate value = SFO x (Defined value + OFFO)

(3) *DEFINE_CURVE options

Label for loadcurve. If there is no label then the label is shown as <none> and the box is red rather than the default blue. A new label can be typed in the box or the right mouse button pressed to get the standard label popup box.

Sets whether the loadcurve will be used in a transient or dynamic relaxation analysis. Either type in the value or use the right mouse button to bring up a popup menu.

Scale factors and offsets for the loadcurve abcissa (x) and ordinate (y) values.

Sets the type of data in the loadcurve: generally this is set to zero. Either type in a value or use the right mouse button to bring up a popup menu.

The loadcurve currently being created or modified is plotted in the bottom left of the loadcurve panel.

If the curve has no cross references then the units for the X and Y axes are shown as Unknown units. If there are cross references, the first reference that PRIMER finds is used and the units displayed on the X and Y axes. All the cross references for the curve can be displayed with the LIST_XREFS button.

The visibility of the curve lines, symbols and the grid is controlled by the GRID, LINES and SYMBOLS buttons.

If the INC_SCALE+OFFSET button is selected, the curve is drawn in green instead of the default yellow to inform the user that the scale factors and offsets are included in the plot.

The plot can be updated at any time by pressing the PLOT button.

When a curve is created the user is forced into INS_AFTER mode until a point is created. The user will not be able to change to another mode ( MODIFY, INS_BEFORE or DELETE ) until this point is created.

The X and Y value boxes for this initial point are blank and coloured green to indicate that a number is required. If a number is typed into one of the boxes the box turns blue.

When numbers are present for X and Y the line for point 1 becomes blue and point 2 becomes green. As many points as necessary can be added using this method.

Any incomplete points (i.e. if either the X or Y values [or both] are blank) will be deleted when changing mode. If the number of points in the loadcurve is greater than 10 a sliding bar appears by the side of the points. The mouse can be used to select which points are visible in the text box. Drag the bar up and down with the left mouse button to move between the points. Alternatively clicking on the up (or down) arrow with the left, middle or right mouse button, increases (or decreases) the points shown by 1, 10 or 100 respectively. The value of a point can be changed in any mode by clicking on the X or Y value box and typing in a number.

(6) Loadcurve modification

Selects modify mode for loadcurve point editing. In this mode only the values of the points can be changed. No points can be added or deleted.

When in this mode the point buttons are greyed out so they cannot be selected.

If a point is currently being edited in INS_BEFORE or INS_AFTER mode it is deleted before the modify mode is selected.

Select either INS_BEFORE or INS_AFTER mode for loadcurve point editing. This allows points to be added to the curve.

When in these modes the point buttons turn green. If a point is selected by clicking with the mouse a new point is created either before or after (depending on which mode) the selected point. If a point is currently being added in this mode and another point is selected the current point is deleted and the new point added.

Selects delete mode for loadcurve point editing. In this mode points can be deleted as well as being able to change the values of the points.

When in this mode the point buttons turn red. If a point is selected by clicking with the mouse it is deleted. If a point is currently being edited in INS_BEFORE or INS_AFTER mode it is deleted before the delete mode is selected.

Moves the slider automatically to the top or end of the points for the loadcurve

Moves the slider so that the point number which is typed in is visible.

Allows a loadcurve to be read from an external file or from a database in PRIMER . Pressing the IMPORT button brings up a new set of buttons instead of the loadcurve points.

Two types of file can be read into the loadcurve editor. T/HIS curve files and raw x,y data. The formats of these files is given in Appendix H . The format of the file to import is selected by using the RADIO buttons. The filename can then either be typed in the file text box or selected by browsing using the ? button. T/HIS curve files can contain multiple curves in one file. In this case the curve number in the file to read should be given. If no number is given the first curve in the file will be read. For the XY data/CSV data option you can specify the number of lines to skip at the start of the file, and also the columns for the X and Y data, should they not be in column 1 and 2.

Allows a loadcurve to be written to an external file from PRIMER . Pressing the EXPORT button brings up a new set of buttons instead of the loadcurve points.

Two types of file can be written from the loadcurve editor. T/HIS curve files and CSV x,y data. The formats of the T/HIS curve data is given in Appendix H. The format of the file to import is selected by using the RADIO buttons. The filename can then either be typed in the file text box or selected by browsing using the ? button.

Reads the selected file into the loadcurve editor and plots the curve. Any modifications to the current curve will be lost when importing a file.

Aborts the import and returns to the normal loadcurve editor window.

The DATABASE button starts the loadcurve database function in PRIMER .

A list of the available loadcurve databases will be shown on the screen. When one is selected a curve can be read from the database.

For further details on databases see Databases: Importing Data from Pre-Defined Database Files and Appendix A.

TEXT_EDIT

The standard "Text edit" function works on Curves, Tables and Functions in the normal way with one special exception for *DEFINE_TABLE.

A *DEFINE_TABLE keyword in Ansys LS-DYNA is exceptional since it takes the form

*DEFINE_TABLE
N lines of factors on loadcurves

*DEFINE_CURVE first of N following loadcurves
*DEFINE_CURVE second of N following loadcurves
etc to the Nth following loadcurve

This means that the order of keywords in the keyword deck is significant and PRIMER must take care that a table is not separated from "its" associated loadcurves during keyword input and output.

As a consequence when a file is written out for text editing it will contain both the *DEFINE_TABLE definition itself, as you would expect, but also vestigial *DEFINE_CURVE definitions for all the associated loadcurves. These "vestigial" definitions will only contain the first line of the curve giving its label and factors SFA, etc. This gives the impression that the values on these first lines can be edited and that these changes will be re-imported back into PRIMER when the Text edit process is complete.

Prior to version 18 this was not the case: such changes would be ignored. From version 18 onwards these changes are read and applied.

Any such changes are made directly to the loadcurve definitions in the database, so the sequence:

• Open editor on *DEFINE_TABLE
• Use Text edit to edit it externally
• Change a value on any of the *DEFINE_CURVE definitions
• Save and exit the editor

Will import the changes to the loadcurves immediately. If the editing panel is then "Aborted" the *DEFINE_TABLE itself will not be changed, since editing takes place on a scratch definition, however any changes to the associated loadcurves will remain.

PRIMER detects this situation and warns you when you quit the edit. However if the changes need to be reverted you will have to do this manually.

RENUMBER Change loadcurve labels

RENUMBER lets you change any or all loadcurve labels within a given model using the standard renumbering panel. To change the label of an individual loadcurve it may be simpler just to MODIFY it.