Derived Load Steps

The Derived Load Steps utility allows you to create a derived load case from other load cases, or from a combination of other load cases and simulation steps. To access the Create/Edit Derived Load Case dialog, click Derived Load Steps on the Results toolbar, or select Create > Derived Load Steps from the Results menu.

linear_superposition_dialog1

Use the Type drop-down menu to select the desired load case that you would like to create:

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Type drop-down menu

There are three types of derived load cases available:

Steps	Create a derived loadstep from other loadsteps. A derived loadstep can contain more than one simulation step, with scale factors optionally applied to them.
Linear-Superposition	Create a derived loadstep with only one simulation step, which is a combination of all the selected loadsteps/simulations with scale factors.
Envelope	Create a derived loadstep with only one simulation step, which compares entity values and stores desired values from selected loadsteps (or animations) based on the Min/Max/Extreme/Range option that is chosen.

Recent enhancements have been made which involve the creation of a Linear-Superposition or Envelope loadcase composed of base and derived loadcases. Finding the minimum or maximum of envelopes, or the maximum value of a set of linear combination loadcases is now possible.

See Envelope or Linear Superposition of Base and Derived Loadcases for additional information (below).

Note	The Envelope utility is not intended for use with Tensor or Vector plots. If it is used with a Tensor or Vector plot, HyperView will simply draw the last loadstep in the derived loadstep list.

You can select simulation steps from the derived loadstep list by selecting them with your mouse or the arrow keys. Use the and buttons, to add or remove the required loadsteps/simulations to the derived loadstep.

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From the Select loadstep drop-down menu, you can select the derived loadstep that you would like to be active.

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Select loadstep drop-down menu

Upon selecting a derived loadstep, the simulation steps contained within that derived loadstep are displayed in the table below the drop-down menu.

linear_superposition_example_table

Example derived loadstep table

The table contains the following categories:

Label

Displays the loadstep number and the time of each simulation step. This field is not able to be edited.

Scale

Displays the scale factor that was defined for each loadstep/simulation step.

Click inside the Scale field to manually change or edit the scale factor for a particular loadstep or simulation step.

To change the scaling factor for multiple loadsteps; select the desired loadsteps in the table, update the value in the Constant Scale text box, and click Apply. The scale field in the table, for the selected loadsteps, will be automatically updated with the new factor.

Simulation steps can also be removed from a loadstep.

The New, Rename, or Delete buttons can be used to add a new derived loadstep, and rename or delete an existing loadstep.

New	Creates a new derived loadstep. When you click the New button, a new derived loadstep is added to the tree structure and is given the default name Derived loadstep "n" (with "n" being the next number in the series). The new derived loadstep becomes the active derived loadstep.
Rename	Renames the active derived loadstep. When you click Rename, the New Label dialog is displayed that allows you to change the label of the active derived loadstep.
Delete	Deletes a derived loadstep.

OK	Apply the changes and exit the Create/Edit Derived Loadstep dialog.
Cancel	Disregard changes and exit the dialog.
Apply	Apply the changes made to the derived loadstep(s).

The Linear Superposition type is used to create Loadsteps that are linear combinations of other loadsteps.

linear_superposition_dialog

Create/Edit Derived Load Case dialog (with Linear-Superposition as the type and the View Load Cases icon activated)

The Loadsteps section lists all the loaded results files in the current session, as well as all the loadsteps/simulations corresponding to each result file, in a tree-like structure.

In addition, the derived load cases list can be displayed by clicking on the View Derived Load Cases icon .

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Create/Edit Derived Load Case dialog (with Linear-Superposition as the type and the View Derived Load Cases icon activated)

This section allows you to specify which loadstep(s), from the currently selected input file, to add to the linear combination definition. You can select items from the list by selecting them with your mouse or the arrow keys. Multiple loadsteps from the tree structure can be selected using the CTRL and SHIFT keys.

Use the and buttons, to add or remove the required loadsteps/simulations to or from the derived loadstep.

The Envelope type is used to identify the most significant loading conditions out of all the selected analysis loadsteps. The created loadstep is a summary of all the selected loadsteps which meet the specified criteria (Min/Max/Extreme/Range).

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Create/Edit Derived Load Case dialog (with Envelope/Max as the type and the View Load Cases icon activated)

The Loadsteps section lists all the loaded results files in the current session, as well as all the loadsteps/simulations corresponding to each result file, in a tree-like structure. You can select simulation steps from the derived loadstep list by selecting them with your mouse or the arrow keys. Use the and buttons, to add or remove the required loadsteps/simulations to the derived loadstep.

Envelope Types:

Min	Finds the minimum values among all the selected loadsteps or simulations (weighted by the appropriate scale factors) defined within the derived loadcase.
Max	Finds the maximum values among all the selected loadsteps or simulations (weighted by the appropriate scale factors) defined within the derived loadcase.
Extreme	Finds the maximum absolute values among all the selected loadsteps or simulations (weighted by the appropriate scale factors) defined within the derived loadcase. The sign of the number is not changed however. For example, the Extreme of 5 and 10 is 10, and the Extreme of 5 and -10 is -10.
Range	Finds the difference between the maximum value and the minimum value among all the selected loadsteps or simulations (weighted by the appropriate scale factors) defined within the derived loadcase. Selecting this option will disable the Envelope trace plot option in the Contour panel.

The example below shows how the various Envelope types are calculated:

envelope_loadcase_chart

When a particular layer is selected in the Contour panel, the Envelope value is obtained by cycling through all the loadsteps for that given layer, and the Min/Max/Range value is then reported. When the layer aggregate is set to Min/Max/Extreme/Average/Range, the result is calculated across all the layers including all the loadsteps defined for the Envelope.

The example table below shows the relation between layer aggregate modes (Min/Max/Range layers within the Contour panel) to an Envelope type of Min/Max/Range for an element with three layers (Top, Mid, and Bottom) across four loadcases (LC1, LC2, LC3, and LC4).

		Step (Raw data from file)				Envelope Type
		LC1	LC2	LC3	LC4	Min	Max	Range
Layer	Top	4	5	7	6	4	7	3
	Mid	2	1	8	3	1	8	7
	Bottom	-4	-2	-3	-7	-7	-2	5
Contour Layer setting	Min	-4	-2	-3	-7	-7	N/A	N/A
	Max	4	5	8	6	N/A	8	N/A
	Range	8	7	11	13	N/A	N/A	15

The image below shows a contour plot with Min, Max, and Range as the Envelope types (the top row shows values from four different loadsteps):

derived_loadsteps_example

In certain use cases, it may be useful to create an envelope or a linear combination of a derived loadcase. As an example of finding the maximum of a set of linearly combined loadcases, or just finding the minimum or maximum of different envelope type loadcases. From the base loadcases provided by the solver, you can create two levels of derived loadcases (as shown in the image below):

derived_loadcases_example_hv

At the second level (Level 2), any combination of base and derived loacases from the first level (Level 1) is allowed. To allow referencing the derived loadcases subsequently, these loadcases are displayed in the Create/Edit Derived Load Case dialog along with the base loadcases. Only the derived loadcase name is displayed in the tree. A full breakdown of a derived loadcase can be viewed by clicking on the View Derived Load Cases icon . You can also easily modify the definition of a derived loadcase by using the left and right arrows located in the middle of the dialog.

derived_load_case_example_dialog_hv

Various checks are performed in the GUI in order to try and prevent the creation of ill-defined derived loadcases. Among them, a recursive error is displayed when a loadcases is pointing to itself through recursion, or going through more than two levels of derived definition. The error message will be prompted with no action taken. It is also important to note that the newly created IDs for a derived loadcase (at level 2) are stored and restored from the session/report template file (and not necessarily the base loadcase IDs). In the case of envelope derived loadcases, the trace plot in the contour panel will display the derived loadcase ID where appropriate.

If loadcases from multiple result files are referenced, it is recommended that you include all the required result files prior to creating any derived loadcases. See Result Files for additional information regarding adding result files.

Note

A linear superposition combination of another set of linearly combined loadcases is not supported for complex data. After the first level of combination, the complex data is extracted and converted to real numbers in the result processing stage, thereby any subsequent combinations (linear additions) are done on the real data and not on complex math. You are advised to verify the results in these cases. The second level of derived loadcases is also disabled with certain file formats of the crash solvers, namely LS-DYNA, PAM-CRASH, and RADIOSS.

The filter provides additional selection control including a name filter. Click the button to activate the text box, enter a loadstep string, and press ENTER. Only the loadstep(s) that match the string are displayed in the tree structure. Enter * into the filter text box and press ENTER to display all of the loadsteps/simulations in the tree structure.

The loadstep string that is used for filtering is not case sensitive.

Once you have used the filter, click Filter again to display the entire tree structure.

Loadsteps listed in the current view of the tree structure can be selected, or deselected, using the All/None/Reverse buttons:

	All loadsteps listed in the tree are selected.
	No loadsteps listed in the tree are selected.
	Current selection status is reversed.

Derived loadsteps can also be saved or imported as configuration files (*.cfg) using the buttons below:

	Saves the definition of the current derived loadsteps as a configuration file.
	Imports/reads a previously saved derived loadstep configuration file.
Click here to see a sample derived loadsteps configuration file.

The following additional options, which allow you to globally control the status of the folders, are available by right-clicking inside the Loadsteps section list:

Collapse All	Closes all model folders in the entire tree structure.
Expand All	Opens all model folders in the entire tree structure.

Constant Scale: This text box allows you to define the linear scaling factor that will be applied to the selected (or highlighted) loadsteps in the table.

-	Select the desired loadsteps in the table (they are highlighted in blue). Note The default setting for the scaling factor is 1.0.

-	The scaling factor can be changed by simply updating the value in the Constant Scale text box and hitting the ENTER key.

Results can be combined from multiple files by selecting a different input file and adding the appropriate loadsteps to the table. Click Result Files to access the Update Result Files dialog, which will allow you to add or remove result files to/from the current session.

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Update Result Files dialog

Add Result file	Use the file browser button , to select a result file (or multiple files) containing the loadsteps of interest. The full path and filenames are displayed. Clicking Open will add the selected file to the Result file list, and the file will also be loaded into the current session. When adding new result files into the current session, only similar file types are allowed. For example, combining Nastran result files and Dyna result files is not currently allowed.
Result file list	Displays all the result files that are currently loaded.
Remove Result	Remove the selected file (or multiple files). The Remove Result option is also available by right-clicking on a row within the Results file list.
Close	Apply changes and exit the dialog.

Once the Update Result Files dialog is closed, the loadstep list will automatically refresh and display any changes that were made.

How do I...

1.	From the Results menu, select Create > Derived Load Steps, or click the Derived Load Steps button on the Results toolbar. The Create/Edit Derived Load Case dialog is displayed.

2.	Click New. A new derived load case is added to the Derived load case drop-down menu. The new load case is given the default name Derived Load Case "n", with "n" being the next number in the series.

3.	Select a load case/simulation from the regular load case list (located on the left-hand side of the dialog).

Note

In the regular load case view, the load case list will only display the list of regular load cases (load cases which are obtained directly from the solver results). In the derived load case view, the load case list will only display the list of derived load cases (load cases which are derived from regular load cases).

Currently, the creation of derived load cases is only allowed from regular load cases. The creation of derived load cases from other derived load cases may be supported in the future.

4.	Select the simulation time steps you want to add to the new load case.

5.	Click . The simulation time steps are added to the new derived load case.

6.	Click Apply to create the new derived load case and remain in the dialog.

Click OK to create the new derived load case and exit the dialog.

1.	From the Results menu, select Create > Derived Load Steps, or click the Derived Load Steps button on the Results toolbar. The Create/Edit Derived Load Case dialog is displayed.

2.	Click New. A new derived load case is added to the Derived load case drop-down menu. The new loadstep is given the default name Derived Load Case "n", with "n" being the next number in the series.

3.	Select a load case/simulation from the regular load case list (located on the left-hand side of the dialog).

Note

In the regular load case view, the load case list will only display the list of regular load cases (load cases which are obtained directly from the solver results). In the derived load case view, the loadcase list will only display the list of derived load cases (load cases which are derived from regular load cases).

Currently, the creation of derived load cases is only allowed from regular cases. The creation of derived load cases from other derived load cases may be supported in the future.

4.	Click . The simulation time steps included in the load case are added to the new derived load case.

5.	Click Apply to create the new derived load case and remain in the dialog.

Click OK to create the new derived load case and exit the dialog.

1.	From the Results menu, select Create > Derived Load Steps, or click the Derived Load Steps button on the Results toolbar. The Create/Edit Derived Load Case dialog is displayed.

2.	From the Derived load case drop-down menu, select a load case to make it active.

3.	Click Delete. The last derived load case that remains in the list becomes the active derived load case.

1.	From the Results menu, select Create > Edit Derived Load Steps, or click the Derived Load Steps button on the Results toolbar. The Create/Edit Derived Load Case dialog is displayed.

2.	Select one or more simulation time steps from the derived load case list.

3.	Click The simulation time steps are removed from the list.

1.	From the Results menu, select Create > Derived Load Steps, or click the Derived Load Steps button on the Results toolbar. The Create/Edit Derived Load Case dialog is displayed.

2.	From the Derived load case drop-down menu, select a load case to make it active.

3.	Click Rename. The Rename dialog is displayed.

4.	Type a new label in the text field and press ENTER.

1.	From the Results menu, select Create > Derived Load Steps, or click the Derived Load Steps button on the Results toolbar. The Create/Edit Derived Load Case dialog is displayed.

2.	Select an item from a list while dragging the pointer to include items above or below the selected item.

Hold down the SHIFT key and select another item from the list.

The range of items between the first and second selections is highlighted.

1.	Hold down the CTRL key.

2.	Select an item from the list in any order.