Combined load cases

A combined load case is a load case that you create from a linear combination of results from individual subcases. Combined load cases allow you to view results for varying combinations of load cases without spending analysis time, resources, and disk space for every instance of a load case combination. For example, you can view combined results, and you can scale results to compare the results of similar loading conditions at different loading values. For a combined load case to be valid, it must have the same constraints.

You can also use combined load cases in margin of safety and load case filtering load case sets. To do so, you must create combined load cases from subcases in SOL 101 Linear Statics - Global Constraints. The combined load cases are saved in the Simulation file and are available from session to session.

After you create combined load cases, you can use them:

• In the Post Processing Navigator, where you can view the combined results.For more information, see Results for combined load cases.

• In margin of safety and load case filtering solutions, where you can add the combined load cases to load case sets. The combined load cases appear in the Load Case Set Editor dialog box, in the Available Load Cases table list, along with the other load cases. For more information, see Load case sets (margin of safety) or Load case sets (load case filtering).

Setting up your analysis

Prior to using the combine load cases functionality, you should give some thought to how you set up your analysis. Be sure to create a separate subcase for each load case you intend to combine. If each subcase contains only a single load, you may find it useful to define the magnitude of the loads with unit values. Then you can scale the result to the actual applied value in the combined load case.

Example: Multiple loading conditions with single linear statics solve

Suppose you are performing a linear statics analysis on a part that experiences top, bottom, and front loading. You've been asked to provide contour displays of the following loading conditions:

• Top loading only

• Bottom loading only

• Front loading only

• Top and front loading

• Bottom and front loading

• Top, bottom, and front loading

You could create six solutions and solve six times, once for each loading condition. This requires both time and disk space, and for large or complex models could require considerable resources.

A better alternative is to create a single solution with three subcases, one for each load. After you solve the model, you can use Load Case Combine to create named, combined load cases representing each of the loading conditions.

Example: Scaling with multiple loading conditions

Suppose you want to examine a variety of loading conditions at different load values. For example, suppose you want to compare the results of top and front loading when the front loading is equal to 5 model units and when it is equal to 7 model units. Without the Combine Load Cases scaling functionality, you would need to create two different simulations, each with its own solution, to solve for the same load with two different values.

Instead, when you define the loads for this model, assign each load a unit value. (That is, a value of 1 in the units system you use.)

After you solve the model, you can create combined load cases where the scale factor applied to the front load value is 5 and 7 respectively.

Where do I find it?

Application	Pre/Post
Prerequisites	A Simulation file as the work part and displayed partNastran as the specified solverStructural as the specified analysisSOL 101 Linear Statics - Global Constraints as the specified solution typeComputed results
Simulation Navigator	Expand Results→right-click Structural→Combined Load Cases

How do I

Create a combined load case

Modify combined load cases in a dialog box

Modify combined load cases in a spreadsheet or text editor

Create a load case set for a margin of safety calculation

Create a load case set from margin of safety results

Learn more

Load case sets (margin of safety)

Results for combined load cases

Exporting and importing load case sets (margin of safety)

Orphan load cases (margin of safety)

Quick links

Command reference

Pre/Post video examples

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Simcenter 3D tutorials

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Margin of Safety methods documentation

Combined load cases, Simcenter 3D 2021.1 Series

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