About Load Sets and Load Cases

You can use load sets and load cases to study the linear responses of a structure subjected to different loading conditions. For example, a simplified simulation of the operating environment of an airplane might be broken into five load cases: take-off, climb, cruise, descent, and landing.

A load case is often defined in terms of unit loads or prescribed boundary conditions (restraints). A load set acts as a unit load that can be scaled when it is applied in a load case.

The simulation computes a simultaneous solution for the different responses to each load case in the step—this is known as a multiple load case analysis. Using load sets and load cases is generally more efficient than the equivalent multiple-step simulation because it takes advantage of the principle of linear superposition.

The overall process for using load sets and load cases is as follows:

1. Create a new load set that acts as an empty container. The load set is shown in the context selector to indicate that it becomes the current context:
   
   
2. Create restraints and/or loads within the load set.
3. Change the current context in the context selector to the desired static perturbation step or harmonic response step:
   
   
4. Create a new load case that includes one or more load sets and is applied within the current step.

If you create loads or restraints separately from load sets within a step, they are applied globally in addition to the load sets.

Load case output is stored in separate frames in the simulation results, and you can create results plots for load case combinations by combining the results from multiple frames. Output requests apply to all load cases in a step.

Load sets and load cases cannot be used for nonlinear simulations—you should instead create multiple analysis cases for these types of applications.