As you may have already seen in the SOLIDWORKS 2020 What's New, Free Body Force calculations in SOLIDWORKS Simulation are no longer limited to Static studies - they are now also available in Nonlinear studies:

From Pg. 163 of the What's New document:

Free Body Forces for Nonlinear Studies
After running a nonlinear static or nonlinear dynamic study, you can list the free body forces at each solution step. In the Nonlinear-Static dialog box, click Compute free body forces.

This functionality also happens to be one of the Focus Areas for testing this week in the Beta Contest (Week 4). Here are a few things you should know:

1. To be able to view free body force results in nonlinear studies, the appropriate option in study properties must be enabled before running the study.

2. Enabling this option will increase both the size of the result file (.CWR) and the time to solve the study. A few customers have noted an increase of only about 10% for either, though it would not be abnormal to see significant deviation from this figure.

3. This option will be disabled by default in each new study, which is by design. If you would like to request the possibility of specifying for this option to be enabled by default in new studies (for example through Simulation > Options > Default Options), please be aware of the following open enhancement:

SPR 1140137 - "*enhancement* Provide a Simulation Default option to govern whether the 'Compute free body forces' option for Nonlinear studies is enabled or disabled by default in new studies."

As always, please submit any unexpected behavior you encounter through a Beta SR, and feel free to add a comment to this post to share any other thoughts you may have.