Although it is not mentioned in the 2020 Beta What’s New document, the SOLIDWORKS Simulation R&D team has been working hard to enhance the surface to surface incompatible bonding algorithm in SOLIDWORKS Simulation 2020. Here are some of the improvements you can see:

1. In Frequency studies, the solver is better able to show ~0 frequencies for rigid body modes, most notably the three rotational degree of freedom modes (4-6 in the image below).
2. The accuracy of stress calculations at interfaces bonded using an incompatible mesh is improved. These enhancements are noticeable in linear static, frequency, and buckling studies for solid-solid, shell-shell, and mixed mesh incompatible bonding, especially if gaps are present between bonded entities.
3. The default option for bonded component contact is now set to Incompatible. You can change the default setting for the Component Contact (including Global Contact option) to a Compatible or Incompatible bonded contact type from Simulation Options > Default Options > Contact

   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.