Is It Possible to Define Infinitely Rigid Bodies?

Question

Is it possible to define infinitely rigid bodies?

Remedy

Yes, this is possible. Select a connector and in the Property Editor change the Connection Type from Flexible to Rigid.

Connectors are usually created when loads or supports are moved away from a part using the Move tool.
They can also be created using the Connectors tool available in version 2016.2 and after.