I am a little bit confused over the concept of translational and rotational degrees of freedom (DoFs) in structures, and their relation to displacement/traction BCs.
Do displacement boundary conditions constrain translational DoFs, only, or also rotational DoFs?
For example, for a 3-D case, if I specify the 3 translational components to be zero, I am effectively constraining all 3 translational DoFs. What does this do to the rotational DoFs? Intuitively, all 3 rotational DoFs would also be constrained.
How does traction BCs play into translational and rotational DoFs?
Part of my confusion is when I look at open-source or commercial structural mechanics solvers, I only see the ability to specify displacement or traction boundary conditions, not anywhere to specify translational or rotational constraints.
Some illustrations would be very helpful in my understanding.
Mathematical expressions would be helpful as well. In particular, I am wondering how rotational and translation DoFs are related to displacements and displacement gradients mathematically.