I often find myself wanting a constraint that only restricts motion in one direction of an axis to improve the behavioural accuracy of my boundary conditions. As an example, imagine a flange bolted to a concrete floor. It would be able to lift off of the ground between the bolts while deflecting, but not into the concrete floor.
Currently this can be done by modeling a floor, meshing it and then adding a contact, but:
1. That can take some time to do with the additional modeling, mesh and contact to create.
2. It requires additional computation time due to calculating the contact.
3. It's annoying that the simulation software in Solidworks has this feature, but not NASTRAN.
My suggestion would be to add the ability to increase our control over all structural constraints to be able to specify ± in addition to each axis of motion/rotation for all types of constraints.
