Fixed Joint Theory
The Fixed Joint rigidly connects the two components and does not allow any relative motion between them. It does not add any degrees of freedom.
The following is an addition to the Prismatic Joint Theory, some of which is also applicable for the fixed joint.
Fixed Joint Formulation
Constraints are added stating that the both parts have the same value of displacements and rotations at the center of joint. In 3D six constraints are added:
In 2D three constraints are added:
The position of the center of joint only affects interpretation of the joint forces and moments.
Joint Elasticity in Fixed Joint
The elastic degrees of freedom are written as