If the element as a whole needs to rotate, that is done by translating the nodes'', you mentioned this fact for solid elements. Now imagine a situation where there is a solid in reality and it is fixed in such a position that its only one edge is grounded (and not behaving as a hinge but actually restricting the rotations of the nodes on that edge as well), so in the ANSYS model you are trying to say that if I make that edge as fixed, it won't solve since it is unstable. What should I do then? Cause in reality only one of the edges of the solid is grounded, You said we can use WEAK SPRINGS option to make the mathematical equations work. Can I input constraint equations to keep the rotations of the nodes on that edge to be equal to zero? But you also mentioned at the same time that the rotational equations for a solid elements do not exist at all in the ANSYS solver.nAnd also, what would this mean if a pick a an edge of a solid model and try to apply a moment there? This cannot be done since the nodes of the solid elements cannot rotate at all? What do you think Array?nAlso, the thing you mentioned about fixing the edge of a solid and regarding it as like a hinge connection, so that does mean the nodes on that edge of solid elements can rotate about each of its center, but cannot resist the rotation? And that is why the the matrix is singular and rigid body motion is caused? Am I right? I mean the rotations of the nodes about each of its center is kind of possible though in the solid by making an analogy to a hinge connection.nAbout the WEAK SPRINGS, how correct and dependable will be my answers? All the forces and moments applied to the model will only travel to the boundary condition I inputted and none will go to the weak springs, is that what you mentioned Array? n''which happens if there are not at least six constraints to ground'', I think you meant to say that atleast six constraints to the ground IN THE CORRECT POSITION. Cause even if there are more than six constraints, there can still be a matrix singularity and hence a rigid body motion. Am I correct?n''You can’t "bend" a single linear solid element'', what about single quadratic solid element. By rotating the nodes on the ends, the mid side node can also translate for a quadratic solid element, as like you said for the quadratic shell element.