Hi, 

I have a question about the members of displacement vector for 3D shell element. I found that the elemental stiffness matrix for 3D shell element in Abaqus is in 24*24 dimension. However, each element have only 4 nodes. Considering the displacement in x, y, z direction, there are only 12 displacement vectors for one element. If I want to calculate the elemental nodal force, which fi = ki*ui, i=1,2......n representing each element number, how should I form ui for each element? 

Also, I have question about whether NFORC field output value represent the elemental nodal force other than nodal force(i.e. the elemental stiffness matrix times nodal displacement for each element other than global stiffness matrix times nodal displacement), and why it has opposite sign against fi = ki*ui?

Thank you!