In this section, we’ll take the theory used to develop the 2D non-linear stiffness matrix and extend that to 3D. This really involves two steps, updating how we calculate the element transformation matrix and then updating the local element stiffness matrix. 

The task here isn’t difficult, the hard work was done in establishing the 2D stiffness matrix in the prerequisite course. We'll focus on whiteboarding the theory here before diving into code a little later.