Steps to Derive k and Assemble into K

Figure 1 is a flowchart illustrating the sequence for computing the stiffness matrix of a simple problem (the concept is similar to more complex problems). Computing the stiffness matrix involves two main steps:

1. Derive local stiffness matrices (k)
2. Assemble k into K, the global stiffness matrix

Figure 1: Flowchart illustrating the derivation of k and assembly of K

It is useful to note that Kiakb may be interpreted as

• stiffness at node a in the degree of freedom i 
• due to movement of node b in degree of freedom k.

Also read about
Constitutive equations
Shape functions
Gaussian quadrature
Jacobian mapping
The role of assembling K in the FEM process