Voigt notation is a way to represent a symmetric tensor by reducing its order. This is very useful when implementing finite element programs in Fortran. For example, the stress tensor in matrix representation is often given as
In Voigt notation, it is simplified to a vector:
For 2D problems, the stress tensor in matrix representation is simply
In Voigt notation, it becomes:
Note that the Voigt notation used in Abaqus software is slightly different. We will cover that later.