Nonlinear Elasticity: Calculating Internal Forces

[hnemati2000]

High
I am working on the geometrically nonlinear finite element method. I now that in this method, the internal forces on each node must be equal to external forces. How can I calculate internal forces?

 

[HallsofIvy]

With the "finite element method" you are using variables to represent the unknown data. The internal forces will be calculated from those variables. Exactly what the formulas are depend on the particular problem- specifically, the relationship of the forces to the properties of this non-linear solid.