# Non linear fea

1. May 30, 2005

### chandran

How non linear fea works. I am studying that and i can't find any material in the web which has some basics.

How the newton raphson method is used in non linear fea

suppose i apply a force f on a structure after that how non linear fea works?

2. May 30, 2005

### PerennialII

About the Newton-Raphson method ... you can view it as a generalization of Newton's method, where in this case the system response is sequentially linearized until convergence (the modified version classically doesn't update the coefficient matrix). Below a link about the method and FE solvers. So what you do in structural applications when your force - displacement response in nonlinear you linearize it sequentially until you've reached a convergent solution (typically e.g. using force residual/norm criteria).

http://www.aaue.dk/bm/ansys/b8km-fe05.pdf
http://uranus.ee.auth.gr/lessons/1/10.html

Last edited: May 30, 2005
3. May 31, 2005

### chandran

What is meant by a residual? How non linear works?

In each iteration what is checked against what? and why it is checked?

4. May 31, 2005

### PerennialII

The nonlinearities were touched in general here :