nonlinear analysis

[mon1299]

HI Everyone,
I am doing nonlinear analysis with large deflection statics.I want to determine the load capacity when the deflection of staructure is large enough with no increase of load.I dont know how I can apply my load. For my model I am considering material nonlinearity and also geometric nonlinearity.I have to use some contact elements also. I have the experiment result. So I know the test load.Is there any one who can help me?
Regards
Amy

 

[cbrn]

Hi,
I don't know if I understand well: do you need to perform a second-order buckling analysis?
If so, the limit load can be determined with a transient analysis where the final load is, say, the limit load you determine with a first-order Eulerian approach (this is based upon the fact that you expect the second-order effects to reduce the limit load). By consequence, this transient analysis is expected NOT to converge. You can set a displacement limit as convergence control, so that it will stop by itself, or let it run until it diverges. Be careful to write the solution items at every timestep, and to save the unconverged solution. If you set the arbitrary time to 1 (one), the limit load will be the applied load multiplied by the last time value for which an equilibrated solution was calculated (i.e. last timestep before the unconverged one). Of course, the finer the timesteps, the more precise the value (but the longer the analysis...).
I hope I didn't misinterprete your needs...

Regards