Learning Forum

[Mike3000]

I am running nonlinear analyses including different aspects of nonlinearity (material, contact). Since displacement controlled analyses tend to be more stable, I would like to perform this type of analyses. However, the goal is to show that the structure is able to withstand certain load levels. In a nonlinear analyses I cannot know beforehand what displacement is associated with a certain (reaction) force.

One way would be to ramp up the displacement by trial and error, monitor the reaction force and manually stop the solution if the reaction force has passed the desired limit to avoid unnecessary iterations after the limit has been passed. Is it possible to automate the stopping procedure?

[Sandeep Medikonda]

Hi, you might have to do this using a command snippet and use shared memory solve (not distributed solve).

Something like:

*do,ls_num,1,10,1

SOLVE

*GET,RF_Value,..

*IF,RF_Value,gt,100,EXIT

*enddo

Look into the following command from the help:
*GET,Parm,NODE,num,RF,DOFLAB 

[Mike3000]

Thank you for your suggestions, Sandeep. If I understand you correctly, I would have to split the total displacement into different loads steps, then solve each load step and check after each load step if the stopping criteria is fulfilled.

Would it also be possible to apply only one load step, check the criteria after each converged substep and stop the solution process if the criteria is fulfilled?

[Sandeep Medikonda]

Hi Mike, 

Yes, to the best of my knowledge, we have to break it down into multiple steps (indirectly break down the displacements) to do this.