Enforced motion Non Linear Transient Response

[r.hall4]

Hi I'm looking to subject a stiffened panel to a uniform pressure and then an enforced motion which builds up to 5mm using time steps.The lateral pressure will be applied first to introduce non linearity into the model and then the enforced motion will begin 1 second later . My plan is then to plot the displacement against the total applied force to find the ultimate buckling load of the section.

I've done this in Ansys with a smaller stiffened panel  but the modelling of the geometry is easier with Nastran in cad.

 

So far I've worked out that you cant use enforced motion in non linear transient analysis .Is there any other way to do this type of analysis in Nastran in cad ?

Best regards , 

Ross 

[plafortune]

Hi, 

As far as I know, Enforced Motion should work in a nonlinear static analysis (is it the one you are trying?). 

Bu sure to apply the BC the right way: Enforced motion needs you to also "block" the dof in the same direction. 

Not very intuitive, but it's the way it works.

Read This. 

Maybe try it on linear static first, to be sure you get the BCs right. 

[r.hall4]

Hi Pierre , 

thanks for your response ,

ideally id like to run a non linear transient response analysis. I need my loads to vary with time as well as being non linear with individual sub steps.

do you know if this is possible ?

[plafortune]

Hi, 

For the loads supported in Nonlinear Transient Response, you can define a table of time versus load factor. 

BUT, I see now that Enforced Motion are not supported in this type of analysis: 

+ + + + + 

Just to confirm something with you: 

Nonlinear Transient Response: a nonlinear DYNAMIC analysis (i.e. you do care about inertia and acceleration effects) 

Nonlinear Static: nonlinear STATIC analysis (i.e. you don't care about inertia and acceleration effects)

Do you really want a dynamic analysis, or just a nonlinear analysis with non-constant loads? 

[plafortune]

Hi again, 

Indeed, enforced motions are available in linear dynamic analysis, but you have to enforce velocity or acceleration: 

Enforced motion encompasses loads such as displacement, rotation, velocity, acceleration, rotational velocity, and rotational acceleration. Accelerations and velocities can only be applied and accessed in dynamic analyses. Enforced motion can be applied to curves, surfaces, and vertices.

From: https://knowledge.autodesk.com/support/inventor-nastran/learn-explore/caas/CloudHelp/cloudhelp/2019/...