Prescribed Translation and Rotation

Altair Forum User

Hi everyone,

I am writing here hoping someone can help me with the following problem.

I have a plate which is connected to one end of a flexural spring (0.8mm thick) through FREEZE contact (please see picture below).
The other spring end is fixed.  I have used 2 loadsteps to perform this analysis:

 

• The plate has to translate downwards of about 1.4 mm. LGDISP non linear static analysis activated.
• From the position reached in the previous point, the plate must rotate about the X axis of an angle 0.25° (DOF4).LGDISP non linear static analysis activated.

 

All displacements have been enforced through SPC.

 

Picture of the model:

 

I have used CNTNLSUB in order to make one subcase follow the other. Unfortunately, from other threads in this forum, I seem to have guessed the 1st loadstep loads (SPC enforced displacements in this case) must be enforced in 2nd loadstep as well.

This proves to be impractical, since my final goal is to simulate bending+torsion in the flexural spring. In fact, I cannot impose the desired rotation in the 2nd loadstep because the plate has to be forced to translate downwards like it is in the 1st loastep.

 

I am attaching my file in order to get the matter as clear as possible.

Thank you in advance for any help you will wish to provide.

 

Best Regards

Matteo

Unable to find an attachment - read this blog

pratik gadve

Use SPCD for enforced disp. I think you have used spc which is not correct. 

Altair Forum User

Hi pratik,

Thank you for your reply. Do you mean that in LGDISP analysis contacts might not work properly if you do not use SPCD?

I've read in the manual that prescribing motion using SPC or SPCD is pretty much equivalent as a matter of fact.

Altair Forum User

Hello. 

Has anybody got any suggestions? I have tried to use the rbe2 in a simpler case (using shell elements) and it works perfectly fine.

Unfortunately the same cannot be said about this case...