Optistruct : Enforced displacement tutorial

Altair Forum User

Hello,

 

is there any tutorial available for referring the set up of enforced displacement (preferably with rbe elements).

 

also, is it possible to run such subcase with NLGEOM ?

 

i tried setting it up with information available in 'Hyperworks Help' and internet but not getting any results.......

 

regards,

Palash

Rahul Rajan_21763

Hi,

Yes it is possible to run NLGEOM case with enforced displacement in spc definition itself.

See attached deck.

Regards

Rahul R

Unable to find an attachment - read this blog

Altair Forum User

Thanks for your answer Rahul.

 

I Created a single SPC definition containing the enforced displacement information and referenced this within the subcase (loadstep) definition and the solver is running...but at the end i am getting 0 results for all the parameters. Can you suggest what could have gone wrong ?

 

Also pls suggest which control cards i should activate to see the reaction forces ?

Rahul Rajan_21763

Use SPCFORCE card for reaction forces.

I hope you would have provided some value in the field for enforced displacement of constraint panel.

 

Regards

Rahul R

Altair Forum User

Thanks for the answer Rahul,

 

yes i have provided the value. I used a local axis system, created rbe rigid elements and created a node in the middle where i constrained it. I want to analyze it with a 1mm displacement in -z direction .pls refer the attached screen shot. pls suggest if i have been wrong somewhere...

 

Many thanks

Palash

tinh

Altair Forum User said:

Thanks for the answer Rahul,

 

yes i have provided the value. I used a local axis system, created rbe rigid elements and created a node in the middle where i constrained it. I want to analyze it with a 1mm displacement in -z direction .pls refer the attached screen shot. pls suggest if i have been wrong somewhere...

 

Many thanks

Palash

Hi

did you switch to 'SPCD' instead of 'SPC'?

Altair Forum User

yes...

 

i have total 3 constraints in my geometry...... first constraint is fixed in all directions, second one is free in X direction and third one is an enforced displacement (with rigid elements) in Z direction. I combined the first two in SPCADD card and specified them as 'Subcase_ SPC' in load step. while i defined the enforced dispalcement SPCD as 'SUbcase_LOAD' in loadstep. 

 

is it correct setup for the problem ?

 

Regards,

Palash

tinh

Yes, but when using SPCD then you must specify those nodes into an SPC in conjunction

I think first and second constraints can be put into same loadcollector (and also SPC nodes of enforcement)

another loadcollector just contains SPCD (it is load)

so you need 2 loadcollectors only, one for SPC, one for SPCD

tinh

oh, i am sorry i did not read the first post

you should follow sample file of sir Rahul L because your loadcase is NLGEOM

Altair Forum User

Hello,

 

It finally worked....

 

Thank you Rahul and tinh.....

 

 

regards.

Altair Forum User

Just one more question.....i activated GPFORCE card (in NLGEOM case)...but i am not getting the reaction forces (on enforced displacement nodes) in .h3d file. is there some other card i need to activate for this case ?

Altair Forum User

HI Palash,

 

GPFORCE is not supported for NLGEOM subcase.

Altair Forum User

thanks for your answer Prakash.

 

so what could be best option for me to view reaction forces in .h3d file ?

 

regards

Altair Forum User

Palash,

 

The workaround is to introduce /ANIM/VECT/FINT in Engine file which will be written in the working directory and run the analysis using RADIOSS solver manager.