How to define a rigid plate?

Member Posts: 7

Hello all!

I want to simulate the compression of a gyroid lattice, which I imported from nTopology as Abaqus input file. The assembly of the rigid plates along with the gyroid lattice is shown in the below figure:

To define the material of the plates as rigid I opted two methods:

1. Defined the stiffness of the plates as rigid under the geometry tab in the mechanical model of the plates and imported the plates along with the lattice to another static structural module. But using this way I am getting the following error message:

2. Created a material with very high Elastic modulus (higher than the gyroid material by a factor of 10E10). But using this material the solution failed to converge. So I lowered the Elastic modulus to a value that is 10E2 times greater than the gyroid material, but it is giving me a higher stress value in the plates.

So, Someone please help me with how can I make the plates behave like a rigid body in this structural analysis.

• Posts: 888Ansys Employee
edited November 25

Hi

Since the plates are not important just neglect the stresses there.

Just scope a remote displacement on the top and bottom plate and on their top and bottom surfaces respectively and set behaviour to rigid and this will make the plates very rigid - again just neglect the stress there.

THat is the easiest way.

The other way is to create the rigid plates in WB, and in a mechanical model system (system E - set them to rigid there) that is combined with the external model (system A below the abaqus model) into a static system (system F). In system F (static) you can then suppress the plates of the original abaqus external model import.

All the best

Erik

• Posts: 21Member

Hi Erik,

Thanks for the reply! I was able to imitate the first workflow you mentioned above, but the second workflow seems to be unclear to me. Because by suppressing the plates it would be difficult to define the boundary conditions. I am importing both the plates from one mechanical model to static structural block along with the Gyroid lattice structure which is imported as an Abaqus input file from an external model.

Regards, Ranjan

• Posts: 888Ansys Employee
edited November 26

Ok that is good.

As for the second point.

Can you please show like i did above, the WB project schematic with the plate mechanical models and the external model.

If I understand this correctly:

Since you have the lattice as an external model and the plates from a mechanical model then it should be very easy to make the plates rigid (I thought the plates where also in the external model together with the lattice). You need to set them to rigid in the mechanical model, mesh them there also - that should work.

Also this might help (set read only to No in the mesh setting in the static system), but do not remesh the lattice (we can use a freeze mesh feature/object on the external model lattice), just let it remesh the plates perhaps.

If this does not work then it seems tricky (https://forum.ansys.com/discussion/13466/rigid-body-meshing-error), perhaps someone else that has managed to resolve this can chime in.

All the best

Erik

• Posts: 21Member

Hi Erik

Thanks a lot for providing the valuable inputs! But I am unable to generate the mesh after defining the stiffness of the plates as rigid as well as not able to define the connections between the plates and the gyroid lattice. I am attaching the archived file of my project below. Can you please have a look and help me to identify my errors.