Lattice Optimization Using Diffirent Mesh Sizes

etrud011

Hello,

I would like to do some lattice optimization in Hypermesh. However, I need to know if it is possible to have a different mesh size for the lattice sections compared to the solid sections. The way I understand lattice optimization in Altair is that the element size you mesh with originally will determine the average length of the lattice struts.

For example; I tetra mesh my model with a size of 2, the lattice beams have an average length of 2. However, I would like to have a mesh size of 0.5 with lattice elements of length 2 (or vice versa).

My game plan is to run a minimize compliance with volume fraction on my model with a penalization of 1.8 (low porosity).

Then use the results of the compliance optimization to split my part into sections for a given element density threshold. I should end up with solids for the lattice elements and solids for the non-lattice elements. The lattice solid sections will then be filled with lattice beam elements from another lattice topology optimization.

I want to remesh each solid individually for different lattice strut sizes and types. Contact surfaces will then be used to connect the solids together and then run the Lattice optimization.

The end goal is to use mesh refinement on the non lattice sections to check the validity of my model as well as experiment with different lattice sizes.

Any advice is greatly appreciated.

 

-Eric

Altair Forum User

Hi Eric,

 

This seems like an interesting project. 

 

Lattice cell size is directly related to mesh size in the model. You can play with MIRAD, R2LRATIO parameters to control radius and length of the lattice structure,

 

usually, the lattice is fined tuned in the second phase which is a size optimization, 

etrud011

Thank you for the reply Prakash.

 

I figured out a way to make this possible but it requires me to create a minimum compliance with volume fraction using a penalty factor of 1.8 and then extract the surfaces of the result. I have been playing around with DISCRETE but it does not generate the same results as in the first step of the lattice optimization process. Is there a way to change this variable in Hypermesh to obtain a penalty factor of 1.8?

 

 

-Eric

Altair Forum User

HI,

 

I will check if there is a way to do this parameters,

etrud011

Hi Prakash,

 

Have you determined if altering the penalty factor is possible for a compliance optimization?

 

-Eric.T

Altair Forum User

Hi Eric,

 

You can set the porosity control to medium, high or low which affects the penalty. 

 

Porosity control LOW will have a penalty of 1.8.

etrud011

Hi Prakash,

 

I had done as you said but my results do not show any difference by changing the porosity values. Is there a way to change the penalty when you are not doing a lattice optimization?

 

-Eric

Altair Forum User

Hi Eric,

 

I have to check if there is a way to change the penalty value manually. 

etrud011

Thank you Prakash, I am eagerly awaiting your response!

Rahul Rajan_21763

Did you defined penalty using unsupported cards in DTPL?Please make sure to use HyperWorks solvers 2017.2.2 version for the run.

etrud011

Altair Forum User said:

Did you defined penalty using unsupported cards in DTPL?Please make sure to use HyperWorks solvers 2017.2.2 version for the run.

 

No I have not, how would I implement the unsupported cards?