## General Mechanical

Topics relate to Mechanical Enterprise, Motion, Additive Print and more

#### Global von -Misses stress constraint in Topology optimization

• Francesco
Subscriber

Hi everyone,

i have to do a topology optimization of This turbine blisk.

It is then divided in 60 sector. Below there is the image of a slice that i use for the analysis. I do a static structure analysis by setting the pressure on the blade ìand the rotational velocity. I upload the image of the static structural settings.

When i do the topology optimization i esclude the surfaces of the blade (suction side and pressure side, in red in the image ). Next i set the consatraints such the mass to retain and max stress. I have a question about the global stress constraint: it  is applied to the whole body, design region and esclusion region? The result of the topolgy optimization of the blade it is a "shell body" with no material inside but only i thin surface, that is the esclusion region. It is obviusly that this kind of body cannot support the pressure acting on it, and think that the max Von-Mises stress is applied only in the sìdesign region. It is possible set the max stress on the esclusion region ?

Regards,

Francesco

• peteroznewman
Subscriber

Francesco,

You could slice the body in two, and put the two bodies into a multibody part so the mesh connects using Shared Topology. Then an entire body with the blade can be an excluded region, while just some faces on the other body can be excluded.

Regards,

Peter

• Francesco
Subscriber

Regards

Francesco

• Sandeep Medikonda
Ansys Employee

Hi Francesco,

What version are you using? In 19.1, the manual says:

• Global von-Mises Stress Constraint: This option is only available when there is at least one upstream Static Structural system. You use this property to make sure that the optimized geometry or structure always supports a specified maximum stress. When selected, the Maximum property also displays. Enter a stress value in the Maximum property as a Constant or using Tabular Data entries.

• Local von-Mises Stress Constraint: This option is only available when there is at least one upstream Static Structural system. You use this property to make sure that the optimized geometry or structure always support a specified maximum stress using the Maximum property that also displays when you select the Local von-Mises Stress option. You specify the stress value of the Maximum property as either a Constant (default) or using Tabular Data entries (via fly-out menu). The application supports multiple Local von-Mises Stress constraints.

So, if you define local von-mises it should only work in the optimization region and shouldn't affect the whole part? Isn't this what you are seeing?

Regards,

Sandeep

• Liansensha
Subscriber

Hi,I also meet the same problem ,i set the consatraints as the max displacement,The result of the topolgy optimization is also  "shell body" with no material inside but only i thin surface,and the max displacement of my new part is more than the max displacement which i set.I find it work in the whole region. Please help me solve this problem.

• peteroznewman
Subscriber

@Liansensha, please open a New Discussion so you can get notified of the replies.  When you post, please insert some images so we can see your geometry.