Learning Forum

[spakerare]

Hi everyone,

I am currently working with version 2019 R2 and I have following problem in a topology optimization for a plattform like shown. The middle hole is fixed while the ones in the corners are external displacement locked in z-direction.

I have several static structural systems connected and my objectives are to minimize compliance for each static structural system as well as a mass reduction. As a response constraint I used global von mises stress with 2,75e^7 Pa.

But when I add a validation system the maximum stress is something like 4e^6 Pa, which is compared to the constraint very low. Thats why I would like to increase this value, resulting in further mass reduction as well. Unfortunately I have no idea, which parameters to change for obtaining a better solution.

Mesh convergence, solution convergence are already checked.

 

Any help is much appriciated

best regards!

[Sandeep Medikonda]

Isn't the constraint not to exceed the specified limit? If so, the optimization algorithm is achieving that...

In the topology optimization, the mean value of the element is used. So, take a look at the elemental mean value in the static structural analysis.

In your static structural analysis, how many load steps are you working with? If it is >1 then I would recommend looking at the stresses at all the intermediary load steps as well.

[spakerare]

firstly, thanks for your response!

yes, it is achieving this but the maximum stress is much lower in the optimized topology. If I use the new topology and run another optimization loop I am achieving to reduce the mass of 30 more volume precent. Except the geomerty I changed nothing.

I work with 4 load steps to simulate a rotating system. so every loadstep has the same force, but with an offset of 90°.

I am not sure about this, but it seems like the solver calculates a mean stress of all load steps, which would be wrong since there is just one force per time step. any idea how to solve this?