compliance error 312 - due to constraints?!?

Altair Forum User

Hi there,

 

for a student project i am trying to set up a topology optimization. The solver output stated an error due to too large compliance.

I run an analysis to check the stresses and displacement and what i noticed is that the stresses seem to be reasonable but the displacement is too big.

I believe that it is a terrible rookie mistake i´ve made here but i cant help to figure it out by myself. I think it might be to poor constraints or a failure within the consistant units.

 

'*** ERROR # 312 ***
 In static load case 1
 the compliance is negative or large 2.79913e+010.'

 

Would it be possible to get help to solve the issue?

 

https://drive.google.com/drive/folders/15O0eUOA_snbKMg00gu2NWn2zxd279v3m?usp=sharing

 

Thanks in advance,

 

Daniel

Altair Forum User

Hi @Selto

 

In all the Loadsteps, SPCs are not referenced. Please check the same and update all the loadsteps. 

 

And also, please check the constraints, unit system used etc... looks like the model is underconstrained. 

<?xml version="1.0" encoding="UTF-8"?>

Altair Forum User

Thank you very much for your response. I updated all the loadsteps and constraints. Regarding the units system i have one more question. I used the following consitent units:

 

mm, t, N/mm²,N

 

Since i used the script for the bearing loads i assumed that i have to insert there the bearing reaction force and that it is transferred to a pressure field?!? I can´t find a way of checking this assumption. Where do you think might be the mess up within the unit system?

 

Thank you very much for your support.

 

Altair Forum User

@Selto

 

Can you point me to the script or share the same?

Altair Forum User

Here we go. It is shared on the altair website somewhere. I used it to apply my pressure fields of the bearing to the faces. Unfortunately i cant review it properly.
 

Unable to find an attachment - read this blog

Altair Forum User

Hi @Selto

 

The script only allows pressures loads and doesn't take into account of any reactions.

 

try to constraint all Dofs and check the results. 

Altair Forum User

So where it states that you have to inut a force and an angle to spread it upon the selected face it actually wants the preassure not the force?

Altair Forum User

I think the script internally converts the force to pressure based on the load swept area.