PROBLEM: Composite Optimisation

Altair Forum User

Hi,

 

I am trying to do the second phase of the composite optimisation process - the sizing part.

 

However, I get the following error : 'invalid design parameters for w.r.t' 

 

I realise that if I change my laminate properties from 'Smear' to 'Total' it works. However, I am not sure if this is correct. 

 

Also, if I add a buckling load, neither of these work.

 

Can you help me? it is urgent.

 

I have attached the FEM file with the issue

 

Best Regards,

Unable to find an attachment - read this blog

Altair Forum User

Hi Rowan,

 

I think the problem is coming from the buckling constraint. Since you have a upper bound of 1, solver will try to remove all the material and this makes the thickness of the laminate to zero.

 

Try to add a minimum laminate thickness constraint and check if you are able to avoid the error.

Altair Forum User

Hi,

 

Thanks for your reply. Even when I put the buckling constraint as lower bound as 1 instead of upper, it gives me the same error. If i add a shear strain constraint, the error does not appear anymore but the shear stress is not fullfilled. 

Altair Forum User

Rowan, 

 

Can you use a bound value close to the results?

Altair Forum User

Rowan,

 

also, try to give a manufacturable thickness to the plies and a laminate thickness constraint to the laminate so that the thickness cannot go to zero.

Altair Forum User

Hi Prakash,

 

I've got the same problem and I can't manage to solve it... I've shared the .fem file in your Dropbox.

Hope you can help me! It is urgent.

 

Thank you!

Altair Forum User

Hi Mcorsa,

 

I don't have access to dropbox link.

 

Please share the .fem file here or through personal message

Altair Forum User

Unable to find an attachment - read this blog

Altair Forum User

Hi,

 

Since I am using HW 12.0 here, after deleting the Freesize desvar in design variables optimization started.

Altair Forum User

FYI,

 

You get that error because the laminate thickness is going to zero. Provide a minimum laminate thickness constraint on the design.

 

Altair Forum User

Yes, I've provided a minimum laminate thickness contraint of 0.2mm in the Freesize desvar (picture) and I've updated it as composite size desvar

But if I have to delete this Freesize desvar, how I set the laminate thickness constraint?

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

Altair Forum User

In 14.0 it should be fine.

 

Since I am using 12.0 I have to delete and update using composite size panel.