Composite optimization

Altair Forum User

Hello there,

 

I'm trying to do a composite optimization whose objective is to minimize mass. I'd like to set as optimization contraint  the composite failure accroding to the Tsai-Wu theory (so that the solver should minimize but still granting the composite resistance).

 

I followed the tutorials, I couldn't find anyone that used such constraint... I tried to figure it out by myself, but I didn't get satisfying results... Can anybody help me please?

 

Thank you

 

 

Altair Forum User

Hi Fede54

 

could you please elaborate what have you tried?

 

What is the composite failure result for Analysis only?

Altair Forum User

Hello,

 

For the analysis I used a laminate made up by plies of different orientations (45°, 90°, 0°, -45° and -90°). I used a PCOMPP property and set TSAI under the [FT] panel. The analysis ran without problems and the composite failure results are less than 1 for each ply (I suppose this means that the resistance is granted for each ply).

 

Then I turned to optimization. As objective I set the mass minimization, while as constraint i used a 'composite failure' response and I set the upper bound to 0.8 (supposing that 1 meant failure, according to Tsai-Wu criterion). So my aim is to reduce the mass of the laminate but still granting a resistance margin.

 

The optimization runs, but it only consists in one iteration and the main result is something like that:

 

       2 CFAIL res_stre           1     8280  TSAI   4.926E-01  <  8.000E-01    0.0
                                          P1
       2 CFAIL res_stre           1     8510  TSAI   4.925E-01  <  8.000E-01    0.0
                                          P1
       2 CFAIL res_stre           1     8511  TSAI   4.838E-01  <  8.000E-01    0.0
                                          P1

 

Can you please tell which are my mistakes? Thank you

Altair Forum User

Fede54,

 

Try with a lower constraint value and check if you can see any reasonable result.

Altair Forum User

Hello,

 

I tried with several lower constant values (until 0.2), but still there is only one iteration and there isn't mass reduction...

 

Anyway, can you please tell me if all the reasonings I've done about the preprocessing phase (in my last reply) are good? Thank you

Altair Forum User

Fede54,

 

Please share the model file.

Altair Forum User

I'm sorry I'm not able to share it the moment...

 

Thank you anyway for your help

Altair Forum User

Hello

 

I think I found out why I can't make on optimization using the 'composite failure' as constraint.

When the optimization starts, this message is displayed:

 

NO DESIGN MATERIAL OR DESIGN VARIABLES FOUND  : ANALYSIS ONLY

 

And this is strange, since I have indeed created a design variable before (in particular I created a 'composite size desvar', which allowed me to use the 'composite failure' as constraint).

 

So it's like if the solver couldn't see my design variable...

 

Can you help me please?

 

Thank you