Size-optimization

Altair Forum User

Hello everybody,

I tried to make a size optimization but I think there is something wrong. If I try to run my optimization calculation discrete sizing than there is no error, but the programm only run two iteration processes and if I try to import the .fem file there is no DSHUFFLE Design Variable.

Can anybody help me ?

Find more posts tagged with

English

OptiStruct

Accepted answers

All comments

Rahul Rajan_21763

Hi,

Could you share us .out file or .fem file for debugging?

Regards

Rahul R

Altair Forum User

Hi Rahul,

yes for sure. Thank you for help

Altair Forum User

Have you any idea ?
I have some time pressure so I would be glad if you can help me soon.

Thank you

Altair Forum User

I tried to make a size optimization but I think there is something wrong. If I try to run my optimization calculation discrete sizing than there is no error, but the programm only run two iteration processes and if I try to import the .fem file there is no DSHUFFLE Design Variable.

Hi Ann123,

Have you included the SZTOSH output card which will write the shuffling ready optimization deck?

Also, the output files says the optimization is not feasible. Can you check the size design variables and responses?

Altair Forum User

Hi,

yes the SZTOSH output card was set. And now I have another problem, if I chance the TMANUF of my plies or the design of my plies I get an error.

*** ERROR # 789 ***
Invalid design properties w.r.t. the design variables were found.
number of invalid property items = 11

Altair Forum User

Ann123,

Make sure the sum of TMANUF (all plies) somehow falls in between the bounds of laminate thickness.

Altair Forum User

If you still have issues with the model, you can share via dropbox link in my signature below.

Altair Forum User

Hi Ann123,

did you manually adjusted the size optimization design properties?

There is no match between the design variable and the design property.

Altair Forum User

Hi Pakash,

well, that could be...but what can I do now ?

Altair Forum User

I have an other Simulation who works, but there I have the same problem, I would like to change the elements of one ply and the TMANUF of one of these to adjust it to the other ones, but than I get the same error...

Altair Forum User

Hi Ann123,

Maybe I need the base Free size model to explore what is happening with the size deck. I can see that there is some information missing or not connected.

Kindly share the free size deck (base model with free size optmization parameters)

Altair Forum User

Hi,

Why mass and diameters result no make sense in my size optimization? I Obtained 6.923E-03 (6.93 kg) and if I calcute the mass using the diamters, density and the long of the tubes my result is 1.55 kg. The responses are weighted compliance and mass, objective function is 'min' weighted compliance and the dconstraint is mass in Ton (0.010 ton ---> 10kg) and the design variables are the diameter Internal and external, here are a screenshot of responses, the view.out, and the excel I´ve done.

Can anybody help me ?

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

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

Altair Forum User

Hi Dany,

During optimization not 100% material is used and that is why you see change in mass.

Can you add this and check if everything matches?

Goto Opticontols>> MATINIT>>1

Altair Forum User

Thanks. Is there any tutorial where explain more about the used of material in size optimization?

regards

Altair Forum User

Hi. Excuse me. I have a doubt with optimization of size, in my values obtained from mass reduction I get a result of 6.216E-03 (6.216kg). If I calculate the weight with the diameters obtained by the program, the lengths and density using steel gives me a result of 1,498E-03 (1,498 kg). Proposing the design variables are the internal and external diameter. Doing even what you suggest from 'Goto Opticontols >> MATINIT >> 1' Annex a capture with the data that I have.

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

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

Altair Forum User

In your working directory, you should see a file which ends with .prop extension.

Can you import or modify your design based on the values available in .prop and check the mass?

Altair Forum User

Hi, can anyone help me, please? What kind of input is needed as upperbound in dconstraint for size optimzacion if I´m using mass as constraint, percentage of mass o tons (kg)???

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

Altair Forum User

Hi Charlye,

Upperbound is the maximum value within which you want your model is to be optimized. For example : If you you give upper bound as 50kg, the solver will try to optimize your model below or upto 50 kg.

Thank you

Altair Forum User

Hi everyone, again.

does anyone know what method use hyperworks to solve size optimization?gradients ??? Thanks

Altair Forum User

Hi Charlye,

OptiStruct uses gradient approach for optimization. If you want to know more detail about optimization in optistruct please go through the below course.

https://certification.altairuniversity.com/course/view.php?id=75

or you can download Opti-Guide book from our University website.

https://altairuniversity.com/academic/

Thank you

Quick Links