Analysis wont run, ERROR #1481

Rahul_P1

I am currently doing a free size tutorial (Prakash Skateboard Optimization) that I found on Altair's site. I completed the model setup (material, plyes, loadcases, etc...) and then tryed to run the analysis but it doesnt run. I recive the following error message :

*** ERROR # 1481 *** in the input data:
Control card without the name in the first field.
(Possibly missing trailing comma in the preceding card,
missing BEGIN BULK card or line before BEGIN BULK has trailing comma.)

I opened the .fem file with notepad++ and there is no Begin bulk line and there are a lot of weird characters in the begining of the file. When I check the .hm file, there are two weird cards that we're present when I downloaded the initial tutorial file. One 'OMIT' that omits writing begin bulk and one omiting to write enddata card. The other card is 'Case unsupported card' which contains the weirds characters that i find in my .fem file.

Any clue on what could be wrong? Maybe there was something to do not listed in the tutorial that I did not do.
The tutorial can be found here : http://training.altairuniversity.com/optimization/composites/composite-optimization-of-a-skateboard/

Thank you!!

Rahul_P1

Remove the OMIT card from control cards to allow HyperMesh to write the BEGIN BULK in the solver file.

Either you can delete from model browser: in model browser, expand cards, right click and delete OMIT.

or

Go to control cards--> find OMIT (highlighted in green)-->click delete and click OMIT.

this will delete OMIT cards for both BEGIN BULK and END DATA cards.

Remove the OMIT and un-supported case control cards under card in model browser to avoid the error.

Rahul_P1

the problem was solved by removing the two case control cards and creating a different Load Collector for my rbe2 constraints. Also as you mentionned, the type of analysis defined in the loadsteps wasn't the one I wanted. I wanted to perform a linear static analysis.

Thank you for your time!

Altair Forum User

Hello
When importing a nastran file into hypermesh I find warnings as shown in the photo below
Can you explain to me where these warnings come from? and how to correct these errors?
Thank you 

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

Altair Forum User

Hi @elmejjati

 

Can you check unsupported cards tag in model browser?

 

All unsupported cards should be available there. 

Altair Forum User

Hi @Prakash Pagadala

Thank you very much for your answers they are very interesting, can you tell me where I can find this model browse?

THANK YOU/emoticons/default_smile.png' srcset='/emoticons/smile@2x.png 2x' title=':)' width='20' />

Altair Forum User

@elmejjati

 

Model browser>> Cards as shown in image: 

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

Altair Forum User

HI @Prakash Pagadala

these are the cards related to the optimization I can not remove them how to keep them but by correcting these problems?

THANK YOU SO MUSH

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

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

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

Altair Forum User

@elmejjati

 

Optimization cards are only supported in OptiStruct profile. You can switch to OptiStruct profile if you want to use these cards for optimization.

 

Optimization cards are not supported in HM with Nastran user profile. 

Altair Forum User

@Prakash Pagadala

I understand now but I sometimes have to import an .nas command file containing the optimization work in hypermesh and later convert it to .fem that's the problem

Altair Forum User

 

@Prakash Pagadala

Another problem appears when I run the optimization calculation in the software optistruct it's the following can you help me to solve it:

 

 Topology Optimization without Minimum Member Size Control activated.
 Using DTPL card, or DOPTPRM,MINDIM is recommended.

 

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

Altair Forum User

@elmejjati

 

Member size controls the minimum and maximum member size in topology run.

 

You can add member size control either from Opticontrol or from Optimization>>Topology>>Parameters>> minmemb/maxmemb

Altair Forum User

Hi @Prakash Pagadala
thank you for your answer, I try what you told me, the old message is gone but a new error is detected./emoticons/default_mellow.png' title=':mellow:' />

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

Altair Forum User

Hi @elmejjati

 

Is the model running without MEMSIZ constraint?

 

Can you just run analysis and check the results?

 

I notice that minimum member size is 0.5. It is recommended that MINDIM be at least 3 times the average element size for all elements

Altair Forum User

Hi @Prakash Pagadala

Can you explain to me more. How can I choose the minimum member size knowing that the size of the elements is 5?

THANK YOU.

Altair Forum User

Hi @elmejjati

 

According to OptiStruct manual minmemb should be equal or greater than 3 times the element size and less than or equal to 12 times element size. 

 

Maxmemb should be atleast 2 times mindim

 

 

If you face any problem, please share the model file with us using the file transfer link in my signature. 

Altair Forum User

Hi @Prakash Pagadala
thanks a lot for your help
here I tried with a size of 12 but still the same mistake/emoticons/default_mellow.png' title=':mellow:'>

here with you will find the .fem file of my work .

 

Altair Forum User

HI,

 

Looks like you selected wrong Dofs for optimization constraints. 

 

Can you please select dof2 instead of Dof1 for displacement constraints and check?