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#1 2021-01-24 01:54:36

Anirudh
Member
Registered: 2017-09-11
Posts: 262

Different stiffness in compression and tension for K_T_D_L

How,
Is it possible while using K_T_D_L on seg2 to assign variable values when the spring is under tension/pulling or being compressed due to external forces? I hope I am clear. Say 100 N/mm in tension and 50 N/mm during compression
Thanks and regards

Anirudh

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#2 2021-01-25 08:43:40

mecour
Member
From: Ostrava (Czech)
Registered: 2011-04-04
Posts: 161

Re: Different stiffness in compression and tension for K_T_D_L

Hello,

I think there is no such possibility in code aster.

mecour

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#3 2021-01-25 11:50:13

mf
Member
Registered: 2019-06-18
Posts: 170

Re: Different stiffness in compression and tension for K_T_D_L

Hello,

it is just an idea: what about using 2 models, one for tension and one for compression and projecting the results between them? You could separate compression and tension into at least 2 MECA_STATIQUE or STAT_NON_LINE. But, I am not sure if that could work,

Mario.

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#4 2021-01-25 19:25:22

Anirudh
Member
Registered: 2017-09-11
Posts: 262

Re: Different stiffness in compression and tension for K_T_D_L

Hi, thanks for reply.
I don't know how that will work. Suppose during simulation  both forces if compression and tension are active,  how can I separate them or turn them off. Because they act by themselves.

Regards
Anirudh

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#5 2021-01-25 20:28:56

mf
Member
Registered: 2019-06-18
Posts: 170

Re: Different stiffness in compression and tension for K_T_D_L

Hello,

obviously, it will depend on how your model will behave. If you don't know when compression/tension occurs or if it all happens at the same time in different locations in your model, then it won't work this way.

Mario.

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#6 2021-01-26 07:37:15

sameer21101970
Member
Registered: 2019-09-06
Posts: 297

Re: Different stiffness in compression and tension for K_T_D_L

Share your model. .mess & .comm , .med files.

FEA Model building has many options. Why you want to switch off compression or tension. Any Specific Reason. Or Ansys is giving such option and want to follow licence softwares.

Last edited by sameer21101970 (2021-01-26 07:37:54)

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#7 2021-01-26 17:33:57

Anirudh
Member
Registered: 2017-09-11
Posts: 262

Re: Different stiffness in compression and tension for K_T_D_L

Hi Mr. Sameer,
It's a simple problem which should have a simple answer. I don't want to turn off anything, it's the physics that can make go spring in compression or tension.You are very new to forum yet talk in a rude manner. And read my previous posts if you think I have any inclination towards paid software like ansys.

Last edited by Anirudh (2021-01-26 17:40:45)

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#8 2021-01-26 18:31:57

sameer21101970
Member
Registered: 2019-09-06
Posts: 297

Re: Different stiffness in compression and tension for K_T_D_L

I very well know tension and compression in spring. I have read your posts, your post every time is towards what is not available with code aster.  It seems you are new to design world and Don t know how to solve design problem by other methods.  Their is no point in discussing with you.

Last edited by sameer21101970 (2021-01-26 18:56:38)

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#9 2021-01-26 20:52:56

mf
Member
Registered: 2019-06-18
Posts: 170

Re: Different stiffness in compression and tension for K_T_D_L

Hello,

maybe K_T_L is able to do what you want? Again, I am not sure. Can anybody elaborate on K_T_L, please? It is not described well in the documentation.

Mario.

Last edited by mf (2021-01-26 20:53:24)

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#10 2021-01-27 14:15:40

dezsit
Member
Registered: 2012-06-27
Posts: 66
Website

Re: Different stiffness in compression and tension for K_T_D_L

Dear Anirudh,

Your question of course absolutely valid, and can be defined such behavior in aster.
A similar one is shown by Johannes Ackva (code-aster/dot/de), using the DIS_CONTACT material "behavior".

In the attached small example I used grounded springs (POI1). We need two of them connected parallel, one for the tension, one for the compression. The key is that the local csys (REPERE='LOCAL") should be opposite (ORIENTATION in AFFE_CARA_ELEM).
In this example we have stiffness equal to 1(force/displacement) in tension and 10 in compression. You can check it with xmgrace (res.func) or numerically (res.tab).

The line spring (SEG2) works similarly.

I would not say it will work in all cases, but in this simple one it provides the expected result. Tweeking with the parameters (eg. JEU in DEFI_MATERIAU) and combining other springs, very different characteristics can be achieved.

Regards,
dezsit


Attachments:
nonLinSpring.tar.gz, Size: 3.38 KiB, Downloads: 16

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#11 2021-01-27 22:47:02

Anirudh
Member
Registered: 2017-09-11
Posts: 262

Re: Different stiffness in compression and tension for K_T_D_L

Hi,
Thanks for the reply.
I will check soon and update my findings here.

Regards
Anirudh

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