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Modeling part using stiffness values

N/A

Hi There,
I am trying to model a part of suspension component with a 1D element with the right
stiffness values using NX6. I do have stiffness values under tensile and compressive
loads, can i use the GENEL elements with these values ?
Is there anyway to model an GENEL from the UGI ?
Many Thanks,
Engrequest
4 REPLIES

Re: Modeling part using stiffness values

Siemens Valued Contributor Siemens Valued Contributor
Siemens Valued Contributor
Hello,

It is possible to use a GENEL to create a linear 1D element. There is no UI in NX for doing this however, so you would need to use deck editing.

But there may be an easier way than using GENEL. Specifically the CBUSH is a 1D with stiffness in all 6 directions. And it is supported in the NX UI. I recommend using it over the GENEL.

You also made the comment that you have stiffness values for compressive and tensile loads. Are they the same stiffness values or different? If they are significantly different, then you are looking at a non-linear type analysis and you could model the non-linear stiffness with a CBUSH or CELAS.

Mark

Re: Modeling part using stiffness values

N/A

Thanks Mark,
The only stiffness values i have are from a tensile and compressive loads(from R&D)
In Cbush physical property card, there is no difference for the compressive and
tensile stiffness, how can i specify both stiffness values?
Thanks,
Engrequest


zzyl90 wrote:
>
>Hello,
>
>It is possible to use a GENEL to create a linear 1D element. There is
>no UI in NX for doing this however, so you would need to use deck
>editing.
>
>But there may be an easier way than using GENEL. Specifically the CBUSH
>is a 1D with stiffness in all 6 directions. And it is supported in the
>NX UI. I recommend using it over the GENEL.
>
>You also made the comment that you have stiffness values for
>compressive and tensile loads. Are they the same stiffness values or
>different? If they are significantly different, then you are looking at
>a non-linear type analysis and you could model the non-linear stiffness
>with a CBUSH or CELAS.
>
>Mark
>
>
>--
>zzyl90
>------------------------------------------------------------------------
>zzyl90's Profile: http://bbsnotes.ugs.com/vbulletin/member.php?userid=198687
>View this thread: http://bbsnotes.ugs.com/vbulletin/showthread.php?t=41649
>

Re: Modeling part using stiffness values

Siemens Valued Contributor Siemens Valued Contributor
Siemens Valued Contributor
Hello Engrequest,

If you need different stiffness values for tension and compression, you can use the CBUSH with the PBUSH and PBUSHT physical property cards. On the PBUSHT you would reference a TABLED entry for the TKNID fields. The TABLED entries represent force vs displacement curves. You can specify these curves such that you have a different stiffness (slope of the force/disp curve) on the tension and compression side.

You can do similarly with CELAS/PELAS/PELAST.

Another option if you just have one stiffness for compression and one stiffness for tension is to use the CGAP element. Here you define stiffness for when the gap is open and a different stiffness for when gap is closed. You can make it such that gap open corresponds to tension and gap closed corresponds to compression.

In all the above scenarios you are looking at a non-linear analysis. Was that your plan? What are you trying to simulate?

Regards
Mark

Re: Modeling part using stiffness values

N/A

Actually it was not my plan to run a non linear solve.
i wanted to simply a big assembly by modeling the suspension wishbones by bar elemnts
with the right stiffness values(obtained from R&D testing) and do a stiffness analysis
on the full assembly.
i use to use a simple bar elements with cross section to distribute the forces only
to the main strcuture analysed but for a stiffness check i need the right elements
stiffness input to the model.

zzyl90 wrote:
>
>Hello Engrequest,
>
>If you need different stiffness values for tension and compression, you
>can use the CBUSH with the PBUSH and PBUSHT physical property cards. On
>the PBUSHT you would reference a TABLED entry for the TKNID fields. The
>TABLED entries represent force vs displacement curves. You can specify
>these curves such that you have a different stiffness (slope of the
>force/disp curve) on the tension and compression side.
>
>You can do similarly with CELAS/PELAS/PELAST.
>
>Another option if you just have one stiffness for compression and one
>stiffness for tension is to use the CGAP element. Here you define
>stiffness for when the gap is open and a different stiffness for when
>gap is closed. You can make it such that gap open corresponds to tension
>and gap closed corresponds to compression.
>
>In all the above scenarios you are looking at a non-linear analysis.
>Was that your plan? What are you trying to simulate?
>
>Regards
>Mark
>
>
>--
>zzyl90
>------------------------------------------------------------------------
>zzyl90's Profile: http://bbsnotes.ugs.com/vbulletin/member.php?userid=198687
>View this thread: http://bbsnotes.ugs.com/vbulletin/showthread.php?t=41649
>