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Pretension

Hi,

While doing a pretension analysis and want to perform loading and unloading analysis with non-linear considerations.Below is how my loadsteps are structured.

Loadstep 1 - Pretension

SPC

NLPARM

PRETENSION LOAD

Loadstep 2 - LOAD1

SPC

LOAD1

NLPARM

Subcase Option:

CNTNLSUB - (Loadstep1)

Loadstep 3 - UNLOAD1

SPC

NLPARM

Subcase Option:

CNTNLSUB - (Loadstep2)

With this procedure only Loadstep1 is running and the run gets sopped. I have 2 questions here

Q1: Do I have to use STATSUB(PRETENS) along with CNTNLSUB in Loadstep2?

Q2: If the above is true then do I also have to use the same STATSUB(PRETENS) in Loadstep3 considering that CNTNLSUB is present?

Attached are the snapshots for the Loadsteps.

Kindly help.

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Altair Forum User

Hi @md.ataul

CNTNLSUB is not supported for Pretension subcase. If you want to include pretension force, you can use PTFORCE and refer the same in NLSTAT>> PRETENSION subcase

use STATSUB (PRETENS) with the static subcase that created pretensioned bolts,

Altair Forum User

Thanks for the reply Prakash,

I'm first running the PRETENSION analysis in Loadstep - 1 lets name it is PRETENS.

Once this is done I am now applying Static Load in Loadstep -2 and used STATSUB(PRETENS).

Now I want to run Loadstep - 3 with the continuation of results from Loadstep-2 (this is unloading analysis where no Load is given and CNTNLSUB(Loadstep -2) is given).

My question is, Do I have to give STATSUB(PRETENS) in Loadstp - 3 also?

Altair Forum User

Hi Atul,

If Load case 3 is meant for complete unloading (no pretension) then do not include STASUB(Pretension). Include this will add pretension during unloading.

Sorry for the mistake in my previous reply. It should be non linear static (NLSTAT) analysis, not static.

Altair Forum User

Thanks Prakash,

WIll go with these suggestions.