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Summary of Large strain capabilities of SOL601

Phenom
Phenom

Hello experts,

 

I look for an overview which special elements  (SHELL 4, 6, 8,9 nodes, CHEXA8, 20, 27, ...) materials (MAT1, MATS1 NLELAST, PLASTIC), properties and special settings, like UPFORM or ELCV or so, are in combination usable for a large strain analysis.

 

Every now and then I detect warnings or errors in f06, that a solution did not use large strain kinematics:

 

     ***WARNING: Large strain kinematic formulation is not applicable with material 15 for PID 3.

But it's really time consuming to figure out what's the special reason for this.

 

Who can help?

With best regards, Michael

 

7 REPLIES

Re: Summary of Large strain capabilities of SOL601

Phenom
Phenom

what material model is material 15 for PID 3?

Production: NX9.0.3.4, NX10.0.2.6
Development: VB.NET (amateur level !)

Re: Summary of Large strain capabilities of SOL601

Phenom
Phenom

Selex_ct,

 

thank you for answering.

Here are my dat-File parts for PSHELL, MAT1, MATS1, TABLES1(NLEAST), CQUAD(8=>9), NXSTRAT (ATS), PARAM (LargeStrains):

 

PSHELL*,3,15,.31,15,+
*,1.0,15,.8333333333,0.0

MAT1*,15,366600.0,,.3,+
*,2.976-6

MATS1*,15,1,NLELAST,,+ *,1,1
TABLES1*,1,,,,+ *,,,,,+ *,1.0-9,.0003666,.1000000008,36660.0002932799,+ *,.2000000006,73320.0002199599,.3000000004,109980.00014664,+ *,.4000000002,146640.00007332,.5,183300.0,+ *,.5999999998,219959.99992668,.6999999996,256619.99985336,+ *,.7999999994,293279.99978004,.8999999992,329939.99970672,+ *,.999999999,366599.9996334,ENDT $*

...

CQUAD8*,100650,3,100514,100585,+
*,100586,100513,101825,101782,+
*,101824,101636,,,+
*

...

NXSTRAT*,100,AUTO,1,UPFORM,+
*,1,LSEARCH,1,,+
*,LSUPPER,1.0,CONVCRI,2,+
*,ATSSUBD,10000,ATSNEXT,1,+
*,ELCV,2,,,+
*

...

PARAM*,LGSTRN,1,,,+
*
PARAM*,OIBULK,YES,,,+
*
PARAM*,OMACHPR,YES,,,+
*
PARAM*,POST,-2,,,+
*
PARAM*,POSTEXT,YES,,,+
*
PARAM*,UNITSYS,MN-MM,,,+

I 'm not shure but I think, something is blocking my PARAM LGSTRN=1 by bad input combination.

At first I thought my elements, because elements of typ CQUAD8 do not support large strains. But with ELCV=2 NX converts CQUAD8 into CQUAD9 which has the capabilites for large strains.

 

Hint: The TABLES1 entry describes a linear curve progression but I think that's not the point.

Can you see a forbitten combination of input parts in dat-file?

 

Best wishes, Michael

Re: Summary of Large strain capabilities of SOL601

Siemens Phenom Siemens Phenom
Siemens Phenom

The problem is that you have TYPE=NLELAST on MATS1. With a nonlinear elastic material, the program simply treats the material as elastic with the exception that it computes the stress for a given strain by a table lookup instead of multiplying by E. The strains are all fully recoverable and there are no other nonlinearities (yield, hardening, large strain, etc.) included.

Re: Summary of Large strain capabilities of SOL601

Phenom
Phenom

JimB,

 

thank you for answering. That explains different points. Additionally I found in "Advanced Nonlinear" that Large Strains are only supported in SOL601 with PLASTIC for both shell and SOLID elements.

 

See here:

2018-01-15_150838.png

 

 

...2018-01-15_152008.png

 

Does it mean, that I can't calculate simulations with nonlinear elastic deformations and large strains or do I misunderstand the difference between large strains in MATS1 and hyperelastic materials?

 

What are the limitations for strain values in MATS1 - NLELAST? - Is there a statement in NX Advanced Nonlinear?

 

Slowly I am beginning to think that I try to simulate the wrong material behavior.

 

Best wishes, Michael

 

Re: Summary of Large strain capabilities of SOL601

Siemens Phenom Siemens Phenom
Siemens Phenom

Yes, with MATS1, large strain formulations are only available for TYPE=PLASTIC materials.

 

As stated before, the only thing that is nonlinear about a nonlinear elastic material is that the stress-strain relationship comes from a table lookup rather than a single value (E). Everything else about the material model is small strain linear.

Re: Summary of Large strain capabilities of SOL601

Solution Partner Pioneer Solution Partner Pioneer
Solution Partner Pioneer

Hello Michael,

What material are you trying to model? Perhaps we can help you figure out which constitutive behaviour you should use. Like Jim said, MATS1 - NLELAST is only to specify stress-dependent material properties. Hyperelastic is a type of constitutive behaviour model where the stress is a derivative of a potential. It is mostly used for rubbers, elastomers, etc., where there is no actual yield stress per say.

Cheers,

Jacques

Re: Summary of Large strain capabilities of SOL601

Phenom
Phenom

Hello Jacques,

 

as I closed this thread (also mentally Smiley Wink), I suggest to continue in other thread

 

Simulation-of-tensile-testing-with-stress-strain-curve-input

 

I think the other one suites better. Thank you for offering help.

Best wishes, Michael