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Input.txt

Hi all,

I am analysing a 2D D-shaped Neo Hookean model in contact with a Rigid link. The details are as written below and also the input file is attached.

/NOPR 
KEYW,PR_SET,1 
KEYW,PR_STRUC,1   
/GO
!* 

/PREP7 
!* 
ET,1,PLANE183 
!* 
KEYOPT,1,1,0
KEYOPT,1,3,2
KEYOPT,1,6,0
!*
ET,2,MPC184
!* 
KEYOPT,2,1,0
KEYOPT,2,2,1
!* 
TB,HYPE,1,1,1,NEO 
TBDATA,1,2.808e6,0, 
MP,DENS,1,1195,
MP,ALPX,2,
MP,DENS,2,0
!*
BLC4,0,0.05,0.05,-0.1
CYL4,0.05,0,0.05,90,0,-90
AADD,1,2
BLC4,0.025,0.025,0.025,-0.05
CYL4,0.05,0,0.025,90,0,-90
AADD,1,2
ASBA,3,4

MOPT,QMESH,MAIN
!*
ASEL,,AREA,,1,,,1
AATT,1,,1,0,
CM,S1,LINE
LESIZE,S1,0.001
AMESH,1

!*

K,9,0.1,0,0
K,10,0.1,0.05,0
K,11,0.1,-0.05,0
L,9,10
L,9,11
LSEL,S,,,5,
LSEL,A,,,9,
LATT,2,,2,
!*
SMRT,1
LSEL,S,LINE,,5,
LSEL,A,LINE,,9,
LESIZE,ALL,0.001
LMESH,ALL
!*
LSEL,NONE
!*
LSEL,ALL
!*
LREVERSE,5,0

/COM,
REAL,3 
ET,3,169
ET,4,172
KEYOPT,4,4,2
KEYOPT,4,5,3
KEYOPT,4,6,2
KEYOPT,4,9,3
KEYOPT,4,10,2
KEYOPT,4,12,4
!*
LSEL,S,,,5 
LSEL,A,,,9
CM,S2,LINE
TYPE,3
NSLL,S,1
ESLN,S,0
ESURF
!*   

LSEL,S,,,8 
TYPE,4 
NSLL,S,1
ESLN,S,0
ESURF
ESEL,ALL
ALLSEL
EPLOT
!*
/SOLN
!*
ANTYPE,0
NLGEOM,ON
NSUBST,25,25,10

DL,4,,UY,
DL,4,,UX,0.001

When I am solving this I am getting errors as Rigid Body motion/ Residual below of convergence criteria. Please help me!!!!!!!!!!!!

Vielen Dank schon im Voraus!

Eine Antwort auf diesen Beitrag verfassen (mit Zitat/Zitat des Beitrags) IP

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Hi Bruce,

Without digging too much into the model, I can only spot fixations in x and y direction. Therefore rigid body motion in z direction is not contraint.

You may want to perform a modal analysis with the model to find out, which part is "flying" and where.

------------------
Gruß, A.

Eine Antwort auf diesen Beitrag verfassen (mit Zitat/Zitat des Beitrags) IP

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Thank you Arnd. I did fix the model in Z direction and fixed the rigid beam in XYZ directions but the problem which I am facing now is residual convergence criteria below the required value. Can you please look into it in detail and please help me on this.

Regads,
Bruce

Eine Antwort auf diesen Beitrag verfassen (mit Zitat/Zitat des Beitrags) IP

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What kind of loads have you got on your model?

Please run a first analysis with nlgeom,off for sanity check.

------------------
Gruß, A.

Eine Antwort auf diesen Beitrag verfassen (mit Zitat/Zitat des Beitrags) IP

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Hi,

I do get the solution now after applying displacement of 1% and 10% in X direction (1mm/10mm for 100mm model)  . It was stupid on my part to overlook the boundary conditions
I want it to displace it by 50% (50mm) but unfortunately I am getting an unconverged solution after time of (0.55s)
The number of substeps for the above variation I used were
NSUBST,250,1000,50.

Can you suggest me how to get a converged solution for the same.

Regards,
Bruce

Eine Antwort auf diesen Beitrag verfassen (mit Zitat/Zitat des Beitrags) IP

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Hi Bruce,

I never analysed a model with such very high deformation. I reckon that the distorsion of the elements is getting quite big, maybe out of the limits. I can imagine that it is possible to re-mesh during calculation, but I can't help you sorting this out.

You should check why you do not get a converged solution on file.err. You can always try increasing the number of substeps significantly. This usually promotes convergency.

------------------
Gruß, A.

Eine Antwort auf diesen Beitrag verfassen (mit Zitat/Zitat des Beitrags) IP

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I get the solution but I get several “ ...u-p elements do not satisfy the volumetric compatibility" output messages during solution. Can anyone tell me how to improve this and how much impact it has on accuracy of a problem.

Thanks,
Bruce

Eine Antwort auf diesen Beitrag verfassen (mit Zitat/Zitat des Beitrags) IP