I am trying to model a disc in 2D as attached here. Because the disc is complete circular object, I tried to tie side A to B using MPC tie constraints. However, Abaqus gives several warnings for the side nodes that “***WARNING: SLAVE NODE 153 INSTANCE FRICTION-DISC-1 WILL NOT BE TIED TO THE MASTER SURFACE ASSEMBLY_FSIDE1_CNS_. THE DISTANCE FROM THE MASTER SURFACE IS GREATER THAN THE POSITION TOLERANCE VALUE”.
I decided to specify a position tolerance value but Abaqus abort the work saying ***NOTES: DISTORTED ISOPARAMETRIC ELEMENTS: ANGLE BETWEEN ISOPARAMETRIC LINES IS LESS THAN 45 DEGREES OR GREATER THAN 135 DEGREES. Nonetheless, when I untick “ Adjust save surface initial position", Abaqus runs successfully with several warnings “ ***WARNING: *TIE BETWEEN SURFACE PAIR (ASSEMBLY_DSIDE2_CNS_, ASSEMBLY_DSIDE1_CNS_) MAY RESULT IN UNREALISTIC DEFORMATION BETWEEN THE SURFACES OR LARGE STRESSES BECAUSE THE MASTER IS NODE-BASED AND NO ADJUSTMENT IS SPECIFIED. DEFINE A SURFACE-BASED MASTER SURFACE OR ADJUST=YES TO AVOID THIS PROBLEM. If I tie using surface to surface, I get the same warning and if I tick "adjust ", Abaqus abort because I have specified a tolerance position.
I have also tried to use an input file and tied the side nodes directly using the tie command, yet I get the same errors. Please any suggestions on how to handle this kind of problem.
Dear Kingsford Koranteng
Please see the attached document, it may be helpful.
Good luck !!
Try to create node sets SideA_Node_i and SideB_Node_i for each pair of nodes from both sides and use
*Equation
SideA_Node_1 , 1, 1.
SideB_Node_1 , 1, -1.
*Equation
SideA_Node_1 , 2, 1.
SideB_Node_1, 2, -1. and so on.
Assogba Ogoubi Cyriaque Thanks for the file . I'm going through it and I hope it helps. Thanks again
Victor J. Аdlucky Thank you for your suggestion. Please why do you suggest an equation constraint instead of a tie constraint? I was thinking the equation constraint is used to describe linear constraints between individual nodes. Moreover, i get this error with the suggestions you provided "***ERROR: THE NUMBER OF TERMS IN THE EQUATION MUST BE AN INTEGER". i thought it was best to use tie constraint since it allows me to fuse together the two region (side A and side B) together to create a complete structure. Please any reasons for the equation constraint and how do I solve the above-mentioned warning. Thanks
Dear Kingsford Koranteng,
I proceed from the fact that there is one-to-one correspondence between the nodes of side A and side B, and we a priori know which pairs of nodes must be tied. These equations just imply that U1( SideA_Nodei)=U1( SideB_Nodei), U2( SideA_Nodei)=U2( SideB_Nodei), i=1,2,..,N, where N is number of pairs. Regarding the error, check that number of terms (i.e. 2) is written without decimal point (unfortunately, I have missed this line in my previous answer)
*Equation
2
SideA_Node_1 , 1, 1.
SideB_Node_1 , 1, -1.
Dear Victor J. Аdlucky ,Yes I really agree with you. I did tried the equation but i still had errors " ***ERROR: DEGREE OF FREEDOM 1 DOES NOT EXIST FOR NODE 11 INSTANCE DISC-1. IT
HAS ALREADY BEEN ELIMINATED BY ANOTHER EQUATION, MPC, RIGID BODY,
KINEMATIC COUPLING CONSTRAINT, TIE CONSTRAINT OR EMBEDDED ELEMENT
CONSTRAINT. THE REQUIRED EQUATION CANNOT BE FORMED.
***NOTE: DUE TO AN INPUT ERROR THE ANALYSIS PRE-PROCESSOR HAS BEEN UNABLE TO
INTERPRET SOME DATA. SUBSEQUENT ERRORS MAY BE CAUSED BY THIS OMISSION".
I have attached here a picture of how i wrote the equation. Please any suggestions on how to handle this problem. Thank you
Dear Kingsford Koranteng,
If it is possible, please upload your .inp file.
Dear Victor J. Аdlucky , I have attached here the inp. file and how I wrote the equation constraints . Thank you
Dear Kingsford Koranteng,
Since in your SAMPLE.inp file element type DCC2D4 is used, the only DOF 11 (temperature) should be presented in equation, for example,
*Equation
2
FSIDE2,11,1.
FSIDE1,11,-1.
On the other hand, this equation constraint is redundant, because temperatures at symmetrical nodes of the node sets FSIDE1 and FSIDE2 are the same.
Dear Victor J. Аdlucky Thank you so much. Like you said, there is only temperature degree of freedom. I'm using a user subroutine dflux and temperature varies at the sliding contact. I was able to successfully run it using only temperature degree of freedom based on your suggestion. Thanks for this, but could you explain why the constraint will be redundant when i'm trying to model the rectangular structures as a complete circular disc and will it applies to when the heat generated at the surface varies?. Thank you
Dear Kingsford Koranteng,
The remark about redundancy was for SAMPLE.inp only.
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