{"id":295788,"date":"2023-08-01T00:19:48","date_gmt":"2023-08-01T00:19:48","guid":{"rendered":"\/forum\/forums\/topic\/solver-pivot-issues-of-elastic-shell-snadwiched-between-poroelastic-solid\/"},"modified":"2023-08-01T00:19:48","modified_gmt":"2023-08-01T00:19:48","slug":"solver-pivot-issues-of-elastic-shell-snadwiched-between-poroelastic-solid","status":"closed","type":"topic","link":"https:\/\/innovationspace.ansys.com\/forum\/forums\/topic\/solver-pivot-issues-of-elastic-shell-snadwiched-between-poroelastic-solid\/","title":{"rendered":"Solver pivot issues of elastic shell snadwiched between poroelastic solid"},"content":{"rendered":"

Hello,<\/p>\n

 <\/p>\n

I have a model of a biphasic\/poroelastic solid reinforced with elastic shells. I have replaced solid 186 elements with CPT216 elements to model the fluid pressure and flux when the construct is under compression. However, I am getting solver pivot errors when running the model. The model has shared topolgy between the solid and shells, and runs completely fine when it has solid 186 elements consititing of a linear elastic material. However, upon changing elements, the error arises.<\/p>\n

Here is a link to the project:<\/p>\n

https:\/\/drive.google.com\/file\/d\/1P1JmyINikenVzwqfqQGCw94MCGd9vIDi\/view?usp=sharing <\/p>\n

It contains the following ADPL command snippet in the analysis section:<\/p>\n

 <\/p>\n

!   Commands inserted into this file will be executed just prior to the ANSYS SOLVE command.<\/div>\n
!   These commands may supersede command settings set by Workbench.<\/div>\n
 <\/div>\n
!   Active UNIT system in Workbench when this object was created:  Metric (um, kg, uN, s, V, mA)<\/div>\n
!   NOTE:  Any data that requires units (such as mass) is assumed to be in the consistent solver unit system.<\/div>\n
!                See Solving Units in the help system for more information.<\/div>\n
 <\/div>\n
\/PREP7<\/div>\n
 <\/div>\n
! Define an element type with the desired real constant (CPT216)<\/div>\n
ET, 9991, CPT216<\/div>\n
KEYOPT, 9991, 12, 1<\/div>\n
! Select the solid elements you want to modify (SOLID186)<\/div>\n
ESEL, S, TYPE,, 13, 57<\/div>\n
! Modify the selected elements to use the specified element type (9991)<\/div>\n
EMODIF, ALL, TYPE, 9991<\/div>\n
 <\/div>\n
ESEL, NONE<\/div>\n
 <\/div>\n
! Define proelastic material for solid elements<\/div>\n
MP,EX,99999,0.001 ! YOUNG’S MODULUS<\/div>\n
MP,NUXY,99999,0.3 ! POISSON’S RATIO<\/div>\n
FPX=2e-15 ! PERMEABILITY<\/div>\n
ONE=1.0<\/div>\n
TB,PM,99999,,2,PERM<\/div>\n
TBDATA,1,FPX,FPX,FPX<\/div>\n
TB,PM,99999,,2,BIOT ! BIOT COEFFICIENT<\/div>\n
TBDATA,1,ONE<\/div>\n
ESEL, NONE<\/div>\n
 <\/div>\n
! Define linear elastic material for shell elements <\/div>\n
MP,EX,88888,0.1 ! YOUNG’S MODULUS<\/div>\n
MP,NUXY,88888,0.3 ! POISSON’S RATIO<\/div>\n
 <\/div>\n
 <\/div>\n
! Select the solid elements you want to modify and assign material 1<\/div>\n
ESEL, S, TYPE,, 9991<\/div>\n
MPCHG, 99999, ALL<\/div>\n
 <\/div>\n
! Select the shell elements you want to modify and assign material 2<\/div>\n
ESEL, S, TYPE,, 1, 12<\/div>\n
MPCHG, 88888, ALL<\/div>\n
 <\/div>\n
! Select all elements<\/div>\n
ALLSEL<\/div>\n
! Continue with the solution phase<\/div>\n
\/SOLU<\/div>\n
 <\/div>\n
 <\/div>\n
Any help would be much appreciated.<\/div>\n
 <\/div>\n
Thanks!<\/div>\n","protected":false},"template":"","class_list":["post-295788","topic","type-topic","status-closed","hentry"],"aioseo_notices":[],"aioseo_head":"\n\t\t\n\t\n\t\n\t\n\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t