Learning Forum

[fraser.shields]

Hello,

 

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.

Here is a link to the project:

https://drive.google.com/file/d/1P1JmyINikenVzwqfqQGCw94MCGd9vIDi/view?usp=sharing 

It contains the following ADPL command snippet in the analysis section:

 

!   Commands inserted into this file will be executed just prior to the ANSYS SOLVE command.

!   These commands may supersede command settings set by Workbench.

 

!   Active UNIT system in Workbench when this object was created:  Metric (um, kg, uN, s, V, mA)

!   NOTE:  Any data that requires units (such as mass) is assumed to be in the consistent solver unit system.

!                See Solving Units in the help system for more information.

 

/PREP7

 

! Define an element type with the desired real constant (CPT216)

ET, 9991, CPT216

KEYOPT, 9991, 12, 1

! Select the solid elements you want to modify (SOLID186)

ESEL, S, TYPE,, 13, 57

! Modify the selected elements to use the specified element type (9991)

EMODIF, ALL, TYPE, 9991

 

ESEL, NONE

 

! Define proelastic material for solid elements

MP,EX,99999,0.001 ! YOUNG'S MODULUS

MP,NUXY,99999,0.3 ! POISSON'S RATIO

FPX=2e-15 ! PERMEABILITY

ONE=1.0

TB,PM,99999,,2,PERM

TBDATA,1,FPX,FPX,FPX

TB,PM,99999,,2,BIOT ! BIOT COEFFICIENT

TBDATA,1,ONE

ESEL, NONE

 

! Define linear elastic material for shell elements 

MP,EX,88888,0.1 ! YOUNG'S MODULUS

MP,NUXY,88888,0.3 ! POISSON'S RATIO

 

 

! Select the solid elements you want to modify and assign material 1

ESEL, S, TYPE,, 9991

MPCHG, 99999, ALL

 

! Select the shell elements you want to modify and assign material 2

ESEL, S, TYPE,, 1, 12

MPCHG, 88888, ALL

 

! Select all elements

ALLSEL

! Continue with the solution phase

/SOLU

 

 

Any help would be much appreciated.

 

Thanks!

[Ashish Khemka]

Hi,

Ansys employees cannot download the attachments. The command snippet is used to change the material. Can you share snapshots of the setup - with that, it might be easier for forum members to comment more on your post.

 

Regards,

Ashish Kumar