bilinear constitutive material model 1

[mel08]

Hello,
i'm trying to create a material model with differing yield strains in tension and compression. The material is essentially isotropic.
I have used the cast iron material model for this (please let me know if there is a better option).
I have defined it with the following code:

et,2,solid185,,2
tb,cast,bb,,1
tbtemp,0
tbdata,,,,,,,
!ENTER COMPRESSION DATA
TB,UNIACOMP,bb,1,3,COMP
TBTEMP,0
TBPT,,SN_Y_C,SS_Y_C
TBPT,,SN_F,SS_F_C
tbpt,,0.01001,0
!ENTER TENSION DATA
TB,UNIATENS,bb,1,3,TENS
TBTEMP,0
TBPT,,SN_Y_T,SS_Y_T
TBPT,,SN_F,SS_F_T
tbpt,,0.01001,0

all the variables used have been defined previously.
But when i try to solve the problem i get the following error messages:


*** ERROR *** CP = 22.312 TIME= 14:36:30
For material 1 at temperature 0, the initial slope (120.8223) of the
stress-strain curve based on the TB,UNIAXIAL table with option (TENS)
is greater than EX (6.0134717-154).

*** ERROR *** CP = 22.312 TIME= 14:36:30
TB,UNIAXIAL table for material 1 at temperature 0 has a tangent slope
of its stress-strain curve (134.261918) greater than EX
(6.0134717-154).

Could anybody help me with how i need to define the material properties.

Thanks in advance!

 

[akimbf]

Hello,

please, i've the same problem with cast iron option.
Could someone help us?

Thanks a lot

 

[musketeer]

Hi,
I think that the slope before yield should match with each other.

 

[Transient1]

The answer to your question can be found in the following issue of PADT's The Focus magazine:

http://www.padtinc.com/epubs/focus/2007/0055_0223/TheFocus_55.pdf