Using an Abaqus UMAT in 2-D versus 3-D

[optimusLime]

Hello,

I am in the process of learning how to implement a UMAT for my abaqus models.

I am starting small - using a single element and implementing isotropic linear-elasiticity theory so I can easily confirm my answers. I have implemented this behavior successfully on a single C3D8 brick element (verified by using Abaqus built-in *ELASTIC keyword).

I am trying the same thing on a single CPS4 element (plane strain). I am attempting to use the same UMAT file as in the 3-D case, with only the following exceptions:

1) Changing the definition of the Jacobian for a plane stress element. That is, using Hooke's law for plane stress as opposed to 3D isotropic Hooke's Law.

2) Using the strain indices appropriate for the CPS4 element (i.e., in plane stress, stress(3) refers to S12 as opposed to S33, as it would in the 3D case).

Something is still not working for my formulation. I submit my job, and in the Abaqus Model Tree, the job status goes from Submitted -> Running and hangs there indefinitely. What's more, the .msg file only goes so far as writing "INCREMENT 1 STARTS. ATTEMPT NUMBER 1, TIME INCREMENT 1.00" and then just ends - no warnings, no errors, no feedback. I have uploaded my plane stress UMAT as ELASTIC_PL_STRESS.for.

I was hoping someone could help me with some feedback if they can identify what it is I'm doing wrong. I'm happy to answer any questions that would facilitate a response.

Thanks!

-MN

 

[optimusLime]

Bump please!

 

[optimusLime]

Oops. Turns out I'm still not used to Fortran's indexing and referred to what should have been the first item in PROPS (e.g. PROPS(1)) as PROPS(0). D'oh.