Dear all,

I have been facing an issue while trying to run a UMAT in Abaqus 6.12. I need to read some information from a data file, information to be used during the calculations the UMAT will perform. However, although Abaqus is able to check the model (finding no syntax errors), it is reporting an error during the execution and it is unable to open the data file. Through simple debugging tricks I have identified the issue, which is the OPEN statement in the fragment of code shown below: If the OPEN statement is commented out the subroutine works just fine. So, the question is: Is this a limitation of Abaqus or a mistake in my use of the OPEN statement in the UMAT?

! OPEN FILE TO READ MECH PROPS

write(*,*)'BEFORE'  !to verify if it makes it until here     

open(unit=10,file='MProps.dat',status='old',action='read')     

write(*,*)'AFTER' !to verify if it makes it until here      

close(10)

Additionally, based on the way in which my UMAT is written, it will open the external file and close it for every Gauss point at every load increment. That form of operation will be extremely inefficient. Is there a way to read the data file once, the first time the UMAT is executed, and keep the information in an internal variable to prevent having to read the data file again and again?

Thanks a lot.