iMechanica - abaqus umat - Comments

The manual 's suggestion is more clear.

Shunlai.Zang — Fri, 29 Aug 2008 02:40:55 -0400

but both of method are feasible..

Yes, the above approach is

Donald X. Chen — Fri, 29 Aug 2008 02:25:01 -0400

Yes, the above approach is quite similar to the manual 's suggestion:

Abaqus, user subroutine reference, 1.1.31–9

~~~~~~~~~~~~~~~~~~~~~

Example: Using more than one user-defined mechanical material model
To use more than one user-defined mechanical material model, the variable CMNAME can be tested for
different material names inside user subroutine UMAT as illustrated below:

IF (CMNAME(1:4) .EQ. 'MAT1') THEN
CALL UMAT_MAT1(argument_list)
ELSE IF(CMNAME(1:4) .EQ. 'MAT2') THEN
CALL UMAT_MAT2(argument_list)
END IF

UMAT_MAT1 and UMAT_MAT2 are the actual user material subroutines containing the constitutive
material models for each material MAT1 and MAT2, respectively. Subroutine UMAT merely acts as a
directory here. The argument list may be the same as that used in subroutine UMAT.

a simple approach could be

jj — Thu, 24 Jul 2008 14:06:39 -0400

a simple approach could be to define 2 umats in the same umat routine. here is how:

1. u can define material props for umat. so for elements that use umat1, provide prop=1, for umat2 prop=2

now combine umats like this:

subroutine umat

...

if (prop=1) then

call umat1(...)

elseif (prop=2) then

call umat2(...)

end

end subroutine umat

subroutine umat1

...

end subroutine umat1

subroutine umat2

...

end subroutine umat2

Since the input arguments are same for all umat routines, its not a lot of work to combine.

this may not be very efficient, there could be better ways of doing it that i am not aware of.

abaqus umat

yongtao lu — Thu, 24 Jul 2008 13:06:20 -0400

I constructed a head model, which includes muscle, soft tissue, skin and bone. I wrote user material subroutine (umat) for muscle and soft tissue, seperately. I am going to define the muscle and soft tissues properties by using my umats. However, I dont know how to define two user material subroutines (umat) in one model. The subroutines share the same name: subroutine umat(...). If I assign two umats, ABAQUS will be confused, wont know which subroutine to go. Is there anybody who knows how to sort this out?

Many thanks,
ben

cardiff university, uk