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User subroutines in ABAQUS

Submitted by Nicholas Epiphaniou on

Dear All,



Could you suggest any literature or online step by step tutorial on how to create your own subroutines in ABAQUS like umeshmotion or umat. Any relevant information would be much appreciated. I am looking for information that are not covered in the ABAQUS manual.



Thanks very much in advace,



Nicholas


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Computational Mechanics Forum
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Yao Jiang

Depends on what element type you use, for solid element for example, UMAT needs Cauchy stress and Jacobian matrix based on the Jaumann rate of the kirchoff stress. I suggest you to first undertand the UMAT example provided by ABAQUS on neo-Hookean material.I found the documentation of 6.8 a little clearer than previous version on this topic.

Thu, 06/11/2009 - 18:45 Permalink
hunghung8X

dear all

I have a problem with multiple user subroutines. I prepared 2 user subroutines . each defines the response of each layer material in one structure.

does any one know how to run both user subroutines simultaneouly in abaqus.

thank you in advance

HungHung

Sat, 06/13/2009 - 06:11 Permalink
unsrohith

hi

The following is taken from abaqus documentation:

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.

best regards

Rohith

 

Sat, 06/13/2009 - 06:41 Permalink