ABAQUS interface

The ABAQUS interface in Z-mat is very robust, due to the complete and flexible UMAT routine in ABAQUS, as well as the full support of user routines in ABAQUS post-processing.

To use Z-mat, a user material needs to be defined in the ABAQUS input file, and the problem launched with the Z-mat script. There is significance to the name of the material given with the *MATERIAL,NAME= option because it gives in fact the name of an external formatted ASCII file for configuring everything to do with the Z-mat material. Example ABAQUS input commands to use Z-mat are shown below.

*SOLID SECTION,ELSET=TUBE,MATERIAL=contact
*MATERIAL,NAME=contact
*DEPVAR
  13
*USER MATERIAL,CONSTANTS=1
0.0

The Zmat launch script (UNIX platforms only) configures the abaqus.env file and handles special linking requirements. The script is quite fully implemented and does not impede in any way the normal operation with ABAQUS's other features, such as other user-programmable features.

The material file then is loaded from the file named contact which could be a complex porous plastic model with solution controls and initialized variables as follows:

***material
  *integration theta_method_a 1.0 1.e-8 1500
  *initialize_variable
     f   0.0
***automatic_time
  *limit f  0.05 
  *security   1.3
  *divergence 2.0
***behavior porous_plastic
 **elasticity isotropic
      young 1789.
      poisson 0.39
 **porous_potential
  *porous_criterion gurson
      q1 1.5
      q2 1.0
      fs function 10.*f;
  *flow plasticity2
  *isotropic_hardening by_point
      sigeq     p
      10.170,   0.00000
      20.204,   0.00084
      66.074,   0.00932
      72.264,   0.02581
      76.941,   0.05418
      80.624,   0.08573
      87.318,   0.14326
      87.318,   1.e20
  *strain_nucleation gaussian
      en 0.005
      fn 0.3
      sn 0.002
***return

Note that material coefficients are only defined in the Z-mat file. Coefficients can be defined by the somewhat more flexible format in Z-mat including tabular, functional and other formats, and can depend on temperature or any of the 9 user defined field variables. Also, some models such as the porous plasticity model above allow the coefficients to depend on integrated variables as well (pay attention to your thermodynamics here).

Up: Z-mat Software
Back: Material files
Next: COSMOS/M interface