Abaqus UMAT Subroutine for Calculation of Localised Yarn Properties
The file chamis_model_final.for provides an Abaqus UMAT subroutine which computes yarn properties for every element based on the local fibre volume fraction data provided in the TexGen .eld export file. The file can be downloaded here.
Instead of providing homogenised properties of yarns to Abaqus, raw fibre and matrix properties are specified and then the Chamis micromechanical model [1] is used to compute yarn properties for every element. Every element will then have unique properties which depend on the fibre volume fraction.
To use this function the ‘MATERIALS’ section in the .inp file should be modified as described below, substituting the fields in italics as appropriate:
*Material, Name=MaterialName *User Material,TYPE=MECHANICAL,CONSTANTS=8 E1,E2,nu12,nu23,G12,G23,matrix E, matrix nu *Depvar 5 *Initial Conditions, Type=Solution, Input=my_model.eld
The inputs for the “user material” keyword are:
- fibre longitudinal modulus E1
- fibre transverse modulus E2
- fibre Poisson ratio nu12
- fibre Poisson ratio nu23
- fibre Poisson ratio G12
- fibre Poisson ratio G23
- matrix Young's modulus
- matrix Poisson ratio
To run the files from the Abaqus command line enter:
abaqus job=mymodel user=chamis_model_final
where mymodel is the name of the *.inp file.
This file was written by Mikhail Matveev [2]
1. Chamis CC. Mechanics of Composite-Materials - Past, Present, and Future. J Compos Tech Res. 1989;11(1):3-14.
