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 .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.

2. Matveev, Mikhail Y. Effect of variabilities on mechanical properties of textile composites. 2015, The University of Nottingham.