Appendix A – Constituent level
183
A2 Implemented material models for face sheets
VUMAT for fabric reinforced composites
With ABAQUS/Explicit 6.8 a built-in VUMAT user subroutine for fabric reinforced composites has been implemented. This subroutine can be activated by naming the material
such that it starts with the string ABQ_PLY_FABRIC (for instance ABQ_PLY_FABRIC_ABS).
This homogenous orthotropic elastic material model enables progressive stiffness degradation due to fiber or matrix damage. In addition, it allows plastic deformation under
shear loading. This is what sets it apart from the standard UD-composite material of
ABAQUS. Throughout the present work it is applied for the face sheets.
The syntax of the input format is given below
*MATERIAL,NAME=ABQ_PLY_FABRIC
*DENSITY
ρ
*USER MATERIAL, CONSTANTS=40
** Line 1:
+1E, +2E, +12ν, 12G, -1E, -2E, -12ν
** Line 2:
+1X, -1X, +2X, -2X, S
** Line 3:
+1G f , -1G f , +2G f , -2G f , 12α, 12d max
** Line 4:
σ y0 , C, p
** Line 5:
lDelFlag, d max , ε plmax , ε max , ε min
*DEPVAR, DELETE=16
16
LINE: 1 Elastic properties
Pos.
Symbol
Description
1
+1E
Young’s modulus along tensile fiber direction 1
2
+2E
Young’s modulus along tensile fiber direction 2
3
+12ν
Poisson ratio
4
12G
Shear modulus
5
−1E
Young’s modulus along compressive fiber direction 1
6
−2E
Young’s modulus along compressive fiber direction 2
7
−12ν
Poisson ratio
8
Not used