Composite Materials Research Progress

38
Jacquemin Frédéric and Fréour Sylvain
5.3. Numerical Applications and Examples
5.3.1. Identification of the Microscopic Failure Criteria of Two Typical Epoxies
from the Knowledge of the Macroscopic Failure Envelope of AS4/3501-6 and
T300/N5208 Composite Plies
In the present paper, two types of high strength carbon fiber reinforced epoxies are
considered: a) AS4/3501-6 and b) T300/N5208 composites having identical fiber volume
fraction: v f =0.6. These two materials constitute good candidates for the present work, since
the microscopic strength of their respective matrix is not yet available (at our knowledge) in
the already published literature, in spite of they are quite often considered for illustrating
scientific works in this field of research (Tsai, 1987).
Strengths [MPa] X I
Table 8. Macroscopic strength data.
X I ´ Y I , Z I
Y I ´, Z I ´ S I
T300/5208 (Tsai, 1987) 1500 1500 40 246 68
AS4/3501-6 (Liu and Tsai, 1998) 1950 1480 48 200 79
Table 9. Quadratic macroscopic stress failure criteria deduced from the strength data.
Quadratic ijkl subscripted coefficients [MPa -2 ] and linear ij subscripted coefficients
[MPa -1 ].
Strength
parameters
I
F 1111
T300/5208 4.44 10 -7
I
F , 2222
I
F 3333
1.02 10 -4
I
F 1212
I
F , 1122
I
F 1133
I
F 2233
I
F 11
I
F ,
22
I
F 33
1.08 10 -4 -3.36 10 -6 -5.08 10 -5 0 0.0209
AS4/3501-6 3.46 10 -7 1.04 10 -4 8.01 10 -5 -3.00 10 -6 -5.02 10 -5 -0.0002 0.0158
The macroscopic strength of single plies are given in Table 8. The coefficients of the
corresponding quadratic macroscopic stress failure criteria, deduced from the classical direct
method, through equation (55) are listed in Table 9.
Table 10. Macroscopic stiffness components [GPa] of 60% volume uni-directionally
fiber reinforced plies. Fiber axis is parallel to longitudinal direction.
Stiffness
components
I
L 11
T300/5208 142.72
AS4/3501-6 137.27
I
L , 22
13.92
I
L 33
I
L , 12
I
L 13
I
L 23
I
L 44
I
L ,
55
5.79 7.19 3.34 7.00
11.60 4.20 5.22 3.68 6.45
I
L 66