162
X. Bi et al.
Fig. 13.6 Cohesive bilinear constitutive model: a normal behavior, b tangential behavior, c mode
mixing
K i =
⎧
⎨
⎩
K
0
i
δ i ≤ δ
0
i
(1 − d i )K
0
i δ
0
i ≤ δ i ≤ δ
f
i i = n, s, t
0
δ i ≥ δ
f
i
(13.6)
K
0
i : initial stiffness of interface;
δ
0
i and δ
f
i : in single mode, the nominal strain values when stratified initiation and
stratification are completely formed.
d i : damage variables that controlling delamination propagation expansion.
After the initiation of delamination, the delamination behavior of the interface
layer is controlled by the delamination softening law. The secondary nominal stress
criterion is used to predict the initiation of mixed mode delamination, as shown in
the following formula, which allows each traction component to interact to produce
X. Bi et al.
Fig. 13.6 Cohesive bilinear constitutive model: a normal behavior, b tangential behavior, c mode
mixing
K i =
⎧
⎨
⎩
K
0
i
δ i ≤ δ
0
i
(1 − d i )K
0
i δ
0
i ≤ δ i ≤ δ
f
i i = n, s, t
0
δ i ≥ δ
f
i
(13.6)
K
0
i : initial stiffness of interface;
δ
0
i and δ
f
i : in single mode, the nominal strain values when stratified initiation and
stratification are completely formed.
d i : damage variables that controlling delamination propagation expansion.
After the initiation of delamination, the delamination behavior of the interface
layer is controlled by the delamination softening law. The secondary nominal stress
criterion is used to predict the initiation of mixed mode delamination, as shown in
the following formula, which allows each traction component to interact to produce