Issue 39
M. A. Lepore et alii, Frattura ed Integrità Strutturale, 39 (2017) 191-201; DOI: 10.3221/IGF-ESIS.39.19
The stress increment processed in FE iterations is equal to
dD
1
n D K K 0
n
,
0
d
n n 0
n
d
(11)
n
d
n
K
,
0
n
0
d
0
d
s
n
d
0
(12)
d
dD
1
s D K K 0
s
,
0
d
s s 0
s
d
s
d
s
K
,
0
s
0
where
n
n n
f
f
1
n
d
,
,
0
dD
max n
0
2
(13)
f
n
n
d
otherwise
0,
s dD
0
d
A null derivative of damage with respect to separation n
implies that damage is considered constant and equal to the last
estimated value when opening displacement at the interface is decreasing or n < max . For this reason, if the current value of normal separation is less than previous max ) is located inside the area under the effective limit curve and the damage D is considered unchanged (Fig. 5). The stress field is calculated using Eqs. (6)-(7). , the corresponding point ( curr , curr
d d n
f ( max
)
P 2
P i
curr
d d n
P 1
K 0
K curr
P n
( t )
( t )
curr
max
n
Figure 5 : Interpolated cohesive law – closing of the interface.
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