Page 428 - Biaxial Multiaxial Fatigue and Fracture

412 V AUBIN, I! QUAEGEBEUR AND S. DEGALLAIX

Table 5. Constitutive equations of model TANA.

g=ge+gp
Strain decomposition -- -
Hooke law -
E'
- --
Yield function f(C,R,X)=J (a-X)-R-k
-
-
-- 2==

and A=/% T C'C uC'CJ
with ~=cc[[~@~]-~]$
-
Tr C'C
Y
- =ry(EP -y)p and q =(IEp -l?ll
Material parameters E, v, G, k, CI, YI. CZ, YZ, a, (Pm, bl, bt, Q1, ap, bp, CP, aN, bN, CN, cc, ry

Material parameter identification

The identification of the models was carried out in two stages. During the first stage, the
parameters of base model NLK were identified using uniaxial tests. Cyclic hardeninglsoftening
curves in tension-compression with various strain amplitudes are then modelled. The parameter
set obtained hm this identification was then inserted in the three other constitutive laws.
During the second stage, only the remaining parameters of the non-proportional models were