iter structural design criteria for in-vessel components (sdc-ic)

ITER G 74 MA 8 01-05-28 W0.2
relaxation, the sum of the incremental elastic strain and incremental irradiation-induced creep
strain is zero, i.e.,
e
ij
c
ij
eÇ + eÇ
= 0 (1)
If the material obeys the creep law given by Eq. 1 of B 3024.1.1.1, then denoting the initial
and relaxed thermal stresses by so and s respectively, Eq. (1) can be solved as follows:
for the uniaxial case,
( )
s = soexp -EB(
T, f) ft
(2)
and for the equi-biaxial case,
æ 3 EB( T, f) ftö
sij = sodij expç
-
÷
è 2 ( 1 - n)
ø
where i , j = 1,2
and E and n are the Young's modulus and Poisson's ratio.
If the material obeys a creep law different from Eq. (1) of B 3024.1.1.1 or if the initial
starting stress is more general than equi-biaxial, Eq(1) can be solved numerically if a closed
form solution cannot be obtained.
B 3024.1.2 Neuber's rule
Neuber's rule can be applied to estimate the maximum elasto-plastic stresses and strains at
notch roots. Consider a notch with an elastic stress concentration factor KT subjected to a
nominal (remote) uniaxial stress So and, for a linear elastic material, corresponding remote
uniaxial strain eo (eo = So/E). The elastically calculated peak stress (S) and strain (e) at the
notch root are given by
S = KTSo
e = KTeo
NeuberÕs rule states that, if we replace the linear elastic material with a material obeying a
uniaxial power-law constitutive equation,
s = Ae n ,
then, denoting the notch root maximum stress and strain by s and e,
s · e = S · e (1)
The above equations can be solved for the maximum stress and strain at the notch roots as
s = SK
e = eK
2n/( 1+
n)
o T
2/( 1+
n)
o T
SDC-IC, Appendix B. Guidelines for Analysis page 26
(3)
(2a)
(2b)