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

ITER G 74 MA 8 01-05-28 W0.2
B 2600 STRAIN DEFINITIONS AND CLASSIFICATION
B 2620 Calculation of equivalent strain ( e)
For a strain tensor with Cartesian components eij (i and j = 1, 2, 3), the equivalent strain is
given by
2
e = { [ e11 - e22 ] + [ e - e ] + e - e
3
2
22 33 2
.
[ 12
] }
2 2
23 31
+ 6 e + e + e
2 1 2
[ ]
33 11 2
BÊ2630 Calculation of the equivalent strain range ( De)
The equivalent strain range De at a point is used to compute the fatigue usage fraction. A
simple procedure for calculating the equivalent strain range, when the components of the
strain tensor vary directly in proportion to a scalar, is given in IC 2630.
In general, when the components of the strain tensor do not vary in direct proportion to a
scalar, the strain range is calculated in the following way:
1) At each instant (t) of the cycle, calculate the components of the strain tensor e(t) at
the point examined:
e11(t); e22(t); e33(t); e12(t); e13(t); e31(t)
2) Calculate the strain range tensors e(t, t') for each pair of instants (t) and (t') of the
cycle. The components of tensor e(t, t') are equal to the difference between the
components of tensors e(t) and e(t'):
e(t, t') = e(t) - e(t')
3) Calculate the equivalent scalar strain range e tt , ©
using one of the following formulae:
{
( ) between the states (t) and (t')
2
2
e( tt ,© ) = . [ e11( tt ,© ) - e22 ( tt ,© ) ] + e22 ( tt ,© ) - e33(
tt ,© )
3
[ e33 tt ,© e11
tt ,© ]
+ ( ) - ( )
6 [ e12 tt ,© e tt ,© e tt ,© ] }
2
2
23 31
+ ( ) + ( ) + ( )
2
[ ]
2 1 2
SDC-IC, Appendix B. Guidelines for Analysis page 16
2