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

ITER G 74 MA 8 01-05-28 W0.2
B 2540 Stress Intensities / Equivalent stresses
BÊ2540.1 Stress intensity - Maximum shear stress theory (Tresca)
For a stress tensor with Cartesian components sij (i and j = 1, 2, 3) and principal components
s1, s2 and s3, the maximum shear stresses are related to the differences in the principal
stresses as follows:
2t12, max = s1 - s2
2t23, max = s2 - s3
2t31, max = s3 - s1
The stress intensity at any point is defined as twice the largest absolute value of t12, max, t23,
max, t31, max and is denoted by s
( 1 2 2 3 3 1 )
s = max s - s , s - s , s - s
This formula can be applied to the total stress tensor as well as to the stress tensor
corresponding to a stress category or a combination of stress categories in the stress
classification of ICÊ2520. When the stress intensity of a combination of several tensors is to
be calculated, care must be taken to first sum the components of all tensors before calculating
the stress intensity. That is, one should calculate the stress intensity of the sum of the tensors,
not the sum of stress intensities.
BÊ2540.2 Stress intensity - Octahedral shear stress theory (von Mises)
For a stress tensor with Cartesian components sij (i and j = 1, 2, 3) and principal components
s1, s2 and s3, the stress intensity at any point is equal to the value obtained by using any one
of the following three equivalent expressions:
2
2
2
{ ( 11 22 ) + ( 22 - 33 ) + ( 33 - 11)
+ ( 12 + + ) }
2 2
23 31
2
s = 12. s - s s s s s 6 s s s
2
2
{ ( 1 2)
+ ( 2 - 3)
+ ( 3 - 1)
}
s = 12.
s - s s s s s
{
2
s = s + s + s - s . s - s . s - s . s } 12
1 2
2
3 2
1 2 2 3 3 1
The first expression is generally valid, whereas the following two can be used only after the
principal stresses have been determined. As before (BÊ2540.1), these formulae can also be
applied to the stress tensor corresponding to a combination of stress categories, in which
case, one should calculate the stress intensity of the tensor sum.
SDC-IC, Appendix B. Guidelines for Analysis page 10
2 12
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