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

ITER G 74 MA 8 01-05-28 W0.2
and a line integration through the thickness is used to calculate the breakdown of stresses at
any position. On the other hand, if the tube is analysed as a beam, then the membrane and
bending stress apply to the cross-section as a whole, and an area integral over the total crosssectional
area of the tube would be more appropriate.
Once a determination has been made as to which type of integration (line integral or area
integral) is more appropriate, a membrane stress component can be defined as the average or
mean value of that stress component along that line or area. The bending component of the
stress is a linearly varying stress which can be defined in such a way that its moment about
the centroid of the line segment or the area is the same as the moment of the total stress
component minus the membrane stress component about the centroid.
BÊ2513 Membrane stress
As an example of a structure other than a single layer homogeneous shell, consider the case
of a first wall design consisting of two face plates of thicknesses h1 and h2 separated by a
coolant channel of height hc where the coolant channels running along one direction (say x2
direction) are separated by regularly spaced webs á(Figure B 2513-1). In general, such a
structure is anisotropic but could be analyzed using various geometrical approximations.
X 3
SDC-IC, Appendix B. Guidelines for Analysis page 4
X 1
Figure BÊ2513-1: First wall cross-section
(1) At an elementary level, when x3 variation of stresses in the x1 direction can be
neglected, a slice of the first wall consisting of halves of two adjacent coolant channels
together with their face plates may be analyzed as a one-dimensional stress analysis
problem. The cross-section of interest is like an I-beam and the stress of interest is the
normal stress s22. For this case the membrane stress ( s22 ) has to be defined as the
m
average stress over the whole cross-section, i.e., based on an area integral.
1
( s ) = ò s
m A
22 22
A
dA (1)
where A is the area of cross-section.
(2) An alternative approach, when x3 variation of stresses in both directions are nonnegligible,
could be to analyze the structure as an isotropic, homogeneous, and multi-
h 1
h c
h 2