8-1 Isogrid-stiffened cylindrical shell with internal isogrid and external rings with
isogrid pattern oriented along circumferential direction for increased bending
stiffness in hoop direction .............. ...............93....
8-2 Isogrid-stiffened cylindrical shell with internal isogrid and isogrid pattern oriented
along circumferential direction for increased bending stiffness in hoop direction;
the zero degree direction for the composite laminates in isogrid and skin panel are
show n .............. ...............99....
8-3 1st iteration of DIRECT windowing for 2 dimensional example, Goldstein-Price
(GP) function (Finkel, 2003), and (b) further iterations on GP function with
potentially optimal boxes shaded and subsequently divided along longest
dim ension(s). ............. ...............107....
A-1 Quadratic fit to al (1.0E-6/oF) .............. ...............110............ ...
A-2 Sixth-order fit to a2 (1.0E-4/oF) ................. ......... ...............110 ..
A-3 Quadratic fit to El (Mpsi) ................. ...............111..............
A-4 Quartic fit to E2 (Mpsi) ................. ...............111..............
A-5 Cubic fit to G12 (Mpsi) ................. ...............112..............
A -6 Q uartic fit to Cl2............... ...............112
B-1 Contour plot of probabilistic safety factor design response surface approximation
and test points along the curve of target reliability ................. .......................1 13
B-2 Contour plot of probability of failure design response surface approximation and
test points along the curve of target reliability. The negative values of probability of
failure are due to the interpolation errors of the design response surface
approxim ation............... .............11
B-3 Contour plot of safety index design response surface approximation and test points
along the curve of target reliability ....._.. ................ ............... 114 ...