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This is Fig. 3a from the paper, "Global optimum design of externally pressurized isogrid stiffened cylindrical shells with added T-rings" by David Bushnell, International Journal of Non-Linear Mechanics, Vol. 37, 2002, pp. 801–831, called "2002 isogrid paper" in the next slide.
Displayed here is a plot of objective versus design iteration obtained during a “global” optimization of a perfect, internally isogrid and T-ring stiffened, hydrostatically compressed cylindrical shell. The plot is produced by the PANDA2 processors called "SUPEROPT", "CHOOSEPLOT" and "DIPLOT".
Each “spike” in the curve corresponds to a new “starting” design obtained randomly by the PANDA2 processor called AUTOCHANGE. Five PANDAOPTs per AUTOCHANGE were specified for the execution of SUPEROPT. SUPEROPT is used to find a "global" optimum design.
The word, "global", is in quotes because PANDA2 cannot rigorously find the global optimum, but finds an optimum design the weight of which might be close to that of the global optimum because optimum designs are found starting from many different points in design space during a single execution of the PANDA2 processor, SUPEROPT.
Notice that during the execution of SUPEROPT in this particular case the optimization converges to several different local optima.
There is a new processor in PANDA2 (2011) called "SUPERDUPEROPT". In an execution of SUPERDUPEROPT the PANDA2 processor SUPEROPT is automatically executed several times in succession.
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