Chapter 5 Robust Performance Tailoring with Tuning - SSL - MIT

has been found that structural design problems tend to have many variables, include
nonlinearities in the cost functions and/or constraints, and may be non-convex. As
a result, non-gradient or heuristic, search techniques have become popular in recent
years. Lagaros et al. apply genetic algorithms to the minimum weight sizing problem
and compare the results to those obtained with gradient methods [67]. Hasancebi
et al. use simulated annealing to determine the optimal size, shape and layout for
minimum weight truss structures subject to stress, stability and displacement con-
straints [51]. Manoharan and Shammuganathan provide a comparison of four search
techniques, Tabu search, simulated annealing, genetic algorithms and branch-and-
bound, applied to the truss sizing problem [79].
Structural optimization has also received a large amount of attention from the
vibration suppression community. Yamakawa formulated the problem of minimum
root mean square (RMS) tip displacement for a cantilevered beam and truss frame
structures with deterministic loading [113] . Chen, Bruno and Salama demonstrated
increased finite-time energy dissipation through combinatorial optimization of passive
and active damping locations in a simulated annealing framework [26]. Langley uses
a Quasi-Newton optimization algorithm to minimize kinetic energy and maximum
strain in a near-periodic beam system by varying bay lengths and loss factors [68].
Keane, Nair and their colleagues at South Hampton University have done extensive
work in vibration minimization through unusual truss geometries. They use genetic
and evolutionary algorithms to design trusses that exploit the intrinsic vibration
filtering capabilities of non-periodic structures to achieve passive isolation [63, 95,
96]. As a continuation of this work, Moshrefi-Torbati and Keane have published
the first experimental validation of topology optimization for passive isolation [91].
The authors built the optimized structure and demonstrated significant vibration
suppression over the traditional design.
As the science requirements for telescope missions became move aggressive the
structural vibration and control communities began to examine the idea of consid-
ering structure and control design in parallel as an alternative to traditional design
methods. Historically, designs are driven by mass and static requirements. The struc-
30