Structural redesign is the process of finding a new design that satisfies a
set of performance requirements starting from a poorly performing design.
Structural redesign is formulated as a two-state problem where the baseline
design exhibits undesirable response characteristics and the objective des
ign satisfies the design requirements. A LargE Admissible Perturbations (LE
AP) methodology is developed to formulate and solve the problem of structur
al redesign of cylindrical shells for modal dynamics. First, the nonlinear
perturbation equations of cylindrical shells for modal dynamics are derived
relating the baseline to the unknown objective design. The redesign proble
m is formulated as an optimization problem. Next, an algorithm is developed
to solve the nonlinear problem and to identify a locally optimal design th
at satisfies the given modal dynamics specifications. The developed LEAP al
gorithm calculates incrementally without trial and error or the repetitive
finite-element analyses the structural design variables of the objective de
sign. Numerical applications of cylindrical shell redesign for modal requir
ements are used to verify the methodology and test the algorithm. The devel
oped methodology identifies incompatible frequency requirements where solut
ions cannot be achieved. Further, systematic redesign applications show tha
t even for strip uniform shells, modes are linked, making satisfaction of m
ultiple frequency objectives impossible.