Integrated Passive and Active Control of Structures
Final rept. May 1990-May 1993
PENNSYLVANIA STATE UNIV UNIVERSITY PARK DEPT OF ENGINEERING SCIENCE AND MECHANICS
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A combination of passive damping and active control is needed on practical structures where sufficient modal damping is not achievable with passive damping alone. The modal theories for structural equations in state space are reviewed and some eigenvector relationship are presented which are not available elsewhere, for use later in the report. Methods for determining sensitivities of eigenvalues land eigenvectors to plant matrix and control inputs are summarized and numerical examples are presented. Procedures are developed for optimizing passive damping through use of the sensitivities of the eigenproperties, for free vibration and forced, random vibrations. Frequency- dependent behavior of viscoelastic damping material by curve-fitting is discussed, which is then used in an overdamped mini-oscillator technique for analysis of an example ten-bar truss. Two approaches are presented for designing the combination of passive viscous damping and full state feedback control. The first is iterative and makes use of eigenvalue sensitivities. The second is based on a perturbation formulation, where the desired changes in eigenvalues and eigenvectors are specified and the corresponding changes in the closed loop characteristic matrix in state space are predicted. Restrictions on the choice of eigenvalues and eigenvectors are discussed in light of related literature on eigenstructure assignment. Fortran computer programs, one coupled with the constrained function minimization program CONMIN, have been written for each type of problem. Space structures, Passive damping, Active control, Analysis, Numerical examples.
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