Optimization of smart composite plates with segmented active constrained layer damping

A rigorous multi-objective optimization procedure isdeveloped to address the integrated structures/controls design ofcomposite plates with surface bonded segmented active constrainedlayer (ACL) damping treatments. The Kresselmeier-Steinhauserfunction approach is used to formulate this multidisciplinary problem.The goal is to control vibration without incorporating a weightpenalty. Objective functions and constraints include damping ratios,structural weight and natural frequencies. Design variables include theply stacking sequence, dimensions and placement of segmented ACLs.The control systems design is performed using two separate optimalcontrol systems based on linear quadratic regulator (LQR) theory andlinear quadratic gaussian (LQG) theory.The optimal designs show improved plate vibratorycharacteristics and reduced structural weight. In addition, the studiesshow that including a greater number of segmented ACL dampingtreatments of relatively smaller size provides optimum designs withbetter overall vibration suppression characteristics and lower structuralweight, in comparison to using fewer ACL treatments of larger size.The choice of control system employed does not produce significantchanges in the results of the optimization studies.The impact of varying the properties and locations of thesegmented ACLs, on the vibration suppression characteristics of theplate, is larger compared to the effect of varying ply stacking sequencealone. Composite tailoring, however, provides a viable means ofimproving vibration control of composite plates with segmented ACLdamping, without altering the ACL configurations or incorporating aweight penalty. Results obtained indicate the importance ofincorporating both structural and control objectives, simultaneouslyrather than sequentially, in the design problem to obtain meaningfuldesign trends in such multidisciplinary problems.