A rigorous multi-objective optimization procedure is developed to address the integrated structures/controls design of composite plates with surface bonded segmented active constrained layer (ACL) damping treatments. The Kresselmeier-Steinhauser function approach is used to formulate this multidisciplinary problem. The goal is to control vibration without incorporating a weight penalty. Objective functions and constraints include damping ratios, structural weight and natural frequencies. Design variables include the ply stacking sequence, dimensions and placement of segmented ACLs. The control systems design is performed using two separate optimal control systems based on linear quadratic regulator (LQR) theory and linear quadratic gaussian (LQG) theory.
The optimal designs show improved plate vibratory characteristics and reduced structural weight. In addition, the studies show that including a greater number of segmented ACL damping treatments of relatively smaller size provides optimum designs with better overall vibration suppression characteristics and lower structural weight, in comparison to using fewer ACL treatments of larger size. The choice of control system employed does not produce significant changes in the results of the optimization studies.
The impact of varying the properties and locations of the segmented ACLs, on the vibration suppression characteristics of the plate, is larger compared to the effect of varying ply stacking sequence alone. Composite tailoring, however, provides a viable means of improving vibration control of composite plates with segmented ACL damping, without altering the ACL configurations or incorporating a weight penalty. Results obtained indicate the importance of incorporating both structural and control objectives, simultaneously rather than sequentially, in the design problem to obtain meaningful design trends in such multidisciplinary problems.