Optimal placement of active/passive members in truss structures using simulated annealing

Abstract

Active structural members with built-in sensing, feedback control, and actuation functions are used herein, along with passively damped members, to augment the inherent damping in truss structures. The effective use of such members makes it desirable to distribute them optimally throughout the structure. For simple structural systems, it is possible to place these members with some degree of optimality on the basis of engineering judgment. However, for more complex systems, the number of possible choices is so large that one may have to rely on a more formal optimization technique. This paper deals with the optimal placement of active and passive members in complex truss structures. The problem falls in the class of combinatorial optimization, for which the solution becomes exceedingly intractable as the problem size increases. This difficulty is overcome herein by use of the simulated annealing technique. We adopt the maximization of the cumulative energy dissipated over a finite time interval as the measure of optimality. The selection of nearly optimal locations for both passive and active members is consistently treated through the use of the finite-time energy dissipation criterion within the framework of the simulated annealing algorithm. Numerical examples are used to illustrate the effectiveness of this methodology.