Simultaneous optimal design of stiffness and damping of a flexible structure reinforced by FRP sheets

Abstract

This paper presents an optimal design of a flexible structure reinforced by fiber-reinforced plastic (FRP) sheets that takes into account both stiffness and damping characteristics. An FRP sheet has a high ratio of strength to weight and is used to reinforce various structures. Vibration characteristics of a structure reinforced by FRP sheets can be easily modified by changing design variables such as the relative volumes of fibers and matrix, the fiber angle and the number of layers. We propose an objective function that takes into account both stiffness and damping characteristics. To improve vibration characteristics, the design variables were determined by using an optimization technique. Vibration characteristics of the optimized structure are superior to those of a structure whose natural frequencies are maximized, because the damping characteristics of the optimized structure are improved as well as the stiffness. The validity of the present method is verified by numerical examples and by comparison with results of experiments.