抄録
There are many studies on natural frequencies of structural systems, where the system is treated as quasistatic. In the viewpoint of safety and reliability, however, dynamic responses become important. The less cycles of stress variations to a material are, the less fatigue is stored in it by the fatigue failure theory, and the body has relatively longer lifes. Therefore, it is desirable for a structure with damping, which is subject to a vibration, that a rate of amplitude reduction is larger. This study considers a shape design problem of structures, and aims to maximize their damping ratios. As a numerical treatment, Finite Element Method and Method of Modal Analysis are applied for beams, and a simple optimization scheme which uses the sensitivity analysis is proposed. The shapes obtained are different from each other depending on values of Rayleigh coefficients.
