2021 年 87 巻 903 号 p. 21-00203
Lure fishing is a special fishing method that using artificial fishing lures as fish baits and has become more and more popular all over the world. Vibration lures are a regular item among fishing lures that perform vibration action in the water for baiting fish. In the present work, to enhance the vibration behavior of vibration lures with a real analytical condition, we propose a free-form optimization method for fundamental frequency maximization design problem of solid structures considering initial stress and apply it in shape optimization of vibration lures. We use the fundamental frequency (i.e., the 1st order) eigenvalue as the objective function and maximize it subject to a weight constraint. As the optimal results, the fundamental frequency eigenvalue of a vibration lure made of Zinc could be enhanced to 2.20 times as much as its initial value under initial stress conditions induced by water pressure and tractive force of fishing line, while the mass of the optimal shape satisfied the mass constraint during the optimal design process. As a comparison, we also perform a design optimization of the vibration lure without considering any external loading, whose fundamental frequency can be also enhanced over 2 times as much as its initial value.