Analysis of Nonlinear Deformations in Japanese Bows (Application of Elastica Theory)

Abstract

Traditional Japanese bows are composite (clad) materials made up of bamboo and wood with very high flexibility. Each bow is composed of multi arcs with different radius of curvature and cross sectional areas along with the length. In using the Japanese bows there are three stages. At first the bow is free standing, then, it is constrained negatively using the chord. The bow is then loaded to form various shapes. Although the shape of archery is similar, Japanese bows are not symmetrical, and the grip is off center, therefore, the characteristic and dynamics of Japanese bows are very complicated. In recent years, large deformation analyses of the flexible bows have attracted attention considerably because of both analytical and technological interests in the design of bows and arrows. In this study, the details of the simulation results of Japanese bows obtained in using a simplified model treated as a nonlinear flexible beam with a large deformation are presented using the elliptic integral derived from Elastica theory. From this investigation, some interesting and valuable information are obtained. Furthermore, using a flexible thin PVC beam specimen, a large deformation experiment is performed to confirm the applicability of the large deformation theory proposed here. The experimental results closely matches that of the theoretical values. Therefore, this analysis is useful in improving the design of bows. This study would be useful to develop technique of Japanese bows in the field of the so-called sports-leisure.