著者

大槻 敦巳 大島 成通

出版者

日本ばね学会

雑誌

ばね論文集 (ISSN:03856917)

巻号頁・発行日

vol.2017, no.62, pp.49-55, 2017-05-31 (Released:2017-12-01)

参考文献数

7

被引用文献数

1

---

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.

著者

大槻 敦巳 大島 成通

出版者

日本ばね学会

雑誌

ばね論文集 (ISSN:03856917)

巻号頁・発行日

vol.2019, no.64, pp.23-31, 2019-03-31 (Released:2019-10-01)

参考文献数

10

---

Traditional Japanese bows have a laminated structure made up of highly flexible bamboo and wood. Each bow is composed of multi arcs having different cross sectional areas along the length and also with different radii of curvature. Three stages setting procedure is required before shooting a Japanese bow. At first the bow is standing free, then, it is bent and constrained to have negative curvature using the bow string (chord), and finally formed into various shapes having positive curvature. Japanese bows does not have a symmetrical shape, and the position of the grip is also shifted from the center of the bow. Therefore, the deformation characteristics and the dynamics to analyze 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. This study presents the details of the theoretical analysis results of Japanese bows obtained by using a simplified model consisting of multi arc segments. Each segment is treated as a large deformable nonlinear flexible beam and deformation analysis of individual arc segments is done by using the elliptic integral derived from Elastica theory. Furthermore, in order to confirm the applicability of the proposed large deformation theory, a large deformation experiment is performed. As a result, the theoretical analysis shows a very good agreement with the experimental results for the large deformed shape of the bow, which was restrained and loaded on the string. Moreover, the dynamic characteristics of Japanese bow and arrow with regard to the parameters such as the radius of curvature and bow arc ratio is evaluated.

著者

大槻 敦巳 竹内 稔朗

出版者

日本ばね学会

雑誌

ばね論文集 (ISSN:03856917)

巻号頁・発行日

vol.2019, no.64, pp.15-21, 2019-03-31 (Released:2019-10-01)

参考文献数

30

被引用文献数

1

---

In recent years, leisure activities, such as tennis, golf, skiing, fishing, etc. are very popular. The performance of various instruments used in such leisure activities is also greatly improved. Scientific analysis on the function of such instruments is essential in order to develop practical instruments in the field of sports-leisure. Various experiential studies that clarify the characteristics of fishing rods have been published. However, there are very few scientific studies about fishing rods in the field of the so-called sports-leisure. This study deals with large deformation of fishing rods that would be useful in the development of the characteristic design of fishing rods. In this report, based on the nonlinear large deformation theory, new fundamental equations are introduced for thin, straight tapered fishing rods with a circular cross-section under concentrated loads at the free end. As a result, it is found that the large deformations of fishing rods can be described by nondimensional load parameters, the ratio of rod diameter at end and bottom, and supporting angles. Furthermore, the experimental verification of this analysis is carried out using a flexible rod acquired in the market. The theoretically predicted results are in fairly good agreement with the experimental data. Consequently, the new deformation theory is proved to be of practical use.

著者

大石 泰史 大島 成通 大槻 敦巳

出版者

一般社団法人日本機械学会

雑誌

シンポジウム: スポーツ・アンド・ヒューマン・ダイナミクス講演論文集 : symposium on sports and human dynamics

巻号頁・発行日

vol.2011, pp.481-484, 2011-10-30

---

Kyudo is a competition which applies an arrow on a target, and a series of operations which shoot an arrow are important. This study will focus on one of their drawing motion. Draw become different a school and by individual physique and thought, but it is not analyzed numerically, and almost of the experience to know what the athlete. In this study, consider the optimization of drawing motion for multipurpose genetic algorithm. We analyzed from the perspective of the forward dynamics, using a human and bow model of Japanese archery for even large deformation beam and the rigid link.

著者

大島 成通 梨田 裕紀 竹上 洋史 大槻 敦巳

出版者

一般社団法人日本機械学会

雑誌

ジョイント・シンポジウム講演論文集 : スポーツ工学シンポジウム : シンポジウム:ヒューマン・ダイナミックス : symposium on sports engineering : symposium on human dynamics

巻号頁・発行日

vol.2009, pp.436-441, 2009-12-02

---

Pole vaulting has progressed rapidly in terms of improved mechanical properties and better appearance by using poles made of flexible fiberglass material. Competitive pole vaulting requires specific characteristics that promote higher jumps. In this research, simulation analysis to optimize the joint torque, pole stiffness and pole length was done by using Genetic Algorithm. Here, the vaulter was expressed by the three-dimensional model including twisting the waist. Genetic algorithm in which the joint torques of the vaulter were expressed in terms of spline interpolating curves. From the results, it was clarified that there is optimal pole characteristic to the vaulter's initial velocity.