日本刀の刀身モデルの衝撃応答

抄録

The Japanese sword is interesting not only from the viewpoint of traditional crafts of arts, but also from the aspect of modern science and technology because the way of making and its functionality as a weapon are really consistent with modern science. The present study is concerned with the joint between tohshin (blade) and tsuka (hilt) of the sword. Only one mekugi-take (retaining peg made of bamboo) with about 5mm in diameter holds Nakago (tang) in the hilt. However the slender mekugi might not be broken, even in the case of violent sword-fighting. This fact has been historically demonstrated in many battles by Japanese swords. In this study, using a Japanese sword model, it is examined theoretically and experimentally why a mekugi used in Japanese swords might not be broken from the viewpoint of impact engineering. Consequently, it is presumed that such a strong force as breaking mekugi-take does not act on it, because of the location of mekugi-ana (a hole for mekugi) in the tang, which has been made by following the traditional code of swordsmiths.