和弓の変形とエネルギー伝達効率に基づいた弓手の技術の評価

抄録

The purpose of this paper was to examine correlations between efficiency of energy transfer and several indices obtained from strain gauges equipped with on a bow, and found a criterion to evaluate a shooter's technique with regard to the left hand. We analysed twisting moment and bending strain of a bow during a bow's restoration.
The conclusions were as follows:
1. The efficiency is significantly correlated with values of twisting moment of a bow in the latter part of the bow's restoration sequence, but not significantly correlated with values in the former part.
2. The efficiency is significantly correlated with values of twisting moment integrated by time (P<.01), and with time when the maximum values of the moment is obtained (P<.05). However, it is not significantly correlated with the maximum value itself.
3. Some spectrums of vibration of bending strain are negatively correlated with the efficiency, especially in the low frequency domain. The number of frequencies at which spectrums are positively correlated with the efficiency is obviously smaller than number of negative correlations. Vibration of twisting moment has little meanings in comparison with that of bending strain because of the magnitude of its energy.
Some of these are widely known as an empirical law. Our conclusions are consistent with it.
Consequently, the conditions of a shooter's technique to transform a bow's energy efficiently are regarded as follows:
* Twisting moment integrated by time is large, and the maximum values of the moment is obtained in the latter part of the bow's restoration.
* Vibration of a bow's bend in low frequency (especially, about 100Hz or 200Hz) is small.