Biomimetic Research for Folding and Deploying Manners of Monopetalous Flower like Morning Glory

本研究通过观察牵牛花和矮牵牛花的花蕾展开方式、花朵展开的图片分析、花瓣和花瓣肋部的拉伸试验、建立花的数值模型和纸质模型以及利用模型模拟花的展开来研究牵牛花和矮牵牛花的展开方式。得到的主要结果如下：1.牵牛花和矮牵牛花具有花瓣和花瓣肋的复合结构，即花瓣肋支撑着薄的花瓣。从拉伸试验中发现，花瓣肋骨的硬度大约是花瓣的三倍。通过展开模拟发现，当所有花瓣都被释放时，牵引花的半径和展开牵引花所需的能量都随着花瓣肋数的增加而减小。然而，当牵牛花的花瓣肋数增加时，重叠的花瓣厚度急剧增加，因此很难将卷起的花瓣放在小花蕾中。牵牛花的展开半径符合Logistic曲线，这是一条基本的生长曲线，即前期展开速度较慢，中期较快，最后又较慢。矮牵牛花在头1619小时内部署缓慢，达到15%的部署，在第二个3~4小时内快速部署，达到40%的部署。然后在停滞12~14小时后以较高的速度展开。

In this research, the unfolding manner of morning glory and petunia flowers were studied by means of the observation of unfolding manner in buds, the picture analysis of unfolding of flower, tensile tests for petals and petal ribs, construction of the numerical and paper models of flowers and the simulation of unfolding of flower using the models. The principal results obtained are as follows :1. Morning glory and petunia flowers have compounded structure with petal and petal ribs, i.e. petal ribs support the thin petals. From tensile tests, it was found that the rigidity of petal ribs are about three times greater than that of petals.2. It was found from simulation of unfolding that the radius of morning glory flower when all petals are released and the energy required for the deployment of a morning glory flower decreases with the increase of the number of petal ribs. However, when the number of petal ribs in a morning glory flower increases, the overlapped petal thickness increases dramatically and consequently it becomes difficult to put the rolled petals in a small bud.3. The deploying radius of morning glory flower follows the logistic curve which is a basic growth curve, i.e. the slow deploying speed in the early stage, high speed in the middle and again slow in the last.4. Petunia flower deploys slowly for the first 1619 hours up to 15 % deployment and quickly for the second 3〜4 hours up to 40 % deployment. And then, it deploys with relatively high speed after the stagnation of 12〜14 hours.