According to the research group of Associate Professor Tahiro Sato of Hokkaido University, the density of bamboo fibers is distributed so as to maximize the bending strength, which is almost the same as the ideal fiber distribution obtained theoretically. I found.As a new biomimetic technology, it is expected to lead to the development of advanced materials.
Bamboo is a natural functional material that is both light and durable.The reason is that there are many hollow parts and many fibers with the same rigidity as steel are embedded in the wood part.On the other hand, looking at the cross section of bamboo, it can be seen that the distribution of the embedded fibers is not uniform, and the density gradually increases from the inside to the outside of the cross section.
Therefore, the research team analyzed the relationship between the fiber distribution in the cross section and the bending strength of the entire trunk using structural mechanics theory.It was compared with the measured data of the fiber distribution obtained from the actual bamboo.
As a result of theoretical analysis, it was found that the fiber distribution that maximizes the flexural rigidity differs depending on the total number of fibers that penetrate the cross section.When the number of fibers is small, the bending rigidity of bamboo is maximized by increasing the fiber density from the inside to the outside according to a linear function.It was found that when there are many fibers, the flexural rigidity is maximized by increasing the fiber density from the inside to the outside according to a quadratic function.
On the other hand, in wild bamboo, the fiber distribution in the cross section is different between the root and the tip, and there are many fibers at the root and few fibers near the tip.Then, the fiber distribution of the measurement data was found to change from the quadratic function form to the linear function form from the root to the tip of the bamboo, which was in agreement with the theory.
From this result, the optimum tilt distribution that maximizes the flexural rigidity of a hollow cylinder in general is very similar to the fiber distribution of the bamboo cross section, and bamboo is a functionally graded material with the highest performance. It is said that it will lead to the design and development of cylindrical structures.
Paper Information: [PLOS ONE] Bamboo-Inspired Optimal Design for Functionally Graded Hollow Cylinders
