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Aluminum tubes are efficient energy absorbing components and are widely used in the automobile industry. In the previous report, the authors investigated the influence of cross-sectional shape on axially compressed aluminum tube by numerical analysis. However, there are only a few reports on length of aluminum tube. This paper deals with the influence of axial length and reinforcing rib on dynamic axially compressed aluminum polygonal tube in order to obtain the basic data of buckling and impact resistance. A numerical analysis of the dynamic deformation process of the polygonal tube was made with a finite element method. The result shows that even if the axial length was changed, there was no difference in the trend of the load-displacement curve in each cross-sectional shape. However, the maximum load part on load-displacement curve was changed. The buckling was generated partially and the deformation was larger at the corners in each axial length and cross-sectional shape.

We propose a new acrylate monomer that exhibits attractive optical properties, such as good transparency, high refractive index, low birefringence, desirable optical properties, and high thermal stability. Tetraphenylethane has four aromatic rings that bind without anisotropy. A polymer with this tetraarylethane structure is expected to exhibit a high refractive index and low birefringence. In this study, we synthesized two acrylate-based polymers via radical polymerization of the acrylate monomer and methacrylate derived from 1,1′,2,2′-tetrakis(4-hydroxyphenyl)ethane. We prepared transparent coatings of the polymers on a synthetic quartz plate via spin coating and measured their refractive indices using a prism coupler. Both of the polymers exhibited a high refractive index (1.60) as compared with common PMMA (1.49) and a low birefringence, which indicated that a tetraarylethane skeleton is the preferred candidate for suppressing the birefringence of a material.