Variability of Elastic Properties of Two-Layered Tubes from Six-Constant Tetragonal Crystals

An analytical analysis of the problem of the longitudinal tension of two-layered tubes with walls made of tetragonal crystals was carried out together with numerical calculations of the effective Young's moduli and Poisson's ratios of the tubes, using the known experimental data on the elastic characteristics of such crystals. The study of the effective elastic properties of two-layered tubes was carried out in the cases of layers of the same thickness, equal volumes, and greater arbitrariness. The effective Young's modulus often exceeds the largest Young's modulus of a pair of layers, and the effective Poisson's ratio can be negative, even if the Poisson's ratios are positive in both layers. In other words, an auxetic of the two-layered tube may correspond to a pair of non-auxetics in two layers of this tube.

Automated summary

This study analyzed the longitudinal tension problem of two-layered tubes with walls made of tetragonal crystals. The effective Young's moduli and Poisson's ratios of the tubes were numerically calculated using experimental data on the elastic characteristics of such crystals. The study found that the effective elastic properties of two-layered tubes vary in cases of equal layer thickness, equal volume, and arbitrary thickness. The effective Young's modulus often exceeds the largest Young's modulus of a pair of layers, and the effective Poisson's ratio can be negative, even if the Poisson's ratios are positive in both layers. In other words, an auxetic of the two-layered tube may correspond to a pair of non-auxetics in two layers of this tube.