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

Abstract

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.

Keywords

• auxetics
• negative Poisson’s ratio
• cylindrical anisotropy
• tetragonal crystals
• tetragonal symmetry
• two-layered tubes