“…Efforts have been made to determine critical velocities of single-layer, homogeneous tubes of materials with various types of symmetry, including isotropic, cubic, transversely isotropic and orthotropic (e.g., [10,11,15,27,30,35,36]). However, for composite tubes containing two or more cylindrical layers of dissimilar materials (e.g., [20,21,29]), very few studies have been conducted to find their critical velocities.…”