Hygrothermal Stability Analysis of Bio-Inspired Meta-Nanocomposite Shells

The present study investigates the effectiveness of a bio-inspired auxetic lattice metamaterial core in enhancing the hygrothermal-torsional stability of carbon nanotube (CNT)-reinforced sandwich cylindrical shells. The shells are subjected to various hygrothermal conditions, including uniform, linear, and nonlinear temperature and moisture gradients. CNTs are embedded within a temperature and moisture-dependent polymer matrix in the face sheets. The proposed bio-inspired auxetic core, inspired by butterfly wing patterns, exhibits superior adaptability, stiffness, and stability due to its negative Poisson's ratio (NPR), showing improved performance compared to conventional re-entrant type. The equilibrium equations are derived using nonlinear Donnell shell theory with von Kármán geometric nonlinearity and solved via the Galerkin method to obtain buckling and post-buckling responses. The model's accuracy is verified against previous studies. The findings reveal that the butterfly-shaped core achieves up to ۲۳.۳۳% higher stability than the conventional re-entrant core, underscoring its potential for lightweight, high-performance auxetic shell structures. Furthermore, an in-depth parametric analysis is conducted to examine the influence of the hygrothermal environment on the shell's stability behavior.

Keywords:

bio-inspired auxetic core , carbon nanotube-reinforced composite , hygrothermal-torsional stability , nonlinear buckling