Controlled dynamic response of a novel auxetic sandwich structure: A tunable tetrachiral core with dual-FG nanocomposite skin

This study explores the free vibration and controlled dynamic behaviour of smart auxetic sandwich panel consisting a tetrachiral auxetic core affixed with dual-functionally graded (FG) nanocomposite skins, using a microscale-focus on chiral unit cell size through representative volume element homogenization-assisted finite element (FE) approach. A piezoelectric sensor-actuator pair, coupled with a constant velocity feedback controller, effectively attenuates vibrations produced in the mechanical meta structure. Controlled dynamic motion equations based on the first order shear deformation theory are obtained via energy-based variational principle and solved under FE framework, considering quadratic interpolation functions. Key findings highlight that, the design parameters of the auxetic core’s unit cell (i.e. ligament arm length and thickness of the cell walls) can significantly alter the ease of flexibility of the chiral core layer, which in turn drastically affects the free vibration and controlled dynamic responses of the sandwich meta structure. Also, carbon nanotube reinforcement into the FG matrix-blend (Al-ZrO₂) of the skin layers substantially improves the structural responses of the sandwich panel. The study validates its numerical approach against existing literature and addresses the impact of several influencing parameters on the micro and macro-mechanical performances of the proposed auxetic structure.