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Item Vibro-acoustics analysis of auxetic core quadrilateral sandwich panel(Springer Science and Business Media Deutschland GmbH, 2025) Prajapati, V.K.; Pitchaimani, J.Vibro-acoustic response characteristics of re-entrant auxetic core quadrilateral sandwich plate are presented. The face sheets and the core of the sandwich panel are made of aluminum material. Mindlin plate kinematics is used to model the plate as a layered structure. Numerical simulation study is performed by using differential quadrature method and Rayleigh integral. Detailed investigation to analyze the effect of geometric parameters of the quadrilateral plate, unit cell parameters, Poisson’s ratio (positive, negative, and zero) of the core and excitation location on the vibro-acoustic performance is presented first time. Results revealed that vibro-acoustic performance of the plate is significantly affected by the geometric properties of the panel and the location of the excitation force. The sound radiation is observed to be high for cores with negative Poisson’s ratio, while sound transmission loss of the panel is not sensitive to the Poisson’s ratio cores. There is no change in response characteristics for a panel with same core density but having different Poisson’s ratio of the core. This work provides new insights into design of lightweight sandwich structures for noise control applications. © The Author(s), under exclusive licence to The Brazilian Society of Mechanical Sciences and Engineering 2024.Item Flutter behavior of quadrilateral auxetic core sandwich plate with bio-inspired three-phase composite facings numerical analysis and experimental verification(SAGE Publications Ltd, 2025) Prajapati, V.K.; Pitchaimani, J.Flutter characteristics of auxetic core quadrilateral sandwich plates with three-phase bio-inspired laminated composite facings are presented. The core is made of aluminum, while the facings are made of graphene nanoplatelets dispersed in bio-inspired glass fiber/epoxy laminates. The equations of motion are obtained using Reissner-Mindlin plate theory and Hamilton’s approach and then solved with the help of differential quadrature method. Experimental verification of free vibration is done for isotropic and hexagonal honeycomb core sandwich panels. Influences of core parameters (aspect ratio, inclined angle, and thickness-to-width ratio), mass fraction of graphene nanoplatelets and fibers, various graphene nanoplatelet distribution patterns, the geometry and aspect ratio of the plate, and bio-inspired layup scheme of laminated facings on the flutter characteristic are explored. The critical aerodynamic pressure is not sensitive to the core parameters and the dispersion pattern of graphene nanoplatelets. Critical aerodynamic pressure of the panel increases significantly with increase in the mass fractions of fiber and graphene nanoplatelet. Furthermore, the increase in the plate angles results in reduced critical aerodynamic pressure. Facing laminate made of helicoidal type bio-inspired lay-up scheme with lower rotation angle enhances the critical aerodynamic pressure compared to the conventional uni-directional, cross-ply, and quasi-isotropic lay-ups. © IMechE 2024.