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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.Item Applicability Two-Dimensional Differential Integral Quadrature Method in Vibration Analysis of Multi-Directional Functionally Graded Porous Viscoelastic Plates(John Wiley and Sons Ltd, 2025) Mohamed, S.A.; Mohamed, N.; Assie, A.E.; Eltaher, M.A.; Pitchaimani, J.; Abo-Bakr, R.This study formulates a differential integral quadrature method (DIQM) to analyze the free vibration characteristics of multi-directional functionally graded material (MFGM) viscoelastic porous plates. The kinematic relations are derived using a unified shear deformation plate theory, while material behavior is governed by the integer-order Kelvin-Voigt viscoelastic constitutive model. Power-law functions define the spatial gradation of material constituents along the length, width, and thickness directions. Two distinct porosity distributions are incorporated to characterize void and cavity variations through the plate's thickness. Hamilton's variational principle yields five coupled governing equations expressed as partial differential equations with variable coefficients. The differential quadrature method (DQM) discretizes these governing equations, with integral quadrature method (IQM) efficiently resolving the variable coefficients. This discretization results in an algebraic system constituting a quadratic eigenvalue problem. The eigenvalues' real and imaginary components provide the damping coefficients and natural frequencies, respectively. The proposed model and solution methodology are validated against established unified shear formulations, MFGM porous plates, and viscoelastic plate solutions available in literature. Comprehensive parametric studies systematically investigate the influence of material gradation indices, porosity parameters, boundary conditions, and viscoelastic coefficients on the natural vibration response of thick MFGM viscoelastic porous plates. The results demonstrate that an increase in either of the material gradation indices leads to a decrease in both of the real and imaginary parts of the fundamental frequencies. © 2025 John Wiley & Sons Ltd.