Modal response of sandwich plate having carbon-epoxy faceplate with different honeycomb core material and geometry considerations

Sandwich-structures are widely used in structural application for their damping nature, attributed by its viscoelastic or honeycomb core. However, the geometry and material variety of the honeycomb core greatly influence the structural dynamics. Previous works don’t deals with the sandwiched plates with composite face sheets and diverse core (different materials and geometry) in a single study; which is attributed for better understanding; in this work. Theoretically, the outer-layers considered to be carbon-fiber-epoxy composite, while multiple cases of core material (epoxy, polystyrene and polyurethane) is assumed. The material properties of outer layer is calculated by mixture-rule. The equivalent porosity factor is introduced in the material model to calculate the material properties of the honeycomb core. Further, the equation of motion is derived using third order shear deformation theory and fundamental-frequencies in simple-supported condition are determined for thickness ratio of face to core-layer (h_f/h_c), shape (circular, triangular, square and hexagonal), and dimension (length and thickness) of honeycomb core to study the effect on the plate dynamics. The results are compared with the findings of Finite-element-analysis (FEA) using ANSYS 16.0. It is observed that the core material, geometry, and h_f/h_c affects plate stiffness. In addition, increase of unit cell wall length and thickness reduces the porosity and increases plate strength. The triangular core have maximum strength with least porosity contrast to circular structured unit cell. Increasing the thickness of core layers reduces plate stiffness and thus a drop of natural frequency. Further, polyurethane core has greater stiffness than epoxy and polystyrene.