Free flexural vibration analysis of symmetric rectangular honeycomb panels using the improved Reddy’s third-order plate theory

The free flexural vibration of symmetric rectangular honeycomb panels is investigated in this paper using the improved Reddy’s third-order theory. Reddy’s third-order theory provides a parabolic distribution of the transverse shear stresses in the thickness direction and represents a close approximation to the true shear strain distribution for a shallow single-layer plate. However, for the case of multilayered laminates, the continuity condition on the inter-laminar shear stresses implies a piecewise continuous shear strain distribution in the thickness direction. To accommodate the effect of the continuity condition of inter-laminar transverse shear stresses, the shear correction factors are introduced to modify the shear strains in the Reddy’s third-order theory. The shear correction factors are calculated using an iterative formulation based on the shear strain energy equivalence. The improved Reddy’s third-order theory coupled with shear correction factors in predicting free flexural vibration of symmetric honeycomb panels is examined by being compared with the experimental value and the finite element analyses based on three-dimensional models.