Shear stiffness D_Qy for C-core sandwich panels

A C-core sandwich panel consists of two facing plates connected top and bottom to a core of C-shaped stiffeners. Sandwich panels of this type have high bending and shear-stiffness characteristic in the direction of the core. In the transverse direction, however, both stiffness properties are relatively weak, in particular the shear stiffness. In this paper, the shear stiffness in the weaker direction for C-core sandwich panels is derived and studied. Due to the geometry and discontinuity of the core configuration, the shear stiffness in the weaker direction must be derived from the first principle. By assuming the recurrence condition, the writers previously derived an approximate expression for the shear stiffness in the weaker direction. The work described here presents a more accurate formulation, taking into account the contact interaction between the facing plates and the flanges of the C-core stiffeners. The compatibility equations are obtained from Castigliano's second theorem. The shear strain of a typical segment is obtained from the principle of virtual work. Explicit formulation for the shear-stiffness property is given in this paper. The accuracy of the derivation is verified using thick-plate analysis. A detailed comparison with finite-element studies and experimental results is also given. Good agreement is obtained between the theoretical predictions as derived and experimental results.