In a C-core sandwich panel, the shear stiffness of the sandwich panel in the weak direction is much smaller.
The deflection of a C-core sandwich beam consists of two parts: flexural deformation and shear deformation. The flexural
deformation of a C-core sandwich beam can be calculated simply from beam theory while the shear deformation is relatively
difficult to calculate due to the mutual action between the facing plates and the C-core stiffener. Considering the
contact between the flanges of the C-core and the facing plates, the shear deformation of a typical segment in a C-core
sandwich panel is analyzed based on compatibility conditions. By using Castigliano’s second theorem, the equation for
calculating the deflection caused by shear action of a C-core sandwich panel under bending is obtained. The accuracy of
the presented equations for calculating the deflection of a C-core sandwich cantilever beam and a C-core sandwich panel
under three-point bending is then verified by comparing with finite element and experimental results reported in the corresponding
reference. It is found that the predicted results from the presented equation agree quite well with finite element
and experimental results, which shows the reliability and accuracy of the proposed equation.