Effects of In-Plane Shear Loads on Transverse Shear Deformations in Composite Panels

An analytical and experimental investigation is performed to clarify the transverse shear deformations that occur in laminated and sandwich composite plates subjected to in-plane shear loads. This is part of a larger study investigating the feasibility of an in-plane shear test as a practical procedure to determine the in-plane shear modulus and/or strength of various material systems as well as the faces and cores of sandwich plates. The theorem of minimum potential energy has been used to determine the deflections and strains in the plate, including the transverse shear deformation effects. Polynomial functions that satisfy all the boundary conditions of the material system are used as trial functions. Comparison of these solutions to those first proposed by Nadai in 1925 revealed that additional terms are added to the original analysis (which used classical plate theory) to incorporate these effects. The methods developed clearly show the effects of the transverse shear deformation and are valid for any sandwich, laminate, or monocoque plate of any aspect ratio. Subsequent finite element and experimental analysis were conducted to verify the analytical study. Both the numerical and experimental results confirm that the analytical results are very good approximations for describing the linear deformation of the panels subject to in-plane shear loads.