A Refined Zigzag Theory for Laminated Composite and Sandwich Plates Incorporating Thickness Stretch Deformation

Most of the existing zigzag theories assume constant transverse displacement across the thickness resulting in zero transverse stretch deformation. This paper presents an enhancement of the previous Refined Zigzag Theory. This is accomplished by considering quadratic through-thickness variation of the in-plane and transverse displacement components. Also, the transverse normal strain is calculated through the assumption of cubic representation of the transverse normal stress. The zigzag functions in the RZT are piecewise linear. This higher order RZT provides improved predictions in the analysis of highly heterogeneous laminates particularly in sandwich plates.