Improved bending analysis of sandwich plates using a zig-zag function

This paper shows the advantages of using the zig-zag function (-1)(zeta k)(k) (ZZF) in the bending analysis of sandwich flat panels. Higher order theories are developed by adding ZZF to displacement fields of known theories. The main advantage of ZZF lies in the fact that it introduces a discontinuity in the first derivative (so called zig-zag effect) of the displacements distribution with correspondence to the core-face interfaces. Results including and discarding ZZF are compared in the bending response of sandwich plates with soft core loaded by harmonic distribution of transverse pressure at the top surface. Different values of face-to-core-stiffness-ratio FCSR as well as length-to-thickness-ratio LTR have been analyzed. It is concluded that: (1) ZZF is highly recommended in the bending analysis of sandwich plates; (2) the use of ZZF makes the error almost independent by FCSR parameter; (3) ZZF is easy to implement and its use should be preferred with respect to other refined theories