Trigonometric zigzag theory for static analysis of laminated composite and sandwich plates under hygro-thermo-mechanical loading

In the present work, the static response of symmetric and anti-symmetric laminated composite and sandwich plates is investigated for elevated temperature and moisture conditions. Analysis is carried out using recently developed zigzag model which is based on a trigonometric (secant) shear deformation in the plate. The theory incorporates inter-laminar shear stress continuity along with the traction free boundary conditions at the top and bottom surfaces. The finite element method is employed for analysis, using the eight noded isoparametric serendipity element, accounting for the C degrees continuity. Numerous examples covering the various features such as effect of thermal and moisture coefficients, material anisotropy, boundary and loading conditions and span to thickness ratio are solved for symmetric as well as anti-symmetric plates. Results in the form of deflection and stresses are presented and validated with the available results in the existing literature. Further, few new results are also provided in this work, to set a benchmark study for the future research.