Free-Vibration Analysis of Epoxy-based Cross-Ply Laminated Composite Folded Plates Subjected to Hygro-thermal Loading

Abstract

This research involves free-vibration analysis of epoxy-based cross-ply laminated composite folded plate structures under hygro-thermal stresses. Finite element analysis has been employed with eight-noded Mindlin-type isoparametric plate elements and rotary inertia. A 6 × 6 transformation matrix is applied to transform the element matrices before assembling the system matrices. This requires implanting a small diagonal element representing in-plane rotation along the five usual displacements. Parametric studies have been performed for cross-ply laminated folded plate structure. All-edge clamped one- and two-fold folded plates are studied for variations in layup, hygro-thermal loads, crank angles and plate thicknesses. Results reveal that increasing hygro-thermal load reduces the stiffness of the structure considerably. Stiffer sections can withstand higher temperature and moisture content than thinner sections. Presence of ridge line in folded plates make the structure stiffer compared to flat plate and hence capable of resisting higher hygro-thermal load.