Effect of preloading on vibration and buckling responses of variable stiffness composite cylindrical shells

Composite cylindrical shell has been utilized in marine shipping industry as a reliable auxiliary wind propulsion device that can reduce fuel consumption. However, due to the special boundary constraints and complex loading cases, the vibration and buckling responses of such devices differ significantly from traditional cylindrical shells. The present research deals with the vibration and buckling behavior of composite cylindrical shells utilizing the promising variable stiffness (VS) concept. The effects of the preloading states and the design constraints were analyzed to explore the effectiveness of VS concept in cylindrical shell structures. Compared to constant stiffness (CS) composite cylindrical shells, VS cylindrical shells are less sensitive to variation in preloading states and geometric imperfections, and the buckling strength can be improved under some combination of loading sates. The effect of boundary constraints on stiffness and bucking strength is less prominent own to VS properties, in that stress concentrations near the end of the cylindrical shell structures can be smoothed out, and the strain distributions are spaced more evenly.