Instability analysis of rotating delaminated tapered composite plates

Tapering in composite structures is introduced by dropping off the plies to yield ta structural properties. The structures need to be stiff at one location, where large displacements are experienced and flexible at the other location for many engineering applications such as wind turbine blades and helicopter rotor blade. A rotating thickness tapered composite plate is subjected to periodic in-plane load and become dynamically unstable for certain combinations of load and excitation frequency. The various effects due to the rotation of the plate such as Coriolis acceleration, the initial stress stiffness, the vibratory displacement dependent additional stiffness and delamination modelling have been considered. The validity of the developed finite element formulation is demonstrated by comparing the results in terms of natural frequencies derived from the present finite element formulation with literature and with the experimental measurements. Various parametric studies are performed to investigate the effects of setting angle, hub radius, rotational speed and periodic load on the vibration responses and instability regions of the rotating delaminated tapered composite plates