Composite Blade Twist Modification by Using a Moving Mass and Stiffness Tailoring

Abstract

In this paper, a new concept for morphing composite blades is proposed, and how this concept changes the twist distribution of the blade is explained. A change in the blade twist is obtained by adding a mass to the blade that produces an extra centrifugal force. This centrifugal force then may produce a moment that can change the blade twist via the extension–twist or bend–twist coupling of the composite lamination. These types of couplings are present in antisymmetrically and symmetrically laminated beams, respectively. The dynamics of the rotating composite blade is modeled by using the geometrically exact fully intrinsic beam equations. The concentrated mass is considered as a nonstructural concentrated mass that has offsets with respect to the beam reference line. The nonlinear partial differential equations are discretized by using a time–space scheme, the converged results are compared with those reported in the literature, and very good agreement is observed. It is found that, for an antisymmetric lamination, the spanwise location of the concentrated mass affects the twist, whereas in the symmetric case, the chordwise position of the concentrated mass is the source of twist change. It is also found that introducing the concentrated mass to a real blade can change the twist dramatically.