Node-Dependent Kinematics and Multidimensional Finite Elements for the Analysis of Single/Double Swept, Composite Helicopter Blades

This paper deals with finite element analysis of helicopter blades with single and double swept geometries made by metallic and composite materials. First, classical and refined beam theories are combined at the element level via a nodedependent kinematic (NDK) concept, which was recently introduced by the authors. Such an NDK approach enables the accuracy/efficiency ratio of the solution to be tuned according to the level of fidelity required by the design phase. Second, one-dimensional NDK models are combined with the possibility to introduce solid elements in those regions of the blade with a sharp variation of the geometries. The numerical examples consider a swept-tip rectangular beam and a doubleswept helicopter blade with a realistic airfoil. Natural frequencies and through-the-layer stress distributions are reported to demonstrate the flexibility and computational efficiency of the proposed methodology.