Structural Analysis Of Stiffened Thin-walled Rotor Blade For Heavy-lift Helicopter

Stiffened thin-walled Structures are characterized by shells which are integrally stiffened by a series of ribs or stiffeners arranged in combinations of lateral, longitudinal and angular patterns. Such configurations possess excellent resistence to damage, delamination and crack propagation while exhibiting high stiffness to weight ratio. In aerospace, though the stiffened thin-walled Structures are commonly used in fuselage structures, wing structures and space vehicle structures, they are not used in conventional rotorblade structures.The large size, heavy load and high stiffness to weight requirement make it impractical to employ the conventional monocoque spar designs to the heavy-lift helicopter rotorblades. Thus it is very important for the development of heavy-lift helicopters to study new rotorblade structures with high stiffness to weight ratios. Considering the potential advantages of stiffened thin-walled Structures, by means of the finite element method,the design method of using stiffened thin-walled Structures for heavy-lift helicopter rotorblades is investigated in the present study. At first, the general purpose finite element code Patran is employed to creat the models of D spars of heavy-lift helicopter rotorblades with stiffened lays, axial stiffeners and helical stiffeners; Then, the analytical solution code Nastran is used to calculate the structural behaviors of these D spars under axial, bending and torsional loads to get their stiffness to weight ratios; Finally, the stiffness to weight ratios of these D spars are compared and analyzed. It is demonstrated that the stiffened thin-walled Structures can be used for heavy-lift helicopter rotorblades and increase the stiffness to weight ratios of rotorblades effectively.