MODULAR MULTI-BODY MODELING METHOD FOR COMPLEX SHAPED BLADES OF HELICOPTERS

In order to improve the flight performance of helicopters and reduce vibration and noise, various complex shaped helicopter blades continue to emerge. This diversity of design poses new challenges to the unified modeling technology of helicopter blades. The traditional finite element modeling method requires the subdivision of elements and the derivation of some mathematical models for different blade shapes, resulting in more complex modeling. Therefore, in order to solve the problem of unified modeling of blades with different configurations, a modular based multi-body modeling method is proposed. This method divides the helicopter blade into multiple modules, and applies specific geometric constraints at the turning points of the non straight module for non straight blades. It can achieve shapes such as up reverse, down reverse, and swept, making it suitable for dynamic modeling of various shaped blades; In addition, modular multi-body modeling can decouple the coefficient matrices between modules, so that the addition or removal of modules only requires adjusting the matrix elements at the corresponding positions, without affecting the dynamic equations of other modules. Specifically, based on the D'Alembert principle, the generalized inertial force, generalized elastic force, and generalized active force of each module are derived; Then, based on the Kane equation, the dynamic equations of each module are obtained; Finally, by introducing displacement coordination conditions between modules, a system dynamics model in the form of differential algebraic equations can be obtained. The numerical results indicate that this method can achieve high-precision dynamic modeling of blades with different shapes.