A novel modeling framework for tiltrotor coupled drivetrain dynamics

The drivetrain system of tiltrotor aircraft is a complicated multibody system. Traditionally, rotorcraft drivetrain systems are modeled by the finite element method using an equivalent mathematical model with all the elements spinning at the same rotational velocity and structural properties scaled according to gear ratios. Such a process can be complex and computationally expensive, especially for large-scale problems. This paper proposes the dynamic analysis of a tiltrotor drivetrain, coupled with flexible blades’ lagwise motion, using a novel multibody system modeling and analysis method based on the transfer matrix method. The proposed method eliminates the need for equivalent processing of the drivetrain system components and does not require the derivation of the overall governing equations based on the Hamilton principle. Instead, they are directly formulated according to the system's topology graph. Virtual branch and geometric elements are introduced to decouple any topological structure of the drivetrain system into multiple independent chain systems, further reducing the modeling complexity.