Structural characteristics of a propulsion mechanical system considering aeromechanical excitations

Abstract

This paper studies the structural dynamic characteristics of an essential mechanical vector device on airship, which is described as a capsule-wing-rotor system. The root flexibility of the capsule and the gyro-effect from the tip rotor are considered to be distinct factors relative to the previous traditional situations, and the inherent structural geometries are also incorporated for multiple parametric analyses. The governing equation is established by Hamilton’s principle, and the analytical solution and the numerical solution are derived by virtue of complex mode theory and Rayleigh-Ritz method, respectively. In case studies, the validity of the numerical solution is verified via a special error test technology. It is demonstrated that the boundary capsule flexibility, the gyro-effect and the system parameters all have great influences on the structural performance. The analyses indicate that the root flexibility tends to decrease the overall frequencies of the structure, and the gyro-effect strengthens the dimensional coupling of the structure intensely, leading to the occurrence of complicated complex-mode vibration phenomenon. The computations of critical boundaries under known aeromechanical excitations show that the design parameters used to stabilize the system are affected by the gyro-effect severely, demonstrating further optimization work for stability improvement is requisite.