Dynamic analysis of axisymmetric vector nozzle mechanism considering clearance joints and flexible component

The axisymmetric vector nozzle is a critical component of aircraft engines. Its moving mechanisms exhibit hinge clearance and structural flexible deformation during manufacturing, assembly, and operation. These nonlinear factors significantly influence the nozzle's dynamic performance. This study aims to establish a high-precision rigid-flexible coupled multi-body dynamics model that comprehensively considers hinge clearance and component flexibility, revealing their mechanisms of action on nozzle motion accuracy and dynamic response. The innovation lies in employing an absolute node coordinate method, a Flores contact force model, and an improved Coulomb friction model to construct a nozzle mechanism model incorporating clearance hinges and flexible triangular tie rods. Experimental validation confirms the model's effectiveness. Simulation results indicate that hinge clearance induces lag in the expansion blade motion response, significantly reducing deflection efficiency; while component flexibility also reduces motion precision, its negative impact is less than that of clearance; flexible components can partially absorb high-frequency vibrations caused by clearance collisions, resulting in smoother velocity responses. Furthermore, the coupled effects of external loads with clearance and flexibility further increase driving resistance. This study provides important references for the dynamic design and analysis of nozzle mechanisms.