Problems of Aviation Gear Dynamics

Abstract

The relevance of gearing dynamics study increases with the development of gear drive designs: increasing their speed and specific transmitted load. As for the standard techniques, the question of dynamic load assessment in gears is considered partially and requires considerable improvement. The article describes the well-known types of failures and consequences of high dynamic loading during operation of aircraft engine gearboxes. A review of the existing assessment methods of gearbox dynamics is carried out, and an original approach to dynamic processmodeling in gears, determining dynamic loads and natural vibration frequencies, based on the experience analysis of the breakdowns and development of highly loaded aircraft gears, is proposed. Recommendations for reducing gearing vibration activity at the design stage are formulated, as well as qualitative approaches to transmissiontechnical condition analysis on the basis of vibration diagnostic methods. A dynamic model of a spur gear, considering variable meshing stiffness as the main source of torsional vibration excitation and dynamic loads, is described. Meshing stiffness function analysis for a pair of gears by means of the finite element method (FEM) makes it possible to assess the influence of tooth geometry parameters, including microgeometry, for example, profile modification. The developed dynamic model is used to develop recommendations for noise and vibration level reduction in spur gears, and for diagnostic feature of fatigue crack propagation in the tooth fillet. The dynamic model was validated in experimental studies on the test bench of CIAM withgear dynamic strain-gauging.