| dc.description.abstract | As the most widely used type of gear transmission system, cylindrical spur gears areprone to generate crack failure during service. Previous studies have shown that crack failurehas a significant impact on the vibration characteristics of spur gears. It is necessary to
analyze the relationship between crack failure and dynamic behavior of transmission system,and to clarify the quantitative relationship between degree of failure and dynamic characteristics of transmission system in order to ensure the operation safety of the gear
transmission system. In view of this, this paper takes cylindrical spur gear as the research object to study the vibration characteristics of transmission syst em with crack failure.
Firstly, taking the time varying meshing stiffness, backlash, bending and torsion effect of the rotor and the flexibility of the box support into account, and comprehensively considering the coupling relationship among the gears, the rotor, the bearing and the box, a rigid flexible coupling non linear dynamic model of a 12 degree of freedom cylindrical spur gear transmission system is established. The dynamic equation of this kind of transmission system is solved by Runge Kutta method to obtain the steady state response of the system. The
analysis shows that the relative dynamic displacement of gear pair along the meshing line has the largest amplitude at the first order meshing frequency, while the vibration displacement of gear and b earing has the largest amplitude at the third order meshing frequency. The relevant results provide a mechanical basis for vibration suppression of gear transmission system.
Secondly, based on the potential energy method, the time
varying meshing stiffness of spur gear pairs with root crack and reference circle crack failure is deduced, and the percentage of crack depth is proposed as an index to characterize the degree of crack failure.
On the basis of this,the effects of root crack and reference circle cr ack failure on the time varying meshing stiffness of gears are further compared, and the differences between them are analyzed. The non linear dynamic model of spur gear transmission system with
crack failure is established by combining the meshing stiffne ss model with gear crack failure
with the established non linear dynamic model of gears, and the influence of crack failure on
the dynamic characteristics of transmission system is investigated. In addition, the failure
mechanism of crack failure is furthe r analyzed. Dimensionless indexes such as kurtosis,
margin factor, peak factor and pulse factor are introduced as criteria for judging the degree of
failure, which provides a reference for early warning of failure of gear system.
This research can provide theoretical basis for on line monitoring and failure diagnosis of gear transmission system, and has certain engineering application value.
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Keywords: spur gear
Keywords: spur gear,, nonlinear dynamicsnonlinear dynamics,, crack failurecrack failure,, fault diagnosisfault diagnosis,, meshing stiffnessmeshing stiffness | en_US |