Dynamic Analysis of Bevel Gear in Presence of Local Damage in NonStationary Operating Conditions

Most of the researches describe models of gearboxes under stationary operating conditions. However, considering the real situation, the assumption of stationarity cannot be kept longer because during service, gearboxes usually run under fluctuating load conditions. The purpose of this chapter is to study the influence of time-varying loading conditions on a spiral bevel gear dynamic behavior in presence of a local damage. The speed–torque characteristic of the driving motor is considered. The load variation induces speed variation, which causes variation in the gearmesh stiffness period. Using an implicit Newmark’s time-step integration, the dynamic response shows impulses corresponding to the meshing of the cracked tooth; their amplitude level depends on the amplitude of the load. In order to put in evidence the time-varying load effects, spectral analysis is unsuited and time–frequency analysis is used instead. The horizontal lines over wide frequency band corresponding to each mesh period of the defected tooth are observed.