Damage Detection in Gearboxes considering Intermittent faults and Time-Varying Loads

The paper develops a simplified two-degree-of-freedom gear model that simulates vibration signals under operational conditions similar to those of wind turbine gearboxes. Nonlinear characteristics were included in the model in order to obtain more realistic results. The two types of faults examined in this study are common periodic gear tooth faults and intermittent gear tooth faults. The latter type of faults appears to be a novel idea in the condition monitoring field. Transient loads are also taken into consideration in this study since such loads are commonly observed in wind turbine systems, and make it even more difficult to detect damage. The analysis of the obtained signals is done using a relatively new method, the Empirical Mode Decomposition (EMD) that works well for nonstationary and nonlinear signals.