Effect of Multiple Defects and Multi-component Failure on the Dynamic Behaviour of a Wind Turbine Gearbox

In the present investigation, a mathematical model is proposed to simulate and examine the dynamic acceleration response of a three-stage spur gearbox. The time-varying gear mesh stiffness (GMS) is estimated based on potential energy method where GMS is given as an input to the lumped parameter-based dynamic model of the three-stage gear box. Here, this dynamic model approximates the physical system with a connected network of concentrated masses and spring systems via 36 degrees of freedom. Further, single-component failures, namely pinion tooth root crack and tooth breakage with various severity levels, are approximated individually in the system. Also, multiple defects (root crack and tooth breakage together) and multi-component failures (pinion tooth failure of each speed stage) are also approximated. The influence of nucleation of defect on the internal excitations of the gear–pinion pair, i.e. on the time-varying GMS, is studied. It is observed that there is a reduction in the values of GMS and amplitude with the existence of pinion tooth defects. The response simulated through the dynamic model is validated with the experimental data, and the results are in good agreement. The proposed analytical model provides few design guidelines for maintenance engineers in identifying the early failures in the system.