Mechanical Analysis Of Coupling System Of Pitch Bearing And Its Installation Structure In Wind Turbine

Wind power generation is an efficient way in dealing with the shortage of energy and the pollution of the environment.With the number of the wind power generators increasing quickly,the reliability problems of the wind power generators are becoming more and more prominent.As the key part of wind power generators' controlling system,slewing bearings' failure affects the reliability of all the wind power generation system.Therefore,it is necessary to research on the loads distribution in the wind turbine pitch bearing and the fatigue life of the bearings.These researches make great sense in improving the reliability of the bearings.In this paper,a reasonable mechanical model is established of the coupling system of the pitch bearing and its installation structure in the wind turbine.The law of the interaction between the parts of the coupling system is studied.And the fatigue analysis is carried out from the point of view of ring structural strength.Firstly,the wind turbine pitch bearing was introduced from aspects of the structural characteristics,the installation characteristics and stress characteristics.The coupling model of the wind turbine pitch bearing and its mounting structure was constructed.According to this model,the ring deformation and the loads distribution of the rolling elements were studied.The deformation of the pitch bearing and its mounting structure under exterior load was analyzed in detail.Secondly,effects of the mounted bolts on the bearing ring's load capacity have been studied.Laws of the load distribution on the rings and the bolts caused by bolt pretension were figured out.Laws of the ring deformation by bolt pretension and laws of the ring deformation caused by bolt quantity were analyzed.Laws of the maximum load on the rolling elements were also analyzed.The results show that with the increase of pre-tightening force,the maximum load of the rolling elements decreases,the bolt load increases and the load of each bolt tends to be balanced.Once again effects of the hardened layer on the pitch bearing's load capacity were researched.The FE analysis was carried out regardless of the effects of the hardened layer.Results of the FE analysis were compared with results calculated by basic theory.And the validity of this model is verified.The hardened layer was simulated with layering methods.According to the thickness of the hardened layer,laws of the internal stress with different thickness of the hardened layers were obtained.Effects of the thickness of the hardened layer on the bearing's capacity were analyzed.Results show that the thickness of hardened layer increases and the bearing capacity increases.Finally,the fatigue life of the ring structure was calculated from the fracture aspect of the ring.Results show that the ring bends repeatedly only considering the exterior force and this phenomenon happens especially obvious somewhere on the ring.Stress concentrates near the bolts.All cause the ring near the bolts to be the weakest.This is in accordance to the practical ring fracture.This article provides some theoretical bases for designing and producing a pitch bearing.