Calculation analysis of yaw bearings with a hardened raceway. (August 2018)

• Record Type: Journal Article
• Authors: He, Peiyu; Hong, Rongjing; Wang, Hua; Ji, Xu; Lu, Cheng
• Is Part Of: International journal of mechanical sciences. Volume 144(2018)
• Page Start: 540
• Page End: 552
• Publication Date: 2018-08
• Subjects: Yaw bearing -- Hardened raceway -- Stress analysis -- Life analysis; Mechanical engineering -- Periodicals; Génie mécanique -- Périodiques; Mechanical engineering; Maschinenbau; Mechanik; Zeitschrift; Periodicals; 621.05
• DOI: 10.1016/j.ijmecsci.2018.06.016
• Languages: English
• ISSNs: 0020-7403

Abstract

Highlights: A quick method to analyze hardened raceway depth of yaw bearing is proposed. The maximum contact stress and half width of the contact area between ball and raceway are obtained according to the maximum contact load and the Hertz contact theory. Combining the 42CrMo material yield strength and the allowable equivalent stress of the core raceway, the relationship between the yaw bearing equivalent stress and the raceway hardened layer is obtained. Compared to the hardened layer depth specified in JB/T2300-2011, the effectiveness of the method calculating the hardened layer depth is verified. The maximum contact load between ball and raceway is obtained by non-linear spring finite element model instead of the solid ball model. Strain gauges are attached to the yaw bearing ring and get the relationship between the load and strain. Two results are compared to verify the effectiveness of the maximum contact load. Local contact ball and raceway finite element model is established. The elastic-plastic model of different layers of the hardened raceway is considered. The ball indentation experiment is used to compare and verify the correctness of the local contact ball and raceway finite element model. The combination of the theoretical life calculation and simulation life calculation provides the basis for analyzing the effect of hardened layers on the yaw bearing. The yaw bearing theoretical life calculation can take account of various influencing factors, such as the material characteristics, the raceway hardness, lubrication conditions, and the influence of the support structure. The fatigue life simulation using Fe-safe software can consider different load spectrum and find the minimum life area and distribution based on the life gradient. Different fatigue life calculation methods are mutually referenced to provide the basis for the optimal design of yaw bearings, which is beneficial to improve the yaw bearing load capacity and service life. Abstract: The yaw bearing is a key support structure of wind turbines and is often exposed to substantial complex loads that cause damage and fatigue failure. Raceway surfaces accommodate high contact stress and require a hardening treatment. The hardened depth has a great influence on both the carrying capacity and fatigue life. We establish a whole finite element model of a yaw bearing and use non-linear springs instead of a ball to obtain the maximum contact load. The results of a strain gauge experiment and an empirical formula are compared to verify the spring model results. A local finite element model of a ball and raceway with different hardened depths is established to analyse the stress distribution and fatigue life. The raceway is divided into a hardened layer, transition layer, and core layer. An indentation experiment verifies the raceway model with different layers. The stress results are compared with Hertz contact theory, and the fatigue life results are compared with yaw bearing fatigue life theory. The influence of different hardened depths on the stress and lifetime of yaw bearings is analysed. Graphical Abstract: Image, graphical abstract