Search

• A Voronoi finite element model for crack initiation life of RCF is built. • The coupling damage model considers the microstructure of material. • The impact mechanism of grain characteristics and material defects is revealed. The material microstructure of plays an important role in crack initiation of rolling contact fatigue. To address crack initiation of tapered roller bearings, the inhomogeneous characteristic of material is considered. The random distribution of material grains is simulated with Voronoi graph, and a Voronoi finite element model of rolling contact fatigue is given. Numerical analysis of damage-life constitutive relation is carried out with finite element analysis. The effect of material microstructure inhomogeneity on initiation life of fatigue crack is studied. Researches show that the smaller the grain size, the more difficult the fatigue crack appearing. The larger the difference of elasticity modulus between non-metallic inclusions and matrix material, the greater the impact on fatigue life of crack initiation. The angular and sharp non-metallic inclusions reduce fatigue life more than rounded shape inclusions. Initiation life of fatigue crack has a minimum value on a critical depth of nonmetallic inclusion. The longer distance between two laterally arranged inclusions, the greater it affect the initiation life of fatigue crack. The effect of distance between two vertically arranged inclusions on fatigue crack initiate depends on the depth of inclusions. [ABSTRACT FROM AUTHOR]

• The wear performance of the defected rail materials under various slip ratios and contact stresses was investigated. • The surface damage of the defected rail materials under various slip ratios and contact stresses was studied. • The effect of slip ratio and contact stress on crack propagation mechanisms near the dent was discussed. The defects on rail surface may have negative effects on the rolling contact fatigue (RCF) performance of the rail materials. This investigation researched on the RCF behaviors of the defected rail materials under various slip ratios and contact stresses. The results show that both the wear loss and the average crack length increase if the slip ratio or the contact stress increases. Moreover, the surface damage characteristics change from simple adhesion spots to significant fatigue crack grouping when slip ratio and contact stress rise. Finally, the experimental results also highlight that the slip ratio provides the deformation area for crack initiation whereas the contact stress accelerates the crack propagation by emphasizing the geometric effects. [ABSTRACT FROM AUTHOR]