Nucleation of squat cracks in rail, calculation of crack initiation angles in three dimensions

11th International Conference on Damage Assessment of Structures

物理学;材料科学

Naeimi, Meysam^1 ; Li, Zili^1 ; Dollevoet, Rolf^1

Section of Railway Engineering, Faculty of Civil Engineering and Geoscience, Delft University of Technology, Delft, Netherlands^1

关键词: Crack initiation angles;    Crack initiation mechanisms;    Explicit finite element analysis;    Loading condition;    Modelling and experiments;    Multi-axial fatigue;    Nonlinear material properties;    Numerical estimation;   

Others  :  https://iopscience.iop.org/article/10.1088/1742-6596/628/1/012043/pdf
DOI  :  10.1088/1742-6596/628/1/012043

学科分类：材料科学（综合）

来源: IOP

【 摘 要 】

A numerical model of wheel-track system is developed for nucleation of squat-type fatigue cracks in rail material. The model is used for estimating the angles of squat cracks in three dimensions. Contact mechanics and multi-axial fatigue analysis are combined to study the crack initiation mechanism in rails. Nonlinear material properties, actual wheel-rail geometries and realistic loading conditions are considered in the modelling process. Using a 3D explicit finite element analysis the transient rolling contact behaviour of wheel on rail is simulated. Employing the critical plane concept, the material points with the largest possibility of crack initiation are determined; based on which, the 3D orientations/angles of the possible squat cracks are estimated. Numerical estimations are compared with sample results of experimental observations on a rail specimen with squat from the site. The findings suggest a proper agreement between results of modelling and experiment. It is observed that squat cracks initiate at an in-plane angle around 13°-22° relative to the rail surface. The initiation angle seen on surface plane is calculated around 29°-48°, while the crack tend to initiate in angles around 25°-31° in the rail cross-section.