The Effect of Material Static Mechanical Properties on the Fatigue Crack Initiation Life of Rail Fastening Clips

Abstract

This paper aimed to study the effect of material static mechanical properties on the fatigue crack initiation life of ω-shaped rail fastening clips, in which the Vossloh 300-1 fastener system was taken as an example. The static mechanical properties of 38Si7 steel (the material of the clip) were first investigated through a series of uniaxial tensile tests. According to the experimental outcomes, a classic assembly system was simulated afterwards using the finite element analysis (FEA) method. On the basis of the Brown–Miller criterion, an in-depth numerical study regarding the critical plane was realized, which allowed fatigue crack initiation to be successfully reproduced by FEA. Finally, a detailed parametric study was performed with the relevant sensitivity analysis. The results showed that the initiation and progression of fatigue cracks in the fastening clip occur in the plane of the maximum shear strain. The fatigue crack initiation life of the fastening clip was extremely sensitive to the elastic modulus, especially more sensitive to the tensile strength. From an engineering viewpoint, the fatigue resistance of the fastening clip could be boosted by (i) increasing the tensile strength of the material to at least 1450 MPa and (ii) rendering the elastic modulus smaller than 160 GPa.