Mixed mode crack tip parameters for different wheel positions relative to a vertical crack at the rail foot

Abstract

Finite element method is used to analyze a rail with a vertical bottom up crack at its foot, under the axle load and surface traction of a wheel. The possibility of crack formation at the foot of the rail in the neighborhood of a welding connection is discussed. A brief review on the importance of T‐stress in brittle fracture is presented. Seven cases with different locations of the crack relative to rail's sleeper contact region are considered. Numerous positions of the wheel are considered, and in each case, 3 crack parameters KI, KII, and T‐stress are calculated. Then, the biaxiality ratio and the mixity parameter for each loading and crack condition are calculated. It is shown that the location of crack and wheel can create mixed mode loading in the cracked rail and that the magnitude of crack tip parameters are strongly dependent on these geometric variables. In particular, the magnitudes of T‐stress and biaxiality ratio are significant in some cases. The effect of friction between the crack faces in the presence of compressive mode I loading on the mode II stress intensity factor is studied. Under mixed mode loading, due to the axle load and surface traction, the most critical condition is the formation of vertical cracks near the sleeper contact region.

Mixed mode I+II fracture parameters and cracking trajectory of heterogeneous multilayer pavement structure containing reflective crack

“…They simulated pavement layers as 3‐D and predict fracture parameters. In other research, Ayatollahi et al 60 used finite element method to analyze a rail with a vertical BUC at its foot. Crack formation at the foot of the rail in the neighborhood of a welding connection was probe in this study.…”

Crack initiation characteristics of brittle materials with I‐II mixed mode crack under uniaxial compression

“…As a constraint parameter, T-stress can be employed to reduce the conservatism of fracture toughness assessment, 1 which has the influence on critical kinking angle and apparent fracture toughness of material. 2 In addition, T-stress has a significant influence on the size and shape of plastic zone ahead of crack tip, 3,4 as well as crack propagation path [4][5][6] and crack propagation model.…”