Main Article Content
The flaws within flash-butt welded joint of a rail may occur during welding and/or operation. They may cause the damage of the welded joint of a rail. The size of flaw that allows the fatigue crack to propagate is defined as the critical initial flaw size. In the present work, the critical initial flaw size of flash-butt welded joint of a rail was studied using the linear-elastic fracture mechanics and finite element method. A semi-circular crack at the bottom surface of rail foot (i.e., the region with the maximum bending stress from wheel load) was selected to represent the flaw. It was observed that the stress intensity factor range of flaw equals to the threshold stress intensity factor range of rail steel, when the flaw size is approximately 2 mm (i.e., the critical initial flaw size). At this critical initial flaw, the propagation of fatigue crack is likely to occur. The finding can be beneficial to the railway engineering, and applied for the maintenance, and improvement of flash-butt welded joint.
ABAQUS User’s Manual. (2016). Abaqus/Standard. ABAQUS.
Beretta, S., Boniardi, M., Carboni, M., & Desimone, H. (2005). Mode II fatigue failures at rail butt-welds. Engineering Failure Analysis, 12(1), 157-165.
BS EN 13674-1: Railway applications - Track - Vignole railway rails 46 kg/m and above. (2002). In British-Adopted European Standard
BS EN 14587-1: Railway applications - Track - Flash butt welding of rails - Part 1: New R220, R260, R260Mn and R350HT grade rails in a fixed plant. (2007). In British-Adopted European Standard.
Cannon, D. F., Edel, K. O., Grassie, S. L., & Sawley, K. (2003). Rail defects: an overview. Fatigue & Fracture of Engineering Materials & Structures, 26(10), 865-886.
D 4.6.1. The influence of the working procedures on the formation and shape of the HAZ of flash butt and aluminothermic welds in rails. (2009). International Union of Railways (UIC).
Desimone, H., & Beretta, S. (2006). Mechanisms of mixed mode fatigue crack propagation at rail butt-welds. International journal of fatigue, 28(5-6), 635-642.
Iwafuchi, K., Satoh, Y., Toi, Y., & Hirose, S. (2004). Fatigue property analysis of rail steel based on damage mechanics. Quarterly Report of RTRI, 45, 203-209.
Kitagawa, H., & Takahashi, S. (1976). Applicability of fracture mechanics to very small cracks or the cracks in the early stage [Paper presentation]. Mechanical Behavior of Materials, American Society for Metals, Metals Park, Ohio.
Lewis, R.& Olofsson, U. (2009). Wheel-rail interface handbook. Elsevier.
Maya-Johnson, S., Ramirez, A. J., & Toro, A. (2015). Fatigue crack growth rate of two pearlitic rail steels. Engineering fracture mechanics, 138, 63-72.
Ozakgul, K., Piroglu, F., & Caglayan, O. (2015). An experimental investigation on flash butt welded rails. Engineering Failure Analysis, 57, 21-30.
Suresh, S. (1998). Fatigue of materials. Cambridge university press.