Elastoplastic modelling of subsurface crack growth in rail/wheel contact problems

Abstract

A B S T R A C T Propagation of small subsurface cracks subjected to shear under repeated rolling contact load is studied. An analytical crack model (Dugdale) with plastic strips at the two crack tips is employed. Compressive stresses promoting crack closure and friction between crack faces are considered. The triaxial stress state is used in the yield criterion. A damage criterion is suggested based on experimental LCF data. In a numerical study, critical crack lengths are found below which propagation of an existing crack should be effectively suppressed.Keywords crack propagation; strip-yield model; subsurface crack.crack length including plastic zone (mm) D = ductility (−) E = elastic modulus (GPa) f = coefficient of friction between crack faces (−) G = shear modulus (GPa) K II = mode II stress intensity factor (MPa √ m) n = number of loading cycles N = number of loading cycles to failure p = contact pressure or pressure perpendicular to crack (MPa) p 0 = maximum pressure under contact load (MPa)s = arc length co-ordinate along crack face (mm) t d = thickness of plastic zone (mm) u 1 , u 2 = displacement along crack of upper (1) and lower (2) crack face (mm) v = speed of rolling contact load (m s −1 ) Oxyz = local co-ordinate system at crack O x y z = global co-ordinate system for rolling contact x p = horizontal position of rolling load (mm) z c = vertical position of crack (mm) γ = shear strain (−) K II = range (i.e. double amplitude) of mode II stress intensity factor (MPa √ m) K II,th = threshold value of mode II stress intensity factor (MPa √ m) ε = normal strain (−) ε = range (i.e. double amplitude) of normal strain (−) µ = friction coefficient in rolling contact zone (−)

Investigation of rail damage considering impact at a welded joint under wet condition

“…Furthermore, Lu et al (2018) specifically focused on fatigue in rail-welded joints, finding that shorter and deeper welds are associated with more severe fatigue damage. LundEN (2007) established an elastoplastic model of subsurface crack growth, through which they identified the critical crack length that effectively inhibits the expansion of existing cracks. Mazzù et al (2018) conducted experiments on a twin-disc test rig, studying The present work has been supported by the National Nature Science Foundation of China (No.…”