Finite element analysis of the wheel-rail impact behavior induced by a wheel flat for high-speed trains: The influence of strain rate

The wheel-rail impact response induced by a wheel flat for high-speed trains is simulated numerically, based on the strain rate-dependent constitutive parameters of wheel-rail materials, using the finite element software LS-DYNA explicit algorithm. Influences of the speed of the train, the length of the wheel flat, and axle load on the wheel-rail impact behavior are discussed over a wide range, in terms of the vertical impact force, von Mises equivalent stress, shear stress, and equivalent plastic strain. The maximum wheel-rail impact forces are 2.6-4.4 times greater than the corresponding static axle loads due to the presence of a wheel flat. The maximum von Mises equivalent stress and equivalent plastic strain have occurred on the wheel-rail contact surface, while the maximum xy shear stress has often occurred on the subsurface of 4-6mm below the contact surface. The wheel-rail impact responses induced by a wheel flat are sensitive to the speed of trains, flat length, and axle load. Besides, the strain rate effect of wheel-rail materials has a significant influence on the maximum von Mises equivalent stress, shear stress, and equivalent plastic strain, while it has no influence on the maximum vertical impact force. These findings are very helpful to guide the maintenance and repair of wheel-rail components in rail transport.