Experimental and numerical calculation data of contact stiffness/Surface roughness/HPT

Understanding the dynamic condition of the interface between a railway
wheel and rail is important to reduce the risks and consider the
effectiveness of countermeasures for tribological problems. Traditionally
the difficulty in obtaining accurate non-destructive interfacial
measurements has hindered systematic experimental investigations. Recently
an ultrasound reflectometry technique has been developed as a direct
observation method of a rolling-sliding interface, however the topography
dependence under the high contact pressures in a wheel-rail contact has
not been clarified. For this reason, a novel in-situ measurement of the
contact stiffness using ultrasound reflectometry was carried out for three
different levels of roughness. A contact pressure equivalent to that in a
wheel-rail interface was achieved by using a high-pressure torsion test
approach. The dynamic change of contact stiffness with slip was measured
using ultrasound and the influence of roughness was investigated. The
measured changes were validated using a newly developed numerical
simulation, and mechanisms to explain the observed behaviour were proposed
in terms of fracture and plastic deformation of the asperity bonds. These
findings could help in understanding the traction characteristics for
different roughness conditions and also assist in understanding damage
mechanisms better, such as wear and rolling contact fatigue.