Infrared temperature measurement of wheel-rail frictional rolling contact with high slip ratios

Thermal loading from wheel-rail frictional heat accelerates wear, plastic deformation, and fatigue, especially at high contact temperatures. Accurate wheel-rail contact temperature measurements, especially under operational conditions, are essential to understand and prevent thermal damage. Existing studies have mostly focused on lower temperatures (below 200 °C), leaving higher, damage-causing temperatures underexplored. To address this limitation, this work utilizes a unique V-Track test rig and a novel high-precision infrared thermal measurement system to generate and continuously measure the high temperatures (maximum 1200 °C) induced by wheel-rail dynamic contact. A wheel braking process was simulated by applying a controllable negative wheel torque, generating slip ratios from 2% to 99%. Emissivity calibration of the V-Track rail samples was conducted to ensure measurement accuracy. Test results revealed that the wheel-rail contact temperature generally rose with slip ratios, reaching up to 1000 °C at a slip ratio of 99%. At a slip ratio of 40%, a “wheel flat” formed with a contact temperature of approximately 624 °C, followed by a rapid drop as the “wheel flat” exited the contact area. This advanced testing system is capable of both generating and precisely measuring high temperatures at the rolling interface, offering insights into thermal damage mechanisms and demonstrating the potential for calibrating and validating thermal contact and damage numerical models. • Generated transient high contact temperatures in realistic application conditions. • Measured the contact temperatures continuously and contactlessly up to 1200 °C. • Generated a “wheel flat” at the wheel-rail contact temperature of 624 °C. • Captured the wheel flat cooling process that follows an exponential decay. • Enhanced the understanding of wheel-rail thermal loading and damage mechanisms.