Reduction of thermal effect on rail stress measurement based on magnetic Barkhausen noise anisotropy

High-speed railway and seamless track acquire quick and accurate method for stress measurement and evaluation. Magnetic Barkhausen noise (MBN) is considered appropriate to measure the stress state of rail track. But the temperature variation not only produces thermal expansion or contraction but also affects the Barkhausen jumps at the same time. Based on the theory of thermal effect on magnetic properties, the longitudinal RMS of MBN signals divided by the transverse RMS, called longitudinal and transverse ratio (LTR), is proposed as a new feature for track stress measurement to decrease the thermal effect on MBN signals. This new feature shows the same sensitivity as RMS, the traditional feature, and stability to temperature variation. With an on-site case study for verification LTR is proved robust in evaluating the track thermal stress accurately.