Study of monitoring thermal stress in seamless welded rails with ultrasonic

This article describes a scheme of ultrasonic system which monitors thermal stress in seamless welded rails. This monitoring system is a non destructive testing system, which adopts digital processing as the core of it and adopts the critically refracted longitudinal wave as the object of measuring. The working principles of ultrasonic probehead and the critically refracted longitudinal wave sound interval measuring unit in this system are also introduced. In order to achieve the demands of railway, the system, which adjusts linearity and removes influence of temperature with system program, is presented, as to raise the accuracy of stress measurement.