基于非线性超声的无缝钢轨锁定轨温检测

针对基于非线性超声的无缝钢轨锁定轨温检测问题,理论分析了材料非线性系数在温度、应力变化过程中的变化情况,试验研究了温度与应力对自由状态及锁定状态下钢轨超声非线性系数的影响,得到了温度与应力共同作用下的非线性超声响应规律。研究结果表明:自由状态下钢轨中传播的超声非线性受温度影响明显,非线性系数随温度升高而增大,随温度降低而减小;锁定状态下钢轨中传播的超声非线性受温度与应力耦合作用,非线性系数在钢轨温度高于锁定轨温时随温度升高而增大,在钢轨温度低于锁定轨温时随温度降低而增大,在钢轨温度为锁定轨温时出现局部极值点。论文从理论和试验两方面证实了非线性超声可以检测无缝钢轨锁定轨温。

Detection of Stress-free Temperature of Continuously Welded Rails Based on Nonlinear Ultrasound

In order to detect the stress-free temperature of continuously welded rails(CWRs)by nonlinear ultrasonic technology,the variations of material nonlinearity parameters with the variation of temperature and stress were analyzed theoretically.Experiments about the effects of temperature and stress on the nonlinearity of ultrasonic waves in both cases of free and constrained rail were studied.The response law describing how the nonlinear parameters of ultrasonic waves change under the influence of temperature and stress was obtained.These experimental results indicate that the nonlinearity of ultrasonic waves propagating in free rail is affected by temperature obviously,and the nonlinear parameters increase with the increase of temperature and decrease with the decrease of temperature.The nonlinearity of ultrasonic waves propagating in constrained rail is under the coupling effect of temperature and stress,which shows that the nonlinearity parameters increase with the increase of temperature when the rail temperature is higher than the stress-free temperature,and increases with the decrease of temperature when the rail temperature is lower than the stress-free temperature.Local extreme point occurs when the rail temperature is stress-free temperature.This paper proves,in both theoretical analysis and experiments,that it is feasible to detect stress-free temperature in CWR by application of nonlinear ultrasonic guided waves.