无缝钢轨中温度对应力非线性超声检测的影响

Effects of temperature on nonlinear ultrasonic testing of stress in continuously welded rails

研究了温度与应力共同作用下的非线性超声响应规律。构建了纵波在无缝钢轨内传播的数学模型,将传统原子间势能引入非线性波动方程,得到了无缝钢轨在自由状态及受约束状态两种情况下超声非线性系数随温度变化的函数关系。在理论分析的基础上,进行了无缝钢轨受约束时内部温度应力变化的实物模拟实验,获得的非线性系数变化趋势与理论预期相一致。研究结果表明:温度和应力都对固体介质非线性影响明显,介质非线性系数随着温度的升高而增大,随着内部压应力的增加而减小。因此,当利用非线性系数检测钢轨纵向应力时,需要对温度的影响进行补偿。

The nonlinear ultrasonic response to the co-action of temperature and stress is studied. A mathematic model is first developed to describe the propagating of ultrasonic longitudinal bulk waves in continuously welded rails(CWRs)by incorporating interatomic potentials into the nonlinear wave equation. The functional relationships describing how the nonlinear parameter changes under the influence of temperature, for both cases of free and constrained CWR are obtained. Experiments on CWR under thermal stress changes are carried out. The experimental results are found to be in good agreement with the theoretical expectation of nonlinear parameter variation trend. These results indicate that both of the temperature and stress have obvious influences on the nonlinear ultrasonic longitudinal waves propagating in solids. The nonlinear parameter of the medium is increased with the increase of temperature and decreases with the increase of internal compressive stress, suggesting that it is necessary to compensate the effect of temperature when using nonlinear parameter to detect the thermal stress in CWR.