超声信号的非线性行为及应用

超声波检测技术广泛地应用于材料与设备的无损检测中.而表征材料与设备性能和缺陷信息的超声回波信号由于与传输介质、缺陷相互作用,再加上各信道中不同种类的噪声介入,变得非常复杂.充分理解和认识超声信号中的非线性行为,对材料和缺陷检测与评估有重要意义.本文以海底管道检测为背景,以缺陷的脉冲超声回波信号为研究对象,通过替代数据法和统计特征量方法,从时域的角度检验了超声信号中的非线性行为特性.通过大量的试验数据分析表明,超声信号中存在明显的非线性行为,而且这种非线性不是由测量过程中测量函数引起,而是由系统本身产生的,即由超声波与目标体相互作用而产生.论文还就超声信号中蕴涵的非线性特征的应用和前景进行了分析和展望.为更深入地认识和利用这些超声信号提供了一种手段.

Nonlinear Behavior of the Ultrasonic Signal and Its Application

Ultrasonic testing technology has been extensively used in non-destructive testing of materials and equipments. The ultrasonic echoes, which indicate the performances of the materials and the information of the flaws, are greatly complicated, because of their noises and the interaction between the ultrasonic wave and the transmitted medium, the flaw among them. To understand the nonlinearity possessed in the ultrasonic echo is greatly important and significant for the testing and evaluation of materials and flaws. This paper, with the background of offshore pipeline ultrasonic inspection, investigates the nonlinear behavior of the ultrasonic signal from the angle of time domain using the methods of surrogate data test and statistical vectors. The results show that there exist distinct nonlinearity in the ultrasonic signals, and also indicate that the nonlinearity is generated not by the testing function, but by the dynamic system, that is to say, the nonlinearity is generated by the interaction between the ultrasonic wave and the reflector. The paper also analyzes the applications and prospects of the nonlinear features.