基于迟滞应力应变关系的非线性声学检测理论与方法研究

Theory and method for nonlinear acoustics detection based on hysteretic stress-strain relation

本文将传统PM(Preisach-Mayergoyz)模型由一维介质拓展到二维介质,引入迟滞细观弹性单元概念,得到迟滞变化的应力应变关系.并采用一阶有限差分方程进行了声场计算和分析,发现空间声场中含有明显的高阶奇次谐波成分.对接收到的全波信号进行滤波、放大、时间反转后加载到接收换能器对应阵元上再进行发射,观察到高次谐波在微损伤区域实现聚焦.这为利用非线性高次谐波检测微损伤提供了可能的途径,也为疲劳损伤等缺陷的早期检测提供了理论和方法依据.

In this paper, PM（Preisach-Mayergoyz） model in one dimension is extended to two dimensions. Hysteretic stressstrain relation could be obtained when hysteretic mesoscopic elastic unit（HMEU） is considered.The sound field is calculatedusingafirst-orderfinitedifferenceequation, andthehigh-odd-orderharmonicwavescanbefoundapparentlyin the sound field. Then, the received full waves are filtered,amplified, time-reversed, and re-emitted through corresponding receiving transducers. The high-order harmonic waves focus on the micro-damage zone. So this method can be used to detect the micro-damages by nonlinear high-order harmony waves. Furthermore, it also provides a method of the early detection of fatigue damages.