金属腐蚀疲劳损伤的非线性Rayleigh表面波评价机理与表征方法研究

Key components which are applied in offshore oil, ship and aerospace industries are subjected to corrosion environment under high temperature and high humidity and impact of wave or wind at the same time. During service, corrosion fatigue damage will be a threat to safety of equipment operation. So realization of nondestructive detection for this damage has potential huge commercial value. Starting from nonlinear acoustics and damage mechanics, this project will investigate a evaluation technique for corrosion fatigue damage by nonlinear Rayleigh surface wave to build a relationship of nonlinear effect-micro-structures-macro-properties. Main content is shown: firstly, based on physical character of micro-crack observed in sample, a nonlinear modulation theory model of Multiple cracks is built and simulated. Secondly, a corrosion fatigue system and nondestructive detection platform of nonlinear Rayleigh wave are set up to realize evaluation and detection of corrosion fatigue in sample, combined with dual-tree complex wavelet transform. At last, research result of this project will promote and support application of nondestructive detection by nonlinear Rayleigh wave for metal corrosion fatigue by theory analysis and experimental method.

在海洋石油开采、船舶、航空航天行业，核心零部件长期工作在高湿度、高盐度的腐蚀环境下，并且同时承受海浪或者大风的冲击。在服役过程中，金属腐蚀疲劳损伤是威胁设备安全运行的重要因素，实现对该损伤的有效无损检测和评价潜在巨大的工业价值。本项目拟开展金属腐蚀疲劳损伤的非线性Rayleigh表面波评价机理与表征方法研究，从非线性声学理论及损伤力学理论出发，构建非线性声学效应-材料微观结构-宏观力学性能三者的关系。主要涵盖：观测受损材料内部微裂纹物理特征，建立多微裂纹非线性调制作用的理论模型，并进行仿真计算；搭建腐蚀疲劳系统与非线性Rayleigh表面波检测平台，结合双树复小波变换信号处理手段，实现受损样品的检测与评价。本项目的研究成果将为推进非线性Rayleigh表面波评价与检测金属腐蚀疲劳损伤的工业应用提供理论支持与实验方法。

本项目以腐蚀疲劳损伤检测为目标，主要开展了以下研究内容：（1）建立了多裂纹的非线性声学理论模型，分析了声波与多裂纹区域非线性效应的产生机理；（2）建立了金属材料腐蚀疲劳损伤的非线性Rayleigh表面波检测理论，采用非线性声学参数表征腐蚀疲劳损伤的损伤程度；（3）采用电子扫描显微镜观测腐蚀疲劳损伤的微观结构，从微细观尺度角度建立了非线性声学效应-微观结构-宏观力学性能三者之间关系；（3）依托项目资金支持，搭建了非线性Rayleigh表面波检测平台，结合双高斯衰减模型信号处理手段实现了声信号降噪分析，提高检测系统的信噪比；（4）开展了激光超声检测技术的理论分析与研究，采用频域阈值现象实现金属材料表面缺陷的定量检测与分析，为微裂纹的高精度检测提出了一种非接触的检测方法。本项目研究成果为腐蚀疲劳裂纹的检测提供了可靠的理论研究模型与有效的检测方案。