板类结构非对称缺陷的超声兰姆波衍射层析成像方法研究

项目名称： 板类结构非对称缺陷的超声兰姆波衍射层析成像方法研究

项目编号： No.11274226

项目类型： 面上项目

立项/批准年度： 2013

项目学科： 数理科学和化学

项目作者： 张海燕

作者单位： 上海大学

项目金额： 89万元

中文摘要： 鉴于目前国际上基于对称缺陷理想模型的兰姆波衍射层析成像忽略了模式耦合的影响，本项目提出更接近实际板类结构缺陷的兰姆波衍射层析成像的理论和测试方法。针对板中某种非对称缺陷如盲孔：从理论上研究兰姆波与缺陷相互作用发生散射和模式转换的传播机理，实现兰姆波散射声场的高精度快速求解；建立Born近似下兰姆波散射波谱与描述缺陷的目标函数之间的关系，形成有效的缺陷参数反演和图像重建的基础；发展有效的反演算法以适用近场散射模型和不完全投影数据的图像重建；突破目前单参数反演的局限性，实现对缺陷尺寸和严重程度的同时重建。从实验上研究兰姆波信号的激发、传播和最佳接收。从技术和方法上研究衍射层析成像在非对称缺陷兰姆波检测中应用的基础和条件，以及多模式兰姆波散射信号的识别、提取和处理。本项目将兰姆波衍射层析成像推向一个新的层次，为非对称缺陷的兰姆波定量无损评价提供一种新思路和理论依据，具有重要的科学意义和应用前景。

中文关键词： 兰姆波；衍射层析成像；非对称缺陷；定量无损评价；

英文摘要： In view of Lamb wave diffraction tomography for an idealized model of symmetric defects currently ignoring the mode coupling effects, this project presents a theoretical and experimental investigation of Lamb wave diffraction tomography for defects that are most likely to be found in practical plate-like structures. For some asymmetric defects such as blind holes in plates, the scattering and mode conversion mechanism of the interaction of Lamb waves with defects is theoretically studied so as to realize fast high-precision solution to Lamb wave scattering acoustic field. The relationship between scattering spectrum and objective function characterizing defects under Born approximation is established, which forms the basis for efficient parametric inversion and image reconstruction. Linear inversion algorithm is developed to adjust the near-field scattering model and image reconstruction of incomplete projection data. This project will break through the limitation of the current single parameter inversion, enabling the simultaneous reconstructions of the defect size and severity. The excitation, propagation and best reception are experimentally studied. The foundation and conditions of Lamb wave diffraction tomography used for asymmetric defects and the recognition, extraction and processing of multimode Lamb wa

英文关键词： Lamb waves；dffraction tomography；asymmetric defect；quantitative nondestructive evaluation；