用于树脂复合材料内部三维变形测量的先进光学相干层析成像方法研究

Polymer composites are important materials widely used in aerospace equipment. To study their mechanical property and damage evolution, effective characterization methods are required. As a high resolution and high sensitivity three-dimensional full-field deformation measurement method, optical coherence tomography (OCT) meets the basic requirements of non-uniform anisotropic mechanical property investigation of polymer composites. But for the specific requirements of mechanical testing and characterization, it is necessary to overcome the deficiency of conventional OCT. This project plans to develop an advanced OCT method for measuring internal three-dimensional deformation of polymer composites with performance of multiscale, high precision and high speed. The specific contents include: 1) establish a computational imaging based three-dimensional parallel detection OCT system, for acquiring internal three-dimensional information with high precision and high speed; 2) develop a novel deformation reconstruction algorithm by combining techniques of digital volume correlation and phase sensitive, for realizing millimeter - micrometer - nanometer scale and high precision deformation reconstruction; 3) verify the reliability of the method by measuring standard samples, and explore the applications of OCT by measuring various materials/structures under different loads.

树脂复合材料是目前航空航天设备中广泛使用的重要材料，其力学特性和损伤演化机制的研究需要相应的测试手段提供有效的实验依据。光学相干层析(OCT)作为一种具有高分辨率、高灵敏度的材料内部三维全场变形测量方法，能满足复合材料内部非均匀各向异性力学特性研究的基本要求。但针对力学表征与测试的具体需求，还应克服目前OCT方法存在的不足。本项目拟研究一种先进光学相干层析成像方法，为实现复合材料内部三维变形的多尺度、高精度和快速测量。具体研究内容包括：1)建立一种基于计算成像的三维并行OCT系统，实现材料内部三维信息的高精度快速获取；2)发展一种数字体图像相关和相位敏感相结合的变形场重构新算法，实现毫米-微米-纳米尺度变形场的高精度重构；3)通过对标准样件和多种材料/结构样件在不同载荷下进行实验测量，验证和探索方法的可靠性及具体适用范围。

面向复合材料内部各向异性力学行为表征的需要，本项目提出研究材料内部变形场测量的新型光学相干层析成像方法。项目主要成果总结如下：1）搭建了一套线场谱域光学相干层析成像系统并开发相关软件，实现了微米级层析分辨率、毫米级深度量程的层析成像和变形场测量；2）提出了一种可辅助光学相干层析成像的荧光数字图像相关方法，可在层析变形场测量过程中实时监测表面全场应变测量结果，被国际同行评价为“the great work”；3）结合聚合物/复合材料固化过程的物理模型，在国际上首次提出一种材料内部固化过程的可视化监测方法，成果受到美国物理联合会《科学之光》AIP Scilight的专访报道；4）对光学相干层析成像技术在实验力学领域的应用进行了综述，指出方法目前仍存在被测对象、成像速度、重构算法等三个方面局限性，为项目后续研究指明方向。