扫描投影云纹技术及其应用

The reliability and safety during running of large structure in aerospace, nuclear power and other fields are the key issue that needs to be solved urgently. Their out-of-plane displacement when loaded is one of the most intuitive and effective parameters. However, full-field testing technology of high-precision and high-resolution on oversized structure (feature size more than 10m) is very rare in the domestic and foreign at this moment.. The scanning projection moiré technology in this project firstly images the specimen grating onto the reference grating plane by using high resolution optical imaging system to form spatial low-frequency moiré fringes. Then the moiré fringe is imaged again. Through step-by-step imaging, the distortion of high density grid lines on object surface is converted to the change of spatial low-frequency moiré fringes. In this way, the measurement resolution is improved. Secondly, sequence moiré and global deformation field reconstruction techniques are applied to study multi-angle scanning projection technology to expand the measurement range. Resolution better than 50μm is expected when the measurement area reaches 10m×3m by solving the problems of system integration, optical path design, components configuration, sensitivity coefficient, error analysis and system calibration. This research result will improve the experimental level in deformation testing of huge area of our country, and provide theoretical and technical support for evaluating the reliability and safety of important equipment.

航天航空、核电等领域各种大型结构运行的可靠性、安全性是急需解决的关键问题，它们承载时的离面位移是反映其运行状态最直观、最有效的参数之一，但目前针对超大型结构全场离面位移高分辨率测试技术非常少见。.本项目所研究的扫描投影云纹技术，首先应用高分辨成像光学系统将试件栅成像到参考光栅平面，与参考栅叠加形成低空间频率moiré条纹；然后对moiré条纹进行第二次成像。通过分步成像，把物体表面高密度栅线的畸变转化为第二次成像所采集低空间频率moiré条纹的变化，以提高测量分辨率。其次应用序列云纹和全域变形场重建技术，研究多视角扫描投影技术以扩大测量范围。并进行系统集成，完成光路设计、元器件配置、灵敏度系数、误差分析和标定等，实现测量面积达到10m×3m以上、分辨率优于50μm的全场离面位移测试技术。该成果将提升我国在超大面积变形测试的水平，为重大装备运行的可靠性、安全性评估提供理论和技术支持。

本项目面向超大型结构全场离面位移的高分辨、高精度测量难题所提出的扫描投影云纹方法，提出适合转动和平动扫描的虚拟云纹模型及标定方法、自适应投影云纹方法、接收系统两级成像模型以及适合大景深、大面积测量的强非线性云纹模型，全面完成了项目任务书中的内容，取得的主要成果如下：.（1）提出了适合扫描测量的虚拟云纹模型，并研究了转动和平动两种扫描方式、图像拼接，实现了保持未扫描单图像测量精度和分辨率情况下将测量范围成倍增加。（2）提出了自适应投影云纹概念，即以最终形成云纹图像的相位分辨率为目标，优化投影栅线的栅距。通过投影栅线编码方法研究，能够在大测量范围上分辨率、精度基本一致的自适应投影云纹图像。（3）提出了一种两级成像模型：第一级成像模型描述了由世界坐标系经过广角镜头到光栅坐标系；第二级是从参考光栅坐标系到成像相机像素坐标系，用针孔相机模型所描述。标定误差有了量级的降低。（4）针对云纹图像存在畸变导致明显的重建误差，建立了一种通用的强非线性的云纹模型，能够适用于多种测量场景，鲁棒地精确地实现高精度的相位提取，解决大面积、大景深以及镜头严重畸变时的三维形貌测量。（5）研究了不同外力作用下各类复杂结构的离面位移响应的解析方法和相应的理论解，如层合结构离面位移响应的理论解、3D屈曲结构的离面位移响应特性、功能梯度结构离面位移的非线性响应、压电层合结构离面位移的响应特性、热效应对功能梯度结构离面位移非线性响应的影响以及表面特性和结构阻尼对离面位移稳定性的影响等。