采样云纹方法作为一种新兴的光学测试技术,利用数字图像处理进行光栅相位分析,可实现低成本、高效率、高精度的物体表面变形计量。该方法能灵活调整采样参数以满足不同场景的测量需求,与扫描电子显微镜(scanning electron microscopy,S...采样云纹方法作为一种新兴的光学测试技术,利用数字图像处理进行光栅相位分析,可实现低成本、高效率、高精度的物体表面变形计量。该方法能灵活调整采样参数以满足不同场景的测量需求,与扫描电子显微镜(scanning electron microscopy,SEM)结合,可以实现变倍视场下的变形分析。开展微尺度下高精度的采样云纹变形场测量,需要轮廓清晰、分布规则的光栅或点阵结构,对光栅制备工艺提出了较高的要求。为进一步拓展采样云纹在微尺度力学测量中的应用,本文介绍了采样云纹法变形测量的基本原理,并且发展了一种基于激光直写光刻的微尺度制栅方法。结合自行研制的高密度光栅,进行了镍基合金GH4169疲劳疲劳失效行为研究,表征了疲劳过程中损伤演化与裂纹闭合效应,研究结果表明采样云纹方法在微尺度变形场测量中具有很好的应用潜力。展开更多
为了探究力学研究中梁、板、柱等基本对象的力学性能,往往需要使用光力学方法对其进行变形测量。这些对象通常具有高长宽比、大尺寸及表面曲率较大的特点,常规的三维数字图像相关(Three-Dimension Digital Image Correlation,3D-DIC)方...为了探究力学研究中梁、板、柱等基本对象的力学性能,往往需要使用光力学方法对其进行变形测量。这些对象通常具有高长宽比、大尺寸及表面曲率较大的特点,常规的三维数字图像相关(Three-Dimension Digital Image Correlation,3D-DIC)方法无法满足高精度和全范围的测量需求,因此需要使用多相机数字图像相关(Digital Image Correlation,DIC)方法。针对不同对象的测量需求,多相机DIC方法需要使用不同的相机布置方法。本文分别研究了适用于梁、板、柱的一字型、矩阵型、圆周型的多相机布置方式,并通过实验测量验证了上述布置方式的可行性及有效性。使用多相机DIC方法,通过工字梁四点弯曲实验、板的热翘曲变形测量实验及薄壁圆筒抗压实验,得到了全场的高精度变形结果,并由此证实了多相机DIC可以通过不同的相机布置方式实现力学研究中全方位的测量需求。展开更多
Photomechanics is a crucial branch of solid mechanics.The localization of point targets constitutes a fundamental problem in optical experimental mechanics,with extensive applications in various missions of unmanned a...Photomechanics is a crucial branch of solid mechanics.The localization of point targets constitutes a fundamental problem in optical experimental mechanics,with extensive applications in various missions of unmanned aerial vehicles.Localizing moving targets is crucial for analyzing their motion characteristics and dynamic properties.Reconstructing the trajectories of points from asynchronous cameras is a significant challenge.It encompasses two coupled sub-problems:Trajectory reconstruction and camera synchronization.Present methods typically address only one of these sub-problems individually.This paper proposes a 3D trajectory reconstruction method for point targets based on asynchronous cameras,simultaneously solving both sub-problems.Firstly,we extend the trajectory intersection method to asynchronous cameras to resolve the limitation of traditional triangulation that requires camera synchronization.Secondly,we develop models for camera temporal information and target motion,based on imaging mechanisms and target dynamics characteristics.The parameters are optimized simultaneously to achieve trajectory reconstruction without accurate time parameters.Thirdly,we optimize the camera rotations alongside the camera time information and target motion parameters,using tighter and more continuous constraints on moving points.The reconstruction accuracy is significantly improved,especially when the camera rotations are inaccurate.Finally,the simulated and real-world experimental results demonstrate the feasibility and accuracy of the proposed method.The real-world results indicate that the proposed algorithm achieved a localization error of 112.95 m at an observation distance range of 15-20 km.展开更多
文摘采样云纹方法作为一种新兴的光学测试技术,利用数字图像处理进行光栅相位分析,可实现低成本、高效率、高精度的物体表面变形计量。该方法能灵活调整采样参数以满足不同场景的测量需求,与扫描电子显微镜(scanning electron microscopy,SEM)结合,可以实现变倍视场下的变形分析。开展微尺度下高精度的采样云纹变形场测量,需要轮廓清晰、分布规则的光栅或点阵结构,对光栅制备工艺提出了较高的要求。为进一步拓展采样云纹在微尺度力学测量中的应用,本文介绍了采样云纹法变形测量的基本原理,并且发展了一种基于激光直写光刻的微尺度制栅方法。结合自行研制的高密度光栅,进行了镍基合金GH4169疲劳疲劳失效行为研究,表征了疲劳过程中损伤演化与裂纹闭合效应,研究结果表明采样云纹方法在微尺度变形场测量中具有很好的应用潜力。
基金supported by the Hunan Provin〓〓cial Natural Science Foundation for Excellent Young Scholars(Grant No.2023JJ20045)the National Natural Science Foundation of China(Grant No.12372189)。
文摘Photomechanics is a crucial branch of solid mechanics.The localization of point targets constitutes a fundamental problem in optical experimental mechanics,with extensive applications in various missions of unmanned aerial vehicles.Localizing moving targets is crucial for analyzing their motion characteristics and dynamic properties.Reconstructing the trajectories of points from asynchronous cameras is a significant challenge.It encompasses two coupled sub-problems:Trajectory reconstruction and camera synchronization.Present methods typically address only one of these sub-problems individually.This paper proposes a 3D trajectory reconstruction method for point targets based on asynchronous cameras,simultaneously solving both sub-problems.Firstly,we extend the trajectory intersection method to asynchronous cameras to resolve the limitation of traditional triangulation that requires camera synchronization.Secondly,we develop models for camera temporal information and target motion,based on imaging mechanisms and target dynamics characteristics.The parameters are optimized simultaneously to achieve trajectory reconstruction without accurate time parameters.Thirdly,we optimize the camera rotations alongside the camera time information and target motion parameters,using tighter and more continuous constraints on moving points.The reconstruction accuracy is significantly improved,especially when the camera rotations are inaccurate.Finally,the simulated and real-world experimental results demonstrate the feasibility and accuracy of the proposed method.The real-world results indicate that the proposed algorithm achieved a localization error of 112.95 m at an observation distance range of 15-20 km.
