数字体积相关方法的开发与应用研究
发布时间：2018-09-17 11:41
【摘要】：全场位移／应变测量对实验力学非常重要,数字体积相关方法是真正三维全场变形测量的工具之一。本论文针对数字体积相关方法的开发、拓展和应用展开研究。1)利用牛顿爬山法、最小二乘法、三次B样条插值,自行开发一套数字体积相关算法。利用两组泡沫金属样品的CT数据,对算法进行了系统评测,发现所开发的数字体积相关算法有较好的表现。在没有噪音的理想情况下,数字体积相关算法的位移误差为0.0065 voxel;在有X-CT噪音的情况下,位移误差增加到0.008 voxel,应变误差增加到100με。通过模拟刚性平动测试分析数字体积相关方法的误差特点,发现误差主要来源于噪音和插值运算,其中插值主要影响其正确度,噪音主要影响其精确度。2)在已开发的数字体积相关算法基础上,提出了基于图像配准和基于位移梯度加性分解的两套异位数字体积相关方法。通过模拟平动、转动、平动转动耦合和单轴压缩变形实验对两种方法进行了评价。在小变形和小转动条件下,这两种方法有着和原位数字体积相关方法相似的精确度。两种方法各有优点,基于图像配准的异位数字体积方法可以计算大变形,基于位移梯度加性分解的异位数字体积相关方法更容易操作。两种方法相互补充,扩展了数字体积相关方法的应用范围。3)泡沫金属的出色性能使其具有重要的应用价值和研究意义。本研究通过异位数字体积相关方法定量表征开孔泡沫铝在四个不同压缩状态下的内部位移场和应变场,获得其在元胞级变形的演变规律。研究发现：位移场观察到的压缩变形是均匀的,但在应变场却观察到局部应变带的产生；应变值的空间分布和频率分布都显示了泡沫铝变形的异质性,而且该异质性与局部孔隙率没有相关性；在元胞尺度上,压缩、转动和剪切是同时增加的,这表明了泡沫铝变形模式的复杂性；由元胞变形导致的附近元胞转动是减轻应变集中的主要变形模式。
[Abstract]:Full-field displacement/strain measurement is very important to experimental mechanics. Digital volume correlation method is one of the real three-dimensional deformation measurement tools. This paper focuses on the development, development and application of digital volume correlation method. Pass algorithm. Using the CT data of two sets of foam metal samples, the algorithm is systematically evaluated. It is found that the developed digital volume correlation algorithm has a good performance. In the absence of noise, the displacement error of digital volume correlation algorithm is 0.0065 voxel, and the displacement error increases to 0.008 voxel with the presence of X-CT noise. Variable error is increased to 10096 And two sets of ectopic digital volume correlation methods based on displacement gradient additive decomposition are evaluated by simulating translation, rotation, translation-rotation coupling and uniaxial compression deformation experiments. There are advantages. The ectopic digital volume method based on image registration can calculate large deformation. The ectopic digital volume correlation method based on displacement gradient additive decomposition is easier to operate. The two methods complement each other and extend the application scope of the digital volume correlation method..3) the excellent performance of foam metal has important application value and research. In this study, the internal displacement and strain fields of open cell aluminum foam in four different compression states were quantitatively characterized by ectopic digital volume correlation method. The evolution rule of deformation at cellular level was obtained. It was found that the compressive deformation observed in the displacement field was homogeneous, but the local strain band was observed in the strain field. The spatial distribution and frequency distribution of strain values show the heterogeneity of the deformation of aluminum foam, and the heterogeneity is not related to the local porosity. At the cell scale, compression, rotation and shear increase simultaneously, indicating the complexity of the deformation mode of the aluminum foam, and the rotation of the nearby cell caused by cell deformation is mitigated. The main deformation modes of variable concentration.
【学位授予单位】：东南大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TB383.4
[Abstract]:Full-field displacement/strain measurement is very important to experimental mechanics. Digital volume correlation method is one of the real three-dimensional deformation measurement tools. This paper focuses on the development, development and application of digital volume correlation method. Pass algorithm. Using the CT data of two sets of foam metal samples, the algorithm is systematically evaluated. It is found that the developed digital volume correlation algorithm has a good performance. In the absence of noise, the displacement error of digital volume correlation algorithm is 0.0065 voxel, and the displacement error increases to 0.008 voxel with the presence of X-CT noise. Variable error is increased to 10096 And two sets of ectopic digital volume correlation methods based on displacement gradient additive decomposition are evaluated by simulating translation, rotation, translation-rotation coupling and uniaxial compression deformation experiments. There are advantages. The ectopic digital volume method based on image registration can calculate large deformation. The ectopic digital volume correlation method based on displacement gradient additive decomposition is easier to operate. The two methods complement each other and extend the application scope of the digital volume correlation method..3) the excellent performance of foam metal has important application value and research. In this study, the internal displacement and strain fields of open cell aluminum foam in four different compression states were quantitatively characterized by ectopic digital volume correlation method. The evolution rule of deformation at cellular level was obtained. It was found that the compressive deformation observed in the displacement field was homogeneous, but the local strain band was observed in the strain field. The spatial distribution and frequency distribution of strain values show the heterogeneity of the deformation of aluminum foam, and the heterogeneity is not related to the local porosity. At the cell scale, compression, rotation and shear increase simultaneously, indicating the complexity of the deformation mode of the aluminum foam, and the rotation of the nearby cell caused by cell deformation is mitigated. The main deformation modes of variable concentration.
【学位授予单位】：东南大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TB383.4
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