基于真实细观结构的准脆性材料三维建模及应用初探

采用连续切片的方法获取准脆性材料的表面图像,利用数字图像处理技术检测材料的细观结构并进行矢量化。通过一种简单的变换,将每一切片矢量化的细观结构转换成单层的三维结构,然后将这些切片连续的细观结构逐层叠加,形成整个试件的三维真实细观结构,并针对准脆性材料图像的特点,编制了能够批量处理数字图像并进行细观结构矢量化的程序,建立了与有限元三维网格模型之间的数据接口,模型数据可直接导入岩石三维破裂过程分析RFPA3D系统中,研究真实细观结构对准脆性材料破坏力学行为的影响。以颗粒材料为例,分析了在单轴受压情况下的三维空间裂纹的产生及扩展过程,计算结果显示颗粒分布与界面显著影响材料的破裂模式。

Actual meso-structure based three-dimensional modeling method for quasi-brittle material and its primary application

A serial sectioning method is applied to capture surface images of quasi-brittle material. Digital image techniques are used to characterize the heterogeneity from surface images of raw material and then the characterized heterogeneity is transformed into vectorization mesostructures. With the assumption that the surface of each section is a representation of the inner structure within a small depth, vectorization meso-structure of each section extends a very small distance along the normal direction to form a layer of 3D cubical mesostructures and the 3D actual mesostructures of the specimen are formed by overlapping these serial layers. And according to the characteristic of surface images of quasi-brittle material, a code for processing a batch of images and vectorizing the mesostructure characterized by digital image techniques is developed and the data interface with 3D FEM grid is established. The data of grid model with actual mesostructure is directly imported into three-dimensional rock failure process analysis code (RFPA^3D), so the influence of actual mesostructure on failure behaviors can be studied in detail under external loading. Here, a granular material specimen is taken as an example to demonstrate the procedure of the 3D mesostructure establishment. Then cracking process of granular material under uniaxial compression loadings in 3D space is simulated. The results show that grains distribution has a significant influence on fracture patterns of granular materials under external loadings.