基于SEM图像分维估算的脆性材料细观结构演化方法研究

借助细观力学试验系统，运用扫描电镜拍摄了不同应力条件下水泥砂浆的实时细观结构图像，综合应用图像分析技术和分形理论，估算了细观结构图像的分形维数，并简要分析了脆性材料的细观结构演化特征。

ANALYSIS ON MESO-STRUCTURE EVOLUTION OF BRITTLE MATERIALS BASED ON ESTIMATION OF FRACTAL DEMENSIONS OF SEM IMAGES

The evolution characteristics of materials play an important role in the research of material damages. Meso-structure images of a cement specimen under various stress levels are investigated by using the scanning electronic microscope (SEM). The fractal dimensions of these meso-structure images are estimated by image analysis and fractal theory. On the basis of the fractal dimension of meso-structure,the characteristics of the evolution of meso-structure are quantitatively analyzed. It is shown that the value of fractal dimensions,derived by the above-mentioned method,increases with the evolution of the damage,and near the end of loading,the fractal dimensions increase prominently,which means that the damage in the cement specimen becomes more chaotic when the strain approaches its limiting value. It has suggested that the fractal dimensions defined in the paper can be used as indicators for damage in cement materials to depict the evolution of damage or micro cracks.