基于数字图像处理的混凝土细观有限元建模

Establishment of microscopic finite element model of concrete based on digital image processing

将混凝土看成由水泥砂浆、粗骨料及两者之间的界面组成的三相复合材料。采用MATLAB图像处理工具,选取窗口大小为5×5的像素矩阵对二值图像进行中值滤波处理,然后以结构元素形状为disk、结构半径为2的像素矩阵进行图像形态学处理,最后对图像进行边缘检测以提取二维混凝土骨料边界。基于8连通区域的图像轮廓跟踪算法,运用几何矢量转换技术得到混凝土细观结构图,并在有限元软件ANSYS中对细观数值模型进行了加载试验。结果表明,用该方法得到的细观数值模型与原图像吻合好,可真实地研究混凝土在宏、细观方面的力学性能。

We consider concrete as a kind of three-phase composite materials composed of cement mortar,coarse aggregate and bonded interface between them.Based on image processing tools of MATLAB,a 5×5 pixel matrix of the window size is selected to deal with the binary image by median filtering.Then a disk structure element with radius of 2 pixels is used for image morphology processing.The aggregate edges of two-dimensional concrete are extracted by edge detection method.Based on the image contour tracking algorithm of 8-connected region,micro-structure image of the concrete is obtained by geometry vector conversion algorithm,and the microscopic numerical model is loaded by ANSYS.The results show the microscopic numerical model obtained by this method agrees well with the original image,and it can be used for research on macro and microscopic mechanical properties of concrete.