Study on Fracture Simulation Method of Brittle Material with Distinct Model

本研究取得的主要成果如下：1.建立了断裂分析的粘弹塑性悬挂单元法。采用Delauney三角剖分法对VEPSEM进行稳定化数值分析，节点随机布置，通过加载板的位移控制考虑重复加载。此外，为了模拟多孔混凝土的断裂，将悬挂单元的半径设置为与单元所涉及的骨料节点半径无关.对不同加载速度、试件形状、尺寸、粗骨料位置等条件下的二维混凝土试件应力-应变曲线及断裂过程进行了模拟和讨论。此外，还对约束混凝土的应力-应变曲线进行了模拟和讨论.从拉伸断裂与剪切断裂的区别和Kaiser效应的机理出发，对混凝土局部断裂声发射的弹性波进行了模拟和讨论。充分模拟了声发射现象.对多孔混凝土的断裂进行了模拟。结果表明，多孔混凝土的模拟断裂过程与实心混凝土的模拟断裂过程没有差异，模拟结果的抗压强度与孔隙比的关系与以往的试验研究结果具有相同的趋势。

The results obtained in this research are summarized as follows :1. The visco-elasto-plastic suspension element method for the fracture analysis was developed. Delauney triangulation was adopted to VEPSEM for the sake of stabilized numerical analysis with random placed nodal points, and repetitive loading was considered by the displacement control of the loading boards. Furthermore, in order to simulate the fracture of porous concrete, the arbitrary radius of suspension elements was set independently from the radii of the aggregate nodes concerned with the element.2. The stress-strain curves and the progress of fracture of two dimensional concrete specimens were simulated and discussed under various conditions of loading speed, shape and size of specimen, and position of coarse aggregate. Furthermore, the stress-strain curves of confined concrete were also simulated and discussed.3. The elastic wave of acoustic emission by local fracture of concrete were simulated and discussed from the view points of the difference between tensile and shear fracture and the mechanism of Kaiser effect. The phenomena of acoustic emission were simulated adequately.4. The fractures of porous concrete were simulated. As the result, it was clarified that there are no differences between the progress of simulational fracture of porous concrete and solid concrete, and the relationship between compressive strength and void ratio of the simulational results has same tendency from previous experimental study.