冲击载荷作用下陶粒混凝土细观损伤的三维数值仿真

发布时间：2018-05-07 15:29

本文选题：随机骨料 + 细观损伤　；参考：《宁波大学》2017年硕士论文

【摘要】：本文采用数值仿真的方法对陶粒混凝土的力学性能和细观损伤过程进行研究。从细观力学角度出发将陶粒混凝土简化为陶粒骨料和砂浆基体组成的二相复合材料。利用大型商业软件ANSYS/LS-DYNA的二次开发功能,建立陶粒混凝土的三维数值细观模型。根据试验设计的试样尺寸、砂浆配合比及陶粒体积分数,计算出陶粒混凝土内部陶粒骨料的颗粒数目;利用蒙特卡洛随机数方法,生成了骨料在试样内部的三维数学模型,建立了陶粒混凝土的空间几何模型;在此基础上利用“投影网格”建模方法,对试样整体进行网格剖分,之后利用ANSYS软件的二次开发功能对骨料和砂浆基体进行自动判断,根据试验得到的陶粒混凝土各组分的力学参数对各组分进行材料属性的赋值。得到陶粒混凝土的三维数值细观模型。进行陶粒混凝土在不同冲击作用下的SHPB束杆冲击压缩试验的仿真研究。得到了陶粒混凝土在不同载荷作用下裂纹的产生、扩展、贯通直至试样整体失效破坏的全过程;模拟得到了SHPB束杆中的应力波信号;模拟重构得到了陶粒混凝土在不同冲击载荷作用下的应力应变曲线;与试验得到的陶粒混凝土的应力应变曲线进行了对比,吻合较好。陶粒混凝土的动态抗压强度随着应力波脉冲载荷的增大而增大,表现出明显的应变率效应,说明陶粒混凝土也是应变率敏感性材料。模拟结果表明:建立的三维数值细观模型可以较好地模拟陶粒混凝土在不同冲击载荷作用下的细观损伤演化过程;陶粒混凝土在不同冲击载荷作用下的损伤破坏从强度较弱的陶粒骨料区域开始,之后向砂浆基体延伸扩展,最后导致试样整体失效。
[Abstract]:In this paper, the mechanical properties and meso-damage process of ceramsite concrete are studied by numerical simulation. From the point of view of mesomechanics, the ceramsite concrete is simplified as a two-phase composite composed of ceramsite aggregate and mortar matrix. A three dimensional numerical mesoscopic model of ceramsite concrete is established by using the secondary development function of large commercial software ANSYS/LS-DYNA. According to the sample size, mortar mix ratio and volume fraction of ceramsite, the number of aggregate particles in ceramsite concrete is calculated, and the three-dimensional mathematical model of aggregate in the sample is generated by using Monte Carlo random number method. The spatial geometric model of ceramsite concrete is established, and the mesh division of the whole sample is carried out by using the "projection mesh" modeling method, and then the aggregate and mortar matrix are automatically judged by the secondary development function of ANSYS software. According to the mechanical parameters of each component of ceramsite concrete, the material properties of each component are assigned. A three-dimensional numerical mesoscopic model of ceramsite concrete is obtained. The impact compression test of SHPB beam under different impact conditions of ceramsite concrete was studied by simulation. The whole process of crack generation and propagation in ceramsite concrete under different loads is obtained, and the stress wave signal in SHPB beam is simulated. The stress-strain curves of ceramsite concrete under different impact loads are obtained by simulated reconstruction, which are in good agreement with the stress-strain curves obtained by experiments. The dynamic compressive strength of ceramsite concrete increases with the increase of the stress wave pulse load, which shows obvious strain rate effect, indicating that ceramsite concrete is also a strain rate-sensitive material. The simulation results show that the three-dimensional numerical meso-model can simulate the meso-damage evolution process of ceramsite concrete under different impact loads. The damage and failure of ceramsite concrete under different impact loads begin in the area of ceramic aggregate with weak strength, then extend to the matrix of mortar, and finally lead to the failure of the specimen as a whole.
【学位授予单位】：宁波大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TU528.2

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