二级配粗骨料随机分布混凝土动态力学性能数值模拟

发布时间：2018-02-10 14:56

本文关键词： 动态破坏混凝土数值模拟二级配冲击荷载　出处：《宁夏大学》2017年硕士论文　论文类型：学位论文

【摘要】：混凝土是民用、工业、安全防护等建筑中应用最普遍的材料之一,有抗压强度高、工艺简单、抗腐蚀性好、抗耐性优良等特点。混凝土结构在应用阶段不仅要考虑缓慢变化准静态荷载,同时还需考虑抗冲击、抗爆炸等动荷载作用,因此有必要进行混凝土动态特性研究。从宏观上看,混凝土是各向同性材料,但从微观上看,混凝土是由粗骨料和水泥砂浆两者构成的复合材料。本文运用ANSYS/LS-DYNA软件对2个模型尺寸二级配混凝土动态力学性能进行了有限元分析,具体研究内容如下:(1)粗骨料的投放,先利用富勒级配曲线及瓦拉文平面转化公式将三维空间问题转化为二维平面问题,即利用瓦拉文平面转化公式计算出粗骨料分布时所需平面面积含量,采用ANSYS/LS-DYNA自带APDL语言编辑二级配圆形粗骨料任意分布面积控制程序,通过控制粗骨料投放平面面积含量,进行粗骨料随机投放。(2)根据粗骨料随机投放程序,进行了粗骨料体积含量、粗骨料最大颗粒直径和粗骨料中间颗粒直径不同二级配混凝土动态破坏过程的数值模拟,提取相应的应力-应变曲线,并对模拟结果进行了分析。数值模拟表明:①随着粗骨料体积含量逐渐增大,二级配混凝土峰值应力在粗骨料体积含量40%时最大;②二级配混凝土峰值应力随粗骨料最大颗粒直径增大而减小;③随着粗骨料中间颗粒直径增大,二级配混凝土峰值应力在粗骨料中间颗粒直径20mm时为最大;④混凝土峰值应力随模型尺寸变化表现出明显尺寸效应;⑤冲击速度低,冲击产生的能量低,宏观裂纹较少;冲击速度高,冲击产生的能量高,宏观裂纹多,碎块较小,数量多。
[Abstract]:Concrete is one of the most common materials used in civil, industrial, safety protection and other buildings. It has high compressive strength, simple process and good corrosion resistance. In the application stage of concrete structure, not only slow change quasi static load should be considered, but also dynamic load such as impact and explosion resistance should be considered, so it is necessary to study the dynamic characteristics of concrete. Concrete is an isotropic material, but from a microscopic point of view, it is a composite composed of coarse aggregate and cement mortar. In this paper, the dynamic mechanical properties of two model size secondary concrete are analyzed by using ANSYS/LS-DYNA software. The concrete research contents are as follows: 1) using the Fuller gradation curve and the Vallavan plane transformation formula, the three-dimensional space problem is transformed into a two-dimensional plane problem. That is to say, the plane area content needed for coarse aggregate distribution is calculated by using the Vallavan plane transformation formula, and the area control program for arbitrary distribution of secondary circular coarse aggregate is edited by ANSYS/LS-DYNA with APDL language, and the content of coarse aggregate in plane area is controlled. The dynamic failure process of coarse aggregate volume content, maximum particle diameter of coarse aggregate and intermediate diameter of coarse aggregate were simulated according to the procedure of coarse aggregate random dropping. The corresponding stress-strain curves were extracted and the simulation results were analyzed. When the volume content of coarse aggregate is 40, the peak stress of secondary concrete increases with the diameter of coarse aggregate and decreases with the increase of diameter of coarse aggregate. The peak stress of secondary concrete is maximum when the diameter of coarse aggregate is 20mm. The change of peak stress with model size shows obvious size effect, such as low impact velocity, low energy produced by impact and less macroscopic crack. The impact velocity is high, the energy produced by the impact is high, the macroscopic crack is many, the fragment is small, the quantity is many.
【学位授予单位】：宁夏大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TU528

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