冲击荷载作用下混凝土动力性能试验研究及有限元分析

发布时间：2018-03-30 22:35

本文选题：混凝土　切入点：霍普金森杆　出处：《湖南大学》2013年硕士论文

【摘要】：混凝土作为工程中最为常用的建筑材料，其静态性能已研究多年且已趋于成熟，然而混凝土的动态力学性能研究还处于探索阶段。为此本文通过试验结合有限元分析对冲击荷载作用下的混凝土力学性能进行基本研究，并对有限元分析中常用的混凝土动态本构模型进行了简单探讨。本文首先介绍了混凝土动态性能研究的基本试验装置——分离式霍普金森压杆，并简单介绍了装置的基本原理，采用直径为100mm的霍普金森杆对直径为92mm的混凝土试块进行了五组气压即五个应变率的冲击试验。试验表明混凝土具有明显的应变率效应，其动态力学性能与静态性能有明显差别。试验得到了各个试件的动态平均应力应变曲线，并由此得出材料的平均应变率、动态抗压强度、峰值应变及割线刚度等基本力学性能。通过试验可得出混凝土不同应变率作用下的动态增大系数，参考CEB规范的推荐公式，比较了动态增大系数的试验值与理论计算值。作为一项日益发展的技术手段，，有限元分析具有试验研究所不具备的优势，包括经济效益、广泛的参数研究等。本文采用LS-DYNA软件对霍普金森压杆试验进行了数值模拟。文中详细介绍了有限元模型的建立，包括单元的选取，接触的定义，另外对软件中现有的动态混凝土本构模型进行了总结，深入介绍其中常用的三种动态本构模型，选取该三种材料模型进行了模拟分析，得到了模拟冲击过程及材料应力应变曲线。将模拟结果与试验结果进行对比，对混凝土本构模型的适用性进行了讨论。
[Abstract]:As the most commonly used building materials in engineering, the static properties of concrete have been studied for many years and tend to mature. However, the dynamic mechanical properties of concrete is still in the exploratory stage.In this paper, the mechanical properties of concrete under impact load are studied by means of experiment and finite element analysis, and the concrete dynamic constitutive model commonly used in finite element analysis is simply discussed.In this paper, the separation Hopkinson pressure bar, a basic test device for the study of dynamic properties of concrete, is first introduced, and the basic principle of the device is briefly introduced.The impact tests on concrete specimens with diameter 92mm by using Hopkinson rod with diameter of 100mm were carried out at five sets of air pressure or five strain rates.The test results show that concrete has obvious strain rate effect and its dynamic mechanical properties are obviously different from static ones.The dynamic average stress-strain curves of each specimen were obtained and the basic mechanical properties such as average strain rate dynamic compressive strength peak strain and Secant stiffness were obtained.The dynamic increase coefficient of concrete under different strain rates can be obtained by test. The experimental value of dynamic increase coefficient is compared with that of theoretical calculation with reference to the recommended formula of CEB code.As an increasingly developing technique, finite element analysis (FEA) has many advantages, such as economic benefit, extensive parameter research and so on.In this paper, the Hopkinson compression bar test is numerically simulated by LS-DYNA software.In this paper, the establishment of finite element model is introduced in detail, including the selection of element and the definition of contact. In addition, the existing dynamic concrete constitutive models in software are summarized, and three kinds of dynamic constitutive models commonly used are introduced in depth.The three material models are selected to simulate the impact process and the stress-strain curves of the materials are obtained.The applicability of the concrete constitutive model is discussed by comparing the simulation results with the experimental results.
【学位授予单位】：湖南大学
【学位级别】：硕士
【学位授予年份】：2013
【分类号】：TU528

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