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  本文選題：混凝土　切入點：霍普金森桿　出處：《湖南大學(xué)》2013年碩士論文

【摘要】：混凝土作為工程中最為常用的建筑材料，其靜態(tài)性能已研究多年且已趨于成熟，然而混凝土的動態(tài)力學(xué)性能研究還處于探索階段。為此本文通過試驗結(jié)合有限元分析對沖擊荷載作用下的混凝土力學(xué)性能進(jìn)行基本研究，并對有限元分析中常用的混凝土動態(tài)本構(gòu)模型進(jìn)行了簡單探討。 本文首先介紹了混凝土動態(tài)性能研究的基本試驗裝置——分離式霍普金森壓桿，并簡單介紹了裝置的基本原理，采用直徑為100mm的霍普金森桿對直徑為92mm的混凝土試塊進(jìn)行了五組氣壓即五個應(yīng)變率的沖擊試驗。試驗表明混凝土具有明顯的應(yīng)變率效應(yīng)，其動態(tài)力學(xué)性能與靜態(tài)性能有明顯差別。試驗得到了各個試件的動態(tài)平均應(yīng)力應(yīng)變曲線，并由此得出材料的平均應(yīng)變率、動態(tài)抗壓強度、峰值應(yīng)變及割線剛度等基本力學(xué)性能。通過試驗可得出混凝土不同應(yīng)變率作用下的動態(tài)增大系數(shù)，參考CEB規(guī)范的推薦公式，比較了動態(tài)增大系數(shù)的試驗值與理論計算值。 作為一項日益發(fā)展的技術(shù)手段，，有限元分析具有試驗研究所不具備的優(yōu)勢，包括經(jīng)濟(jì)效益、廣泛的參數(shù)研究等。本文采用LS-DYNA軟件對霍普金森壓桿試驗進(jìn)行了數(shù)值模擬。文中詳細(xì)介紹了有限元模型的建立，包括單元的選取，接觸的定義，另外對軟件中現(xiàn)有的動態(tài)混凝土本構(gòu)模型進(jìn)行了總結(jié)，深入介紹其中常用的三種動態(tài)本構(gòu)模型，選取該三種材料模型進(jìn)行了模擬分析，得到了模擬沖擊過程及材料應(yīng)力應(yīng)變曲線。將模擬結(jié)果與試驗結(jié)果進(jìn)行對比，對混凝土本構(gòu)模型的適用性進(jìn)行了討論。
[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.
【學(xué)位授予單位】：湖南大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2013
【分類號】：TU528

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本文編號：1687987