混凝土动态计算本构新模型

发布时间：2018-03-20 18:21

本文选题：计算本构模型　切入点：数值模拟　出处：《中国科学技术大学》2013年博士论文　论文类型：学位论文

【摘要】：混凝土作为一种建筑材料在国防和土木工程中得到了广泛的应用,研究混凝土结构在弹体冲击或炸药爆炸作用下的响应和破坏问题对武器和防护结构的设计具有重要意义。本文的主要工作是建立混凝土动态计算本构新模型,并将其应用于混凝土靶板在弹丸高速撞击下的侵彻问题和炸药爆炸载荷作用下的响应问题中,成功预测了弹体的侵彻深度、残余速度、减加速度以及混凝土靶板中裂纹的扩展和演化过程。本文主要包括以下几个方面的内容：在现有混凝土本构模型和一些最新实验数据的基础上,发展混凝土动态计算本构新模型。该模型能反映混凝土材料的基本特性如压力相关性,应变率相关性,应变软化,加载路径相关性,多孔性以及高低围压下的损伤等。针对混凝土材料的拉伸损伤,本文引入拉伸主应变损伤法则来描述混凝土材料的拉伸开裂行为。对于混凝土材料的动态强度,本文在分析了现有混凝土压缩和拉伸动态材料实验数据后,在两个假设的基础上,提出了新的混凝土动态增强因子(DIF)的经验公式。此模型的两个假设是：惯性效应只对混凝土材料的动态压缩强度有影响,对动态拉伸强度没有影响；在相同的应变率条件下,混凝土材料的动态压缩强度增量与动态拉伸强度增量相同。我们将采用单单元模型的数值计算来验证本构模型的正确性。对卵形弹高速侵彻钢筋混凝土靶板进行数值模拟。本文对卵形弹贯穿48MPa、140MPa、38MPa有限厚度混凝土靶板,以及卵形弹侵彻39MPa半无限混凝土靶板进行了数值模拟,并将数值模拟得到的残余速度、侵彻深度和(减)加速度结果与实验数据进行了比较,发现两者吻合得较好。同时,数值模拟还揭示了混凝土靶板在卵形弹弹体贯穿过程中裂纹的演化过程,数值模拟中得到的开坑直径和漏斗坑直径与实验数据也吻合得较好。对平头弹以不同速度撞击钢筋混凝土靶板进行数值模拟。数值模拟得到的混凝土靶板裂纹形貌与实验照片吻合得较好。同时,对平头弹撞击混凝土靶板进行了参数研究,分析了平头弹撞击速度,平头弹直径和质量,混凝土靶板厚度和直径对混凝土靶板中裂纹演化的影响,得到了一些有益的结论。对炸药爆炸载荷作用下钢筋混凝土的响应和破坏进行数值模拟。模拟了炸药接触爆炸和炸药处于封闭空间内的爆炸问题。数值模拟得到的混凝土靶板的裂纹形貌与实验观察进行了比较,两者吻合得较好。同时,对混凝土接触爆炸问题进行了参数研究,分析了不同厚度不同直径混凝土靶板对裂纹演化的影响。将Hoek-Brown破坏准则引入空穴膨胀理论,并对混凝土靶板的侵彻问题进行数值计算。首先将Hoek-Brown破坏准则和弹性-脆性-理想塑性应力应变关系引入到球形空穴膨胀理论中,用以描述混凝土材料的本构关系和破坏过程,弥补了以往的空穴膨胀理论中混凝土材料本构较为简单的缺陷。本构模型抓住了混凝土材料的基本力学行为,如压力相关性,应变软化,能较真实地反映混凝土材料的力学行为。本文通过数值计算的方法预测了卵形弹侵彻和贯穿混凝土靶板的侵彻深度和残余速度,数值计算与实验数据吻合得较好。
[Abstract]:Concrete as a building material has been widely used in national defense and civil engineering, response and failure problems of concrete structures in explosive projectile impact or explosive under the action has important significance for the design of weapons and protective structure. The main work of this paper is to establish the dynamic constitutive model of concrete calculation of the new, and the response of the explosion load penetration problems and its application in the explosive concrete target in high velocity projectile impact condition, predicting the depth of penetration, projectile residual velocity, propagation and evolution of acceleration and the crack in the concrete target. This paper mainly includes the following aspects:
In the existing concrete constitutive model and some new experimental data, a new constitutive model to calculate the dynamic development of concrete. The model can reflect the basic characteristics of concrete materials such as pressure correlation, strain rate, strain softening, loading path dependence, porous and low confining pressures for concrete tensile damage damage. This paper introduces the main material, the tensile strain damage rule to describe the tensile cracking behavior of concrete material. The dynamic strength of concrete materials, based on the analysis of the existing concrete compressive and tensile dynamic material experimental data, based on two assumptions on the proposed new concrete dynamic enhancement factor (DIF) of the empirical formula two. A hypothesis of this model is: the inertial effect has influence only on the dynamic strength of concrete compression, has no effect on the dynamic tensile strength should be in the same; The dynamic compressive strength increment of concrete material is the same as that of dynamic tensile strength under variable rate condition. We will use the numerical calculation of single element model to verify the correctness of the constitutive model.
Numerical simulation of high speed ovoid projectile penetration into reinforced concrete targets. The ovoid projectile runs through 48MPa, 140MPa, 38MPa in concrete target of finite thickness, as well as the oval 39MPa projectiles of semi infinite concrete targets was simulated, and the numerical simulation of residual velocity and penetration depth (minus) and comparison acceleration results and experimental data were found in goodagreement. At the same time, the numerical simulation also reveals the concrete target through the evolution process of crack in the oval projectile, the diameter of the crater and the crater diameter and the experimental data obtained in numerical simulation are in good agreement.
The wadcutter numerical simulation with different impact velocity of reinforced concrete targets. By numerical simulation and experiment of concrete slab crack morphology photographs well. At the same time, the wadcutter impact concrete target is studied and analyzed the wadcutter impact velocity, flat projectile diameter and mass, thickness and diameter of concrete target in effect on the evolution of crack in the concrete target, and some useful conclusions are obtained.
The response of reinforced concrete explosion loads and failure to carry out numerical simulation. Simulation of explosives and explosives in a closed contact explosion explosion problem in space. Numerical simulation of crack morphology and experimental observation of concrete target are compared, which is in good agreement with the explosion problem. At the same time, contact of concrete was studied analysis of the impact of concrete targets, different diameter plate of different thickness on crack evolution.
The Hoek-Brown failure criterion into the cavity expansion theory, and the numerical calculation of penetration problems. Firstly Hoek-Brown failure criterion and elastic - brittle - ideal plastic stress-strain relationship into the spherical cavity expansion theory, used to describe the constitutive relationship and failure process of concrete materials, to make up for the past the simple hole defects of expansive concrete material theory. The constitutive model captures the basic mechanical behavior of concrete materials, such as pressure correlation, strain softening, can reflect the mechanical behavior of concrete materials. Through the numerical method to predict the ovoid projectile penetration and perforation penetration depth of concrete target and the residual velocity, numerical calculation agree well with experimental data.

【学位授予单位】：中国科学技术大学
【学位级别】：博士
【学位授予年份】：2013
【分类号】：TU528.01

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