挡墙对爆炸形成的空气冲击波防护效应的三维数值模拟研究

本文对爆轰产物采用JWL状态方程，通过多流体网Euler型算法，应用自行编制MMIC3D程序，模拟了在爆点附近有无障碍物的三雏爆炸场的初始发展的情况，以及不同形状的防护挡墙对爆炸效应的影响，计算结果基本符合物理规律，这说明本文采用的模型及算法是合理的，并可用来进一步模拟爆炸对远场的作用效应，得到了对实际具有参考价值的计算结果。     

爆炸冲击波在城市地下通道内传播规律的数值模拟

城市地下过街通道是城市重要的交通系统组成部分,也经常会成为恐怖分子爆炸袭击的对象。为了更好的了解爆炸冲击波在地下过街通道中的传播规律,本文通过数值模拟分析了13KG炸药在通道爆炸后冲击波的传播。分析过程中分别考虑了炸药起爆位置及通道顶盖对冲击波传播的影响。分析结果表明当TNT在通道内起爆后,通道顶部的角落将受到更大的冲击波压力作用,当冲击波从出口向外传播时将发生明显的射流现象;当通道出口有顶盖时,炸药在出口的起爆将明显加强通道内部及出口梯道的压力峰值。     

空中爆炸冲击波作用的数值仿真实验研究

研究了爆炸冲击波作用的数值仿真实验方法,分析了用经验公式计算冲击波超压峰值的差异及其原因。基于LS-DYNA软件、ALE算法和流固耦合理论建立了爆炸冲击波的数值实验方法,并将数值实验结果与爆破现场试验数据、经验公式计算结果进行对比,验证了数值仿真实验技术的有效性。分析了LNG储罐的爆炸冲击响应和冲击波超孔压响应,得到冲击波遇到储罐结构后的绕射过程。实验表明:爆炸荷载数值实验方法可用于大型LNG储罐工程的抗爆问题研究。     

模拟高原水下爆炸特征参数的实验研究

高原地区进行的水下爆破工程,因水体表面气压随海拔的升高而线性降低,其装药爆炸后的特征参数是否发生变化,对爆破施工有重要意义;采用密闭的高压爆炸容器,模拟高原气压条件,对雷管水下爆炸参数进行了实验研究,研究结果表明：在海拔0---4500m范围内随着气压降低,冲击波峰值压力大小与气压无关。冲击波衰减时间却有一定增长,导致比冲击波能微小增大;气泡脉动周期按二阶多项式规律显著增大,仍由于气压随海拔升高丽变小,装药深度处的总静水压力随之降低,使比气泡能微量减小,而爆炸总能量基本不变。     

爆炸力学数值方法及其模拟研究的简要综述

回顾了爆炸力学计算的基本理论、计算方法及其应用现状,总结了自主开发爆炸与冲击问题数值模拟程序的过程,主要分析了爆炸与冲击问题数值模拟程序MMIC（3D）、可视化软件Visc2D和Visc3D、驾驭式计算技术及模糊界面处理技术在爆炸场数值模拟中的应用．流体与固体耦合、可视化计算中的着色、数值计算中的驾驭式技术和界面处理,以及三维数值计算等是爆炸力学计算方法研究中亟待解决的问题,也是爆炸力学数值计算的发展方向和趋势．     

甲烷爆炸实验教学的数值模拟设计与实践

该文基于CFD代码GASFLOW-MPI建立了20 L球型爆炸罐的数值模型,以一步甲烷燃烧反应化学模型为基础,考虑换热对爆炸的影响,研究了6%～15%不同浓度下甲烷爆炸的压力特性曲线及温度场变化,定量分析了热损失对甲烷爆炸特征参数的影响。将数值模拟结果与实验结果进行的对比验证表明,基于CFD代码GASFLOW-MPI的数值模拟结果能够准确复现甲烷爆炸实验过程,证明了甲烷爆炸过程中热量传递对爆炸过程产生的重要影响。     

爆炸水池水下爆炸振动传播的测试分析

采用UBOX-爆破振动记录仪对爆炸水池中炸药爆炸振动效应进行了研究,记录炸药在水池中爆炸时产生的地震波,并对其进行分析,得到振速、装药量和距离的关系,为以后实验室条件下水池安全布药提供指导,并验证了减振改造的效果。     

粉尘爆炸实验教学的数值模拟设计与实践

研究基于工业通风除尘管道中常用的T型三通管模型,应用FLACS软件建立了用于粉尘爆炸实验的三通管道数值模型,模型采用均匀网格划分,正方体网格边长为0.012 m,模型边界条件选择Euler方程.并用实验室自建的水平三通管道粉尘爆炸测试装置进行了模型验证,物理实验与数值模拟的相对误差完全满足实际实验教学需求.在建立的三通...     

弹性血管二维分岔模型的有限元分析及数值模拟

采用任意拉格朗日—欧拉方法(ALE),对二维弹性分岔血管中的速度场和压力场进行了分析.通过弹性分岔血管中与刚性分岔血管中速度场和压力场的比较,结果表明:在刚性分岔血管中,其分岔口的速度和压力都比较大;而在弹性分岔血管中,由于管壁的弹性影响,其分岔口的速度和压力都比刚性分岔血管的小,更加接近于正常的生理状况.所以,弹性血管比刚性血管的模拟效果好,它既能够方便于我们了解心血管疾病的机理,尽早地预防心血管疾病,又能够为临床实验工作提供一种好的理论分析方法.     

冷喷涂中粒子形状和速度参数对撞击过程影响的数值模拟

为了解冷喷涂中粒子形状和速度参数对其沉积过程的影响,采用显示有限元算法和任意拉格朗日-欧拉(ALE)网格划分法,研究了冷喷涂圆球和椭球状铝合金颗粒以不同初始速度撞击镁合金基板过程中,粒子和基板的变形行为和温度变化,以及对其反弹性能、基板坑深和最大相对接触面积的影响。结果表明:粒子形状对碰撞过程中粒子和基板的局部变形有较大影响,表现在对称截面的塑性变形和温度分布具有非对称性;椭球粒子沿其长轴方向垂直撞击基板时,截面局部变形比沿其短轴方向撞击基板情况剧烈;提高粒子撞击基板速度后,其反弹动能与其初始动能百分比不断降低,基板坑深增加,粒子和基板间的最大相对接触面积增加;但球形和椭圆形颗粒形状对基板坑深的影响较小。     

Effect of Foam Cladding for Blast Mitigation:Numerical Simulation

Two numerical simulations were performed to investigate the protective effect of the foam cladding. One simulation is based on a previous experimental study, which is a ballistic pendulum with and without a foam cladding subjected to close-range blast loading. The other model is a steel beam with and without a foam cladding under blast loading. The overpressure due to the blast event can be calculated by the empirical function ConWep or by an arbitrary Lagrangian-Eulerian (ALE) coupling model. The first approach is relatively simple and widely used. The second approach can model the propagation of the blast wave in the air and the interaction between the air and the solid. It is found that the pendulum with the foam cladding always swings to a larger rotation angel compared to a bare pendulum. However, the steel beam with an appropriate foam cladding has a smaller deflection compared to the bare beam without a foam cladding. It is concluded that the protective effect of the foam cladding depends on the properties of the foam and the protected structure.     

Effect of Shock Wave on Fabricated Anti-Blast Wall and Distribution Law Around the Wall Under Near Surface Explosion

The loads of shock wave effect on fabricated anti-blast wall and distribution law around the wall were investigated by using near surface explosion test method and FEM. The pressure-time histories and variety law on the foreside and backside of the anti-blast wall were adopted in the tests of variety of different explosion distances and dynamites, as well as in the comparison between the test and numeri-cal calculation. The test results show that the loads of shock wave effect on the anti-blast wall were es-sen-tially consistent with calculation results using criterion under surface explosion when explosion dis-tances exceed 2 m, the distribution of overpressure behind wall was gained according to variety law based on small-large-small. It is also demonstrated that the peak overpressure behind wall had com-monly appeared in wall height by 1.5—2.5 multiples, and the peak overpressures of protective building behind wall could be reduced effectively by using the fabricated anti-blast wall.     

Effect of Shock Wave on Fabricated Anti-Blast Wall and Distribution Law Around the Wall Under Near Surface Explosion

The loads of shock wave effect on fabricated anti-blast wall and distribution law around the wall were investigated by using near surface explosion test method and FEM.The pressure-time histories and variety law on the foreside and backside of the anti-blast wall were adopted in the tests of variety of different explosion distances and dynamites,as well as in the comparison between the test and numerical calculation.The test results show that the loads of shock wave effect on the anti-blast wall were essen-tially consistent with calculation results using criterion under surface explosion when explosion distances exceed 2 m,the distribution of overpressure behind wall was gained according to variety law based on small-large-small.It is also demonstrated that the peak overpressure behind wall had commonly appeared in wall height by 1.5--2.5 multiples,and the peak overpressures of protective building behind wall could be reduced effectively by using the fabricated anti-blast wall.     

Numerical Simulation of the Flat Ribbon Wound Explosion Containment Vessels Subjected to Internal Blast Loading

In order to constitute engineering design methods of the flat ribbon wound explosion containment vessels, the dynamic response of such vessels subjected to internal explosion loading is simulated using LS-DYNA3D. Three winding angles, 10°, 15°and 20°, are considered. It is shown that among ribbon vessels investigated, the center displacement of outermost ribbons of the vessel with 10°winding angle is the smallest under the same blast loading. The response of vessels loaded in inner core is local. From the center of the cylindrical shell to the bottom cover, the maximum strain gradually decreases. The ribbons are subjected to tension in the length direction and compression in the width direction. Blasting shock energy concentrates on where is close to center section of blasting. For comparison, numerical simulation of a monobloc thick-walled explosion containment vessel is also investigated. It can be found that the biggest deformation of the flat ribbon wound explosion containment vessels is bigger than that of the monobloc thick-walled explosion containment vessel in the center section of blasting under the same TNT. Numerical results are approximately in agreement with experimental ones. It is proved that the ribbon vessels have the valuable properties of " leak before burst at worst" compared with the monobloc vessels through numerical simulation.     

A Review of Current Researches on Blast Load Effects on Building Structures in China

The damages of building structures subjected to multifarious explosions cause huge losses of lives and property. It is the reason why the blast resistance and explosion protection of building structures become an important research topic in the civil engineering field all over the world. This paper provides an overview of the research work in China on blast loads effect on building structures. It includes modeling blast shock wave propagation and their effects, the dynamic responses of various building structures under blast loads and the measures to strengthen the building structures against blast loads. The paper also discusses the achievements and further work that needs be done for a better understanding of the blast loads＇ effects on building structures, and for deriving effective and economic techniques to design new or to strengthen existing structures.     

Numerical Simulation of Response of SRC Columns Subjected to Blast Loading

The dynamic characteristics and failure modes of steel reinforced concrete (SRC) columns subjected to blast loading are complicated because of the transient stress wave in the SRC columns and the interaction between steel and concrete. This paper presents a numerical simulation of the response of SRC columns subjected to blast loading using hydrocode LS-DYNA. In the numerical model, a sophisticate concrete material model (the Concrete Damage Model) is employed with consideration of the strain rate effect and the damage accumulation. An erosion technique is adopted to model the spalling process of concrete. The possible failure modes of SRC columns are evaluated. It is observed that the failure of SRC columns subjected to blast load can generally be classified into three modes, namely, a direct failure in concrete body due to the stress wave, a transverse shear failure near the support sections due to the high shear force, and a flexural failure pertaining to large local and global deformation of the reinforcing steel.     

Numerical Simulation, of Response of SRC Columns Subjected to Blast Loading

The dynamic characteristics and failure modes of steel reinforced concrete （SRC） columns subjected to blast loading are complicated because of the transient stress wave in the SRC columns and the interaction between steel and concrete. This paper presents a numerical simulation of the response of SRC columns subjected to blast loading using hydrocode LS-DYNA. In the numerical model, a sophisticate concrete material model（the Concrete Damage Model）is employed with consideration of the strain rate effect and the damage accumulation. An erosion technique is adopted to model the spalling process of concrete. The possible failure modes of SRC columns are evaluated. It is observed that the failure of SRC columns subjected to blast load can generally be classified into three modes, namely, a direct failure in concrete body due to the stress wave, a transverse shear failure near the support sections due to the high shear force, and a flexural failure pertaining to large local and global deformation of the reinforcing steel.     

气淬高炉渣颗粒凝固行为数值模拟

针对气淬粒化装置中高炉渣颗粒的凝固行为,采用凝固熔化模型、流体体积函数模型和离散坐标辐射模型进行了三维瞬态模拟。考虑炉渣凝固过程中的物性参数变化,主要研究了颗粒的凝固过程、相界面移动速度、颗粒温度分布及周围空气速度分布。结果表明:颗粒凝固过程中固相分布不均匀,迎风面固相厚度大于背风面,这主要由迎风面空气速度比背风面快所致;固相-模糊区界面和模糊区-液相界面移动速度先增加后降低,这是由于在颗粒凝固前期导热系数的影响占主导地位、在凝固后期导热热阻的影响占主导地位;在凝固过程中,颗粒温度由外向内逐渐升高,内部温度降低缓慢。