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1.
Numerical simulation of TNT underwater explosion was carried out with AUTODYN soft-ware. Influences of artificial viscosity and mesh density on simulation results were discussed. Deto-nation waves in explosive and shock wave in water during early time of explosion are high frequency waves. Fine meshes (less than 1 mm) in explosive and water nearby, and small linear viscosity co-efficients and quadratic viscosity coefficients (0.02 and 0.1 respectively, 1/10 of default values) are needed in numerical simulation model. According to these rules, numerical computing pressure profiles can match well with those calculated by Zamyshlyayev empirical formula. Otherwise peak pressure would be smeared off and upstream relative errors would be cumulated downstream to make downstream peak pressure lower. 相似文献
2.
Analysis of structural response under blast loads using the coupled SPH-FEM approach 总被引：3，自引：0，他引：3
A numerical model using the coupled smoothed panicle hydrodynamics-finite element method （SPH-FEM） approach is presented for analysis of structures under blast loads. The analyses on two numerical cases, one for free field explosive and the other for structural response under blast loads, are performed to model the whole processes from the propagation of the pressure wave to the response of structures. Based on the simulation, it is concluded that this model can be used for reasonably accurate explosive analysis of structures. The resulting information would be valuable for protecting structures under blast loads. 相似文献
3.
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。 相似文献
4.
The explosion inside tunnel would generate blast wave which transmits through the longitudinal tunnel. Because of the close-in effects of the tunnel and the reflection by the confining tunnel structure, blast wave propagation inside tunnel is distinguished from that in air. When the explosion happens inside tunnel, the overpressure peak is higher than that of explosion happening in air. The continuance time of the blast wave also becomes longer. With the help of the numerical simulation finite element software LS-DYNA, a three-dimensional nonlinear dynamic simulation analysis for an explosion experiment inside tunnel was carried out. LS-DYNA is a fully integrated analysis program specifically designed for nonlinear dynamics and large strain problems. Compared with the experimental results, the simulation results have made the material parameters of numerical simulation model available. By using the model and the same material parameters, many results were adopted by calculating the model under different TNT explosion dynamites. Then the method of dimensional analysis was used for the simulation results. As overpressures of the explosion blast wave are the governing factor in the tunnel responses, a formula for the explosion blast wave over-pressure at a certain distance from the detonation center point inside the tunnel was derived by using the dimensional analysis theory. By comparing the results computed by the formula with experimental results which were obtained before, the formula was proved to be very applicable at some instance. The research may be helpful to estimate rapidly the effect of internal explosion of tunnel on the structure. 相似文献
5.
In order to improve the present aviation ejection escape system, the application of explosion cutting technique to aviation escape system is proposed to weaken the strength of canopy before ejecting it. A series of mini cutting explosives are designed to investigate the process of splitting PMMA plate. The phenomenon of spallation in PMMA is observed. The effects of different parameters of mini cutting explosives on the cutting depth are obtained. Consequently the appropriate material of half-circular metal covers, explosive types and the ranges of charge quantities are determined. On the other hand, the cutting process of aviation PMMA plate by mini cutting explosives is simulated by means of nonlinear dynamic analysis code LS-DYNA. In finite element analysis,Arbitrary Lagrangian Euler (ALE) algorithm is used to depict the fluid property of high energy explosives. Continuous damage material model is used to simulate the complicate dynamic damage behavior of PMMA due to explosion shock waves. Only sliding contact option is defined to fulfill the fluid-structure interaction between explosives and PMMA plate by distributed parameter methods. Phenomenon of spallation observed in the experiment is presented in the simulation. The relationship between the penetration depth of PMMA plate and charge linear density obtained by numerical simulation agrees well with experimental result. 相似文献
6.
采用LS-DYNA3D动力有限元程序对钢球撞击双层带间隙保护板炸药柱的爆炸过程进行了数值模拟分析。分析中采用了流固耦合与动力学接触模式,获得了钢球撞击的临界起爆速度,爆炸产生的峰值压力。研究表明,采取适当的保护措施,炸药制成的部件或装置的安全性能够得到保证。 相似文献
7.
This paper presents the explosion cratering effects and their propagation laws of blast waves in dry standard sands using
a 450 g-t geotechnical centrifuge apparatus. Ten centrifuge model tests were completed with various ranges of explosive mass, burial
depth and centrifuge accelerations. Eleven accelerometers were installed to record the acceleration response in sand. The
dimensions of the explosion craters were measured after the tests. The results demonstrated that the relationship between
the dimensionless parameters of cratering efficiency and gravity scaled yield is a power regression function. Three specific
function equations were obtained. The results are in general agreement with those obtained by other studies. A scaling law
based on the combination of the π terms was used to fit the results of the ten model tests with a correlation coefficient of 0.931. The relationship can be
conveniently used to predict the cratering effects in sand. The results also showed that the peak acceleration is a power
increasing function of the acceleration level. An empirical exponent relation between the proportional peak acceleration and
distance is proposed. The propagation velocity of blast waves is found to be ranged between 200 and 714 m/s. 相似文献
8.
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。 相似文献
9.
郑云英 《淮南师范学院学报》2007,9(3):93-95
文章主要讨论了自由边界上平面横波的反射问题,得到了非均匀反射横波的波速、反射系数、衰减率等物理量的解析表达式。数值结果揭示了入射横波的频率、孔隙流体与固相骨架的耦合系数和固相骨架粘性等对波速、衰减率等物理量的影响。 相似文献
10.
Wan Decheng 《上海大学学报(英文版)》1999,(1)
１ Ｉｎｔｒｏｄｕｃｔｉｏｎ Ｔｈｅｐｒｏｂｌｅｍｏｆｔｈｅｉｎｔｅｒａｃｔｉｏｎｂｅｔｗｅｅｎｒｅｇｕｌａｒｗａｔｅｒｗａｖｅｓａｎｄａｓｕｂｍｅｒｇｅｄｏｂｓｔａｃｌｅｉｓｒｅｌｅｖａｎｔｔｏｔｈｅｄｅｓｉｇｎａｎｄｏｐｅｒａｔｉｏｎｏｆｏｆｆｓｈｏｒｅａｎｄｃｏａｓｔａｌｓｔｒｕｃｔｕｒｅｓ．Ａｋｎｏｗｌｅｄｇｅｏｆｔｈｅｆｒｅｅｓｕｒｆａｃｅｄｅｆｏｒｍａｔｉｏｎｓａｎｄｖｏｒｔｅｘｆｌｏｗｉｓｎｅｃｅｓｓａｒｙｆｏｒｅｓｔｉｍａｔｉｏｎｏｆｄｒｉｆｔｆｏｒｃｅｓａｎｄｓｕｐｅｒｈａｒ… 相似文献
11.
万德成 《上海大学学报(英文版)》1999,3(1):30-35
The interaction between regular water waves and a submerged obstacle in a channel is studied numerically. The fluid viscosity is taken into account and the volume of fluid method is used to deal with the free surface. The incident regular waves are generated by use of numerical absorbing wave maker paddle. The present method can be used to predict the nonlinear deformations of the transmitted regular waves, and to simulate the vortex flow near the obstacle and the shear flows beneath the free surface. 相似文献
12.
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 总被引：5，自引：0，他引：5
吴开腾 《内江师范学院学报》2003,18(2):5-11
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。 相似文献
13.
膨化硝铵炸药以其优良的爆炸性能得到了广泛的推广应用,但其生产工艺复杂;采用硝酸铵与水、复合蜡、复合添加剂混合制成温度为105℃-110℃的溶液,将这种混合液在真空度为-0.07- -0.09 MPa压力下脱水干燥制粉,得到一种粉状膨化硝铵炸药;通过对炸药进行微观结构和性能测试,结果表明,该炸药生产工艺简单,各组份混合均匀性好,炸药的安全性能和爆炸性能优良。 相似文献
14.
Simulation of Airblast Load and Its Effect on RC Structures 总被引：1，自引：0，他引：1
In the analysis of a structure subjected to an explosion event, the determination of the blast load constitutes a crucial step. The effect of the blast load on the structure depends not only on the peak shock overpressure, but also the impulse (hence the duration). For structures with a regular geometry, the blast load may be fairly well estimated using appropriate empirical formulae; however, for more complex situations, a direct simulation using appropriate computational techniques is necessary. This paper presents a numerical simulation study on the prediction of the blast load in free air using a hydrocode, with focus on the sensitivity of the simulated blast load to the mesh grid size. The simulation results are compared with empirical predictions. It is found that the simulated blast load is sensitive to the mesh size, especially in the close-in range, and with a practically affordable mesh grid density, the blast load tends to be systematically underestimated. The study is extended to internal blast cases. An example concrete slab under internal explosion is analyzed using a coupled analysis scheme. The internal blast load from the simulation is examined and the response of the RC slab is commented. 相似文献
15.
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。 相似文献
16.
Simulating blast and fragment loading simultaneously in a single computation requires the combined use of multiple states of the art solvers. A pipe bomb is an example of simple improvised explosive device (IED) that consists of a piece of pipe filled with explosive material and capped at both ends. To simulate the explosion of a pipe bomb and the damage it causes, a coupled multisolver approach based upon finite element and finite volume methods is applied. The numerical calculation presented demonstrates the ability of ANSYS AUTODYN(?) to correctly simulate the threats of lEDs and provides insight into how the most significant physical phenomena affect the results. 相似文献
17.
Numerical Simulation of Dynamic Response and Collapse for Steel Frame Structures Subjected to Blast Load 总被引：4，自引：0，他引：4
The progressive collapse of steel frame structures under the blast load was investigated using LS-DYNA. The multi-material Eulerian and Lagrangian coupling algorithm was adopted. A flu-id-structure coupling finite element model was established which consists of Lagrange element for simulating steel frame structures and concrete ground, multiple ALE element for simulating air and TNT explosive material. Numerical simulations of the blast pressure wave propagation, struc-tural dynamic responses and deformation, and progressive collapse of a five-story steel frame structure in the event of an explosion near above ground were performed. The numerical analysis showed that the Lagrangian and Eulerian coupling algorithm gave good simulations of the shock wave propagation in the mediums and blast load effects on the structure. The columns subjected to blast load may collapse by shear yielding rather than by flexural deformation. The columns and joints of steel beam to column in the front steel frame structure generated enormous plastic defor-mation subjected to intensive blast waves, and columns lost carrying capacity, subsequently lead-ing to the collapse of the whole structure. The approach coupling influence between struc-tural deformation and fluid load well simulated the progressive collapse process of structures, and provided an effective tool for analyzing the collapse mechanism of the steel frame structure under blast load. 相似文献
18.
The progressive collapse of steel frame structures under the blast load was investigated using LS-DYNA.The multi-material Eulerian and Lagrangian coupling algorithm was adopted.A fluid-structure coupling finite element model was established which consists of Lagrange element for simulating steel frame structures and concrete ground,multiple ALE element for simulating air and TNT explosive material.Numerical simulations of the blast pressure wave propagation,structural dynamic responses and deformation,and progressive collapse of a five-story steel frame structure in the event of an explosion near above ground were performed.The numerical analysis showed that the Lagrangian and Eulerian coupling algorithm gave good simulations of the shock wave propagation in the mediums and blast load effects on the structure.The columns subjected to blast load may collapse by shear yielding rather than by flexural deformation.The columns and joints of steel beam to column in the front steel frame structure generated enormous plastic deformation subjected to intensive blast waves,and columns lost carrying capacity,subsequently leading to the collapse of the whole structure.The approach coupling influence between structural deformation and fluid load well simulated the progressive collapse process of structures,and provided an effective tool for analyzing the collapse mechanism of the steel frame structure under blast load. 相似文献
19.
通过对掏槽爆破的实验研究,利用火药和猛炸药的联合装药方式,改变了以往的单一装药结构．模拟实验的结果表明,联合协同装药结构与单一装药结构的掏槽效果有着显著的区别．前者的掏槽效果要优于后者;同时通过炸药水下的测试结果表明,改进以后的装药结构的冲击波峰值压力的持续时间明显提高,即联合装药的爆炸生成气体量要大于单一装药,为爆破工程上快速高效的掘进提供了理论依据。 相似文献
20.
In this paper,a new pressure reducing valve(PRV) with an orifice plate is proposed.The main objective is to explain the mechanisms of pressure reduction and energy conversion in the new PRV.A numerical simulation method was used to investigate the PRV internal flow field and to analyze the throttling effects of the orifice plate and the transform of thermal parameters as outlet pressure,outlet temperature,velocity,and superheat.A structure improvement method for the valve body and orifice plate is put forward to reduce energy loss.The governing equations for internal flow numerical simulation are composed of the continuity,momentum,energy and k-ε transport equations,based on isotropic eddy viscosity theory.Different valve plug displacement models were built to describe the double throttling process.Our analysis shows that the steam pressure drops twice and the degree of superheat increases.There are also lots of eddies which clog the flow channel and disturb the steam flow in the valve cavity after the valve plug and the outlet cavity.After modifying the structure,the numerical results show a better performance of steam flow. 相似文献