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1.
The using of FEM and especially LS-DYNA3D code for the simulation of a heat transfer during the heating of the explosive charge
is discussed in this paper. The characterization of explosive material properties (density, thermal conductivity, specific
heat, heat of decomposition, the decomposition kinetics) is described. LS-DYNA3D code is used for the fitting of the appropriate
kinetic model and for the simulation of the heat transfer during the slow cookoff test. The results of simulations are compared
to the experimental values for the SEMTEX 1A plastic bonded explosive. 相似文献
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Insensitive munitions design against thermal stimuli like slow or fast cook-off has become a significant requirement for today's munitions. In order to achieve insensitive munitions characteristics, the response of the energetic material needs to be predicted against heating stimuli. In this study, a 2D numerical code was developed to simulate the slow and fast cook-off heating conditions of confined munitions and to obtain the response of the energetic materials. Computations were performed in order to predict the transient temperature distribution, the ignition time, and the location of ignition in the munitions. These predictions enable the designers to have an idea of when and at which location the energetic material ignites under certain adverse surrounding conditions. In the paper, the development of the code is explained and the numerical results are compared with available experimental and numerical data in the literature. Additionally, a parametric study was performed showing the effect of dimensional scaling of munitions and the heating rate on the ignition characteristics. 相似文献
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为研究快速拼装式防爆墙墙后超压分布规律及影响因素,基于2D映射3D网格建模技术,采用AUTODYN有限元软件分别对TNT当量为6.82 kg,爆高1 m、爆距3 m、墙厚0.5 m,墙体高度为1.5 m、2 m、2.5 m的计算模型和比例爆距分别1.58 m/kg~(1/3)、1.28 m/kg~(1/3)、1.05 m/kg~(1/3)的计算模型以及比例爆距为1.05 m/kg~(1/3),爆高1 m、墙高2 m、墙厚0.5 m,爆距为2 m、3 m、4 m的计算模型进行了模拟,分析了墙体高度、比例爆距和炸药位置对墙后超压分布的影响。结果表明:墙体高度增加将显著增强防爆墙消波性能,墙体高度在1.5~2.5 m范围内变化时,墙后消波系数变化较大;随着比例爆距的减小,墙后较远处消波系数有所增大;随着测点高度和爆高增大,测点处受到的防爆墙保护效应将减小。综合考虑以上因素对墙后测点超压的影响,拟合出了计算墙后超压大小的公式,计算结果与数值模拟结果能较好的吻合。 相似文献
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Underwater explosion arising from high explosive detonation consists of a complicated sequence of energetic processes. It
is generally very difficult to simulate underwater explosion phenomena by using traditional grid-based numerical methods due
to the inherent features such as large deformations, large inhomogeneities, moving interface and so on. In this paper, a meshless,
Lagrangian particle method, smoothed particle hydrodynamics (SPH) is applied to simulate underwater explosion problems. As
a free Lagrangian method, SPH can track the moving interface between the gas produced by the explosion and the surrounding
water effectively. The meshless nature of SPH overcomes the difficulty resulted from large deformations. Some modifications
are made in the SPH code to suit the needs of underwater explosion simulation in evolving the smoothing length, treating solid
boundary and material interface. The work is mainly focused on the detonation of the high explosive, the interaction of the
explosive gas with the surrounding water, and the propagation of the underwater shock. Comparisons of the numerical results
for three examples with those from other sources are quite good. Major features of underwater explosion such as the magnitude
and location of the underwater explosion shock can be well captured.
Received: 2 April 2002 / Accepted: 20 September 2002 相似文献
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AbstractThe accurate representation of the 3D stress fields at the bonded areas of adhesive joints is essential for their design and strength evaluation. In the present study, higher-order beam models developed in the framework of the Carrera Unified Formulation are employed to reduce the complexity and computational cost of numerical simulations on adhesive joints. The different components of the adhesive joint, i.e. adherends and adhesive, are modeled as beams with independent kinematics based on the Hierarchical Legendre Expansion (HLE). HLE models make use of a hierarchical polynomial expansion over the cross-section of the beam, thus allowing for the control of the accuracy of the stress solutions via the polynomial expansion. Recalling the Finite Element method, the beam axis is discretized by means of 1D elements. In this manner, generic geometries of the adhesive bonded joints can be studied. The proposed model is assessed through comparison against numerical and analytical references from the literature for single lap and double lap joints. Finally, a detailed 3D analysis is performed on the single lap joint problem, showing that the stress gradients along the adhesive are correctly and efficiently described if the proposed methodology is employed. 相似文献
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The results of numerical calculations of water-droplet explosions initiated by intense CO(2)-laser radiation are presented. The theoretical model for this process is based on the solution of the value of the thermal-boundary problem in an inhomogeneously heated droplet, including the kinetic equation describingvapor generation in a superheated liquid. The main characteristics of droplet explosions (e.g., degree of explosive evaporation and time of explosion) are calculated. It is established that these characteristics depend on the heating rate of the droplet and on its radius. The results point to the fact that two droplet-heating regimes can be distinguished-slow heating and rapid heating-based on the behavior of the explosive boiling process. This division represents the competition of real physical processes in an irradiated droplet and makes it possible to separate the basic, specific features of the explosion process. 相似文献
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A typical insensitive high explosive such as LX-17 has a large carbon content. The detonation behavior of these explosives
is affected by a slow coagulation of carbon atoms by diffusion and their possible transformation from one chemical bonding
type to another. We have used the Brenner bond order potential to compute the melting line of diamond at high pressure and
high temperature by molecular dynamics and Monte Carlo simulations, with the goal to refine the potential for the study of
the kinetics of the graphite–diamond transition. The slow diffusion-controlled kinetics of carbon clusters has been examined
by including a time-dependent surface correction to the Gibbs free energy of these clusters in the nonequilibrium CHEQ code.
We also propose a new explosive burn model which incorporates a partial release of the heat of detonation in a fast reaction
zone, followed by a diffusion-limited release of the remaining energy. Hydrodynamic applications of the new burn model to
LX-17 show that computed expansion and compression results both agree closely with experimental data.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
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《工程爆破》2022,(1)
准确预测三波点的位置和揭示三波点的规律,对工程防护和实现弹药的高效损伤有着重要作用。基于LS-DYNA有限元软件,利用数值模拟方法研究了TNT炸药在混凝土地面上形成爆炸冲击波的三波点运动轨迹,并初步揭示了炸高、药量和炸药形状等因素对三波点高度的影响。研究表明:在爆炸场中,爆炸冲击波以炸药为中心向四周传播,三波点轨迹的高度均呈现逐渐增高的变化趋势。不论改变炸药的药量还是炸高,三波点高度的增速在中场(4.07.0 m)都较缓,而进入远场(>7.0 m)增速骤增。当炸药的炸高和药量相同,炸药形状不同时,圆柱状炸药在中场爆炸形成的三波点高度比长方体炸药略高,且高度增速都较缓;而在远场三波点的高度基本相等,且增速急剧上升,趋于定值。与炸药形状的影响相比,炸高和药量对TNT炸药爆炸冲击波的三波点高度的影响较大。 相似文献
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准确预测三波点的位置和揭示三波点的规律,对工程防护和实现弹药的高效损伤有着重要作用。基于LS-DYNA有限元软件,利用数值模拟方法研究了TNT炸药在混凝土地面上形成爆炸冲击波的三波点运动轨迹,并初步揭示了炸高、药量和炸药形状等因素对三波点高度的影响。研究表明:在爆炸场中,爆炸冲击波以炸药为中心向四周传播,三波点轨迹的高度均呈现逐渐增高的变化趋势。不论改变炸药的药量还是炸高,三波点高度的增速在中场(4.0~7.0 m)都较缓,而进入远场(7.0 m)增速骤增。当炸药的炸高和药量相同,炸药形状不同时,圆柱状炸药在中场爆炸形成的三波点高度比长方体炸药略高,且高度增速都较缓;而在远场三波点的高度基本相等,且增速急剧上升,趋于定值。与炸药形状的影响相比,炸高和药量对TNT炸药爆炸冲击波的三波点高度的影响较大。 相似文献
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文中根据实验和数值分析结果,阐述了2号岩石铵梯矩形装药用于小直径炮孔(42mm)控制断裂爆破技术的可能性及合理性;介绍了2号岩石铵梯矩形装药传爆性能和爆炸作用过程的实验结果;探讨了矩形装药孔壁爆炸作用的数值分析方法. 相似文献
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In this paper, we report high resolution simulations using a fifth-order weighted essentially non-oscillatory (WENO) scheme with a third-order TVD Runge-Kutta time stepping method to examine the features of the detonation for gas and condensed explosives. A two-stage chemical reaction model and an ignition and growth model are employed to describe the chemical reaction process for gas and condensed explosives. Based on the Steger-Warming vector flux splitting method, a splitting method is employed when the vector flux does not satisfy the homogeneity property for simulating detonation wave propagation for condensed explosives. The sensibility of flame propagation process and explosion overpressure on obstacles is also numerically performed. Meanwhile, an interface tracking algorithm is developed and coupled with a two-dimensional multi-material code indigenously for simulating the response of materials to impact, shocks and detonations. Numerical experiments are performed to investigate the influences of liner cone angle, wall thickness and initiation mode on shaped charge jet formation process. The results of calculations show good agreement with experimental results, and indicate that the interface treatment algorithm is especially suitable for simulating explosive loading on thin-wall structure such as shape charges. 相似文献
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Current practice in analysis and design of structures to withhold surface explosions considers only airblast forces on structures. A surface explosion, in fact, generates both ground shock and airblast pressure on a nearby structure. In this paper, the influences of simultaneous ground shock and airblast forces on structural responses are investigated. Blast-induced surface ground motions and airblast pressures estimated in a previous study are employed as input in the analysis. A previously developed three-dimensional homogenized material model for a masonry wall including the equivalent elastic properties, strength envelope and damage threshold is used to model masonry wall. Another material damage model developed for reinforced concrete structures is used for modelling RC behavior due to explosive loads. These material models are programmed and linked to an available computer program LS-DYNA3D through its user subroutine capability. A one-story masonry infilled RC frame is used as an example in the study. Dynamic response and damage of the example structure to simultaneous ground shock and airblast forces, or separately to ground shock only or airblast forces only are calculated. It is found that in general, airblast load governs structural response and damage when the scaled distance is small. However, under certain conditions, structural damage will be critically underestimated if ground shock is neglected. When the scale distance increases, the relative importance of the ground shock on structure response increases, and ground shock will dominate the surface explosion effects on structures at large scaled distance. At large scaled distance, the ground shock and airblast force effects on structures decoupled and structure response and damage to ground shock and airblast force can be analyzed separately. 相似文献
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In this work, we present a reduction procedure for 3D models describing phase transformations in copper-based shape memory alloys (SMAs) and develop a robust numerical algorithm for the computational analysis of thin single-crystal slabs of these alloys. Starting from a general Landau-type 3D model for the SMA dynamics we have developed a new mathematical “slow manifold” model that allows us to describe effectively the main features of the thermomechanical behaviour of CuAlNi alloys. Results of the mathematical modelling of the thermomechanical fields in CuAlNi SMAs are discussed with numerical examples. 相似文献