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1.
用二维梁-颗粒模型BPM2D(Beam-Particle Model in Two Dimensions)模拟了刚性弹体侵彻和贯穿素混凝土板的过程.梁-颗粒模型BPM2D是在离散元法基础上,结合有限元法开发的二维数值计算模型.在模型中用三种类型梁单元形成混凝土数值试样.每种类型梁单元的力学性质均按韦布尔(Weibull)分布随机赋值以模拟混凝土细观结构的非均匀性,同时梁单元的强度随应变率不同而变化.利用此模型分析了弹体侵彻下混凝土板的破坏过程,并给出不同弹体初始速度条件下各时刻混凝土和弹体内部速度场.通过将计算结果与实验数据及LS—DYNA程序模拟结果相比较,表明梁-颗粒模型可有效应用于计算和模拟脆性材料动态破坏问题. 相似文献
2.
The axisymmetric response of an infinite plate to an impacting projectile is determined analytically on the hypothesis that, for large deformations, a ductile plate behaves to a good approximation like a membrane under uniform tension. The lowest projectile velocity that results in perforation (the ballistic limit), and the residual velocity after perforation, then are determined on the basis of a critical-strain failure criterion. A figure of merit that depends only on the material properties of the target and characterizes the resistance of the material to impact appears naturally in the analysis. Variations in the ballistic limit with target thickness and projectile dimensions can be determined when this figure of merit is known. The theoretical ballistic limit and residual velocity for a steel cylinder impacting a titanium plate are found to agree with available measured values. Further support for the membrane model and an estimate of its range of validity are obtained by comparing the maximum displacement of an impulsively-loaded, circular membrane with experimental data for circular plates. 相似文献
3.
We conducted an experimental study to understand the mechanisms and dominant parameters for 7.62 mm APM2 bullets that perforate 6082-T651 aluminum armor plates at oblique impacts. The 7.62-mm-diameter, 10.7 g, APM2 bullet consists of a brass jacket, lead filler, and a 5.25 g, ogive-nose, hard steel core. The brass and lead were stripped from the APM2 bullets by the targets, so we conducted ballistic experiments with both the APM2 bullets and only the hard steel cores. These projectiles were fired from a rifle to striking velocities between 400 and 1,000 m/s into 20-mm-thick plates at normal impact (β?=?0o) and at oblique angles of β?=?15o, 30o, and 45o. Measured residual and ballistic-limit velocities for the full bullet and the hard core were within a few percent for normal impact and all oblique angles. Thus, we showed that the perforation process was dominated by the hard steel core of the bullet. In addition, we conducted large strain, compression tests on the 6082-T651 plate material for input to perforation equations derived from a cavity-expansion model for the steel core projectiles. Model predictions were shown to be in good agreement with measured ballistic-limit and residual velocity measurements for β?=?0o, 15o, and 30o. We also presented a scaling law for the bullet that showed the ballistic-limit velocities were proportional to the square root of the product of plate thickness and a material strength term. 相似文献
4.
为探究某9 mm手枪弹侵彻木质靶板的弹道特性,以中密度板(medium density fiberboard, MDF)为研究对象进行了弹道侵彻试验,通过减装药和角度可调节靶架获得了不同速度和弹着角下弹头的剩余速度和侵彻深度等关键信息;通过Poncelet阻力模型对试验结果进行了分析,并得出侵彻深度与侵彻速度之间的关系式;建立了手枪弹侵彻MDF的数值计算模型,对不同速度和不同弹着角的弹头偏转行为进行了研究,并得到了临界跳飞角度与着靶速度之间的函数关系。结果表明,弹头正侵彻25 mm厚度的MDF时,能量损失量与入射速度具有线性相关性;弹头侵入MDF时均会产生负方向偏转,弹头速度降低或者弹着角减小均会使负方向偏转角度增大,当弹头低速穿透MDF或者弹着角小于45°时,弹头侵彻MDF过程中会产生较大角度偏转,在射出MDF时出现弹道转正现象。 相似文献
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为更加准确地计算93钨合金弹超高速撞击Q345钢板问题,构建了修正的金属本构模型。引入GRAY三相物态方程描述材料相态变化,采用Johnson-Cook强度模型描述撞击后期材料的力学行为。结合封加波损伤演化模型以及Johnson-Cook失效模型描述不同应力三轴度下材料的拉伸、剪切失效行为;引入曹祥提出的断裂演化模型,描述材料失效后应力归零的过程。通过对比超高速撞击数值模拟结果与实验结果,验证了本构模型的适用性,并进一步分析了典型弹靶撞击条件下破片群的空间分布特征。研究结果表明:基于修正金属本构模型获得的超高速撞击靶板穿孔直径、弹体侵蚀长度、破片群扩展速度结果与实验结果一致;GRAY三相物态方程能够相对准确地给出弹体撞击首层靶板以及剩余弹体、破片群撞击第2层靶板时弹靶材料的熔化情况;封加波损伤演化模型能够准确判断超高速撞击过程中靶板是否产生层裂破坏;综合封加波损伤演化模型、Johnson-Cook失效模型以及曹祥提出的断裂演化模型后,数值模拟获得的破片群撞击后效靶板的穿孔面积与累积数量的统计曲线结果与实验结果一致;获得了典型条件下的柱形93钨弹体超高速撞击Q345靶板破片群空间分布结果... 相似文献
7.
In the present paper, a four-stage perforation model that accurately predicts the residual velocity is developed by adopting an energy method. The four stages are plug formation, dishing formation, petal formation and projectile exit. In addition, some important experimental results are presented and analyzed to validate the present perforation model. In the experiments, high speed camera system is used to record the perforation process. Observations on target damage and measurements of initial velocities and residual velocities with the aid of the system are presented. Numerical simulations are carried out for projectiles against single and layered plates adopted in the experiments. The perforation process is studied and the deformation and failure modes are obtained. The predictions of numerical simulations and analytical model are found in reasonably good agreement with those of experiments, and can be used to predict the ballistic limit and residual velocity of stiffened plates perforated by rigid projectiles. 相似文献
8.
We conducted an experimental and analytical study to better understand the mechanisms and dominant parameters for 7.62 mm
APM2 bullets that perforate 7075-T651 aluminum armor plates. The 7.62-mm-diameter, 10.7 g, APM2 bullet consists of a brass
jacket, lead filler, and a 5.25 g, ogive-nose, hard steel core. The brass and lead were stripped from the APM2 bullets by
the targets, so we conducted ballistic experiments with both the APM2 bullets and only the hard steel cores. These projectiles
were fired from a rifle to striking velocities between 600 and 1,100 m/s. Targets were 20 and 40-mm-thick, where the 40-mm-thick
targets were made up of layered 20-mm-thick plates in contact with each other. The measured ballistic-limit velocities for
the APM2 bullets were 1% and 8% smaller than that for the hard steel cores for the 20 and 40-mm-thick targets, respectively.
Thus, the brass jacket and lead filler had a relatively small effect on the perforation process. Predictions from a cylindrical
cavity-expansion model for the hard steel core projectiles are shown to be in good agreement with measured ballistic-limit
and residual velocity data. The results of this study complement our previous paper with 5083-H116 aluminum target plates
in that the ultimate tensile strength of 7075-T651 is about 1.8 times greater than that of 5083-H116. We also present a scaling
law that shows a square root relationship between ballistic-limit velocity and plate thickness and material strength. 相似文献
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Oblique perforation of thick metallic plates by rigid projectiles with various nose shapes is studied in this paper. Two perforation mechanisms, i.e., the hole enlargement for a sharp projectile nose and the plugging formation for a blunt projectile nose, are considered in the proposed analytical model. It is shown that the perforation of a thick plate is dominated by several non-dimensional numbers, i.e., the impact function, the geometry function of projectile, the non-dimensional thickness of target and the impact obliquity. Explicit formulae are obtained to predict the ballistic limit, residual velocity and directional change for the oblique perforation of thick metallic plates. The proposed model is able to predict the critical condition for the occurrence of ricochet. The proposed model is validated by comparing the predictions with other existing models and independent experimental data.The English text was polished by Keren Wang 相似文献
11.
In the present paper, a four-stage perforation model that accurately predicts the residual velocity is developed by adopting
an energy method. The four stages are plug formation, dishing formation, petal formation and projectile exit. In addition,
some important experimental results are presented and analyzed to validate the present perforation model. In the experiments,
high speed camera system is used to record the perforation process. Observations on target damage and measurements of initial
velocities and residual velocities with the aid of the system are presented. Numerical simulations are carried out for projectiles
against single and layered plates adopted in the experiments. The perforation process is studied and the deformation and failure
modes are obtained. The predictions of numerical simulations and analytical model are found in reasonably good agreement with
those of experiments, and can be used to predict the ballistic limit and residual velocity of stiffened plates perforated
by rigid projectiles.
The project supported by the National Natural Science Foundation of China (90305018)
The English text was polished by Yunming Chen 相似文献
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为研究药型罩对聚能射孔弹侵彻页岩储层的射孔和损伤致裂效果的影响机理,建立了射孔弹-空气-页岩三维模型,设置药型罩的锥角分别为50°、60°、70°和80°,壁厚分别为0.5、1.0和1.5 mm,材料分别为铜、钢、钛和钨。利用ANSYS/LS-DYNA软件进行数值计算,分别从射流速度与形态、页岩射孔效果及页岩孔裂隙形成规律特征等进行系统性分析。研究结果表明:在射孔弹结构中,随着药型罩锥角的减小,射流速度提高、杵体速度降低、侵彻深度增大同时开孔孔径减小。在一定范围内,适当减小药型罩的壁厚,可以提高射流速度、减小杵体质量、增大侵彻深度和开孔倾斜度。药型罩材料对射流速度、杵体结构和页岩射孔效果均有显著影响,其中钨药型罩射孔弹的侵彻深度最大但开孔孔径最小,钛药型罩射孔弹的侵彻深度最小但开孔倾斜度最大,铜比钢药型罩射孔弹的侵彻深度略大但开孔孔径略小。通过研究不同对照组的页岩孔裂隙形成规律特征发现,页岩孔裂隙发育主要发生在杵体对页岩的再扩孔阶段,减小射流初始扩孔孔径、增大杵体直径、提高杵体速度,可以促进页岩孔裂隙发育程度。 相似文献
14.
孔眼流入对水平井中流动影响的实验研究 总被引:12,自引:0,他引:12
设计并建立了水平井筒变质量流动模拟实验装置。对具有射孔完井的水平井筒变质量流动进行了实验研究,利用先进的数据采集系统获取了大量的实验数据。对水平井井筒单孔眼段流动阻力损失分析可知,流动阻力由三部分组成:管壁摩擦阻力、加速损失和混合损失。对实验数据进行处理得出了混合损失和主流流速与孔眼流速之间的关系。对于一定的主流流速,混合损失随孔眼流速的增大而增大,同时,对于一定的孔眼流速,混合损失随主流流速的增大而增大,此时孔眼的流入对水平井筒中的流动造成的影响比较显著。孔眼的流入增加了井筒中流动的复杂性。对实验数据进行的回归结果表明,在本实验条件和范围内,主流流速和孔眼流速是造成混合损失的主要因素。 相似文献
15.
In a previous paper, we presented a scaling law for the ballistic-limit velocity for the 7.62 mm APM2 bullet and five aluminum alloy plates. This scaling law predicts that the ballistic-limit velocity is proportional to the square root of the product of the plate thickness and a material strength term. In this note, we show that this same scaling law can be used to accurately predict ballistic-limit velocity for the larger 12.7 mm APM2 bullet.
相似文献16.
Based on the three-stage perforation model, a semi-theoretical analysis is conducted for the ballistic performances of a rigid kinetic projectile impacting on concrete plates. By introducing the projectile resistance coefficients, dimensionless formulae are proposed for depth of penetration (DOP), perforation limit thickness, ballistic limit velocity, residual velocity and perforation ratio, with the projectile nosed geometries and projectile-target interfacial friction taken into account. Based on the proposed formula for DOP and lots of penetration tests data of normal and high strength concrete targets, a new expression is obtained for target strength parameter. By comparisons between the results of the proposed formulae and existing empirical formulae and large amount of projectile penetration or perforation tests data for monolithic and segmented concrete targets, the validations of the proposed formulae are verified. It is found that the projectile-target interfacial friction can be neglected in the predictions of characteristic ballistic parameters. The dimensionless DOP for low-to-mid speed impacts of non-flat nosed projectiles increases almost linearly with the impact factor by a coefficient of 2/(πS). The anti-perforation ability of the multilayered concrete plates is dependent on both the target plate thickness and the projectile impact velocity. The variation range of the perforation ratio is 1–3.5 for concrete targets. 相似文献
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18.
We conducted an experimental and analytical study to understand the mechanisms and dominant parameters for ogive-nose rods
and 7.62 mm APM2 bullets that perforate 5083-H116 aluminum armor plates. The 20-mm-diameter, 95-mm-long, ogive-nose, 197 g,
hard steel rods were launched with a gas gun to striking velocities between 230–370 m/s. The 7.62-mm-diameter, 10.7 g, APM2
bullet consists of a brass jacket, lead filler, and a 5.25 g, ogive-nose, hard steel core. The brass and lead were stripped
from the APM2 bullets by the targets, so we conducted ballistic experiments with both the APM2 bullets and only the hard steel
cores. These projectiles were fired from a rifle to striking velocities between 480–950 m/s. Targets were 20, 40, and 60-mm-thick,
where the 40 and 60-mm-thick targets were made up of layered 20-mm-thick plates in contact with each other. The measured ballistic-limit
velocities for the APM2 bullets were 4, 6, and 12% smaller than that for the hard steel cores for the 20, 40, and 60-mm-thick
targets, respectively. Thus, the brass jacket and lead filler had a relatively small effect on the perforation process. In
addition, we conducted large strain, compression tests on the 5083-H116 aluminum plate material for input to perforation equations
derived from a cavity-expansion model for the ogive-nose rods and steel core projectiles. Predictions for the rod and hard
steel core projectiles are shown to be in good agreement with measured ballistic-limit and residual velocity data. These experimental
results and perforation equations display the dominant problem parameters. 相似文献
19.
为研究卵形弹丸贯穿中等厚度混凝土靶体的贯穿规律,开展直径60 mm尖卵形弹丸贯穿不同厚度混凝土靶体的侵彻实验,获得了不同撞击速度的弹丸贯穿不同厚度混凝土靶体的剩余速度规律。结合无网格SPH方法、RHT混凝土本构以及状态方程,对贯穿实验进行数值模拟,对不同工况下的弹丸过载规律以及靶体的损伤过程的分析发现:弹丸贯穿中等厚度混凝土靶体的贯穿过程分为开坑阶段、隧道稳定侵彻阶段以及靶背影响出靶阶段,在相同初始撞击速度下的靶背影响区的厚度随着靶体厚度的增加而增大。实验结果与数值模拟结果对比,表明模型能够有效模拟弹丸贯穿混凝介质问题,研究结果可为贯穿机理的研究提供参考。 相似文献
20.
高速旋转弹头侵彻运动金属薄板的数值模拟 总被引:5,自引:0,他引:5
提出了一种利用LS-DYNA程序计算弹头翻转角度曲线的方法。在侵彻过程中,弹头的速度为300 m/s,转速分别为0、3 600和6 370 r/s;金属薄板的速度分别为0、40和80 m/s。其中,弹头直径为7.62 mm,圆形金属薄板的直径为80 mm,厚度为2 mm。材料模型选择了考虑应变、应变率效应和温度效应的Johnson-Cook材料模型。通过数值模拟结果的比较来研究不同弹头转速和金属薄板速度对侵彻过程中弹头最终速度、翻转角度和弹道偏移的影响。 相似文献