共查询到19条相似文献,搜索用时 140 毫秒
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基于CONWEP对多层梯度点阵夹芯板在爆炸载荷下的动态响应进行了模拟研究。在相同爆炸载荷下,对四种梯度点阵模型的后面板中心挠度峰值进行了对比分析,讨论了各模型每层芯子的总变形能随相对密度比的变化规律,并对多层点阵夹芯板各层的变形情况进行了比较。分析结果表明:对于三层金字塔点阵夹芯结构,强弱相间的点阵夹芯板充分利用了前两层芯子的变形吸能,从而对第三层芯子和后面板起到了很好的保护作用;且在350g TNT炸药和200mm爆距的爆炸载荷下,相对密度比为0.5的强弱相间点阵夹芯板的后面板中心挠度峰值最小,抗爆冲击性能最优。 相似文献
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爆轰驱动对钨珠终点弹道性能的影响 总被引:1,自引:0,他引:1
通过实验比较了理想球形钨珠和经历爆轰驱动的钨珠(初始为球形)主要终点弹道性能的差异,结果表明:(1) 钨珠经爆轰驱动后,发生轻微的质量损失和变形现象,直径6.0 mm和7.5 mm钨珠的质量损失平均为8.4%;(2) 对于理想球形钨珠,在同一初始速度条件下,衰减系数为常数,空气阻力系数仅与初始速度有关,两者成线性关系,而对于经历爆轰驱动的钨珠,衰减系数不再为常数,空气阻力系数与飞行速度有关,两者成线性关系;(3) 爆轰驱动明显降低了钨珠的穿甲能力,但长距离飞行后,钨珠仍具有较强的穿甲能力,是破片式战斗部或杀爆战斗部较理想的选择。 相似文献
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如何准确界定“近距离爆炸(close-in explosion)”一直是防护工程研究领域的热点。本文中基于已被充分验证的精细化有限元模型,研究了TNT球形装药自由场爆炸冲击波传播与爆轰产物高速膨胀共同作用的特点和规律,发现在比例爆距小于0.80 m/kg1/3的范围内,爆轰产物对刚性壁面的爆炸荷载影响显著,提出球形装药近距离爆炸的比例爆距界定标准为0.30~0.80 m/kg1/3。研究发现,在近距离爆炸下,爆炸波在入射角为0°~5°范围内的刚性壁面反射荷载峰值会出现急剧下降的现象,这是由爆轰产物喷射的不均匀性和随机性导致的;近距离爆炸下,刚性壁面反射超压出现了两个峰值的现象,这是由冲击波和爆轰产物分别与刚性壁面相互作用导致的。提出了近距离爆炸情况下两个荷载峰值的计算公式,以及适合工程结构响应计算的简化荷载模型;揭示了近距离爆炸下刚性壁面反射超压的分布规律。 相似文献
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箱型结构内部爆炸能够造成比空爆更严重的破坏效果。本文中设计了3个边长600 mm、板厚4 mm的实验试件,并分别用98.4、194.7和355.8 g的TNT炸药进行了内部爆炸实验,得到了所有试件的变形特征。箱体壁板的变形都呈现向外凸出(鼓起)的特点,壁板中心的最终挠度随着爆炸TNT当量的增大而近似成线性增长,拟合了箱体壁板挠厚比与爆炸当量之间的经验公式。通过三维数字图像相关技术,得到了箱体壁板的动态响应过程:爆炸发生后,壁板中心最先产生向外鼓起;壁板中心随后变形增长,同时变形向四周传播;壁板中心变形达到最大值后,板的变形会产生一定量的振荡回缩。 相似文献
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为了研究冲击波作用下引信传爆装置的响应规律,进行了以主发炸药为RDX-8701、被发装置为聚奥-9C(JO-9C)装药的传爆管(含导爆药柱)的殉爆实验。通过观测残留传爆药、壳体和见证块变形,判断传爆管的爆炸程度,分析了殉爆过程中JO-9C爆轰波的成长历程及传播规律。采用AUTODYN软件建立了殉爆实验有限元模型,计算模型中主要考虑了主发炸药产生的爆炸冲击波对传爆管的冲击响应。基于流固耦合方法,通过调整距离模拟计算得到了传爆管的临界殉爆距离和殉爆安全距离。结果表明,传爆管上端的侧角受到爆炸冲击后产生的爆轰波沿斜下方传播,使传爆药柱完全爆轰,并引起导爆药柱发生殉爆;数值模拟结果显示,JO-9C装药的传爆管临界殉爆距离为5.7 mm,殉爆安全距离为8.8 mm。 相似文献
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低温下小尺度钝感炸药非理想爆轰实验研究 总被引:3,自引:1,他引:3
钝感炸药爆轰波法向速度Dn与当地曲率密切相关,为研究这种非理想行为,测量了-30 ℃下直径为10、12.5、15、30 mm的钝感炸药的定态爆轰速度和爆轰波形,并与24 ℃下的实验结果进行了比较。研究表明,低温下爆速随药柱直径的增加而增加;直径相同时,温度越高,爆轰波形越平坦;温度相同时,直径越大,爆轰波形越平坦;直径较小时,低温下的爆速小于常温下的爆速,相应的法向爆速与当地曲率的关系曲线Dn()位于常温下曲线的下方;直径较大时,低温下的爆速大于常温下的爆速,相应的Dn()关系曲线位于常温下曲线的上方。 相似文献
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采用实验研究、理论分析和有限元模拟相结合的方法,研究了横向爆炸载荷作用下薄壁圆管的动态响应。利用弹道冲击摆锤系统,对圆管在爆炸载荷下的动力响应进行了实验研究,分析了薄壁圆管的变形模式;基于地基梁模型,建立了横向爆炸载荷作用下圆管跨中挠度的理论模型,并进行了无量纲化;通过有限元模拟,分析了圆管的几何参数对其变形模式和跨中挠度的影响,并与理论结果进行了对比。研究结果表明:随着TNT药量增加圆管的变形区域和跨中挠度增大;圆管的长径比、厚度及爆炸载荷参数对圆管的变形模式有较大影响;理论预测、有限元模拟结果与实验结果吻合较好。 相似文献
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为评估内部爆炸作用下多层钢筒结构的防护效果,考察多层钢筒结构动态响应和变形吸能特征,采用两端开口、总厚度为50 mm的4层圆柱形Q345钢筒,在8.90~18.18 kg TNT药量下进行爆炸实验,并在容器外壁进行应变电测。实验后钢筒结构爆心局部发生塑性变形,内层钢筒变形最大,但未发生破坏。根据研究得到初步认识:采用爆心单位环面变形吸能的设计方法,可以较好地预估给定药量下所需钢筒的厚度;不同药量下,轴向距离超过多层钢筒结构的1/4内径后,其外壁环向变形峰值约减小为爆心截面环向应变峰值的1/2。 相似文献
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对316L不锈钢的非比例循环粘塑性本构描述 总被引:1,自引:0,他引:1
对循环硬化的316L不锈钢提出了一个考虑非比例循环加载下流动和硬化特性的粘塑性本构模型。模型中,通过随动硬化的背应力演化以各向同性阻力演化非比例循环路径及其历史的依赖关系来表征材料的非比例循环附加硬化和非比例循环流动特性,将模型用于预测316L不锈钢的圆形,正菱形应变路径的复杂循环变形行为,其预言结果与实验结果吻合很好。 相似文献
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Rahul K. Verma Toshihiko Kuwabara Kwansoo ChungA. Haldar 《International Journal of Plasticity》2011,27(1):82-101
Recently non-proportional deformation has received increased attention from researchers working in the area of experimental and computational modeling of metal deformation. However, most of them are numerical in nature with limited experimental data available, making it further difficult to model non-proportional deformation. In the present work, two-stage uniaxial tests, along with uniaxial cyclic and biaxial tests for different stress ratios, have been performed to evaluate deformation behavior of ultra-low carbon high strength automotive steel. Behaviors like cross-effect and hardening stagnation, which are attributed to the evolution of complex dislocation structures, were observed in this steel. It was also noticed that this steel exhibits tension-compression asymmetry. As for constitutive modeling, a modified asymmetric yield function is proposed to be used with a combined isotropic-kinematic hardening model. Also methods to account for the hardening stagnation during reverse loading and the cross-effect during two-stage deformation are proposed. The resulting constitutive model showed reasonably good agreement with experimental results. 相似文献
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In this work, we develop a physically-based crystal plasticity model for the prediction of cyclic tension–compression deformation of multi-phase materials, specifically dual-phase (DP) steels. The model is elasto–plastic in nature and integrates a hardening law based on statistically stored dislocation density, localized hardening due to geometrically necessary dislocations (GNDs), slip-system-level kinematic backstresses, and annihilation of dislocations. The model further features a two level homogenization scheme where the first level is the overall response of a two-phase polycrystalline aggregate and the second level is the homogenized response of the martensite polycrystalline regions. The model is applied to simulate a cyclic tension–compression–tension deformation behavior of DP590 steel sheets. From experiments, we observe that the material exhibits a typical decreasing hardening rate during forward loading, followed by a linear and then a non-linear unloading upon the load reversal, the Bauschinger effect, and changes in hardening rate during strain reversals. To predict these effects, we identify the model parameters using a portion of the measured data and validate and verify them using the remaining data. The developed model is capable of predicting all the particular features of the cyclic deformation of DP590 steel, with great accuracy. From the predictions, we infer and discuss the effects of GNDs, the backstresses, dislocation annihilation, and the two-level homogenization scheme on capturing the cyclic deformation behavior of the material. 相似文献
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为了讨论率敏感材料软钢钢梁受矩形脉冲载荷作用下的动力响应问题,通过直接离散有限变形弹
塑性连续体最小加速度原理中的Lee泛函得到基本控制方程,并将包含应变率的Cowper-Symonds方程嵌入
应力-应变关系方程,使该计算模型计及材料的应变率效应,因而能够准确描述钢梁受爆炸和冲击载荷作用下
的动力响应问题。该计算模型的有效性通过与通用有限元程序ABAQUS比较而得到了验证,并进一步与已
有的刚塑性解做了对比。利用该计算模型进行数值计算,分析了均布和集中脉冲载荷作用下钢梁动力响应的
应变率效应,结果发现对于钢梁存在新的异常行为响应模式,应变率导致异常区域偏移和扩大,已有的刚塑性
解在一定载荷强度范围内不能准确预报钢梁的实际位移。 相似文献
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ON NONPROPORTIONAL CYCLIC PLASTIC BEHAVIOR OF STEEL 40 总被引:1,自引:0,他引:1
Cai Lixun Yang Xianjie Southwest Jiaotong University Chengdu P. R. China 《Acta Mechanica Solida Sinica》1995,8(1):84-93
An experimental investigation was carried out on the flow characteristicand hardening of steel 40 subjected to complex combined axial-torsional cyclicstraining. For a specific cyclic strain path, the steel has mainly cyclic softeningbehavior when the strain amplitude is small. While with an increase of the effectivestrain amplitude, the softening becomes small, but there is the cyclic softening eventhough the steel is subjected to the cyclic loading by a square strain path. However, thesteel has cyclic additional hardening by a nonproportional path, compared with theproportional cycling. Generally, the additional hardening is small and its historicaleffect is not obvious at small strain amplitude. The additional hardening is remarkableby a cross-triangular strain path of large strain amplitude. The memory of the historyof nonproportional cyclic loading, the direction of plastic flow and the plastic modulusof the steel were also studied. 相似文献