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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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研究爆速直径效应的爆轰冲击波动力学方法 总被引:1,自引:0,他引:1
利用爆轰冲击波动力学(DSD)的广义几何光学模型,得到了圆杆药柱中拟定态二维爆轰波阵面形状的解析解。在两步反应模型假定下建立了DSD的边界条件,用爆速亏损表示阵面上炸药未反应分数,就可得到渐近爆速与药柱直径的关系,即得到计算爆速直径效应的模型。本文模型的实际意义是利用直径效应已有的大量实验数据,给定DSD方法所需要的、又难以实验测定的各种常用炸药的爆速曲率常数(dDn/d)0,以及渐近状态下爆轰波与药柱边界的夹角。 相似文献
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正庚烷云雾爆轰特性的研究 总被引:2,自引:2,他引:2
本文从理论和实验上研究了正庚烷的云雾爆轰特性。实验中采用红外技术、传感器技术、烟膜技术分别测量了正庚烷云雾引爆的延迟时间tDDT,爆速D,爆压p和爆轰波阵面结构。在理论上提出了含有化学反应项的液滴燃烧模型,进行了正庚烷云雾爆轰过程的数值模拟。计算结果和实验基本符合。 相似文献
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爆轰传播研究的近代进展 总被引:1,自引:0,他引:1
综述了八九十年代国外爆轰传爆研究的主要方向和进展,包括直径效应、曲率效应、发散爆轰波的传播、爆轰冲击波动力学、爆轰传播的数值模拟和炸药爆轰性能的有关问题等。斩近分析理论和爆轰冲击波动力学的工作,对发散爆轰传播规律的认识正在不断深化,提出了一些有效的理论方法,从而为更精确的爆轰数值模拟技术,尤其是爆轰驱动等勺的精确计算开辟了新的道路。 相似文献
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凝聚炸药非理想爆轰的数值模拟 总被引:2,自引:0,他引:2
本文对凝聚炸药非理想爆轰的数值模拟进行了系统介绍。对敏感、钝感炸药的理想与非理想爆轰的数值模拟方法、宏观反应速率方法及近年发展起来的DSD(DetonationShockDyntimics)方法和波阵面追踪法,以及对这些方法的适应能力、存在的主要问题进行了分析与讨论。 相似文献
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相对于有限元法,边界单元法在求解断裂问题上有着独特的优势,现有的边界单元法中主要有子区域法和双边界积分方程法.采用一种改进的双边界积分方程法求解二维、三维断裂问题的应力强度因子,对非裂纹边界采用传统的位移边界积分方程,只需对裂纹面中的一面采用面力边界积分方程,并以裂纹间断位移为未知量直接用于计算应力强度因子.采用一种高阶奇异积分的直接法计算面力边界积分方程中的超强奇异积分;对于裂纹尖端单元,提供了三种不同形式的间断位移插值函数,采用两点公式计算应力强度因子.给出了多个具体的算例,与现存的精确解或参考解对比,可得到高精度的计算结果. 相似文献
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2008年5月12日,汶川M80地震在四川省绵竹市清平乡文家沟内诱发一巨型滑坡。通过现场调查得知,滑坡前后缘高差455m,厚度20~30m,滑面为基岩层面,初始方量2750×107m3。滑体在运动中转化为碎屑流。滑坡-碎屑流总的水平运动距离为4022m,垂直运动距离为1443m,遗留的堆积物体积达5×107m3。滑坡距映秀—北川断裂仅36km,位于其下盘,地震烈度达XI度。滑坡导致文家沟中48人遇害,并形成一条完整的地震次生地质灾害链。初步分析表明滑坡启动速度快,滑坡向碎屑流转化过程明显、地点明确。碎屑流运动过程复杂,伴有强烈的“气垫效应”和“前缘气浪冲击效应”。作者认为,文家沟滑坡的高启动速度是长持时强烈地震动作用的结果,与山体的猛烈碰撞是导致滑体解体并转化为碎屑流的原因。 相似文献
2008年5月12日,汶川M80地震在四川省绵竹市清平乡文家沟内诱发一巨型滑坡。通过现场调查得知,滑坡前后缘高差455m,厚度20~30m,滑面为基岩层面,初始方量2750×107m3。滑体在运动中转化为碎屑流。滑坡-碎屑流总的水平运动距离为4022m,垂直运动距离为1443m,遗留的堆积物体积达5×107m3。滑坡距映秀—北川断裂仅36km,位于其下盘,地震烈度达XI度。滑坡导致文家沟中48人遇害,并形成一条完整的地震次生地质灾害链。初步分析表明滑坡启动速度快,滑坡向碎屑流转化过程明显、地点明确。碎屑流运动过程复杂,伴有强烈的“气垫效应”和“前缘气浪冲击效应”。作者认为,文家沟滑坡的高启动速度是长持时强烈地震动作用的结果,与山体的猛烈碰撞是导致滑体解体并转化为碎屑流的原因。 相似文献
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Junfeng Li 《Acta Mechanica Sinica》2014,30(3):281-281
One of the core issues in modern celestial mechanics is the orbital dynamics in the near-regime gravitational field of as- teroids, which provides deep insights into the mathematical nature of a class of nonlinear systems, and plays as a critical basis for in situ explorations of different science goals. Lots of efforts have been made to reveal the characteristics of orbital motion in the vicinity of asteroids, and to improve the skills of asteroid research in methodology. 相似文献
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Maxime Sauzay 《Comptes Rendus Mecanique》2006,334(6):353-361
Experimental studies of the plasticity mechanisms of polycrystals are usually based on the Schmid factor distribution supposing crystalline elasticity isotropy. A numerical evaluation of the effect of crystalline elasticity anisotropy on the apparent Schmid factor distribution at the free surface of polycrystals is presented. Cubic elasticity is considered. Order II stresses (averaged on all grains with the same crystallographic orientation) as well as variations between averages computed on grains with the same crystallographic orientation but with different neighbour grains are computed. The Finite Element Method is used. Commonly studied metals presenting an increasing anisotropy degree are considered (aluminium, nickel, austenite, copper). Concerning order II stresses in strongly anisotropic metals, the apparent Schmid factor distribution is drifted towards small Schmid factor values (the maximum Schmid factor is equal to 0.43 instead of 0.5) and the slip activation order between characteristic orientations of the crystallographic standard triangle is modified. The computed square deviations of the stresses averaged on grains with the same crystallographic orientation but with different neighbour grains are a bit higher than the second order ones (inter-orientation scatter). Our numerical evaluations agree quantitatively with several observations and measures of the literature concerning stress and strain distribution in copper and austenite polycrystals submitted to low amplitude loadings. Hopefully, the given apparent Schmid factor distributions could help to better understand the observations of the plasticity mechanisms taking place at the free surface of polycrystals. To cite this article: M. Sauzay, C. R. Mecanique 334 (2006). 相似文献
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Tuan Hung Le Luc Dormieux Laurent Jeannin Nicolas Burlion Jean-Franois Barthlmy 《Comptes Rendus Mecanique》2008,336(8):670-676
This paper is devoted to a micromechanics-based simulation of the response of concrete to hydrostatic and oedometric compressions. Concrete is described as a composite made up of a cement matrix in which rigid inclusions are embedded. The focus is put on the role of the interface between matrix and inclusion which represent the interfacial transition zone (ITZ). A plastic behavior is considered for both the matrix and the interfaces. The effective response of the composite is derived from the modified secant method adapted to the situation of imperfect interfaces. To cite this article: T.H. Le et al., C. R. Mecanique 336 (2008). 相似文献
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A. N. Rozhkov 《Fluid Dynamics》2005,40(6):835-853
The phenomena of hydrodynamic breakup of liquid jets, drops, films, bridges, and filaments are reviewed for liquids with viscoelastic properties. The reasons for breakup are capillary instabilities, collisions with rigid obstacles, and other forms of dynamic action. The relationship between the properties of the liquids and the features of the breakup process is discussed. 相似文献
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Flow stability analysis and excitation using pulsating jets 总被引:1,自引:0,他引:1
Classical flow stability applied to transition from laminar to turbulent flow may also describe the behavior of vorticity fluctuations created by a pulsating jet placed along a solid boundary. A numerical laminar flow experiment involving a pulsating jet placed along the surface of a duct with flow separation downstream, resulted in eliminating most part of the separated flow region. Applying the same approach to a turbulent flow, it was possible to develop a turbulent stability flow formulation and apply successfully turbulent pulsating jet flow separation control. To cite this article: D. Skamnakis, K. Papailiou, C. R. Mecanique 333 (2005). 相似文献