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桥梁作为交通枢纽中的重要关卡,受到强冲击载荷作用后的毁伤效果一直是国内外关注的热点问题。炸药爆炸是对其进行毁伤的最为有效的手段之一,研究爆炸冲击波在桥梁结构中的传播规律对桥梁结构抗爆设计和爆炸事故救援具有至关重要的作用。为此,搭建了桥梁的局部结构并进行爆炸毁伤实验,为数值模拟研究提供数据参考。采用自主开发的三维爆炸与冲击问题仿真软件EXPLOSION-3D对仿桥梁结构的爆炸冲击波传播问题进行了数值模拟研究。将数值模拟结果与实验结果进行对比,验证了数值算法的有效性;进一步通过对比不同位置处的压力时程曲线来分析爆炸冲击波在仿桥梁结构中的传播规律,并分析了炸药在不同位置处爆炸和不同当量炸药爆炸对桥梁结构毁伤的影响规律。基于数值仿真结果,得到了给定工况下炸药对仿桥梁结构内的人体和车辆的毁伤程度。最后,通过对比分析不同工况的数值模拟结果,从仿真的角度给出了安全预防建议。 相似文献
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利用金属丝电爆炸物理数学模型对电爆炸物理过程开展了数值模拟,研究了不同直径铝丝电爆炸特性,进一步分析了金属丝内沉积能量、电压击穿时刻、电压峰值随金属丝直径的变化规律,并与相关实验数据作了对比。 相似文献
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针对灭火战斗部引战配合设计,研究爆炸作用驱动液体(水基灭火剂)抛撒初始阶段的特性。依据典型灭火战斗部的结构建立数值仿真模型,采用LS-DYNA软件进行仿真计算,分别获得了加载系数(驱动装药与液体的质量比)对壳体破裂时间和壳体破裂初期液体/空气界面运动速度的影响规律,以及液体/空气界面后续的运动特性。进行了同条件下爆炸驱动水基灭火剂抛撒实验,得到了不同加载系数条件下壳体破裂初期液体/空气界面的运动速度。实验结果与数值仿真结果吻合良好,表明所采用的数值仿真方法具有正确性和有效性,对相关问题的研究具有重要参考价值。 相似文献
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H.S. TÜRKMEN 《Journal of sound and vibration》2002,249(4):663-678
The results from a theoretical and experimental investigation of the dynamic response of cylindrically curved laminated composite shells subjected to normal blast loading are presented. The dynamic equations of motion for cylindrical laminated shells are derived using the assumptions of Love's theory of thin elastic shells. Kinematically admissible displacement functions are chosen to represent the motion of the clamped cylindrical shell and the governing equations are obtained in the time domain using the Galerkin method. The time-dependent equations of the cylindrically curved laminated shell are then solved by the Runge-Kutta-Verner method. Finite element modelling and analysis for the blast-loaded cylindrical shell are also presented. Experimental results for cylindrically curved laminated composite shells with clamped edges and subjected to blast loading are presented. The blast pressure and strain measurements are performed on the shell panels. The strain response frequencies of the clamped cylindrical shells subjected to blast load are obtained using the fast Fourier transformation technique. In addition, the effects of material properties on the dynamic behaviour are examined. The strain-time history curves show agreement between the experimental and analysis results in the longitudinal direction of the cylindrical panels. However, there is a discrepancy between the experimental and analysis results in the circumferential direction of the cylindrical panels. A good prediction is obtained for the response frequency of the cylindrical shell panels. 相似文献
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应用高速纹影系统记录激光束辐照在Ly12铝靶时所产生的汽化羽扩张、空气爆炸波、熔融物质喷溅以及穿靶等现象.并由扫描摄影记录的轨迹图测出汽化羽的扩张速度为150~190m/s,空气冲击波速度为450~500m/s,靶表面高压蒸汽速度为5~7.8km/s。 相似文献
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The two major noise sources that cause environmental problems for the U. S. Army are helicopters and large weapons such as artillery, tanks, and demolition. These large weapons produce blast sounds that contain little energy above 200 Hz and that are particularly troublesome to deal with because they excite rattles in structures. The purpose of this study was to systematically test subjective response to the presence or absence of rattles in otherwise similar blast sound environments. A second purpose of the study was to test if there were structural changes that could reduce annoyance within the indoor blast sound environment. This study was done using a specially constructed test house and highly repeatable shake table to generate the blast sounds. The data clearly show that no commonly used environmental noise measure adequately describes the indoor environment when the blast excites rattles. Although the indoor blast ASEL changes by only about a decibel or so (and the indoor blast CSEL changes by even less), the subjective response changes by up to 13 dB. At low blast levels, the increase in human annoyance response is largest, and this annoyance response offset decreases to about 6 dB when the outside, flat-weighted peak sound-pressure level of the blast increases from 112 to 122 dB. 相似文献
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通过X-ray衍射方法对高炉渣中非晶态与晶态的含量进行了定量分析研究。定量分析过程包括标准样品制备、配样与衍射以及数据处理分析。数据处理包括非晶态衍射峰及晶态峰在一定衍射角度内的积分、线性拟合与定量系数确定。提出了X-ray衍射方法所用的高炉渣标准样品的制备方法,包括100%非晶态标样和100%晶态标样。提出了由100%非晶态和100%晶态为标准样品时,高炉渣中非晶态含量的测定方法,适用于非晶态含量较高(>80%)的高炉渣的定量分析。结合数学处理和X-ray衍射结果,可得到原始高炉渣中非晶态含量和晶态含量,以及相应的比例系数,适用于非晶态含量高的高炉渣(>90%)。 相似文献
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基于多光谱成像技术的水稻叶瘟检测分级方法研究 总被引:8,自引:0,他引:8
实时、可靠的植物病害检测是进行科学的植物喷药作业的基础,也是精确农作的关键技术之一。目前水稻稻瘟病害检测鉴定方法存在着专业知识要求高、花费大、效率低等缺点。文章提出了利用包含绿、红、近红外三波段通道的多光谱成像技术对水稻叶瘟病进行检测。研究目的是建立能够快速、准确分析稻叶瘟病情的检测模型,实时过滤掉背景噪声、自然枯叶等干扰因素,实现对水稻生长状况进行及时、有效、非破坏性检测。研究表明,利用多光谱成像技术提取水稻叶面及冠层图像信息,可以快速有效地检测稻叶瘟病情。通过实验建立的稻叶瘟病情检测分级模型,对于营养生长期的水稻苗瘟的识别准确率为98%,叶瘟的识别准确率为90%,为实施科学的稻叶瘟防治提供了决策支持。 相似文献