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41.
Measurement and Analysis of Spall Characteristics of High-Pure Aluminium at One-Dimensional Strain Loading 下载免费PDF全文
With an impact velocity varying from 196.9m/s to 317.9m/s and ratios of flyer/sample thickness of 2:4 and 3:6, the free-surface velocity profiles of the shock compressed high purity aluminium (HPA 99.999%) samples are measured with a velocity interferometer system for any reflector. Based on the vibrating features of the velocity profiles, the damage behaviour of HPA is analysed. The results indicate that the vibrating amplitude increases with increasing shock stress, and the subsequent reverberations describing the spall become more obvious. When the shock stress in the material is below a critical or smaller than the threshold level, the free-surface velocity profile replicates virtually the form of the compression pulse inside the sample. When the impact stress exceeds a critical value (1.4 GPa), the micro damage would appear, and the free-surface velocity profile changes significantly, showing a series of short-duration reverberations in the profile. When the impact stress exceeds the threshold of damage, a compressive disturbance called the "spall pulse" appears in the free-surface velocity profile, and the subsequent reverberation becomes regular again. The measured spall strength of HPA is much higher than those of commercially pure aluminium reported in many references. In addition, the strength of HPA is similar to that of single-crystal aluminium. 相似文献
42.
在平面问题中,如果已知边界某点处的应力函数值和偏导数值为零,吊边界上的外载荷来构造出Airy应力函数。章利用虚拟荷和坐标变换的办法,避免了在构造Airy应力函数时可能出现的问题。 相似文献
43.
The stress-strain behavior and copper are studied by the molecular dynamics incipient yield surface of nanoporous single crystal (MD) method. The problem is modeled by a periodic unit cell subject to multi-axial loading. The loading induced defect evolution is explored. The incipient yield surfaces are found to be tension-compression asymmetric. For a given void volume fraction, apparent size effects in the yield surface are predicted: the smaller behaves stronger. The evolution pattern of defects (i.e., dislocation and stacking faults) is insensitive to the model size and void volume fraction. However, it is loading path dependent. Squared prismatic dislocation loops dominate the incipient yielding under hydrostatic tension while stacking-faults are the primary defects for hydrostatic compression and uniaxial tension/compression. 相似文献
44.
强脉冲载荷作用下弹-塑性薄圆板的大挠度动力响应 总被引:3,自引:1,他引:2
利用有限变形弹塑性连续体的最小加速度原理 ,建立了分析圆板动力响应问题的数值方法 ,并通过对均匀分布的脉冲载荷作用下铰支圆板位移响应的细致分析 ,探讨了响应过程中的饱和冲量现象 ,指出对于高载范围内的脉冲载荷 ,相应于最大变形的饱和冲量确实是存在的。结果还表明 ,虽然圆板的弹塑性动力分析非常复杂 ,但基于最小加速度原理的数值计算方法却具有简单、直接的优点。 相似文献
45.
提出分析中心裂纹板剪切断裂的断裂过程区D-B模型的叠加原理,考虑了压剪断裂的摩擦阻力和体现有限权宽影响的载荷修正,以非常简便的方法推导出计算断裂过程区长度和位移的公式。 相似文献
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从洛仑兹力方程的旋量形式出发,讨论了电磁场中电荷运动的轴向电场和轴向磁场问题以及平面波的脉冲和Larmor功率。这些问题是研究自共振激光加速器的基础。From the spinorial form of the Lorentz force equation, the problems about axial electric field and axial magnetic field of charge motion in electromagnetic fields, as well as plane wave pulse and Larmor power have been discussed in this paper. These problems are the foundation of studying the autoresonance laser accelerator (ALA). 相似文献
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Bao Quan Huang 《中国化学快报》2009,20(5):627-630
A novel axially substituted silicon(IV) phthalocyanine, namely di-pyridyloxy axially substituted silicon(IV) phthalocyanine 2 was synthesized and characterized by UV/vis, IR, elemental analysis, MS as well as 1H NMR spectroscopy. Hydrophobic 2 was encapsulated by amphiphilic triblock copolymer poly[Nε-(benzyloxycarbonyl-lysine]-poly(ethylene glycol)-poly[Nε-(benzyl oxycarbonyl) (PLL(Z)-b-PEG-b-PLL(Z)) to form hydrophobic 2-loaded polymeric complex micelle (PIC) (2-loaded PIC). Atom force microscopy (AFM) image showed that 2-loaded PIC formed a spherical nanocarrier with approximately 35-50 nm in diameter. The fluorescence intensity and lifetime of 2-loaded PIC was significantly enhanced by the incorporation 2 into PIC nanocarrier. 相似文献