两种塑料粘结炸药的Steven试验及撞击感度研究

采用2kg钢质弹丸对PBX2、PBX1炸药进行了Steven试验,试验中采用锰铜压力计测试了样品中的压力变化过程,通过高速录像照片估算了点火反应的延迟时间,通过冲击波超压传感器测量了炸药的反应超压。结果表明PBX1炸药和PBX2炸药的点火反应阈值速度分别约为35.0～35.5m·s-1、40～46m·s-1,在同样撞击速度下PBX1炸药的点火延迟时间明显小于PBX2炸药,这表明PBX2炸药较PBX1炸药钝感。     

基于环境函数分析的制导工具误差补偿方法研究

制导工具误差精确计算和有效补偿尤为重要，文中基于环境函数法，给出了用标准弹道环境函数进行工具误差射前修正的模型，推导了用实际弹道环境函数进行工具误差实时补偿的模型，为制导工具误差的补偿分析提供了有益的参考。仿真结果表明，能够实现对制导工具误差的有效补偿。     

Synthesis and properties of novel phenolic resins modified with nanosized copper particles

Phenol–formaldehyde (PF) resins modified with nanosized copper particles were synthesized by an in situ polymerization process. X‐ray diffraction analysis and transmission electron microscopy revealed that the copper particles in the resulting PF resins had a spherical geometry with a size of 30–60 nm in diameter, and there were about 5% of the particles which were agglomerated. The thermal properties of the resulting PF resins were investigated using TGA. It was found that the copper nanoparticles markedly improved the thermal stability of the PF resins at lower temperatures. The initial decomposition temperature of the modified PF resins could be increased by 47 °C compared to unmodified resins. However, the copper nanoparticles increased the rate of degradation of the PF resins at elevated temperatures. The effects of copper nanoparticles on the thermal properties of the PF resins when used as binders for friction materials are beneficial. The toughness of the resulting PF resins was also studied. The results revealed that copper nanoparticles obviously improved the brittleness of the PF resins. The impact strength of the modified PF resins was increased by 66.6% compared to unmodified resins. Copyright © 2006 Society of Chemical Industry     

Toughening of epoxy resins with thermoplastics. Ii. Tetrafunctional epoxy resin-polyetherimide blends

A series of blends has been prepared by adding a polyetherimide (PEI), in varying proportions, to a tetrafunctional epoxy resin, tetraglycidyl-diaminodiphenylmethane (TGDDM), cured with 4,4′-diaminodiphenylsulphone (DDS). All the materials exhibited two-phase morphologies which were characterised by dynamic mechanical thermal analysis and scanning electron microscopy. Addition of the thermoplastic gave a modest improvement in fracture properties (K_1c and G_1c), as determined by three-point bending experiments, although no obvious correlation with the marked morphological changes was observed.     

Bending Vibrations of Long Rod during Face Impact

The possibility is investigated for failure of long rods under face impact caused by the stability loss of longitudinal deformation. The formula is obtained for calculating the maximum tensile stress during bending under the action of prescribed duration and intensity.     

冲击载荷下复合材料层合杆的动力屈曲

研究复合材料层合杆被一质量块以某一速度沿轴向进行碰撞而导致的动力屈曲现象,采用不同的横向剪切理论,并用差分方法对杆的动力屈曲方程进行求解。文中考察了冲击块质量、初挠度、应力波、横向剪切等因素对临界冲击速度以及屈曲模态的影响。     

A Study of the Fracture Behavior of Unindirectional Fiber- Reinforced Composite Using Coherent Gradient Sensing (CGS) Interferometry

The feasibility of using Coherent Gradient Sensing (CGS) interferometry for studying the fracture behavior of unidirectional fiber-reinforced composites is investigated in this paper. First, the solution for the deformation field surrounding the tip of a crack in an orthotropic material is summarized. Specifically, the most singular term in the asymptotic expansion is explicitly presented. Then, the quantities that relate to the CGS measurements are derived in terms of the spatial position, stress intensity factors, and material constants. Based on these results, synthetic CGS fringe patterns are plotted numerically, and the effects of material anisotropy and crack-tip mixity on the shape of CGS fringe pattern are investigated. In addition, a finite difference interpretation of CGS fringes caused by the finite spacing of the CGS diffraction gratings is taken into account in the simulation. Finally, the initiation fracture toughness and the subsequent resistance curve behavior of a particular unidirectional graphite/epoxy composite are measured using the CGS method. The optically measured stress intensity factors compare successfully to values obtained from the load measurements and the available analytical solutions. This revised version was published online in August 2006 with corrections to the Cover Date.     

Role of controlled debonding along fiber/matrix interfaces in the strength and toughness of metal matrix composites

In metal matrix composites toughness is derived primarily from the plastic work of rupture of ductile matrix ligaments between the fractured fibers and from the plastic work of simple shear separation along steps connecting major fracture terraces. In the optimization of tensile strength in the longitudinal and transverse directions together with the respective works of fracture the most important factor is the control of the extent of debonding along interfaces between the fibers and the matrix, which develops locally in the course of deformation in a continuously changing mix of modes. In Al alloy matrix composites reinforced with Al₂O₃ fibers an effective means of controlling the key interface fracture toughness is through coarsening of Al₂Cu intermetallic interface precipitates which prescribe a ductile fracture separation layer. A combined experimental approach and micromechanical modeling, utilizing a specially tailored novel tension/shear: traction/separation law provides the means for further optimization of overall behavior. This revised version was published online in July 2006 with corrections to the Cover Date.