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A long-pulse low-velocity gas gun with a gas buffer is used to induce impact damage in cast Composition B and hot pressed PBXN-5. To obtain different damage states, a range of projectile velocities are used by control-ling the launching pressure of gas gun. The stress history during impact loading is recorded. Various methods are used to characterize the damage state of impacted explosive samples. The microstructure is examined by use of scanning electronic microscopy (SEM) and polarized light microscopy (PLM). The densities and ultrasonic atten-uation are also measured. The results show that both Composition B and PBXN-5 exhibit some damage character-istics of brittle materials. However, due to the difference in compositions, PBXN-5 exhibits better resistance to impact loading than Composition B. 相似文献
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为探究增材制造金属蜂窝结构在防护领域的潜在应用,采用激光选区融化(SLM)技术制备钛合金蜂窝试样,进行单轴面内压缩力学实验,在平台段出现了周期压溃卸载现象,这不同于传统的塑性/脆性材料蜂窝平台段特征;结合数字摄像机和扫描电子显微镜,分析结构变形模式与断口破坏机理;基于参数化有限元数值分析,研究壁厚对蜂窝结构压溃卸载的影响规律。研究结果表明:SLM技术制备的钛合金蜂窝试样打印精度高,力学性能差异小;钛合金蜂窝结构面内受压时,结构剪切带区域蜂窝边连接处断裂造成结构应力-应变曲线周期性压溃卸载;破坏处断口可观察到明显的韧窝,呈现明显的塑性破坏形貌;壁厚减薄可以有效增大破坏时蜂窝短边的旋转角度,降低最小弯曲半径,从而显著改善压溃卸载现象,提升结构承载稳定性。 相似文献
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用炸药爆轰的方法制备了纳米超微金刚石,用X射线衍射,透射电镜,激光拉曼光谱,红外吸收光谱,差热和热失重等表征了纳米金刚石超微粉的特性,分析了合成材料对纳米金刚石结构和生质的影响,纳米超微金刚石兼具纳米颗粒和超硬材料的双重特性。 相似文献
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高聚物粘结炸药(PBX)是战斗部的关键组成部分,其动态力学行为,特别是动态断裂特性关系到战斗部的安全性和使用可靠性。基于内聚裂纹模型,对PBX模拟材料(PBX-M)的动态巴西实验进行数值模拟,对比霍普金森杆实验中测得的拉伸应力曲线,以及高速摄像结合数字图像相关方法得到的试样表面位移场和应变场。对比结果发现,拉伸应力峰值的数值模拟结果比实验结果小约5%,拉应变集中带的数值模拟结果与实验结果的偏差小于15%,验证了内聚裂纹模型的有效性。根据数值模拟结果,探讨了PBX-M试样在动态巴西实验过程中的起裂和裂纹扩展规律,给出了裂纹宽度的定量化信息。 相似文献
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为了从细观尺度上对高聚物黏结炸药(PBX)的力学性能进行模拟,将蒙特卡洛方法中级配的概念引入高体积分数的PBX细观模型,与Voronoi方法相结合,形成了一种可以考虑级配分布的Voronoi多边形颗粒生成方法,通过颗粒修正、收缩、切角和平滑等处理,建立了考虑级配和体积分数达94%及以上的PBX细观结构模型,模型在边界处还可保持周期连续性。采用数值流形(NMM)方法对不同颗粒级配条件下的三组PBX细观模型进行了单轴压缩模拟。将NMM模拟所得等效弹性模量与文献实验结果进行了比较。分析了模拟结果与实验结果之间出现偏差的原因,讨论了PBX细观结构模型生成方法的合理性。结果表明,PBX的等效弹性模量随体积分数的提高而增大,并且体积分数越高,增速越快;同时,当体积分数低于30%及高于85%时,颗粒的级配对等效模量的影响较小,而当30%≤体积分数≤85%时,颗粒级配对等效模量影响显著。 相似文献
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Deformation and Failure of Polymer Bonded Explosives 总被引:2,自引:0,他引:2
The deformation and failure of pressed polymer bonded explosives under different types of loads including tension, compression and low velocity impact are presented. Brazilian test is used to study the tensile properties. The microstructure of polymer bonded explosives and its evolution are studied by use of scanning electronic microscopy and polarized light microscopy. Polishing techniques have been developed to prepare samples for microscopic examination. The failure mechanisms of polymer bonded explosives under different loads are analyzed. The results show that interfacial debonding is the predominant failure mode in quasi-static tension, while extensive crystal fractures are induced in compression. With the increase of strain rate, more crystal fractures occur. Low velocity impact also induces extensive crystal fractures. 相似文献