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To increase the detectability of split Hopkinson pressure bar (SHPB) of low-impedance materials, modifications were conducted on traditional SHPB apparatus with a PMMA tube to output transmitted signal, and weak signals were further amplified by semiconductor strain gauges. Experiments on soft rubbers and cushioning foam materials were carried out. In order to analyze the accuracy of the experimental results, the stress equilibrium issues involved in the assumptions of SHPB were investigated. First, by way of re-constructing loading process of incident wave, the stress-strain curve was obtained, along with the stress equilibrium ratio of specimen. Secondly, the influences on the accuracy of stress-strain curves were investigated through the elastic modulus comparisons. And the results illustrate that the bilinear incident wave from experiments can ensure the stress equilibrium deformation of specimen after 2 normalized times, much sooner than ramp incident waves. Moreover, it even facilitates specimen deformation with a constant strain rate. The results confirm that the detectability of the modified SHPB can be down to tens kPa with enough accuracy level. 相似文献
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为研究硼酸改性端羟基聚硅氧烷-二氧化硅轻质冲击硬化聚合物复合材料抗冲击特性及其机理,进行了单轴压缩、冲击试验;结合高速摄影和数字图像相关技术以及有限元仿真,研究材料的变形过程。结果表明:该材料在准静态载荷下呈黏性流动态,而在动态载荷下呈现固体状态,其流动应力提高了104倍以上;当受到冲击载荷时,材料表现出一定的抗冲击性能,且抗冲击性能随着冲击速度和颗粒含量的提高而增强,材料在冲击过程中处于压力-剪力耦合应力状态,剪力所起作用随着冲击速度提高而逐渐增强;高速摄影结果显示,材料在冲击过程中发生阻塞转变,其中动态压缩导致材料局部硬化并表现出抗冲击特性,剪应力决定了材料抗冲击性能的应变率敏感性。因此,提高材料动态剪切响应是改善材料抗冲击性能的最优途径。 相似文献
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基于Hopkinson压杆实验技术的含能材料动态力学性能测试方法研究进展 总被引:2,自引:0,他引:2
评述了基于Hopkinson压杆实验技术的高度变率下含能材料动态力学性能测试方法的研究进展.鉴于含能材料的低杨氏模量、密度、波阻,采用Hopkinson压杆测试其力学性能时存在一些问题,如应力平衡、波阻抗匹配等.研究表明,常规的Hopkinson压杆试验装置不能得到准确、可信的试验数据,采用波形整形、压电晶体等方法可以解决应力平衡和波阻抗不匹配等问题.Hopkinson压杆实验技术还能为含能材料在高应变率下本构关系的建立以及损伤模式的分析提供实验结果,并指出了今后含能材料力学性能研究的若干方向.附参考文献44篇. 相似文献
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基于基础激励对固支的3类铝合金加筋板进行振动测试。测试过程中采用应变片监测试样的动态响应。在应变历程的基础上用雨流计数法和Miner线性累积模型得到时域内加筋板的疲劳累积损伤。利用固有频率的改变,拟合用于预测板结构疲劳损伤的新模型,改进先前固有频率下降5%的失效判据。同时,还研究了筋条截面形状与筋间距对铝合金板振动疲劳行为的影响。结果表明,加装T型或L型截面的铆接筋条后铝板的疲劳寿命延长,对于筋条截面积大小相同的筋条,T型截面筋条的加筋板其疲劳寿命长于L型的。此外,振动疲劳寿命表现出对筋间距的敏感性。 相似文献
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