Department of Mechanical, Industrial & Systems Engineering, University of Rhode Island, Kingston, RI 02881, USA.
Department of Mechanical, Industrial & Systems Engineering, University of Rhode Island, Kingston, RI 02881, USA.
Mater Sci Eng C Mater Biol Appl. 2015 Apr;49:727-734. doi: 10.1016/j.msec.2015.01.068. Epub 2015 Jan 22.
The propagation of stress waves in epoxy-glass particulate composites and graded materials was studied experimentally. Materials tested in this study consisted of an epoxy matrix with various concentrations of spherical glass particles having a mean diameter of 42μm. Plate impact experiments were performed using a gas gun. Embedded within the specimens were manganin stress gauges used to record propagating compressive longitudinal stress waves through the material. High strain rate experiments using a Split Hopkinson Pressure Bar (SHPB) apparatus were also performed to evaluate the dynamic strength of the specimens, while quasi-static compression tests were undertaken to characterize their quasi-static behavior. Ultrasonic wave speed measurements were carried-out in order to obtain additional material properties and characterize the gradation in functionally graded materials (FGM). It was found that low volume fractions of particles are detrimental to the performance of the material under impact loading, while concentrations in the range of about 30 to 45% by volume exhibit characteristics of higher degrees of scattering. This suggests that materials in this latter range would be more effective in the thwarting of destructive shock waves than the homogeneous matrix material. Impact testing of FGM specimens suggests that impact loading on the stiff (high volume fraction) face results in much higher levels of scattering. Therefore, such materials would be effective for use in light weight armor or as shielding materials due to their effective attenuation of mechanical impulses.
实验研究了环氧树脂-玻璃颗粒复合材料和梯度材料中应力波的传播。本研究中测试的材料由具有 42μm 平均直径的各种浓度的球形玻璃颗粒组成的环氧树脂基体构成。使用气体炮进行了板冲击实验。在样品中嵌入了锰铜压力计，用于记录通过材料传播的压缩纵向压应力波。还使用分离式 Hopkinson 压杆 (SHPB) 装置进行了高应变率实验，以评估样品的动态强度，同时进行了准静态压缩实验以表征其准静态行为。进行了超声波速度测量，以获得额外的材料性能并表征功能梯度材料 (FGM) 的梯度。结果发现，低体积分数的颗粒对冲击载荷下材料的性能不利，而体积分数在 30%至 45%范围内的浓度表现出更高程度散射的特征。这表明在后者范围内的材料在阻止破坏性冲击波方面将比均质基体材料更有效。FGM 样品的冲击测试表明，在硬（高体积分数）面受到冲击载荷会导致更高水平的散射。因此，由于其对机械脉冲的有效衰减，此类材料将有效用于轻质装甲或屏蔽材料。
