Dynamic compressive response of porous polymeric materials characterized with high speed imaging and enhancement of energy absorption

多孔材料在一辆车与另一辆车或行人相撞时具有吸收碰撞能量的潜力，因为这类材料表现出延长的应力平台。准确的流动应力评估对于开发合适的吸波材料是非常重要的。在这项研究中，利用分离式霍普金森压杆(SHPB)对动态加载下的压缩响应进行了表征。采用高速成像技术，采样时间为1~4us，对有或无穿孔的丙烯酸树脂方块进行了表征。采用阴影成像法对其变形行为进行监测。现有穿孔的效果与聚合物立方体的力学响应有关，通过SHPB用三个应力波来评估。捕捉到的图像显示，随着变形的进行，应变的非均匀分布向均匀分布转变。研究了几何缺陷对结构动力响应的影响。

Porous materials have a potential for absorbing impact energy during the crashing of a vehicle either against another vehicle or a pedestrian, since the class of materials exhibits an extended stress plateau. Accurate evaluation of flow stress is noted to be important to develop a suitable absorber. In this study, compressive response was characterized under dynamic loading by using a split Hopkinson pressure bar (SHPB). High speed imaging with the sampling time of 1~4 us was applied for the characterization of acrylic resin cube with or without perforations. The deformation behavior was monitored with shadowgraph imaging. The effect of existing perforations was co-related with the mechanical response of the polymer cube evaluated by the SHPB with three stress waves. The captured image revealed that the heterogeneous distribution of strain changed to homogeneous with deformation progress. As a result, the effect of geometrical imperfection on the dynamic response was characterized.