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

多孔材料在车辆与另一辆车辆或行人碰撞时具有吸收冲击能量的潜力，因为这类材料表现出延长的应力平台。准确评估流动应力对于开发合适的吸收剂非常重要。在本研究中，采用分离式霍普金森压杆（SHPB）来表征动加载下的压缩响应。采用采样时间为1~ 4us的高速成像技术对有孔或无孔的丙烯酸树脂立方体进行了表征。用阴影成像法监测变形行为。现有射孔的影响与聚合物立方体的力学响应相关，通过三种应力波的SHPB评估。捕获的图像显示，随着变形的进行，应变的非均匀分布逐渐变为均匀分布。分析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.