软基体混合胞孔材料的力学性能及抗多次冲击性能

为了探索具有优异吸能性能的软基体混合胞孔材料的力学性能，研究该类材料在多次冲击下的冲击响应和材料的可恢复性，对一种软基体混合胞孔材料—人工软骨仿生超材料（artificial cartilage foam，ACF）进行了不同速度下的单轴拉伸和压缩实验，得到了ACF材料在不同应变率条件下的应力-应变曲线。并利用落锤冲击实验机对ACF材料和另一种软基体混合胞孔材料—发泡聚丙烯材料（expanded polypropylene，EPP）进行了多次冲击下的对比测试，得到了2种材料在单次和多次冲击下的动力学响应。实验结果表明:ACF材料是一种应变率敏感的材料，随着应变率的提升，材料的弹性模量、抗拉强度和抗压强度均逐渐提高；在50 J 冲击能量作用下，ACF材料能够吸收96%以上的冲击能量，远高于EPP材料的70%，ACF材料具有更加优异的吸能性能；5次冲击后ACF材料的最大峰值力、最大变形量和吸能能力几乎不变。相比于EPP材料，ACF材料有良好的可恢复性，且具有稳定的多次抗冲击能力。这些研究为软基体混合胞孔材料在多次冲击防护中的应用提供了实验依据。

Mechanical properties of the mixed cellular material with soft matrix and its response to repeated impacts

The mixed cellular materials with soft matrix are a new type of cushioning and protective materials which have excellent energy absorption properties. In order to study the effect of strain rate on the mechanical behaviors of this kind of materials, uniaxial tensile and compression experiments were conducted on the artificial cartilage foam (ACF) material, at different velocities to obtain the stress-strain curves of the ACF material under different strain rate conditions. Based on the obtained stress-strain curves, the elastic moduli and material strengths of the ACF material were gained under different strain rate conditions. And the comparative tests of the ACF material and expanded polypropylene (EPP) material of the same size and thickness under multiple impacts were carried out by a drop-hammer impact test machine. By comparing the impact responses of the two materials under single and multiple impact loads, the energy absorption characteristics, and the stability of the energy absorption characteristics of the two materials were analyzed. The results reveal that the ACF material is a strain rate-sensitive material, and the stress-strain curves under different strain-rate conditions take on the same trend. The elastic modulus, tensile and compressive strengths of the material gradually increase with the increasing strain rate. Under the action of 50-J impact energy, the ACF material can absorb more than 96% of the impact energy, higher than the 70% of the impact energy absorbed by the EPP material. Moreover, the maximum displacement of the ACF material is only 40% of that of the EPP material. Therefore, the ACF material has more excellent energy absorption performance than the EPP material. The peak force, maximum displacement, and energy absorption ability of the ACF material were almost unchanged after five impacts. Compared with the EPP materials, the ACF material has more favorable recoverability and more stable repeated impact resistance. The research of the work can provide an experimental basis for the application of the mixed cellular materials with soft matrix in multiple impact protection.