Abstract Polyurea is widely used as a protective coating material for structures subjected to impulsive loads. In this study, the mechanical properties of polyurea were investigated experimentally over a wide range of loading rates. Firstly, quasi-static tests were performed using conventional hydraulic machine at strain rates of 7.7 × 10−4 - 7.3 × 10−3 s−1 for direct tension and at speeds of 1.67 × 10−5 - 1.67 × 10−4 m/s for puncture. Then high-speed tests were carried out using a high-speed servo-hydraulic testing machine (INSTRON VHS 160/100-20) at strain rates of 3.3–500.3 s−1 for direct tension and at speeds of 0.1–10 m/s for puncture. Deformation and failure processes of the polyurea specimens under high-speed tension were recorded with the aid of a high-speed camera. The testing results show that polyurea is a strain rate sensitive material. Under tensile loads, the initial yield stress and the strength increase with the increment of the strain rates while the fracture strain decreases. Under puncture loads, the yield force and the strength of the polyurea sheets also increase with loading rates. However, the strain rate effect on the failure deformation of the polyurea is only observed when the loading rate is less than 2 m/s. Based on the testing data, mechanism that causes the dynamic effect of polyurea material properties was discussed and some empirical relations were derived for engineering applications.

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高应变率下喷涂聚脲拉伸和穿刺行为的实验研究

摘要 聚脲广泛用作承受冲击载荷的结构的保护涂层材料。在这项研究中，聚脲的机械性能在很宽的加载速率范围内进行了实验研究。首先，使用传统液压机在 7.7 × 10−4 - 7.3 × 10−3 s−1 应变率下进行准静态试验，直接拉伸速度为 1.67 × 10−5 - 1.67 × 10−4 m/ s 用于穿刺。然后使用高速伺服液压试验机（INSTRON VHS 160/100-20）以3.3-500.3 s-1的应变速率进行高速试验，直接拉伸速度为0.1-10 m/s用于穿刺。借助高速摄像机记录了聚脲试样在高速拉伸下的变形和破坏过程。测试结果表明，聚脲是一种应变速率敏感材料。在拉伸载荷下，初始屈服应力和强度随着应变速率的增加而增加，而断裂应变减小。在穿刺载荷下，聚脲片材的屈服力和强度也随着载荷速率的增加而增加。然而，仅当加载速率小于 2 m/s 时，才观察到应变速率对聚脲失效变形的影响。根据试验数据，探讨了聚脲材料性能动​​态影响的机理，并推导出了一些工程应用的经验关系。仅当加载速率小于 2 m/s 时，才观察到应变速率对聚脲破坏变形的影响。根据试验数据，探讨了聚脲材料性能动​​态影响的机理，并推导出了一些工程应用的经验关系。仅当加载速率小于 2 m/s 时，才观察到应变速率对聚脲破坏变形的影响。根据试验数据，探讨了聚脲材料性能动​​态影响的机理，并推导出了一些工程应用的经验关系。