复合纸板力学性能和应变率相关性测试与表征

为了研究复合纸板材料在不同应变率下的力学响应,利用万能材料试验机和高速率拉伸试验机进行了准静态和动态拉伸试验,同时利用高速摄像机和数字图像相关法(Digital image correlation,DIC)记录拉伸破坏过程和应变场。试验结果显示,纸板材料的拉伸力学性能和破坏机制具有明显的应变率相关性。随着应变率的增大,材料的拉伸强度显著增大,断裂应变在中应变率范围内也表现出明显的应变率效应。对比试验结果和3种应变率效应比表征模型的拟合结果,基于Cowper-Symonds表达式的表征模型,能够很好地描述纸板材料在中低应变率下的应变率效应。该模型对薄壁纸管能量吸收性能的模拟和理论研究,以及冲击防护结构设计提供了理论支撑。

Testing and Characterization of Mechanical Properties and Strain Rate Dependence of Composite Paperboard

To investigate the mechanical properties of composite paperboard at different strain rates, quasi-static and dynamic tensile tests were carried out by universal material testing machine and high-speed testing machine. Meanwhile, the tensile failure process and strain field were recorded by using high-speed camera and digital image correlation (DIC) method. The test results reveal that the mechanical properties and failure mechanism of paperboard show significant strain rate dependence. With the increase of strain rate, the tensile strength of the studied material increases significantly, and the fracture strain also shows obvious strain rate dependence at intermediate strain rate. By comparing the test results with the fitting results of the three models of strain rate dependence ratio, the characterization model based on Cowper-Symonds equation can well describe the strain rate dependence of composite paperboard at low and intermediate strain rates. The proposed model can be used not only for the simulation and theoretical research on the energy absorption performance of thin-walled paper tube, but also for the design of impact protection structure.