应力调整对石英玻璃珠低速冲击破碎行为的影响

结合高速摄影技术，应用SHPB加载装置，分别使用钢制、铝制和有机玻璃制3种透射杆，对直径约7.90、11.80、15.61 mm 3种尺寸的石英玻璃珠进行了低速冲击实验。根据不同透射杆条件下的玻璃珠破碎过程中的载荷-位移曲线，结合有限元软件计算玻璃珠在冲击作用下载荷的变化情况以及实验过程中玻璃珠的应变，探讨了应力调整对玻璃珠破碎过程的影响。结果表明:相同冲击条件作用下，改变透射杆的材料，会改变玻璃珠破碎过程中的载荷分布，即透射端边界波阻抗的改变会导致反射波发生改变，从而导致玻璃珠内部载荷发生变化；透射杆为铝材和有机玻璃材质时，玻璃珠在破碎过程中的载荷明显下降，在加载过程中伴随着垫块的变形，玻璃珠内部的应力调整时间变长；透射杆为钢杆时，玻璃珠的应变主要表现为两端最大，越靠近中间应变越小，对于透射杆为铝杆和有机玻璃杆的玻璃珠，透射端局部出现了卸载行为。采用有机玻璃透射杆之后，局部应力和变形降低的结果使得玻璃珠在经受较大的变形之后发生破碎，表明玻璃珠的破碎行为由局部变形和局部变形梯度共同控制。

Effect of stress-state adjustment on fragmentation behavior of quartz glass beads subjected to low-velocity impact

By using a SHPB device combined with high-speed photography technology, low-velocity impact experiments of quartz glass beads with diameters of 7.90, 11.80 and 15.61 mm were carried out by means of respectively three kinds of transmission bars, i.e., steel bar, aluminum bar, and polymethyl methacrylate (PMMA) bar. According to the load-displacement curves in the breakage process of glass beads under different transmission bar conditions, combined with the load adjustment of glass beads under impact and the strain of glass beads during the experiment, the influence of stress adjustment on the breakage process of glass beads subjected to low-velocity impact is explored. The results show that under the same impact conditions, the adjustment of the material of the transmission bar will alter the load distribution in the glass bead during impact breakage, that is, the change of the wave impedance at the transmission end will change the reflected wave, which leads to the load adjustment in the process of multiple reflection loading. When the transmission bar is made of aluminum and PMMA, the load in the glass bead decreases obviously during the crushing process, and the stress adjustment duration of the glass bead becomes longer with more deformation of the cushion block during the loading process. When the transmission bar is made of steel, the strain in the glass bead is the largest at both ends, while the closer to the middle of the bead, the smaller the strain. For the glass beads loaded with aluminum and/or PMMA transmission bar, local unloading behavior is found at the transmission end of bead. By employing the PMMA transmission bar, the local stress and deformation both decrease, resulting in the glass bead being broken with larger deformation. It is further shown that glass bead breakage is controlled by local deformation and local deformation gradient.