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采用中心裂纹圆盘-霍普金森压杆(CCCD-SHPB)试验系统对大理岩中心裂纹圆盘试件进行不同加载速率下的纯Ⅰ型加载试验,研究岩石材料动态断裂韧性的加载速率相关性。考虑到试验中所使用的圆盘试件是带有中心切口的非理想裂纹,结合试件的实际加工情况,提出采用切口尖端形状为小圆弧形的预制裂纹,介绍了试件的制作方法,并利用有限元计算论证了采用这种形状非理想裂纹试件的试验可行性。结果表明,采用圆弧形裂尖、裂纹宽度为1 mm的中心切口非理想裂纹圆盘试件来代替理想裂纹圆盘试件是可行的,误差不超过2.13%。分析试验数据得出:非理想裂纹圆盘试件在纯Ⅰ型加载条件下,其断裂韧度表现出明显的速率相关性,且随着加载速率的增大而增大。
The center cracked disk-Hopkinson pressure bar (CCCD-SHPB) test system was used to test pure marble loading specimens at different loading rates, and the loading rate dependence of dynamic fracture toughness of rock materials . Considering that the disc specimen used in the experiment is a non-ideal crack with a center notch, a prefabricated crack with a small arc shape at the tip of the notch is proposed according to the actual machining conditions of the specimen. A method for manufacturing the specimen is introduced The experimental feasibility of using this kind of non-ideal crack specimen was demonstrated by finite element analysis. The results show that it is feasible to use the center notch non-ideal cracked disk specimen with a circular crack tip and a crack width of 1 mm instead of the ideal crack disk specimen with an error of no more than 2.13%. Analysis of experimental data shows that the fracture toughness of non-ideal cracked disk specimen shows a significant rate dependence under the pure type I loading condition, and increases with the increase of loading rate.