岩石非理想裂纹圆盘试件动态断裂韧性测试的有限元分析及试验研究

Experiment and finite element analysis of rock dynamic fracture toughness test on nonideal crack disc specimens

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。

With central cracked circular disk-split Hopkinson pressure bar（CCCD-SHPB） test system, the pure type I loading tests on the marble center cracked specimens are taken under different loading rates. Relationship between loading rate and dynamic rock fracture toughness of materials is determined. The disc specimen in test has a nonideal crack with center incision. Combining with the actual processing of specimens, the paper presents the prefabricated crack with the notch tip shape of small arc and introduces the machining method for specimens. The feasibility of the nonideal crack test specimen is demonstrated with finite element analysis.The resu＞s show that it is feasible to use the nonideal crack disc specimens with circular arc crack tip and the crack width of 1 mm to replace the ideal crack disc specimens; the error does not exceed 2.13%. Under the condition of pure type I loading, the fracture toughness of nonideal crack specimen shows obvious correlation with loading rate, and it increases with the loading rate increasing.