用P-CCNBD试样测定岩石动态扩展韧度和观察动态止裂现象

发布时间：2018-04-16 15:36

本文选题：预裂人字形切槽巴西圆盘 + 动态扩展韧度　；参考：《岩土力学》2017年11期

【摘要】：关于动态断裂的全过程,包括动态起裂、扩展和止裂的报道在科学文献中受到日益增长的关注。研究岩石的动态扩展和动态止裂,用分离式霍普金森压杆径向冲击大直径(φ160 mm)的预裂人字形切槽巴西圆盘(pre-cracked chevron notched Brazilian disc——P-CCNBD)试样的试验,测定了大理岩的I型动态扩展韧度,而不仅是动态起裂韧度。确定的方法是试验数值解析法,而不是通常的准静态法,因为,大尺寸试样在动态试验中不满足应力平衡条件。裂尖起裂时刻和裂纹扩展速度采用应变片和裂纹扩展计监测;将有关试验数据,包括霍普金森压杆施加在试样上的的动态荷载输入有限元程序,对P-CCNBD进行三维动态数值模拟,再结合普适函数的半解析修正,得到动态应力强度因子的时间历程。结果表明,P-CCNBD大理岩试样的动态起裂韧度随加载率的增大而增大,试样的动态扩展韧度略低于动态起裂韧度,且扩展韧度随裂纹扩展速度的加快而增大。此外,对裂纹扩展速度振荡和扩展路径曲折现象进行了分析,讨论了P-CCNBD试样实现动态止裂的可能性。
[Abstract]:The whole process of dynamic fracture, including dynamic initiation, extension and crack arrest, has attracted increasing attention in the scientific literature.The dynamic propagation and crack arrest of rock were studied. The I-type dynamic propagation toughness of marble was measured by means of radial impact of split Hopkinson compression bar on large-diameter (蠁 160mm) pre-cracked herringbone chevron notched Brazilian disc (P-CCNBDD) specimen.It is not only dynamic initiation toughness.The method of determination is the numerical analytical method, rather than the usual quasi-static method, because the stress balance condition is not satisfied in the dynamic test of large-sized specimens.The crack tip crack initiation time and crack growth velocity are monitored by strain gauge and crack propagator, and the relevant test data, including the dynamic load applied on the specimen by Hopkinson compression bar, are input into the finite element program to simulate the three-dimensional dynamic numerical simulation of P-CCNBD.The time history of the dynamic stress intensity factor is obtained by using the semi-analytical correction of the universal function.The results show that the dynamic initiation toughness of P-CCNBD marble increases with the increase of loading rate, the dynamic propagation toughness of the specimen is slightly lower than that of the dynamic crack initiation toughness, and the propagation toughness increases with the acceleration of the crack growth rate.In addition, the phenomena of crack propagation velocity oscillation and propagation path twists are analyzed, and the possibility of dynamic crack arrest of P-CCNBD specimen is discussed.
【作者单位】：河南理工大学能源科学与工程学院;煤炭安全生产河南省协同创新中心;四川大学土木工程及应用力学系;
【基金】：国家自然科学基金面上项目(No.51674101,No.41672282) 河南省重点实验室开放基金(No.S201605)~~
【分类号】：TU45

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