动载荷作用下含偏置裂纹三点弯曲梁破坏过程的数值模拟

NUMERICAL SIMULATION OF DYNAMIC FAILURE PROCESSES OF THREE-POINT BENDING BEAM WITH OFFSET NOTCH

偏置裂纹三点弯曲梁被广泛应用于研究I–II复合型裂纹的扩展过程。利用岩石破裂过程分析(RFPA)程序,对含偏置裂纹三点弯曲梁在动载荷作用下的破坏过程进行数值模拟,研究偏置裂纹的位置(用γ来表达)对三点弯曲梁破坏模式的影响。数值模拟结果表明:当γ≤0.745时,偏置裂纹尖端首先起裂,并沿着一定的角度向上扩展,最终贯通整个试样的高度;当γ>0.745时,在偏置裂纹发生扩展的同时,在梁底部中心位置也萌生出一条中心裂纹,但最终只有中心裂纹贯通整个试样的高度。数值模拟在现了实验中观测到的2种典型破坏模式及其对应的临界γ值。

Three-point bending beam with offset notch is usually used to study the mixed I-II crack propagation in rock.Rock failure process analysis（RFPA） code is used to study the failure process of three-point beam with offset notch when subjected to dynamic loading,the effect of position of offset notch（denoting with γ） on the failure patterns is investigated.The numerical results are shown as follows：（1） when γ ≤0.745,it is the propagation of offset crack in upward direction that leads to final fracture of the specimen;（2） and when γ 〉 0.745,the fracture of the beam is due to the newly formed crack at the middle span although the pre-existing offset crack also propagates upwards.The two typical failure patterns as well as the critical value of γ,which are obtained from the numerical simulations,agree well with the experimental observations.