含倾斜弱面介质中动态裂纹扩展行为研究

为研究冲击荷载下运动裂纹遇到介质中倾斜弱面后的动态断裂行为,采用霍普金森杆作为冲击加载装置,利用高速相机记录倾斜弱面介质中运动裂纹的扩展过程,并结合数字图像相关方法对裂纹周围应变场的演化过程、裂纹尖端的开裂应变以及裂纹的扩展速度进行了分析。结果表明,在冲击荷载下,运动裂纹在遇到弱面后易偏向弱面扩展,裂纹偏转后的开裂应变和扩展速度都显著提高。此外,应力加载率对运动裂纹的扩展有显著影响。随着加载率的提高,动态裂纹沿弱面扩展一定距离后将再次进入基质扩展,且运动裂纹沿弱面扩展的偏移距离逐渐减小。在高加载率下,裂纹沿弱面扩展的速度基本保持稳定,但再次穿过弱面后的裂纹数量和长度不断增加。在相同加载率下,弱面的强度越低,裂纹沿弱面扩展的距离越长。

Experimental study on influences of inclined weak interface on the dynamic crack propagation behavior

In order to study the dynamic fracture behavior of layered materials with weak plane under impact loads combined with the split Hopkinson pressure bar, which is applied as an impact loading configuration, the dynamic fracturing process is recorded using the high speed camera, and the digital image correlation method is adopted to evaluate the strain fields around crack, failure strain and crack velocity. The results show that the running crack is more favorable to deflection after the crack encounters a weak plane under dynamic loading conditions, and the failure strain drops slightly after it deflects, while the crack velocity jumps to a high stage. Besides, the loading rate plays a significant role in crack propagation when passing through the weak interface. The crack length along the weak plane decreases with the increase of loading rate, and the running crack will expand to the matrix after it propagates to a certain distance along the weak plane. The crack velocity along the weak interface remains constant under a high loading rate, whereas both the number and the length of the crack increase after it passes through the weak plane. Moreover, the crack length along the weak plane increases with the decrease of the strength of the weak plane at a given loading rate.