爆炸荷载下不对称Y型裂纹扩展规律的试验研究

Study on the regularity of asymmetric Y-shaped cracks propagation under blast loading

采用爆炸加载透射式动焦散测试系统,研究了爆炸荷载下不对称Y型裂纹扩展的动态行为。试验结果表明:爆炸荷载下两相向运动裂纹在相遇前裂纹尖端奇异场相互影响,焦散斑扭曲,裂纹尖端应力场改变,相遇前沿偏离水平方向相向扩展,偏离角度逐渐增大,相遇后偏离角度逐渐减小并朝对方已有裂纹方向扩展;两分支裂纹相交于主裂纹,翼裂纹主要从与入射应力波夹角较小和长度较长的分支裂纹起裂,沿周向最大拉应力垂直方向扩展;入射应力波夹角较小和长度较长的分支裂纹对入射应力波夹角较大和长度较短的分支裂纹扩展及其尖端应力强度因子有抑制作用;分支裂纹尖端动态应力强度因子均值随分支裂纹与应力波夹角增大而减小,分支翼裂纹扩展速度呈现振荡式变化规律。研究结果为实际工程中分析相互贯通裂纹的扩展规律提供了可靠依据。

Using a dynamic caustics blast loading system, we studied dynamic behavior of asymmetric Y-shaped cracks propagation under blasting loading. It was found that before two opposite moving cracks encountering, their tip singular fields affected each other, the shape of caustics spots distorted and stress fields of the crack tip changed. Moreover, two moving cracks propagated along the deviating horizontal direction, and the deviation angle gradually increased. However, after two opposite moving cracks encountering, the deviation angle gradually decreased, and two moving cracks propagated along the direction of the existing crack. It can be seen that two branched cracks intersected at the main crack, and the wing crack easily initiated from the branched crack with a smaller incident angle of stress wave and a longer length, and propagated along the vertical direction of the maximum tensile stress. However, this kind of branched crack may inhibit the propagation and the stress intensity factor of the branched crack with a larger incident angle and a shorter length. The average values of dynamic stress intensity factor of the branched crack decreased with the increase of the incident angle of stress wave. In addition, the propagation velocity of the branched wing crack presented oscillating change law. Therefore, the results provide a reliable basis for the analysis of crack propagation in practical engineering.