Abstract Studies show that sharp and blunt notches can be classified in the same research system. In the present study, the virtual-real caustics experimental method is applied to investigate the influence of the notch curvature on the impact fracture behavior of the three-point bending beam with a notch. Moreover, the loading characteristics of the drop hammer impact and the dynamic process of specimen fracture are analyzed in detail. Obtained results demonstrate that the drop hammer impact under the experimental conditions is a process of multiple loadings. It is found that as the notch curvature decreases, the moment of the crack initiation gradually postpones and the whole crack propagation time increases at first and then decreases. The initiation behavior of the notch under the impact loading of the drop hammer is an energy-controlled process rather than a loading force-controlled process. Furthermore, it is found that as the notch curvature decreases, both the peak value of the dynamic stress intensity factor and the corresponding peak value of the propagation velocity of the crack tip increase significantly after the initiation. Obtained results from the extended finite element method (XFEM) show that as the crack initiating gradually decreases, the stress σy at the notch end decreases with the decrease of the notch curvature. Meanwhile, the peak position of the stress gradually shifts to both sides of the notch end as the curvature decreases.

中文翻译：

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缺口曲率对三点弯曲梁冲击断裂的影响

摘要 研究表明，尖刻和钝刻槽可以归为同一个研究体系。本研究采用虚实焦散实验方法研究缺口曲率对带缺口三点弯曲梁冲击断裂行为的影响。此外，还详细分析了落锤冲击的加载特性和试样断裂的动态过程。得到的结果表明，实验条件下的落锤冲击是一个多重载荷的过程。发现随着缺口曲率的减小，裂纹萌生的时刻逐渐推迟，整个裂纹扩展时间先增加后减小。落锤冲击载荷下缺口的起始行为是一个能量控制过程，而不是一个加载力控制过程。进一步发现，随着缺口曲率的减小，裂纹尖端动应力强度因子的峰值和相应的裂纹尖端传播速度的峰值在起始后均显着增加。扩展有限元法(XFEM)得到的结果表明，随着裂纹萌生的逐渐减小，缺口端部的应力σy随着缺口曲率的减小而减小。同时，随着曲率的减小，应力的峰值位置逐渐向缺口端的两侧移动。动应力强度因子的峰值和相应的裂纹尖端扩展速度峰值在引发后均显着增加。扩展有限元法(XFEM)得到的结果表明，随着裂纹萌生的逐渐减小，缺口端部的应力σy随着缺口曲率的减小而减小。同时，随着曲率的减小，应力的峰值位置逐渐向缺口端的两侧移动。动应力强度因子的峰值和相应的裂纹尖端扩展速度峰值在引发后均显着增加。扩展有限元法(XFEM)得到的结果表明，随着裂纹萌生的逐渐减小，缺口端部的应力σy随着缺口曲率的减小而减小。同时，随着曲率的减小，应力的峰值位置逐渐向缺口端的两侧移动。缺口端的应力σy随着缺口曲率的减小而减小。同时，随着曲率的减小，应力的峰值位置逐渐向缺口端的两侧移动。缺口端的应力σy随着缺口曲率的减小而减小。同时，随着曲率的减小，应力的峰值位置逐渐向缺口端的两侧移动。