不同厚度三点弯曲梁的裂纹扩展动态焦散实验

Dynamic Caustics Experiments on Crack Propagation of Three-point Bending Beams with Different Thickness

采用动态焦散线实验方法,对冲击作用下不同厚度的三点弯曲梁进行了研究,分析了厚度对其动态断裂过程的影响。结果表明:不同厚度三点弯曲梁在动态冲击实验中,预制裂纹起裂时间和扩展时间受到试件厚度的影响。厚度越大,起裂越慢,扩展时间越长;试件起裂后,不同厚度下裂尖的扩展速度和动态应力强度因子值随时间的变化曲线均呈现先快速上升后波动下降的趋势;裂尖扩展速度和动态应力强度因子的峰值随着厚度的增大呈现先上升后下降的趋势;厚度影响了反射应力波对裂纹扩展的抑制作用。

Through the dynamic caustics experiment,three-point bending beams with different thicknesses under impact loading were studied,and the influence of thickness on its dynamic fracture process was analyzed.The results show that in the dynamic impact experiment of three-point bending beams with different thicknesses,the initiation time and propagation time of the prefabricated crack are affected by the thickness of the specimen.When the thickness is larger,the crack initiation is slower and the propagation time is longer;After the specimen cracks,the growth rate of the crack tip and the value of the dynamic stress intensity factor with time under different thicknesses show a rapid rise first and then a decline in fluctuations;The peak growth rate of the crack tip and the peak value of dynamic stress intensity factor show a trend of increasing first and then decreasing with the increase of thickness;The thickness affects the inhibitory effect of the reflected stress wave on crack growth.