三点弯曲试样动态应力强度因子计算研究

利用Hopkinson压杆对三点弯曲试样进行冲击加载,采集了垂直裂纹面距裂尖2mm和与裂纹面成60°距裂尖5mm处的应变信号。根据裂尖附近测试的应变信号计算试样的动态应力强度因子,并与有限元计算结果进行比较,结果表明由于裂尖有一段疲劳裂纹区,通过裂尖附近应变信号来计算动态应力强度因子时,如果裂尖位置确定不准及粘贴应变片位置不够准确对计算结果将带来很大影响。因此利用应变片法计算动态应力强度因子时,为了获得更准确的计算结果,在实验后应对试件裂纹面进行分析测量,重新确定裂尖位置,必要时需对应变片至裂尖距离进行修正后再计算动态应力强度因子值。

A Computational Study on Dynamic Stress Intensity Factor of Three-point Bending Specimen

Three-point bending specimen was impacted by Hopkinson pressure bar equipment,the signals of the specimen strains were collected at two points.One of the points was two millimeter away from crack tip and perpendicular to crack suiface,the orther was five millimeter away from crack tip and at sixty degrees direction along the carck surface.then DSIF(dynamic stress intensity factor) of the specimen was computed by the strain signals near the crack tip.The obtained dynamic stress intensity factor was compared with that by finite element method The results indicates that the position of crack tip and strain gauge is important for computing dynamic stress intensity factor by strain signals because there is crack fatigue area near crack tip.When dynamic stress intensity factor is computed by the strain signals near the crack tip,the crack surface should be analyzed to confirm the crack tip position again to gain reasonable result.If condition is necessary,we should revise the distance between strain gauge and crack tip in computing dynamic stress intensity factor.