孔边裂纹塑性应变疲劳扩展试验研究

 简介了循环J积分ΔJ*path体系，以16MnR钢单边椭圆孔边裂纹试件进行了6种循环应力比的恒幅应变疲劳裂纹扩展试验，采用材料应变疲劳循环加载条件下的应力-应变关系，通过弹塑性有限元素法计算ΔJ*path参量，研究了孔边高应变区裂纹塑性应变疲劳扩展规律。结果表明：ΔJ*path能够作为缺口高应变区裂纹塑性应变疲劳扩展的控制参量，与裂纹扩展速率da/dN之间的指数关系，可通过相同材料的标准试件应力疲劳裂纹扩展由Paris公式与ΔJ*path=ΔK2/E转换得到。

EXPERIMENT RESEARCH OF PLASTIC STRAIN FATIGUE CRACK GROWTH IN THE NOTCH

The concept of cyclic J integral Δ J * path proposed by the authors was briefly illustrated. In order to study the behavior of plastic strain fatigue crack growth (PSFCG) in the high strain zone of the notch , the constant amplitude PSFCG tests with six R ratios were performed on the single edge elliptical notch crack plates(SENCP) fabricated from 16MnR steel, while Δ J * path was calculated employing the material stress strain relation under the PSFCG from the elastic plastic finite element method. According to these experiment results, Δ J * path can be employed as a parameter predicting the PSFCG rate in the notch, and the d a /d N vs. Δ J * path relation for PSFCG is consistent with the Paris equation of the same material obtained by elastic stress fatigue crack growth test carried on the standard specimen, except that the Δ J * path was used in terms of the Δ K through Δ J * path =Δ K 2/E .