【作者】 王利发； 刘建中； 丁传富； 吴学仁； 胡本润；

【Author】 WANG LiFa LIU JianZhong DING ChuanFu WU XueRen HU BenRun(Beijing Institute of Aeronautical Materials, Beijing 100095, China)

【机构】 北京航空材料研究院；

【摘要】 大量研究表明长裂纹和物理小裂纹扩展行为差异的主要原因是由于裂纹闭合程度不同造成的,消除裂纹闭合效应影响后的长裂纹与小裂纹的裂纹扩展行为应趋于一致。文中使用恒Kmax 增Kmin值降低ΔK的试验方法来测试裂纹扩展门槛值。此方法在测出ΔKth时应力比R已经很高,实际上已不存在裂纹闭合效应的影响。通过对比试验结果表明,恒Kmax法测试长裂纹扩展门槛值能有效去除裂纹闭合效应的影响,用测得的门槛值近似表述小裂纹门槛值,能给出偏于保守的结果更多还原

【Abstract】 Numerous investigators have suggested and verified that crack closure is a major factor in causing some of the difference between the growth of small and large cracks. Small and large cracks growth behavior will be similar by removing crack closure effect. Constant K_max/increasing K_min method was used to obtain crack growth threshold data. In the testing, stress ratio near threshold region was high and crack closure effect was removed. Results showed that constant K_max method can remove crack closure effect in crack growth threshold test. The method provided a conservative result in contrast with small fatigue growth threshold test result.更多还原